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The concept of a nano-laboratory inside an SEM involves performing a sequence of tasks in a continuous pattern. Robotic systems with nanoscale motion resolution facilitate in-situ manipulation and characterization of nanomaterials to assemble nanodevices inside SEMs. Precise motion control of micromanipulators is required at both macro and micro-nano scales to effectively execute multiple sequential experimental tasks in nanofabrication. However, managing the entire nanomanipulation setup is challenging due to the constricted workspace inside an SEM and the lack of proper process feedback information at that scale. This study explores the application of path planning algorithms to generate a collision-free motion path for the micromanipulators operating within the confined space of an SEM. A MATLAB-based computational tool is first developed using PRM and Dijkstra's path planning algorithms. Considering environmental constraints, the program generates an optimal motion path for the micromanipulators, facilitating automatic configuration changes within the SEM chamber. It ensures a seamless workflow and facilitates the smooth integration of additional experimental tools within the existing setup. Manipulation strategies using the nanorobotic setup are established based on the application of the developed path planning module. A pick-and-place 3D nanomanipulation technique of CNTs using cooperative control of dual micromanipulators has been demonstrated for nanodevice construction. Additionally, the electrical response of individually manipulated CNTs is recorded using a two-probe measurement technique. [ABSTRACT FROM AUTHOR]

Ensuring driving stability in wheeled mobile robots (WMRs) within dynamic environments is crucial for reliable navigation. This study presents the design and testing of a double-wishbone suspension (DWS), which is specifically tailored for a highly maneuverable six-WMR configuration, to address stability challenges in unstructured terrains. During the suspension design phase, critical factors such as the link length, position of shock absorber, spring and damping coefficients, and roll center location were optimized using the non-dominated sorting genetic algorithm (NSGA). The proposed DWS module ensures robust and stable driving performance for medium-sized WMRs. It effectively reduces rollovers and external shocks on uneven terrains while maintaining consistent traction across all wheels. Unlike current applications of the DWS in robotics, all the optimized parameters of the DWS with the NSGA algorithm are tailored for high-speed travel and are proficient at absorbing impacts that are encountered during outdoor driving. For practical implementation, a fabricated platform with optimal design parameters was subjected to field tests to evaluate its driving performance, both in prolonged driving on a circular route and in outdoor settings, with bumpy obstacles. The study presents a comprehensive stability analysis of the DWS and the proposed mobile robot, with a specific emphasis on rollover scenarios. The experimental results unequivocally demonstrated that the six-WMR equipped with the proposed DWS outperforms its counterpart without the DWS. This study highlights the reliability of the proposed DWS in the six-WMR configuration for efficient outdoor operations in unstructured terrains. [ABSTRACT FROM AUTHOR]

This paper presents a mobile supernumerary robotic approach to physical assistance in human–robot conjoined actions. The study starts with the description of the SUPER-MAN concept. The idea is to develop and utilize mobile collaborative systems that can follow human loco-manipulation commands to perform industrial tasks through three main components: (i) an admittance-type interface, (ii) a human–robot interaction controller and (iii) a supernumerary robotic body. Next, we present two possible implementations within the framework — from theoretical and hardware perspectives. The first system is called MOCA-MAN, and is composed of a redundant torque-controlled robotic arm and an omni-directional mobile platform. The second one is called Kairos-MAN, formed by a high-payload 6-DoF velocity-controlled robotic arm and an omni-directional mobile platform. The systems share the same admittance interface, through which user wrenches are translated to loco-manipulation commands, generated by whole-body controllers of each system. Besides, a thorough user-study with multiple and cross-gender subjects is presented to reveal the quantitative performance of the two systems in effort demanding and dexterous tasks. Moreover, we provide qualitative results from the NASA-TLX questionnaire to demonstrate the SUPER-MAN approach's potential and its acceptability from the users' viewpoint. [Display omitted] • Extension of the MOCA-MAN concept into the unified SUPER-MAN framework. • Evaluation of the framework through multiple experiments using two specific robotic platforms: MOCA and Kairos. • A usability study with 12 human subjects performing industrial-like tasks with and without robotic assistance. • Demonstration of the SUPER-MAN's effectiveness for both interaction and load-handling tasks based on both objective and subjective analysis. • SUPER-MAN allows for robotic assistance in conjoined loco-manipulation tasks without constraining user mobility. [ABSTRACT FROM AUTHOR]

This paper presents a novel TSA mechanism with an adjustable offset between strings, which enables a variable transmission system. TSA is designed to be used in a variety of applications, including exoskeletons, and robotics. The fixed contraction range of TSAs limits their ability to provide comprehensive support. The proposed mechanism overcomes this limitation by adjusting the offset between strings. The mechanism consists of six parts with two motors. Each motor in the mechanism operates to adjust offset with only one motor and operates simultaneously to twist the strings. This enables the contraction range of TSA to be varied a wide range. Furthermore, an analytical model is also introduced for controlling the contraction range of TSA. In the experiment, the proposed mechanism shows the contraction range of TSA to be increased by up to 20%. Additionally, it showed that it is possible to vary the maximum force of TSA by up to 47%. Moreover, the analytical model has a low error. These findings suggest the promising potential for the developed TSA mechanism in a variety of applications. • Propose of a novel Twisted String Actuator (TSA) with continuous variable transmission through variation of offset between strings. • The proposed mechanism used epicyclic gear structure and expanding mechanism. • A new analytical TSA model for the proposed mechanism. • Evaluate analytical models via Normalized Root Mean Square Error (NRMSE) and Nominal Range Sensitivity Analysis (NRSA). [ABSTRACT FROM AUTHOR]

This paper introduces the concept of underactuated vacuum gripper (UVG), which combines two strategies, that is, underactuation and vacuum grasping. The idea is to achieve shape adaptation while improving grip stability by augmenting an underactuated gripper with suction cups. A general theory to predict the contact forces for a UVG is developed and used for comparison reasons with a standard underactuated counterpart. Multibody simulations have been performed to verify the analytical model and quantitatively evaluate the performance of the system in terms of three metrics, namely, grasp stability, contact force distribution, and pull-out force. Finally, the experimental results obtained from a physical prototype of an underactuated linkage-driven gripper equipped with suction cups are illustrated, attesting to the feasibility and potential gain of the system. [ABSTRACT FROM AUTHOR]

