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A solution of the constant cutting velocity problem of quick-return mechanisms is the main concern of this paper. An optimal sliding mode control in the task space is used to achieve uniform and accurate cuts throughout the workpiece. The switching hyperplane is designed to minimize the position error of the slider-dynamics in an infinite horizon. A Jacobian compensator is used to exploit the mechanical advantage and ensure controllability. The velocity profile is constructed in terms of the mechanism and workpiece geometric properties. Stability of the closed-loop dynamics is verified with the Lyapunov stability theory. Experiments are carried out in a quick-return mechanism prototype to validate the proposal.

Proportional-Derivative (PD) control is one of the most widely used controllers, especially for robot manipulators. When the robot presents gravitational terms, PD control cannot guarantee position convergence, therefore compensation is required such as PD with gravity compensation, PD+G. PD+G control requires knowledge of the gravitational term and there exist several results that prove global asymptotic stability. However, there is no method to tune the PD gains. In this work, a novel method to tune the PD+G controller is proposed. The tuning method is obtained using the global asymptotic stability result of the La Salle's theorem and robot dynamics properties. A comparison between previous works is realized via simulations and experiments to verify our approach. The results show fast and smooth convergence to the desired reference without overshoots.

In this work, a position control for slider-crank mechanisms without Jacobian and joint measurements is presented. A Jacobian compensator that depends on the sign of the direction of rotation of the input link and the output link is proposed. A linear sensor is mounted at the slider to measure its position. Simulations and experiments are presented using two different Whitworth mechanisms to validate and compared the proposed approach with Jacobian-based controllers.

In this paper, a constant speed control of slider-crank mechanisms for machine tools is proposed. A joint-task space hybrid controller based on a second-order sliding mode control and time-base generator was used to guarantee a constant speed trajectory tracking and a complete turn of the mechanism crank. A switching criterion was implemented in order to avoid the singularities located at the two extreme positions of the slider stroke. A trapezoidal speed profile with parabolic blends was designed directly over task space slider trajectory considering a constant cutting speed, the workpiece dimensions and the slider stroke length. Stability of the second-order sliding mode control was validated with the Lyapunov stability theory. Simulations were carried out to verify this approach.

In this paper the problem of guiding a parabolic trough solar concentrator through a system based on a water displacement mechanism is addressed. The actuator mechanism consists of a set of four on/off electrovalves in ”H-bridge” configuration, a small water pump, a sun sensor and two containers half-filled with water, installed on the side ends of the concentrator. To guide and balance the concentrator, a sliding mode controller (SMC) to enable / disable the opening and closing of the valves that control the direction and flow of water between the two containers is proposed. The validity of the implementation of the proposed law of control applied to the actuator mechanism is verified with stability analysis and simulation results.

In this paper, the Cumulative Usage Factor (CUF) of a High Pressure Core Cooling System (HPCS) reactor nozzle of a Boiling Water Reactor was calculated. This fatigue damage has been caused by the sudden injection of cold water into the reactor vessel through such nozzle. For this purpose, a three-dimensional analysis was carried out. Accordingly, a transient heat transfer analysis was developed. The temperature distribution was determined. With this information, the stress analysis was carried out. The safe end was restricted to move along its axial direction and the forging end was free to expand axially and radially. The resultant stress field established the magnitude of the alternative stresses. In the last step, a fatigue analysis was developed. The most critical point is the junction of the nozzle with the thermal sleeve. The fatigue performance was evaluated during a period of sixty years. It was assumed that 1.5 cycles per year will take place. The fatigue curves of ASME code section III were used. The results showed that the Cumulative Usage Factor (CUF) vary with the temperature injection, being 0.4090 when the water injected was 4.44°C and 0.3797 when the water temperature was 37.77°C. Both of them were estimated for a period of 60 years of operation. Therefore, damage is reduced as the temperature of the injected water increases. Besides, it is advisable to at least follow the recommendations of the NUREG ́s 1800 and 1801 [1, 2]. In this way, the aging of the nozzle is adequately managed.

The design and development of highly accurate prostheses for individual cases according to the patient’s condition is one of the current challenges in the fields of medicine and engineering. The use of tomographic archives uploaded to a specialized computer program for its rendering (creation of a 3-D model) allows specialists decide on the surgical approach to take, by creating a model which possesses precise dimensions, corresponding to the exact anatomy of the patient. The use of computational programs (CAD/CAM programs) not only allows the development of better designs, but also the evaluation of the proposed models through a force moment analysis in conjunction with the assignment of the endorsed materials for its posterior development by setting the prototypes to the Maximum Shear Stress principle and analyzing the results of its displacement’s and the Stress von Mises’ tests, specialists have the opportunity to know if the final design will be able to support the muscular tensions and occlusion forces caused by the elongation of the muscular fibers.

