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Industrial cobotics is presented as a way of business competitiveness by combining human skills and decision making with robotic advantages. The place and safety of humans in cobotic (collaborative robotic) systems are the subjects of much discussion. This article provides a qualitative overview of the main multidisciplinary fields related to the place of human operators during the design process of humans–robots’ systems and discusses paths for effective consideration of the human challenge during this kind of design projects. The added value of this article is its multidisciplinary aspect. Readers will find in this article a technological overview of cobotics, different methodologies and design models focused on final users, interesting examples of evaluation indicators potentially adapted to an effective consideration of humans during the design process of cobotic systems (economic, technical, and human) and guidelines seeking to support cobotic system designers to succeed considering final users during the design process. This work has been supported by the French National Research Agency (ANR) as part of the research project HECTTOR: Humans Committed to Organisations and Work Transformations in the « Factories of the Future » through cobotisation—(ANR-17-CE10-0011)

International audience; In this paper, both vibration reduction and task accuracy improvement for flexible redundant manipulators, using the resolution of redundancy, is addressed. The exciting force of flexural motion, which is induced by the motion of the manipulator, causes undesired deflection at the end-effector. The null space inherent in redundancy feature is exploited to damp out the vibration while maintaining the end-effector posture. In order to exploit all the degrees of freedom in the null space, a feedback control design based on torque optimization has been introduced using analytical method for the redundancy resolution. The simulation analysis is presented to test the effectiveness of the proposed approach.

International audience; This communication aims to present a cross-perspective – robotics, industrial engineering, sociology and ergonomics – research project experience dealing with development of collaborative robotics in SMEs. Our conviction is that Industry 4.0 must imply: (1) “departitioning” of disciplines involved in the design of work situations and (2) construction of hybrid approaches for understanding and transforming work. In this communication, we propose to relate such an experience on the basis of a research project - funded by the French National Agency for Research (ANR), and focused on transformation of French Small and Middle Companies (SMC’s) in relation to introduction of Collaborative Robotics. Collaborative Robotics is of particular interest for us as it embeds promises and pitfalls of articulation between technologies and work. However, these promises may be discussed and tempered by confronting them to actual design issues, work organization and transformation of work management.

International audience; This communication discusses the resulting changes in the field of design project management generated by the industry of the future and its promises, with a special focus on collaborative robotics. Among the guiding issues of this work, we will focus on the importance of including such an intention to cobotize some or all of the tasks initially assigned to human operators, during the strategic stakes of the design process and to instruct and support it by the potential contributions of a bottum up approach centered on the real activities, mobilized and deployed during the realization of the tasks which are objects of cobotization. This discussion is based on an industrial case study, aimed at assisting a finishing workstation (the last stage of a production process) for fragile mechanical parts used in the manufacture of metal parts for the aeronautics sector.

Redundancy in robotic manipulators has many advantages. It is successfully used to achieve better dexterity, and to avoid obstacles, singularities, or the kinematic limitations. However, redundancy makes the inverse kinematics (IK) problem harder to solve. The damped least squares (DLS) is a powerful method for calculating the IK of redundant robots, but it suffers from noncyclicity issue, where a closed curve motion in the Cartesian space of the end-effector (EEF) does not map into a closed curve in the joint space. This results in nonrepetitive motion in the joint space, even though the EEF motion is repetitive. In this article, we present a solution for the noncyclicity problem in the DLS method. The proposed scheme was successfully tested both in simulation (9 DoF robot) and on a real robotic manipulator (7 DoF robot).

Collaborative redundant manipulators are becoming more popular in industry. Lately, sensitive variants of those robots are introduced to the market. Their sensitivity is owed to the unique technology of integrating torque sensors into their joints. This technology has been used extensively for collision detection. Nevertheless, it can be used in other collaborative applications. In this study, we present a novel control method that uses the torque feedback at the joints to perform automatic adjustment of the self-motion manifold during a contact with surrounding obstacles, while allowing the user to control the robot at the end-effector (EEF) level. This makes the interaction with sensitive redundant manipulators more intuitive to users. Experimental tests on KUKA iiwa robot proved the effectiveness of the proposed method for navigating obstacles during a contact with robot’s structure while keeping the precision in the task under execution.