Virtual holonomic constraints (VHCs) are extensively used in robotic applications such as bipedal walking. Although it is well-known that VHCs result in periodic motion of underactuated systems, achieving the same is challenging in physical systems due to parameter uncertainty. VHCs are typically imposed using feedback linearization and simulations show and experiments confirm that the internal dynamics can become unstable in the presence of parameter uncertainty. To address the challenging problem of generating stable periodic motion, we propose an extended high-gain observer (EHGO) based controller to enforce the VHCs. The proposed solution successfully recovers marginal stability of the internal dynamics. To stabilize a desired periodic orbit, we use the impulse controlled Poincaré map (ICPM) approach, where impulsive inputs are intermittently applied on a Poincaré section. Experimental results demonstrate that the model-based VHC controller and discrete ICPM controller together fail to stabilize the desired periodic motion but the EHGO-based VHC controller and ICPM controller successfully achieve stable periodic motion. [ABSTRACT FROM AUTHOR]

In recent years, there has been significant progress in developing specialized 3D printing techniques that cater to various demanding applications. However, the current state of this technology is challenged when it comes to complex in situ printing scenarios, which require a controlled printing platform. The lack of a stable printing platform is a fundamental limitation of its use in in situ applications. To address this issue, we present a novel platform-independent 3D fabrication process that enables printing on platforms with non-cooperative movement. The process overcomes the challenge of high-speed tracking, motion compensation, and real-time printing by developing a closed-loop visual feedback-controlled robotic printing process. The proposed process incorporates a marker-based visual detection and tracking controller setup, which is discussed in detail. The algorithm consists of two loops running asynchronously: a high-speed inner control loop and an outer measurement loop. This setup enables precise and accurate tracking of the printing platform, compensating for any disturbances during the printing process. Our experimental results demonstrate the successful printing of simple linear geometries, even with low-disturbing platform velocities. Moreover, the tracking controllers' ability to handle measurement occlusion is validated, showing the proposed process's robustness and effectiveness. Our work provides a significant step towards enabling 3D printing in complex in situ printing scenarios. [ABSTRACT FROM AUTHOR]

Robotic machining systems have been widely implemented in the assembly sites of large components of aircraft, such as wings, aircraft engine rooms, and wing boxes. Milling is the first step in aircraft assembly. It is considered one of the most significant processes because the quality of the subsequent drilling, broaching, and riveting steps depend strongly on the milling accuracy. However, the chatter phenomenon may occur during the milling process because of the low rigidity of the components of the robotic milling system (i.e., robots, shape-preserving holders, and rod parts). This may result in milling failure or even fracture of the robotic milling system. This paper presents a feasible spindle speed interval identification method for large aeronautical component milling systems to eliminate the chatter phenomenon. It is based on the chatter stability model and the analysis results of natural frequency and harmonic response. Firstly, the natural frequencies and harmonics of the main components of the robot milling system are analyzed, and the spindle speed that the milling system needs to avoid is obtained. Then, a flutter stability model considering the instantaneous cutting thickness is established, from which the critical cutting depth corresponding to the spindle speed can be obtained. Finally, the spindle speed interval of the robotic milling system could be optimized based on the results obtained from the chatter stability model and the analysis result of the natural frequency and harmonic response of the milling system. The effectiveness of the proposed spindle speed interval identification method is validated through time-domain simulation and experimental results of the large aeronautical component milling system. [ABSTRACT FROM AUTHOR]

In Networked Control System (NCS), the absence of physical communication links in the loop leads to relevant issues, such as measurement delays and asynchronous execution of the control commands. In general, these issues may significantly compromise the performance of the NCS, possibly causing unstable behaviours. This paper presents an original approach to the design of a complete digital control unit for a system characterized by a varying sampling time and asynchronous command execution. The approach is based on the Embedded Model Control (EMC) methodology, whose key feature is the estimation of the disturbances, errors and nonlinearities affecting the plant to control and their online cancellation. In this way, measurement delays and execution asynchronicity are treated as errors and rejected up to a given frequency by the EMC unit. The effectiveness of the proposed approach is demonstrated in a real-world case-study, where the NCS consists of a differential-drive mobile robot (the plant) and a control unit, and the two subsystems communicate through the web without physical connection links. After a preliminary verification using a high-fidelity numerical simulator, the designed controller is validated in several experimental tests, carried out on a real-time embedded system incorporated in the robotic platform. [ABSTRACT FROM AUTHOR]

In this paper, a new type of robotic finger is introduced that uses a twisted string actuator (TSA) and modular passive return rotational (PPR) joints. The design is intended to be simple, compact, lightweight, and energy-efficient while producing high grasping force with a relatively small motor. The PPR joints are based on the beam-buckling principle and are designed to match the non-linear TSA force profile, resulting in high grasping force throughout the finger's full flexion motion and passive finger extension. To evaluate the performance of the robotic finger, we fabricated a prototype and conducted experiments to assess its object grasping cycle, passive finger extension, grasping force, stable grasping condition, shape adaptability, and energy consumption. The finger weighs 170 grams and achieved a high force throughout the flexion motion, producing a maximum grasping force of 43.3 N at full flexion using a stall torque of 32 mNm. The modularity of the PPR joint allows for scalability and adaptability to handle different objects. We also demonstrated the finger's potential as a wearable sixth robotic finger (SRF), evaluating its object grasping competency, shape adaptability, and wearability. The finger was able to grasp various objects with a maximum payload of 1.0 kg and a hanging payload of up to 5 kg. Overall, the proposed robotic finger has the potential to be used as an SRF to compensate for arm disorders' grasping capability. [ABSTRACT FROM AUTHOR]

Robotics in construction is an emerging field that aims to automate various construction activities. Among the various innovative technologies for the construction sector, in this paper we focus on robotic solutions for the bricklaying task. In particular, we describe and explain in detail the implementation of a control framework for a recently introduced multi-robot bricklaying concept, specifically designed for laying activities with large and heavy blocks. The multi-robot system subject of this work is based on the collaboration of a robotic manipulator and a crane. The control architecture proposed to perform the construction task belongs to the Explicit Reference Governor (ERG) formalism. The ERG is a constrained control structure that enforces the constraints of the system and ensures that the robotic system operates correctly and safely. The efficiency of the proposed solution is confirmed by experimental validation on a custom-made crane and a KUKA LBR IIWA14R820 robotic arm. [Display omitted] • Implementation of a constrained control for a multi-robot bricklayer system for construction activities. • The proposed control scheme does not rely on any online optimization problems. • Detailed explanation of the full-scale prototype and implementation of the control algorithm. • Experimental validation on a custom-made overhead crane and a robotic arm. [ABSTRACT FROM AUTHOR]