Substitution for the loss of human members due to different natural consequences has been a reality for many thousands of years. Over time, the evolution of knowledge and technologies, just as the discovery of new materials, gave rise to inventions in the fields of robotics, in particular biomechanics, that have provided human beings with complementary limbs that are improved upon every day. Based on the advances of electronic components, more efficient systems are developed for patient monitoring, which allows for more accurate control and monitoring of the prosthesis, as well as the vital signs of the patient. With the help of technology, efficient treatments are applied or to recover bodily parts as far as possible. This paper presents the design for a prototype of a monitoring system for spinal prosthesis, which an system Arduino UNO®, an infrared sensor, an accelerometer and a micro SD memory are used. In addition, computational tools are used for the development of the algorithm, which allow the monitoring of the prosthesis. As a result, measurements are obtained in the Arduino® system for the behaviour and movement of the prosthesis such as the displacement of the vertebra and angular velocities, which are stored in a micro SD. The application of new technologies in spinal prostheses is also obtained in order to make a diagnosis less costly and available in real time.

In the present work, the importance and consideration of the use of scaffold structures for biomaterials is highlighted in order to be applied in prosthetic cases where it is possible to consider a three dimensional porous structure, maintaining the mechanical properties that are necessary for the right functioning of the models under preoperative and postoperative loads. The requirements for biodegradable and bioactive properties of the models are indicated by surgical specialists, with the purpose of considering both the shape and type of the scaffold and its influence in the building of diverse mechanical supports. A specific maxillofacial application case of models, a mandibular implant, whose numerical-experimental properties and behaviors based on bone, polymers and metal alloy structures used in the manufacturing of models, were used to compare the variation of the scaffold structure types. Furthermore, models printed in 3D using an acrylonitrile butadiene styrene (ABS) polymer with different fiber orientations and type of scaffolds will be considered as an initial part of the case studies.

Nowadays, one billion people live with some form of disability, and face difficulties in the development of activities and integration into society. In future years, this problem will increase. The generation of devices for the rehabilitation of people who suffer some kind of disability is a task that has been studied and attacked for years. The exoskeleton (exo means “outside” in Greek) is an external skeleton that encloses the body of the arthropod as an armor, performing a mechanical function of structural support and protection. Conventional manufacturing processes, present advantages as well as disadvantages, within its disadvantages are the long times for its manufacture and construction, and high cost of manufacturing, since it is not a serial production. The guidelines and actions of the methodology for the manufacture of an exoskeleton of assistance for human gait with problems of acute transverse myelitis.

Electromyography (EMG) is usually done with wet electrodes. They are commonly made with Ag/AgCl (silver chloride). In this case, an interface with the skin is created with a gel. The problem with such electrodes is that the signal is affected by the way the electrodes are fixed over the skin and the use of gel. Besides, they irritate the skin and they are sensible to artifacts of movement and other interferences. In order to avoid these problems, dry electrodes with microneedles, which records the EMG signals, were manufactured. The microneedles pierced the stratum corneum of the skin. They improved the contact with the skin and avoided the interference caused by the dead cells. Besides, the application of a conductor gel and the preparation of the skin was not required. The mecroneedles were manufactured on a copper substratum with a laser beam. They were coated with gold, which is a biocompatible material. Although the size of the microneedles was very small, a good shape was obtained. The manufacturing process was carried out with a high precision and its repeatability was guaranteed. This manufacturing process is quick and cheap. The determination of the operation parameters of the dry electrodes was based on the contact impedance between the skin and the electrode. The performance of the proposed electrodes was compared with the performance of the commercial wet electrodes. The average impedance obtained were 6.5 and 9 kΩ for the wet and dry electrodes, respectively.

Photovoltaic energy production systems generate electricity without emitting pollutants into the atmosphere and do so from a free, unlimited resource. The highest level of energy conversion from the photovoltaic panels can be obtained by placing them perpendicular to the sun’s rays falling on their surface; this is done by installing solar tracking systems. This work proposes the use of two four-bar mechanisms as the driving force for a solar tracker; we propose the use of analytical synthesis for such mechanisms. This procedure is aimed at optimising the transmission angle, increasing mechanical advantage and decreasing driving torque. A mathematical model was used to prove synthesis results and a prototype of the solar tracker was built.