Simulation and model-based design software packages are widely used in many engineering disciplines. When it comes to robotics those tools are very important for robot design, simulation and the development of control algorithms before the implementation on the real robot. Simulink by MathWorks® is an advanced model-based design tool. It is popular in education, industry and research. In addition, Simulink supports several hardware components, facilitating a rapid deployment of the developed programs on the target hardware. In this study, the SimulinkIIWA interface for controlling KUKA iiwa robots from Simulink is presented and compared to the KUKA Sunrise Toolbox (KST). This interface is based on the User Datagram Protocol (UDP) and allows graphical real-time control of iiwa robots from Simulink without a need for writing any code. The interface supports different robot control modes, at the joints level and at the end-effector (EEF) level. Example applications are also provided showing the flexibility and the ease of use of the proposed interface.

International audience; Collaborative robots (cobots) are presented as a way of business competitiveness by combining human skills with robotic advantages. The place of human operators in this context is the subject of much discussion. Including his role, his safety and his security. This study presents a methodological contribution for the management of cobotic projects. It aims to develop profitable, safe and acceptable solutions for the final users. This article presents the different steps of the design process of a collaborative robotic cell to improve a recycling laundry pods workstation. Initially, the current activity was analyzed through observations and interviews with users. Next, improvement scenarios were proposed, discussed and prioritized. After that, a feasibility study was carried out and led to technical prototyping. This was evaluated by end users to improve the solution before the investment.

International audience; In the context of human-robot manipulation interaction for service or industrial robotics, the robot controller must be able to quickly react to unpredictable events in dynamic environments. In this paper, a FIR filter-based trajectory generation methodology is presented, combining the simplicity of the analytic second-order trajectory generation, i.e. acceleration-limited trajectory, with the flexibility and computational efficiency of FIR filtering, to generate on the fly smooth jerk-constrained trajectories. The proposed methodology can generate synchronized (fixed-time) and time-optimal jerk-limited trajectories from arbitrary initial velocity and acceleration conditions within 20 microsecond. Other jerk-constrained trajectories such as jerk-time fixed trajectories, which are particularly suitable for vibration reduction, can be easily generated. Experimental validations carried out on a seven axis Kuka LBR iiwa are presented.

International audience; This study investigates the application of Newton method to the problems of collision avoidance and path planning for robotic manipulators, especially robots with high Degrees of Freedom (DOF). The proposed algorithm applies to the potential fields method, where the Newton technique is used for performing the optimization. As compared to classical gradient descent method this implementation is mathematically elegant, enhances the performance of motion generation, eliminates oscillations, does not require gains tuning, and gives a faster convergence to the solution. In addition, the paper presents a computationally efficient symbolic formula for calculating the Hessian with respect to joint angles, which is essential for achieving realtime performance of the algorithm in high DOF configuration spaces. The method is validated successfully in simulation environment. Results for different methods (Newton, gradient descent and gradient descent with momentum) are compared in terms of quality of the path generated, oscillations, minimum distance to obstacles and convergence rate.

International audience; Christoffel symbols of the first kind are very important in robot dynamics. They are used for tuning various proposed robot controllers, for determining the bounds on Coriolis/Centrifugal matrix, for mathematical formulation of optimal trajectory calculation, among others. In the literature of robot dynamics, Christoffel symbols of the first kind are calculated from Lagrangian dynamics using an off-line generated symbolic formula. In this study we present a novel and efficient recursive, non-symbolic, method where Christoffel symbols of the first kind are calculated on-the-fly based on the inertial parameters of robot’s links and their transformation matrices. The proposed method was analyzed in terms of execution time, computational complexity and numerical error. Results show that the proposed algorithm compares favorably with existing methods.

International audience; This paper addresses the problem of reducing the elastic deformations and the residual vibrations of flexible loads when they are handled by a robot manipulator. During the manipulation of the low-stiffness load, such as bumper or exhaust system in automotive industry, large motion-induced deformations and vibrations may be induced. These deformations will have detrimental effects on the settling time, on the accuracy and on the integrity of the operational process in a constraint environment. The trajectory shaping approaches, i.e smoothing filter or input shaping method are well-known solutions for the suppression of the residual vibration at the end of a rest-to-rest motion. However, using trajectory shaping technique alone may not be sufficient to suppress the static elastic deformations during the transfer phase of the object. Thus, the main contribution of this paper is to propose a two stages feedforward based approach that combines trajectory shaping technique for vibration reduction, with a deformation compensation trajectory. The latter exploits the rotation space of the manipulator to mitigate the flexural motion of the flexible load. The effectiveness of the proposed method is demonstrated by experimental validations on an industrial robot Kuka iiwa.