Patients with hemiplegia are usually restricted to performing general bilateral activities of daily life (gbADLs). Bilateral training has been verified to contribute to the rehabilitation of physical functions. Although robotic systems are gradually being employed in the field of rehabilitation, few studies have performed simulations with regards to gbADLs for training. Therefore, a novel end-effector bilateral rehabilitation robotic system (EBReRS) for the upper limb is developed in this article for the task rendering of gbADLs, in which the gbADL-corresponding workspace is obtained via modularly designed bilateral parallelogram mechanisms. In addition, the interaction rendering of multiple bimanual modes (uncoupled, trans-soft-coupled, trans-semi-coupled, and rotation-coupled) is achieved by implementing the admittance model, the inner force field between robotic end-effectors, and the outer force field distributed around. Experiments of the proposed four rehabilitation training modes were carried out on the healthy subject, with the results showing a feasible method of the EBReRS in the simulation of multiple bimanual coordinated rehabilitation training tasks. In the future, the constructed EBReRS is expected to be exploited for home rehabilitation as a coordinated training device. • A novel robotic system EBReRS with stretchable structure and modular design is built. • The active rehabilitation training with controllable difficulty is achieved. • Multifold bilateral training modes are achieved under inner and outer force fields. • Patient-centered adjustment of training intensity for the affected side is achieved. • Practical validation of the built prototype EBReRS is conducted. [ABSTRACT FROM AUTHOR]

Nasotracheal intubation (NTI) is an advanced airway management technique, in which a flexible endoscope is inserted into the patient's trachea from the nasal cavity. Due to the hand-eye coordination requirement, the operation of the flexible endoscope in a narrow workspace is a challenge, even for experienced surgeons. In this study, a novel robotic nasotracheal intubation system (RNIS) is proposed to automatically steer the endoscope along the upper respiratory tract. The configuration of the RNIS meets the motion requirement of the flexible endoscope. A lumen center detection method with Kalman filter is designed to determine the position of the lumen center in endoscopic images. Then, a fuzzy logic-based control strategy is developed to enable the RNIS to achieve automatic endoscope steering. Control parameters are updated online using a fuzzy logic algorithm to handle uncertainty. Movements in three degrees of freedom of the endoscope are controlled by the RNIS using visual feedback. Finally, experiments based on a motion simulator and a training mannequin are conducted. Results demonstrate that the proposed RNIS can successfully steer the flexible endoscope along the upper respiratory tract. Automated robotic endoscopes outperform manual operations in terms of operational accuracy. [ABSTRACT FROM AUTHOR]

A robotic brace based on 3-R P R parallel mechanism has been proposed to assist trunk moving and train the trunk core muscle groups in our early work. The mechanical performance of the robotic brace affects the wearer's activities and comfort in clinical application, which is determined by the structural parameters of the parallel mechanism. We tried to seek the optimal structural parameters using an improved genetic algorithm, where the workspace and singularity are regarded as optimization objectives. Two prototypes with generic and optimal structural parameters were built to analyze performance improvement. Force control experiments were conducted under three postures including left lateral bending, natural, and right lateral bending. The results show that the prototype with optimal structural parameters has lower energy consumption, closer magnitude of the driving current, and a lower driving current for each linear actuator. Furthermore, an improved robotic brace was designed based on the optimal structural parameters and the feasibility was validated through the wearing experiment. [ABSTRACT FROM AUTHOR]

Because of the complexity of interaction between the robot and the environment, robotic peg-in-hole assembly has always been a hot research topic in the fields of robotics and assembly automation. Dynamic movement primitives (DMPs) are an effective learning from demonstration (LfD) method, making the robot easily obtain the motion trajectories and even quickly master the assembly skills. However, the traditional DMPs have defects in reversibility, which makes the robot unable to deal with the situation of assembly jamming. In addition, the direct execution of a single demonstration trajectory may bring about excessive contact force, which will aggravate the wear of the robot or assembly parts. Therefore, in this article, based on reversible DMPs and trajectory optimization, a new robotic assembly approach is proposed. Specifically, the traditional DMPs are extended to support the reversible execution first. Then, the trajectory optimization strategy including the admittance control, exception technique and multiple trajectory iteration is designed, so as to reduce the contact force and torque during the assembly process and improve the assembly compliance. Ultimately, three robotic peg-in-hole assembly experiments are carried out on the UR5 robot platform, and the results confirm the feasibility and effectiveness of the proposed approach. [ABSTRACT FROM AUTHOR]

• MRI-compatible robot for pituitary tumor resection via nasal access. • 6-DOF robot with a six-times stiffness changing capability. • A stiffness dependent kinematic model suited for the environment and procedure. • A solution for MRI-guided endonasal transsphenoidal surgery. Neurosurgical interventions are often complicated and require procedure-specific solutions for a better outcome. A pituitary tumor is one of the common brain tumors resected by trans-sphenoidal surgery. Magnetic resonance imaging (MRI) provides better vision when compared to other imaging modalities. Simultaneous resection and imaging of pituitary tumors under MRI can improve the surgical outcome. Herein, we propose the first MRI-compatible robotic system for pituitary tumor removal via trans-sphenoidal/endonasal access. The presented system follows the current gold standard procedure of pituitary tumor resection and integrates it with a commercial MR scanner to provide a widely applicable system. The robotic system is the procedure-, anatomy-, and geometry-specific with 6-degree-of-freedom actuated by a bed-type actuation platform in the MRI room. A K-means clustering algorithm detects the tumor and develops and updates the brain model periodically during MR-guided interventions. The robot has procedure-specific stiffness changing capability with a unique stiffness-dependent kinematic model. The workspace subtended by the robotic system in all stiffness cases satisfies the workspace required for surgical procedures. The accuracy and repeatability of the robot are also in a desirable range. The procedure and patient-specific robot design are evaluated by in-vivo experiments in the live porcine under MRI. This work is a step toward a dual-arm surgical system for pituitary tumor removal under MRI guidance and experimental results validate the proposed solution and supplement further development to achieve a clinically applicable system. [ABSTRACT FROM AUTHOR]