Although in the scientific literature there are studies regarding optimization of structural members subject to static loads or even cyclic in-phase loads, the optimization of structures subject to cyclic, out-of-phase multiaxial loads is still an unexplored issue. In this paper, we present an approach to the problem of size optimization of rectangular cross-section members subject to multiaxial in-phase and out-of-phase cyclic loads. The objective of the optimization is to minimize the cross sectional area of such elements while retaining their fatigue endurance. Under the proposed methodology, optimum values of the area are achieved for six loading cases and for three values of the height to width ratio of the cross section, and these values are reported. The novelty of the approach lies in the inclusion of two multiaxial high cycle fatigue criteria, i.e., Dang Van and Vu-Halm-Nadot ones, as constraints for size optimization problems, fully integrated within an in-house developed tool, capable of handling non-proportional stresses. A plot of the feasible solution space for this optimization problem is also obtained.

This paper presents a novel methodology based on polynomial-interpolation technique to generate the trajectory in order to intercept two or more moving objects. This methodology is efficient for the slowmaneuvering objects with constant acceleration in industrial settings, like objects moving on a circular or linear conveyor. The position, velocity and acceleration as a function of time of the free-particles are used as input to the methodology. With this kinematic information is possible to generate the multiple interception trajectory. The multiple interception trajectory allows to the endeffector of a robotic arm to be oriented along each of the free particle's-trajectory to avoid impact due to the direction of their velocities. The implementation of the proposing methodology is ilustrated through a simulation examples, which consist of the interception of two objects moving along a well-known trajectory via two degrees of freedom robot arm. The endeffector tracking the desired follower-trajectory to intercept two moving objects in the task space.

This paper describes a methodology to construct a linear model of a double pneumatic cylinder. The in and out airflow is regulated by two on/off solenoid valves. The proposed methodology simplifies the handling of the two on/off solenoid valves by using a nonlinear relation between the on/off times of the valves and a single continuous control input. This relation represents an open loop control that gives a linear input/output response with maximum speed, and with reduced dead-band. Numerical simulations are given in order to validate the proposed methodology.

This paper presents a novel approach to on-line, robot-motion planning for multiple moving-objects interception with constant acceleration. The position, velocity and acceleration of the free particles TFL are used as a kinematic information to generate the multiple interception trajectory TFP. The polynomial interpolation technique is implemented in a 2 dof robot with an operational space control esquem with nonlinear PID + regresor to track the follower-trajectory TFP. The simulation consists of multiple 2D interception of two objects moving along a well-known parabolic trajectory via a 2dof robot interceptor.

The purpose of this work is to obtain a simple optimal linear model of a single pneumatic cylinder, which is controlled by two on/off solenoid valves. Here it is proposed an strategy to find a relation between the driving times to handle the on/off valves and a single continuous control input. This relation represents an open loop control that generates a system with linear input/output response, with maximum speed response, and with zero deadband. So, this relation improves the results of the pulsing scheme given previously by van Varseveld and Bone (1997).

This paper presents a novel approach to on-line, robot-motion planning for multiple 3D moving-objects interception. Using a polynomial interpolation technique. The proposed approach utilizes the time parametric function of one or more moving objects to generate the multiple 3D interception trajectory. This methodology is efficient for the slow-maneuvering objects with constant acceleration in industrial settings, like objects moving on a circular conveyor. The multiple 3D interception trajectory allows the end-effector of a robotic arm to be oriented along the objects trajectory to avoid impact. The implementation of the proposed technique is illustrated via a simulation example. It consists of the multiple 3D interception of two objects moving along a well-known sinusoidal trajectory in the three-dimensional space.

This paper presents a novel approach to on-line, robot-motion planning for multiple 2D moving-objects interception. The proposed approach utilizes the time parametric function of one or more moving objects to generate the multiple interception trajectory. This methodology is efficient for the slow-maneuvering objects with constant aceleration in industrial settings, like objects moving on a conveyor. The multiple interception trajectory allows the end-effector of a robotic arm is oriented to the objects trajectory to avoid impact. The implementation of the proposed technique is ilustrated via a simulation example. It consists for the multiple interception of two balls moving along a well-known parabolic trajectories via an autonomous robot.

This work is the first of a series of two articles on the application of soft-computing techniques for the trajectory planning of multi-robotic systems. In this first article the motion planning problem of robot manipulators and the particular case of Multi-movers are defined. A brief introduction of the basic elements of soft-computing is given, and the applicability of such elements for the trajectory planning problem of robot manipulators is discussed. Also, the artificial potential field method is presented for the modelling and characterization of obstacles and as a mean of driving a planner towards the desired goal. A genetic algorithm (GA) based path is presented to illustrate the applicability of such techniques for the path planning in a 2D space and a global path planner for planar robot manipulators is developed based on GA optimisation considering static obstacles.