Rand-guiding of collaborative redundant manipulators allows an unskilled user to interact and program the robot intuitively. Many industrial applications require precise positioning at the end-effector (EEF) level inside cluttered environments, where manipulator's redundancy is required. Yet, the potentialities of redundancy while hand-guiding at EEF level are not fully explored. This paper addresses the subject of precision in hand-guiding at EEF level while using the redundancy for in-contact obstacle navigation. In the presence of a contact with an obstacle, the proposed null space control method actuates in a way that the manipulator slides compliantly with its structure on the body of the obstacle while preserving the precision of the hand-guiding motion at EEF level. Force/torque (FT) data from a FT sensor mounted at the robot flange are the input for EEF precision hand-guiding while the torque data from the joints of the manipulator represent the contact between robot structure and obstacles. Experimental tests were carried out successfully using a KUKA iiwa industrial manipulator with 7 degrees of freedom (DOF). Where, the EEF is hand-guided on a straight line while the robot is sliding on the obstacle with its structure, results indicate the precision of the proposed method.

International audience; Human–robot collision avoidance is a key in collaborative robotics and in the framework of Industry 4.0. It plays an important role for achieving safety criteria while having humans and machines working side-by-side in unstructured and time-varying environment. This study introduces the subject of manipulator’s on-line collision avoidance into a real industrial application implementing typical sensors and a commonly used collaborative industrial manipulator, KUKA iiwa. In the proposed methodology, the human co-worker and the robot are represented by geometric primitives (capsules). The minimum distance and relative velocity between them is calculated, when human/obstacles are nearby the concept of hypothetical repulsion and attraction vectors is used. By coupling this concept with a mathematical representation of robot’s kinematics, a task level control with collision avoidance capability is achieved. Consequently, the off-line generated nominal path of the industrial task is modified on-the-fly so the robot is able to avoid collision with the co-worker safely while being able to fulfill the industrial operation. To guarantee motion continuity when switching between different tasks, the notion of repulsion-vector-reshaping is introduced. Tests on an assembly robotic cell in automotive industry show that the robot moves smoothly and avoids collisions successfully by adjusting the off-line generated nominal paths.

Collaborative robots (Cobots) are indispensable tools in the factories of the future. Owing to their safety centered design, Cobots are allowed to work side by side with humans, making their use as an assistive third hand appealing for tedious assembly tasks. Consequently, we propose a robot that can be hand-guided to lift and hold parts in place while the human performs assembly tasks. Such functionality reduces the risk to workers (falling components for example), provides precision, allows lifting heavier parts, and increases productivity by allowing human workers to focus on more value-added tasks.

This study introduces the Geometric Dynamics Algorithm (GDA) for representing the dynamics of serially linked robots. GDA is non-symbolic, preserves simple formulation, and is convenient for numerical implementation. GDA-based algorithms are deduced for efficient calculation of various dynamic quantities including (1) joint space inertia matrix (JSIM) (2) Coriolis matrix (3) centrifugal matrix (4) and the time derivative of JSIM. The proposed algorithms were analyzed in terms of their computational complexity. Results compare favorably with other methods.

In the upcoming industrial revolution (Industry 4.0) automation and robotics play a central role. Humans and robots are expected to share the same workspace and work safely side by side. Consequently, various collaborative robots have been introduced to the market. Nevertheless, those robots are still limited in their reactions. In some cases they are restricted to reducing their working speed as a response to the proximity of humans or they initiate an emergency stop, particularly if a contact is detected. In this paper, our work on real-time human robot collision avoidance is presented. Unlike the existing solutions, in our method the robot is provided with agile reactivity to human presence. The system is engineered to achieve natural collision avoidance behavior. As a result, the robot acts with smooth avoidance motion upon the proximity of human, giving him/her the space required to do his/her work in shared tasks between a human co-worker and robot.

International audience; Increasingly, robots have more degrees of freedom (DOF), imposing a need for calculating more complex dynamics. As a result, better efficiency in carrying out dynamics computations is becoming more important. In this study, an efficient method for computing the joint space inertia matrix (JSIM) for high DOF serially linked robots is addressed. We call this method the Geometric Dynamics Algorithm for High number of robot Joints (GDAHJ). GDAHJ is non-symbolic, preserve simple formulation, and it is convenient for numerical implementation. This is achieved by simplifying the way to recursively derive the mass-matrix exploiting the unique property of each column of the JSIM and minimizing the number of operations with O(n2) complexity. Results compare favorably with existing methods, achieving better performance over state-of-the-art by Featherstone when applied for robots with more than 13 DOF.