Structure-integrated force measurement in hexapod structures or kinematics offers great potential for spatial process force control in six degrees of freedom. Although force control has been studied for many years, research questions remain unanswered, especially when regarding parallel kinematic machine tools with numerical control and integrated sensors. This contribution summarizes the technology of structure-integrated force sensing in hexapod machine tools and develops two approaches to use the measured signals for direct hybrid/parallel force control. For different use-cases, such as teach-in or synchronous force/position control with variable task frame, different approaches of set-point specification and injection of manipulated values are studied from a practical point of view. As a result of the work, the feasibility of the force control with structure-integrated sensors on a commercial CNC can be confirmed through appropriate experiments. Furthermore, the realized G-Code integration represents a practical solution for programming force-controlled machine tools in an easy and concise way from the NC programme. [ABSTRACT FROM AUTHOR]

In this paper, a novel adaptive robust controller is presented for high-accuracy tracking control of servomotor rigid robotic systems based on a modified nonsingular terminal sliding scheme incorporated with an adaptive time-delay estimation (TDE) technique. To effectively estimate unknown systematic dynamics, the model-free estimation is designed with a basic TDE and a new self-learning mechanism, which is able to automatically find the proper nominal input gains for the best TDE error. The control objective is then realized by a control process which consists of a model-compensation phase, highly robust control term and reaching-guarantee law. The compensator uses the TDE terms obtained to eliminate the dynamic effect. For providing the flexible robustness to the control system, the robust gain is actively adjusted based on information of the estimation system. The reaching-control rule employs nonlinear folding functions to promptly drive a synthesized sliding manifold back to zero. Finite-time stabilities of both the adaptive TDE and the closed loop system are proven using Lyapunov-based constraints extended from new folding-convergence analyses. The effectiveness and feasibility of the closed loop system are confirmed throughout intensive real-time experiments under various testing conditions. [ABSTRACT FROM AUTHOR]

Abstract It is important for the mechatronic design of robotic systems to rely on accurate models. To that end, system identification methods are a convenient tool to obtain the values of the unknown dynamic parameters which play a key role. In this paper, it is investigated the application of the principle of energy equivalence to easily obtain a suitable model for identification of the inertial parameters and friction of planar mechanisms. The methodology here proposed is then applied to the prototype RePlaLink , a 5R haptic mechanism. Experimental data was obtained to carry out the identification, and the results were then validated by using a different trajectory than the one used for the identification of the unknown parameters. It was found that the identified model developed for the mechanism using the herein described methodology, was able to predict the dynamic behavior of the mechanism. [ABSTRACT FROM AUTHOR]

Equilibrium points exploration is crucial for successful nonprehensile manipulation of multi-link objects by cooperative arms which is promising for a class of future robotics applications. This paper presents the equilibrium area numerical analysis, with experimental verification, for nonprehensile manipulation of a three-rigid link object by two cooperative arms in a plane. Inspired by an assistive nursing robot project for manipulating a patient, the interaction between the object and the arms is performed in a way that one of the arms contacts two links of the object while the other arm contacts the object third link. It would be a useful step for the most complicated process of a patient manipulation. The purpose of the equilibrium area analysis is to obtain the equilibrium contact area, associated with different interaction forces, for statically holding the object at all its possible configurations. The dynamic model of the system is presented from which the static equations are deduced. Static equations are analyzed in the presence of friction forces and motion constraints leading to equilibrium contact lengths for a range of angles leading to equilibrium area for every object's configuration. Numerical simulation results for the equilibrium area analysis are presented. Experimental results, for validating the presented numerical results, are also introduced. [ABSTRACT FROM AUTHOR]

In this paper, the tracking control problem of a biomimetic exoskeleton powered by a pair of pneumatic artificial muscles is considered. The antagonistic configuration of the pair of pneumatic muscles, which is biologically inspired, enables safe and reliable actuation in applications of orthopaedic rehabilitation. However, during the inflation-deflation process, the pneumatic muscles introduce nonlinearity and hysteresis which deteriorate the control performance. A model of the antagonistic artificial muscles is adopted to develop a computed-torque control for feedforward compensation of the nonlinear dynamics of the actuated joint. A PID control action is used in combination with the feedforward compensation to achieve fast and accurate tracking control performance. The model, which possesses a reduced set of parameters as functions of the inflation/deflation phase, enables efficient nonlinear compensation. The experimental tests on the biomechatronic device, compared with other state-of-the-art approaches for controlling pneumatic artificial muscles, show better tracking performance in terms of convergence rate and robustness, justifying the convenience of using the proposed control methodology in the design of tracking controllers for exoskeletal biomechatronic devices. [ABSTRACT FROM AUTHOR]

This paper presents the design of an optical torque sensor that can structurally decouple the effect of axial-interference for use in various robotics applications. Torque sensors are widely used in the joints of intelligent service or wearable robots to realize safe human-robot interaction. Whole robot body sensing using torque sensors is essential for safe interaction. However, most torque sensors are bulky, heavy and expensive. Therefore, many optical-based torque sensors have been proposed to deal with such problems, but the issue of axial-interference still remains. We resolved the axial-interference problem via the geometrical structure of the sensor body and differential signaling using two reflective optical sensors. The moment interference error was successfully decreased from 4.49% (with one optical sensor) to 0.11% (with two optical sensors) using the proposed sensor structure while maintaining a compact size, lightweight, and low cost. Static tests and dynamic tests were carried out and analyzed for accuracy error, hysteresis, and repeatability. We then compared the performance of an impedance controller that is widely used in service and wearable robots using the proposed sensor and a commercial torque sensor with respect to various control loop rates. The control performance of the proposed sensor was comparable to that of commercial sensors. [ABSTRACT FROM AUTHOR]

The Industry 4.0 paradigm emphasizes the crucial benefits that collaborative robots, i.e., robots able to work alongside and together with humans, could bring to the whole production process. In this context, a yet unreached enabling technology is the design of robots able to deal at all levels with humans’ intrinsic variability, which is not only a necessary element to a comfortable working experience for humans, but also a precious capability for efficiently dealing with unexpected events. In this paper, a sensing, representation, planning and control architecture for flexible human–robot cooperation, referred to as FlexHRC, is proposed. FlexHRC relies on wearable sensors for human action recognition, AND/OR graphs for the representation of and the reasoning upon human–robot cooperation models online, and a Task Priority framework to decouple action planning from robot motion planning and control. [ABSTRACT FROM AUTHOR]

In this paper, we present a design of mastication robot for texture analysis of foods in similar environment of human masticatory process respect to the following two things: First, subminiature load cells were installed at each artificial tooth of the upper jaw in order to directly measure interaction forces between the each tooth and foods. Collecting the sensor signals on each tooth, we can see which of teeth dominantly interacts with foods and analyze different patterns of the interaction forces among the incisor, cuspid and molar teeth. Second, we developed linear actuators for human masticatory muscles, which size, acting force, and coordination of attachment match with human counterpart. By appropriately coordinating the linear actuators, the resultant jaw motion can replicate the human chewing motion; thus, it generates similar patterns of the interaction forces between human teeth and foods. Two experiments for realization of the chewing motion and analysis of interaction forces between each tooth and food samples were conducted to evaluate the effectiveness of the developed mastication robots. [ABSTRACT FROM AUTHOR]

As the shoe durability is affected directly by the dynamic force/pressure between the shoe and its working environments (i.e., the contact ground and the human foot), a footwear testing system should replicate correctly this interaction force profile during gait cycles. Thus, in developing a robotic foot for footwear testing, it is important to power multiple foot joints and to control their output torque to produce correct dynamic effects on footwear. The cable conduit mechanism (CCM) offers great advantages for designing this robotic foot. It not only eliminates the cumbersome actuators and significant inertial effects from the fast-moving robotic foot but also allows a large amount of energy/force to be transmitted/propagated to the compact robotic foot. However, CCMs cause nonlinearities and hysteresis effects to the system performance. Recent studies on CCMs and hysteresis systems mostly addressed the position control. This paper introduces a new approach for modelling the torque transmission and controlling the output torque of a pair of CCMs, which are used to actuate the robotic foot for footwear testing. The proximal torque is used as the input signal for the Bouc–Wen hysteresis model to portray the torque transmission profile while a new robust adaptive control scheme is developed to online estimate and compensate for the nonlinearities and hysteresis effects. Both theoretical proof of stability and experimental validation of the new torque controller have been carried out and reported in this paper. Control experiments of other closed-loop control algorithms have been also conducted to compare their performance with the new controller effectiveness. Qualitative and quantitative results show that the new control approach significantly enhances the torque tracking performance for the system preceded by CCMs. [ABSTRACT FROM AUTHOR]

This paper addresses the dynamic identification and model feed-forward control implementation of a Novint Falcon haptic device. Firstly, inverse and forward kinematic problem of the device is obtained. Subsequently, equations describing the robot’s dynamics is derived using Newton–Euler approach which includes friction of active joints. The unknown dynamic parameters including mass and moment of inertia of constituting parts along with dry and viscous friction coefficients is identified practically by a white-box identification approach using LS technique. Furthermore, the torque digital scale coefficient which Novint Falcon’s firmware uses is identified. To the end of obtaining some of regressors a novel numerical-based differentiation approach is presented. Having an experimentally verified dynamic model in hand, the model is used in a model feed-forward impedance controller in order to omit the effect of natural dynamics of the robot, including active joints frictions from displayed impedance. Experimental tests reveal that the implemented force sensor-less controller performs 26% more accurate in terms of output force comparing device’s official controller. [ABSTRACT FROM AUTHOR]

Recently, the wearable robotic field has become extremely prolific in terms of active devices for human body assistance. Nevertheless, unfortunately, owing to strictly motor and sensor requirements in terms of mechanism, weight, size and dexterous manipulation capabilities, portable hand exoskeletons for rehabilitation and assistance have not been developed as much as the exoskeletons for lower and upper limbs; in fact, only a few of them present an outcome of their use in the clinical practice as positive as expected. This research work aims at designing an aid for the hand function based on exoskeleton technologies for patients who have lost or injured their hand skills. In particular, this paper presents a novel Series Elastic Transmission (SET) used as power transmission on a Hand Exoskeleton System (HES) based on a Series Elastic Actuator (SEA). The elastic element of the transmission has been designed through the innovative topology optimization approach which has led to manufacture a component whose mechanical features strictly replicate the desired ones. The authors have validated the proposed approach by testing a real elastic component. Suitable mechanical tests, whose results are reported in the paper, were executed in order to evaluate the goodness of the design procedure. [ABSTRACT FROM AUTHOR]

The detection of small surface abnormalities on large complex free-form surfaces represents a significant challenge. Often surfaces abnormalities are less than a millimeter square in area but, must be located on surfaces of multiple meters square. To achieve consistent, cost effective and fast inspection, robotic or automated inspection systems are highly desirable. The challenge with automated inspection systems is to create a robust and accurate system that is not adversely affected by environmental variation. Robot-mounted laser line scanner systems can be used to acquire surface measurements, in the form of a point cloud 1 1 PC: point cloud, PCA: principal component analysis, CAD: computer-aided design, ROC: receiving operating characteristic, TP: true positives, FP: false positive, FN: false negative, TPR: true positive rate, TNR: true negative rate, SVM: support vector machine, CV: cross validation. (PC), from large complex geometries. This paper addresses the challenge of how surface abnormalities can be detected based on PC data by considering two different analysis strategies. First, an unsupervised thresholding strategy is considered, and through an experimental study the factors that affect abnormality detection performance are considered. Second, a robust supervised abnormality detection strategy is proposed. The performance of the proposed robust detection algorithm is evaluated experimentally using a realistic test scenario including a complex surface geometry, inconsistent PC quality and variable PC noise. Test results of the unsupervised analysis strategy shows that besides the abnormality size, the laser projection angle and laser lines spacing play an important role on the performance of the unsupervised detection strategy. In addition, a compromise should be made between the threshold value and the sensitivity and specificity of the results. [ABSTRACT FROM AUTHOR]

In this work, a revolute joint-based asymmetric Schönflies motion (SM) haptic device with 4-Degree-of-Freedom (DOF) force feedback capability is developed. The SM haptic device is composed of a redundantly actuated parallel sub-module which has translational 3-DOF output motion, a pantograph limb which takes the role of providing 1-DOF rotational output motion, and a revolute joint allowing the relative motion between them. All five DC motors without gearhead are placed on the ground by employing proper parallel transmission linkages for power transmission. The large singularity-free workspace and the improved kinematic characteristics are secured by redundantly actuating the 3-DOF sub-module. Thus, the SM haptic device has excellent features such as the unlimited 1-DOF rotational output motion, minimal friction, minimal inertia, and large dexterous workspace. Mobility analysis, kinematic modeling, singularity analysis, optimal design, and linear inertia modeling of the SM haptic device are conducted. Then a prototype with two operational modes such as gravity compensation and linear inertia compensation modes is implemented. Through friction measurements, motion tests for gravity and/or linear inertia compensation modes, and virtual wall experiments, it is confirmed that the prototype possesses minimal friction as well as good gravity and linear inertia compensation performances sufficient for the high-quality haptic device applications such as medical training, robot-assisted surgery, etc. [ABSTRACT FROM AUTHOR]