International audience; In this work, redundancy resolution has been employed to increase the Cartesian mechanical rigidity of 7 DOF robot manipulators during tasks requiring stiff interactions with the environment (e.g. milling or drilling). The Cartesian static stiffness of the end-effector for a given joint configuration is deduced from an identified joints stiffness model. The Cartesian reflected rigidity evolution over an analytically computed self-motion of the manipulator shows significant variations that clearly highlight the need to select the right set of joint angles among the possible ones. A global optimization scheme of the redundant DOF is proposed to determine the stiffest robot configurations for a given pose of the end-effector. An experimental study on 7 DOF KUKA LBR iiwa then shows the relevance of the proposed approach in finding the redundant robot joint angles that optimize this rigidity criteria.

This paper derives a jerk-shaped profile to address the vibration reduction of underdamped flexible dynamics of motion system. The jerk-limited profile is a widespread smooth command pattern used by modern motion systems. The ability of the jerk-limited profile to cancel the residual vibration of an undamped flexible mode is clearly explained using an equivalent continuous filter representation and the input shaping formalism. This motivates the design of a new jerk-shaped profile, named Damped-Jerk profile, to extend the previous result to the more common case of underdamped systems.Both simulations and experimental results demonstrate the effectiveness of the proposed Damped-Jerk profile to reduce damped vibration.; International audience; This paper derives a jerk-shaped profile to address the vibration reduction of underdamped flexible dynamics of motion system. The jerk-limited profile is a widespread smooth command pattern used by modern motion systems. The ability of the jerk-limited profile to cancel the residual vibration of an undamped flexible mode is clearly explained using an equivalent continuous filter representation and the input shaping formalism. This motivates the design of a new jerk-shaped profile, named Damped-Jerk profile, to extend the previous result to the more common case of underdamped systems.Both simulations and experimental results demonstrate the effectiveness of the proposed Damped-Jerk profile to reduce damped vibration.

A new and fast registration algorithm has been proposed to update the tool-path of a deburring robot, intended to machining composite workpieces under gravity and clamping deformations. A Subdivision Iterative Closest Point algorithm, which considersdifferent parts of the contour with respect to curvature, allows to obtain far better results than classical methods, without complicated assumptions or computations.The procedure has shown to be effective for porthole and nose-cone deburring. Experimental tests conducted on robotic milling workcell demonstrated the efficiency of the registration method.; International audience; A new and fast registration algorithm has been proposed to update the tool-path of a deburring robot, intended to machining composite workpieces under gravity and clamping deformations. A Subdivision Iterative Closest Point algorithm, which considersdifferent parts of the contour with respect to curvature, allows to obtain far better results than classical methods, without complicated assumptions or computations.The procedure has shown to be effective for porthole and nose-cone deburring. Experimental tests conducted on robotic milling workcell demonstrated the efficiency of the registration method.

To increase their competitiveness, companies use more and more robotic systems to perform various complex tasks. These robots are very attractive because they are flexible and low-cost. A main current issue is the co-activity with human. With the very recent introduction of the new low-cost motion capture system Leap Motion, which has characteristics of accuracy unmatched to this cost for the moment, authors propose a first work concerning the real-time reproduction of 3D human motion by a robotic system. The aim is to reproduce complex tasks in 3D without any constraints for the operator. This device allows to generate a very accurate point cloud of positions and directions. To ensure a good repeatability of the movement on an UR10 robot, interpolation of these data by polynomial splines minimizing the L1 norm are done. This formalism has been developed recently and presents a linear complexity calculation with data and maintains the shape of the data even when the discretization is not uniform in space.

robot. The focus of this paper is on the particular influence of the jerk limited profile on the dynamic behaviour of a 3-axis Cartesian robot. This robot is used for the unloading of the moulding machines. The predominating performances criteria are the movement time and the residual vibrations induced by high dynamical demands. The performances of a jerk limited movement law are evaluated using an analytical model of the controlled system. We show that the jerk lime parameter can be used to limit the residual vibrations while preserving the movement time by a combined action on the position loop gains. Experimental measurements demonstrate the effectiveness of the proposed approach.

Vibration-free positioning is a basic objective in industrial high-speed systems, i.e. systems for which axes are submitted to significant dynamical demands. The focus of this paper is on the pragmatic formalisation of the influence of some jerk-controlled movement laws on the residual vibrations. Analysis of limited-jerk, harmonic-jerk and minimum-jerk laws is conducted on a simplified axis drive model that accounts for axis control parameters and for predominant mode effects. Experimental measurements performed on industrial test-setups demonstrate the effectiveness of the proposed approach in estimating the evolution of the vibration level according to each movement law.