The attempt to use industrial robots for technological and interaction tasks, i.e., robotic machining and robotic assembling, implies on the one hand the knowledge of the interaction force, on the other hand the reduction of physical sensors. The aim of this work is the development of a virtual force sensor to estimate the interaction force between a conventional industrial robot and the environment. The goal is achieved by exploiting a task oriented dynamics model calibration combined with of a thermal friction model of the robot. The dynamics model is calibrated by means of exciting trajectories made by suitable paths selected by a genetic-based two-stage optimization. The virtual sensor is proven by means of a polishing application. The proposed approach is successfully compared with state-of-the-art approaches. Finally, the use of the virtual force sensor in a closed-loop architecture highlights the effectiveness of the method in real applications. [ABSTRACT FROM AUTHOR]

This paper presents the development and experimental validation of a low weight and inertia, human-size and highly dexterous dual arm system designed for aerial manipulation with multirotor platform. The arms, weighting 1.8 kg in total and with a maximum lift load per arm around 0.75 kg, provide five degrees of freedom (DOF) for end-effector positioning and wrist orientation. A customized aluminum frame structure supports the servo actuators, placing most part of the mass close to the shoulder structure in order to reduce the inertia. A double flange bearing mechanism in side-by-side configuration isolates the servos from impacts and radial/axial overloads, increasing robustness. This is important to prevent that the arms are damaged during physical interactions with the environment, as they should support the kinetic energy of the whole platform. The motivation in the development of a dual arm aerial manipulator is extending the range of applications and tasks that can be performed with respect to the single arm case, like grasping large objects or assembling. The paper covers the kinematic and dynamic modeling of the aerial robot, proposing a control scheme that deals with the technological limitations of the smart servo actuators. The performance of the arms and the interactions with the aerial platform are evaluated in test bench experiments. The proposed dual arm design is validated through outdoor flight tests with two commercial hexarotor platforms equipped with standard industrial autopilots. [ABSTRACT FROM AUTHOR]

The posture changing ability of multi-legged walking robots is significant for walking in rough terrains. Six-legged walking robots are nonlinear and redundant systems with uncertainties and disturbances. The rabidity, accuracy, and robustness of posture control are important for enhancing the posture changing ability. In this study, a new nonsingular fast terminal sliding mode (NFTSM) is proposed for the posture control of six-legged walking robots. The NFTSM controller is designed with a nonsingular terminal sliding manifold and a fast terminal sliding-type reaching law based on the posture control model of six-legged walking robots. The stability, rapidity, and robustness of the controller are analyzed. Simulation and experiment results show that fast, accurate, and robust performance is obtained for the posture control of six-legged walking robots using the NFTSM controller. [ABSTRACT FROM AUTHOR]

Touch sensing can help robots understand their surrounding environment, and in particular the objects they interact with. To this end, roboticists have, in the last few decades, developed several tactile sensing solutions, extensively reported in the literature. Research into interpreting the conveyed tactile information has also started to attract increasing attention in recent years. However, a comprehensive study on this topic is yet to be reported. In an effort to collect and summarize the major scientific achievements in the area, this survey extensively reviews current trends in robot tactile perception of object properties. Available tactile sensing technologies are briefly presented before an extensive review on tactile recognition of object properties. The object properties that are targeted by this review are shape, surface material and object pose. The role of touch sensing in combination with other sensing sources is also discussed. In this review, open issues are identified and future directions for applying tactile sensing in different tasks are suggested. [ABSTRACT FROM AUTHOR]

In the study presented in this paper , the problem of the design and implementation of a two-axis sun tracking system was addressed by applying a set of two robotic systems, one for the automatic orientation of the photovoltaic modules and the second for providing the reference trajectory (robotic sensor). The design methodology was based on mechatronic concepts, in particular the VDI 2206 standard, according to which the system is divided into interconnected modules to be designed, validated, and integrated. This approach provides an efficient energy collection system in terms of the mechanism, instrumentation system, energy supply, and automatic trajectory tracking control. Experimental results illustrate the behavior of the proposed system, which achieves a better performance than fixed systems, as well as one-axis tracking mechanisms. [ABSTRACT FROM AUTHOR]

Monitoring water resources and their quality is an activity that is gaining more importance through the years. Efficient and intelligent monitoring systems must be developed by taking advantage of cutting edge technologies like robotic agents. The utilization of autonomous surface vehicles equipped with water quality sensors is a promising approach to continuously measure physico-chemical parameters related to water quality. However, most of current related works do not acknowledge for the increasing availability and affordability of these systems. Therefore, the current approaches do not generalize well to account for multiple objectives and the involvement of multiple agents. The present work provides one of the first approaches considering the usage of multiple agents equipped with multiple water quality sensors so that online modeling of water bodies is done. Furthermore, the measurements are done considering a Voronoi Region Partitioning system using an underlying Bayesian Optimization with multiple objectives. Results show that the system can robustly obtain very accurate surrogate models despite the limited available information and energy autonomy constraint of the vehicles. When compared with coverage and patrolling-based approaches, the proposed system outperforms these approaches on average by 23.6% and 43.5%, respectively, regarding the error of modeling. The performance of this approach is also enhanced by its robustness and scalability when compared to offline monitoring missions. [Display omitted] • A multiple-model acquisition system through multiple ASVs for online monitoring. • A centralized multi-ASV system based on active region partitioning and data sharing. • Performance evaluation of the Multi-Objective Optimization system. • Evaluation and comparison with similar water quality monitoring approaches. [ABSTRACT FROM AUTHOR]

To meet the demand of surrounding detection of a humanoid robot, we developed an omnidirectional vision system for robot perception (OVROP) with 5 Degrees of Freedom (DOFs). OVROP has a modular design and mainly consists of three parts: hardware, control architecture and visual processing part (omnidirectional vision and stereovision). As OVROP is equipped with universal hardware and software interfaces it can be applied to various types of robots. Our performance evaluation proves that OVROP can accurately detect and track an object with 360° field of view (FOV). Besides, undistorted omnidirectional perception of surroundings can be achieved through calibrations of both monocular and stereo cameras. Furthermore, our preliminary experimental results show that OVROP can perceive a desired object within 160 ms in most cases. As a result, OVROP can provide detailed information on surrounding environment for full-scope and real-time robot perception. [ABSTRACT FROM AUTHOR]

A novel controller for three-dimensional contouring control of three-degrees-of-freedom (3-DOF) robotic manipulators is presented in this paper. The proposed controller comprises of an independent joint controller, designed in the configuration space, and a sliding mode controller that enforces desired dynamics for the tracking error projections to the Frenet-Serret frame. Therefore, the presented controller has a hybrid structure and it is named as hybrid contouring controller. In this paper, contour tracking with constant magnitude tangential velocity is discussed. Reference trajectory is generated using the time based spline approximation in order to provide a smooth reference path. The proposed hybrid contouring controller was experimentally compared with the independent joint controller that is designed in the acceleration control framework with disturbance observer. Experimental results, undertaken on a delta robot, showed that hybrid contouring controller outperforms independent joint control architecture. [ABSTRACT FROM AUTHOR]

This paper presents impact dynamic analysis of a differential gears based underactuated robotic arm colliding with a moving target. The robotic arm employs a set of one-input-dual-output planetary gears to distribute driving torque of the underactuated joints, which takes advantage of the underactuation to cope with collision. Based on an analysis of the movement relation of three joints, the driving torque is resolved into generalized force corresponding to coordinates of two underactuated joints for establishing a dynamic model of the underactuated robotic arm. Along with the dynamic equation, impulse-momentum equations involving the restitution coefficient of the system (arm and target) are used to establish the impact dynamic model which can extrapolate the impact momentum on the drive component. With the impact dynamic model, the impact-absorbing capability of the underactuated robotic arm is illustrated that the impact momentum on the drive component is reduced by a factor of three compared with a 2-DOF fully actuated rigid robotic arm. Impact experiments were carried out to validate the inference results presented in this paper by using of a prototype of the proposed arm. [ABSTRACT FROM AUTHOR]

New manufacturing processes and extended movability of modern machine tools, such as five-axis kinematics or hexapods, increase the demand for in-process measurement of spatial forces and torques in up to 6 degrees of freedom (DoF). The approach proposed in this paper is based on the idea of integrating 6 single-axis force sensors into the machine’s structure and converting these sensor forces to spatial forces and torques at the tool centre point (TCP) using a measurement model. This concept is advantageous to costs, ruggedness and available workspace when compared to state-of-the-art 6 DoF force/torque transducers. At the same time, the achievable measuring accuracy is similar and also significantly better than the accuracy of drive current based force evaluation. On the other hand, structure and machine influences have to be addressed by suitable measurement models. This article presents design, parametrization, verification, and characterisation of these measurement models on the example of four integration concepts, two in rigid bar frameworks and two in bar kinematics. Further, experimental results are shown which are classified in comparison to a 6 DoF F/T sensor and drive current based force measurement. Finally, other influences, such as structural design and deformations, as well as the integration of sensors and models into the machine’s control software are discussed. [ABSTRACT FROM AUTHOR]

The parallel robot in this research is mainly designed for the human-machine collaboration, which has two working modes: follow-up mode and pressing mode. In order to better realize these two functions, the measurement of the interaction force is mainly concerned. In the arrangement of the hardware, different from the six-dimensional force sensor method and current estimation method commonly used in industry, the structure-integrated force sensors (SIFS) measurement method is used. In the calculation method, a back propagation neural networks (BPNN) method is introduced to calculate the interaction force. Then, based on the prior knowledge of physics, a new interpretable linear neural networks (ILNN) method is proposed. The details of the ILNN algorithm and its differences from the classic neural network methods are given. Finally, the experimental results of the direct Newton–Euler method, the least square method, the BPNN method, and the ILNN method are compared. Experimental results show that the inference accuracy of the ILNN method is slightly better than the direct Newton–Euler method and the least square method, and its generalization ability is much better than the BPNN method. The use of the ILNN method based on the FIFS arrangement makes the measurement of the interaction force more accurate and reliable. [ABSTRACT FROM AUTHOR]

The future robotics will be more and more closer to human in many applications such as in a future manufacturing, human rehabilitation, sport training and physical assistance, or medical and robotized surgery. Also, a domain of object co-manipulation jointly by human and robot is a very interesting and promising way of research. All these lead necessarily to a physical Human-Robot Interaction (commonly called pHRI) which brings new issues and challenges. Therefore, the classical approaches of robotic are not anymore suitable. The objective of this special issue is to collect articles that report the most recent accomplishments and results in the area of physical human-robot interaction and human-robot co-manipulation of objects. [ABSTRACT FROM AUTHOR]

This paper presents a time-domain vibration observer and controller for physical Human-Robot Interaction (pHRI). The proposed observer/controller aims at reducing or eliminating vibrations that may occur in stiff interactions. The vibration observer algorithm first detects minima and maxima of a given signal with robustness in regards to noise. Based on these extrema, a vibration index is computed and then used by an adaptive controller to adjust the control gains in order to reduce vibrations. The controller is activated only when the amplitude of the vibrations exceeds a given threshold and thus it does not influence the performance in normal operation. Also, the observer does not require a model and can analyze a wide time frame with only a few computations. Finally, the algorithm is implemented on two different prototypes that use an admittance controller. [ABSTRACT FROM AUTHOR]

Today, in domains like automation and robotics systems consist of various sensors and computation nodes. Due to the temporal dependency in quality of measured data, such Cyber-Physical Systems (CPS) commonly have real-time requirements on communication. In addition, these systems shall become more flexible and scalable, e.g., by adding new components to the CPS. This would be most suitable if a CPS could react to the presence of a new component and reconfigure itself to run afterward with the new component integrated to the CPS. This capability is covered by the term Plug-and-Produce. In this paper, we propose a concept to enable Plug-and-Produce within a CPS whose network uses different communication media, e.g., Ethernet and CAN. To enable real-time communication provided by different communication protocols, their different synchronization mechanisms have to be combined to get a common time base within the entire system. For this purpose, we consider Ethernet as well as CAN-based real-time communication protocols and their synchronization mechanisms. The proposed concept for self-reconfiguration aims to be integrated into our three layered software architecture that is presented as well. [ABSTRACT FROM AUTHOR]