This paper deals with the specific influence of the jerk value on the behaviour of industrial high-spee systems. The physical relationships between the jerk maximum value, the vibratory level reached and the effective movement time are formalised on a axis-drive model taking account of the main control parameters and effects of a predominating deformation mode. Experimental tests conducted on three test-setups with different architectures and characteristics demonstrate the effectiveness of the suggested approach in estimating the evolution of the maximum residual oscillations.

International audience; This paper is concerned with preliminary results on robot vibratory modes on-line estimation. The dominating oscillatory mode of the robot arm is isolated by comparing the robot position given by the motors encoders and an external measure at the tool-tip of the robot arm. In this article the external measurement is provided by a laser tracker. The isolation of the oscillation permits to identify the vibratory mode, \textit{i.e.} the natural frequency and the damping ratio of the undesired phenomena. Here we propose a comparison between the algebraic method and the sliding modes for the parameter identification. This comparison is motivated by the fact that both methods provide finite time convergence. Experimental identifications are proposed on a 6 degrees of freedom (DOF) manipulator robot, Stäubli RX-170B.

This paper presents a new powder transportation system that uses a high frequency flexural stationary wave coupled with a low frequency horizontal displacement of a beam to produce the transport of the powder. The ultrasonic wave is produced with the help of piezoelectric cells glued under the beam and is used to decrease the friction coefficient between the powder and the beam surface. The powder transport mechanism has been described using a simplified mathematical model.

International audience; Jerk-limited trajectories are a widespread solution for the trajectory planning of industrial machines Tools or robots. It is known that jerk limitation can reduce vibrations and in some cases can totally suppress residual vibration induced by a lightly damped stationary mode. However, for systems with time-varying mode, which is classically the case for configuration dependent mode or load mass variations, the previous result vanishes. This paper proposes to extend the jerk-limited profile (JL) properties to time-varying vibration problem. First, a guideline for designing a dissociated jerk-limited profile (DJL) based on simple and pragmatic Finite Impulse Response (FIR) filtering methodology is presented. Following the guideline, the time-varying vibration reduction principle is detailed. Then, experiments conducted on an industrial 3-axes Cartesian manipulator are presented. The experimental results show that the residual vibration magnitude is reduced to less than 23% of the original level obtained with JL profile and the settling time is reduced by 10%, demonstrating the efficiency of the proposed DJL trajectory planning.

International audience; In this paper, an improvement of the dynamic accuracy of a flexible robot joint is addressed. Based on the observation of the measured axis deformation, a simplified elastic joint model is deduced. In the first step, the non-linear model component's is analyzed and identified in the cases of the gravity bias and the friction term. In the second step, a non asymptotically algebraic fast identification of the oscillatory behavior of the robot axis is introduced. Finally, the performances of the identification approach are exploited in order to improve the dynamic accuracy of a flexible robot axis. This is done experimentally by the combination of the adaptation of the jerk time profile to reduce the end-point vibration and the model-based precompensation of the end-point tracking error.

In this article, we justify the use of parametric planar Pythagorean Hodograph spline curves in path planning. The elegant properties of such splines enable us to design an efficient interpolator algorithm, more precise than the classical Taylor interpolators and faster than an interpolator based on arc length computations.

International audience; The use of industrial robots in many fields of industry like prototyping, pre-machining and end milling is limited because of their poor accuracy. Robot joints are mainly responsible for this poor accuracy. The flexibility of robots joints and the kinematic errors in the transmission systems produce a significant error of position in the level of the end-effector. This paper presents these two types of joint errors. Identification methods are presented with experimental validation on a 6 axes industrial robot, STAUBLI RX 170 BH. An offline correction method used to improve the accuracy of this robot is validated experimentally.

In this paper, a trajectory generator based on causal modeling is presented. This strategy is applied to the velocity constraint trajectory generation of an automatic subway. The constraints take into account of passengers comfort by the use of imposed maximum jerk and acceleration values. The proposed velocity generator is enhanced by the use of torque model of the DC machines. The proposed velocity planning method is applied to a model of the VAL subway and comparisons with the present control structure are provided.

International audience; This paper presents a practical approach to adapt the trajectory planning stage for industrial robots to realize continuous machining operations. Firstly, L1 interpolation is introduced to generate efficiently the tool-paths in the form of shape-preserving quintic splines. Then, the tool-tip feedrate planning in Cartesian space is done using a smooth jerk limited pattern and taking into account the joints kinematics constraints. Experimental validations conducted on a 6-axis industrial robot demonstrate the effectiveness of the proposed methodology of trajectory planning in the context of machining.