This paper presents an approach, which allows the utilization of the entire flexibility of modular robot cells. Solution independent requirements of products to be assembled are automatically extracted from their individual CAD files and used for the optimal selection and task oriented programming of cooperating devices in the robot cell. These devices and the products to be manufactured are Cyber-Physical-Systems (CPS), which possess individual virtual models of their requirements and abilities. Based on the communication between the CPS and the fusion of their models, the feasibility of the required assembly tasks with the devices available in the robot cell is determined. The product description is used to optimally assign the required assembly processes to cooperating devices in the robot cell and allows an automated planning and execution of all required tasks. This work presents the overall system architecture, the necessary subsystems and the various models in the virtual representations of the devices and products for a sufficient description of the conditions of entire robot cell to reach the before mentioned goals. [ABSTRACT FROM AUTHOR]

Several pneumatic grippers with accelerometers attached to their fingers have been developed and tested. The first gripper is able to classify the hardness of different cylinders, estimate the pneumatic pressure, monitor the position and speed of the gripper fingers, and study the phases of the action of grasping and the influence of the relative position between the gripper and the cylinders. The other grippers manipulate and assess the firmness of eggplants and mangoes. To achieve a gentle manipulation, the grippers employ fingers with several degrees of freedom in different configurations and have a membrane filled with a fluid that allows their hardness to be controlled by means of the jamming transition of the granular fluid inside it. To assess the firmness of eggplants and mangoes and avoid the influence of the relative position between product and gripper, the firmness is estimated while the products are being held by the fingers. Better performance of the accelerometers is achieved when the finger employs the granular fluid. The article presents methods for designing grippers capable of assessing the firmness of irregular products with accelerometers. At the same time, it also studies the possibilities that accelerometers, attached to different pneumatic robot gripper fingers, offer as tactile sensors. [ABSTRACT FROM AUTHOR]

Hydraulics is a promising technology for robots. However, traditional hydraulic infrastructures are often large and power-inefficient, with large power sources that hinder mobility. In contrast, electro-hydrostatic actuators are relatively power efficient, but their cost and weight can be excessive in systems with a higher number of degrees of freedom. In this paper, we propose a new alternating pressure control system for hydraulic systems with a higher number of degrees of freedom based on an alternating pressure source system. In this system, the valves open and close in synchronization with a pump with sensor feedback, allowing either pressure or position in each actuator to be controlled independently. With the proposed system, a centralized pump can be used with simplified tubing and simple on–off valves. Moreover, we developed a dynamic duty ratio system that improves performance and reduces pump utilization time. The experimental results confirmed that both the position and pressure of each actuator can be controlled in parallel on a multi-degree-of-freedom system. [ABSTRACT FROM AUTHOR]

The hip is the strongest joint of the human body. A wide range of disorders and fractures can affect the hip. The use of therapeutic robots has the potential to reduce the physical workload of rehabilitation and to improve repeatability. In this paper, a simple hip-joint rehabilitation robot (HipBot) is presented to perform combined movements of abduction/adduction and flexion/extension. HipBot has 5-DOF and can perform combined movements. This system can learn specific exercise motions through a GUI and perform them without the physiotherapist. In addition, HipBot is capable of performing rehabilitation on both right and left legs (individually). The simple mechanism covers the requirements of stability and robustness necessary for hip-joint rehabilitation. The mechatronic design and control technique are described. The robot system was tested in a small group of healthy subjects. The experimental results carried out on healthy subjects proved the high performance of the rehabilitation device and showed its great potential. [ABSTRACT FROM AUTHOR]

This paper introduces a method of design and implementation of a two-wheeled inverted pendulum (TWIP) robot with friction compensation. Friction in the drive mechanism is a critical factor of robot self-balancing and affects its performance. The friction parameters are identified based on the dynamic model of the drive mechanism. The dynamics of the whole robot system are obtained by the Lagrangian function method and take the robot drive mechanism friction into account. Sliding mode controllers for self-balancing and yaw motion are designed independently, although the TWIP robot is coupled as a nonlinear system. A low cost but low accuracy gyro and accelerator in consumer electronics grade is adopted to estimate the pitch angle and pitch rate. Using the sensor data from the gyro and accelerator fused with the help of a Kalman filter, the robot body pitch angle is obtained precisely, and these are the key state variables for TWIP control. The effect on the sensor installation location is analysed and corrected with innovation, and the precision of the pose estimation is improved accordingly. Several physical experiments are conducted, and the results demonstrate that the proposed method is effective. [ABSTRACT FROM AUTHOR]

This paper analyzes a set of dynamic trajectories for planar two-dof redundantly actuated cable-suspended parallel mechanisms. In recent literature, the global dynamic trajectory planning problem of cable-suspended mechanisms was addressed and some of the characteristic properties of such robots were revealed. In this paper, actuation redundancy is introduced and the dynamic trajectory planning is addressed using a series of periodic trajectories (i.e. straight line and circular periodic trajectories) and the application of the antipodal theorem. The experimental results obtained show that introducing actuation redundancy increases the dynamic capabilities of the robots. Also, cable tensions acquired via tension sensors confirm that cables always remain taut during all experimental verifications at feasible frequencies and that they are consistent with the tension variations predicted by theory. Furthermore, special frequencies are specified that are similar to those encountered with non-redundant mechanisms. Additionally, an alternative architecture is proposed to deal with cable interferences and it is shown that the novel architecture leads to improved dynamic capabilities when compared to the original architecture. [ABSTRACT FROM AUTHOR]

This article addresses the control problem of robots with unknown dynamics and arbitrarily-switched unknown constraints. Such kind of robots will be shown to be unknown hybrid systems with arbitrary switching and an Adaptive Sliding Mode Fuzzy Control (ASMFC) strategy is proposed that handles the unknown dynamics of the robot along with the unknown constraints arbitrary switching. The ASMFC is a synergy of finding a Common Lyapunov Function (CLF) between the resulted switched subsystems of the considered robots, employing the Fuzzy Logic Systems (FLS), and the use of the Sliding Mode Control (SMC). The CLF accommodates the constraints arbitrary switching, the SMC adds robustness against possible parameters drift, and the FLS approximates the unknown robot dynamics. All unknown parameters are adapted online and all closed loop signals are guaranteed to be bounded. The proposed strategy is validated by conducting an experiment on a KUKA Lightweight Robot (LWR) doing a typical force-guided peg-in-hole assembly task that falls in the category of robot systems under consideration. Excellent tracking performance is obtained when using the ASMFC strategy. Comparison is conducted with the performance of a PD controller that is widely used in commanding industrial robots and the superiority of the proposed strategy is shown. [ABSTRACT FROM AUTHOR]