In this article, we present a learning model that can control the kinematics motion of a simulated anthropomorphic arm in reaching and grasping tasks of a static prototypic object placed behind an obstacle of varying position and size. The network, composed of two generic neural network modules, learns to combine multi-modal arm-related information (trajectory parameters) as well as obstacle-related information (obstacle size and location). We based our simulation on the Via Point notion, which postulates that the reach motion planning is divided into successive positions of the arm. In order to determine these particular positions, some specific parameters have been extracted from an experimental protocol and constitute the pertinent parameters to be integrated into the model. This net of neural net determines the total path able to reach and grasp the prototypic object while avoiding an obstacle.

This paper deals with the design and the experiments of the upper part of the ROBIAN biped robot. The motivation of the ROBIAN project is related to the study of the human being locomotion system. The major application of ROBIAN prototype is the development of a real testing bed of active/passive prosthesis devices enhancing research on the human being locomotion mechanism handicaps. The analysis of the wrench six components exerted by the upper part of a virtual manikin on the locomotion apparatus leads to the identification of two coupling relations. Based on the dynamic equivalence concept between mechanisms, the ROBIAN torso mechanism is identified. This concept leads to a four degrees of freedom mechanism able to reproduce the dynamic effects of the upper limbs during the walking gait. The mechanism parameters are optimized with respect to several design criteria and constraints. Then the prototype is built and mounted on the ROBIAN locomotion apparatus through a six components force sensor. Experimental results presented in this paper validate the proposed approach. The experimental coupling coefficients are identified. The influence of the masses motion on the ZMP trajectory are also given, showing the effectiveness of the torso mechanism contribution during a walking gait.

This paper explores a new type of a parallel platform human interface manipulator based on virtual reality (VR) for mechanism design applications. A motion control of a six-link robot manipulator actuated by three active joints is presented here. The main components of the system include a user interface, a software simulating the environment, and a VR control system. The model of the VR system is built based on a force feedback behavior that enables the operator to feel the actual force feedback from the virtual environment just as he/she would from the real environment. A primary stabilizing controller is used to develop a haptic interface device where realistic simulations of the dynamic interaction forces between a human operator and the simulated virtual object/mechanism is required. The stability and performance of the system are studied and analyzed based on the Nyquist stability criterion. Experiments on cutting virtual clay are used to validate the theoretical developments. It was shown that the experimental and theoretical results are in good agreement.

This paper presents a Q-learning approach to state-based planning of behaviour-based walking robots. The learning process consists of a teaching stage and an autonomous learning stage. During the teaching stage, the robot is instructed to operate in some interesting areas of the solution space to accumulate some prior knowledge. Then, the learning is switched to the autonomous learning stage to let the robot explore the solution space based on its prior knowledge. Experiments are conducted in the RoboCup domain and results show a good performance of the proposed method.

The work presented here concerns the design and manufacturing possibility of a polymodular autonomous microrobot moving like an earthworm. The study consists of the development of a new locomotion actuator based on shape memory alloys. This actuator is formed by a flexible frame forced in post-buckling by its assembly on a rigid skeleton cage. This mechanical structure, forming a knot in the microrobot chain, uses its two post-buckling equilibrium positions to achieve first the support and second the local lengthening enabling the movement of the microrobot. Initially, we present the technical solution designed for the locomotion actuator and the mechanical characterization of its malleable structure. Then, we present the instrumentation by educated SMA of a malleable structure and the capability of microrobot locomotion task in a vertical tube.

Although numerous sophisticated nonlinear control algorithms exist in literature, it is still state of the art to use simple linear joint controllers in industrial robotic systems. Most nonlinear concepts are based on a more or less accurate inverse model of the robot. In this paper a forward-model-based control system, the so-called Model Following Control (MFC), for robot manipulators is presented. Its theoretical basics and its concept are explained. The quality and the applicability of the MFC control concept has been analyzed in many experiments. The MFC system is compared with classical linear controllers and nonlinear feedforward controllers with respect to robustness. Qualitative as well as quantitative results are presented and discussed.

Mobile manipulation involves the most important key issue in robotics: integration. While hardware integration seems to be nearly solved due to the increasing dominance of PC-compatible systems, software integration is still a challenge, since a lot of issues arise with the variety of operating systems, device drivers, application libraries, and programming languages which need to be merged in any real-world robotic system. This paper presents a software architecture, which seamlessly integrates robot arms, mobile bases, vision systems and sensing devices, in a distributed, homogeneous agent framework. Based on the Java platform, the agent-based architecture allows great flexibility in the integration of components, and provides a simple yet extensible and powerful software layer to develop further mobile manipulating environments. Detailed software issues, as well as preliminary results are shown, which pave the way towards the development of network-ready applications involving mobile and manipulating artifacts.

The present paper presents a new approach to a leader–follower-based dynamic trajectory planning for multirobot formation. A near-optimal trajectory is generated for each robot in a decentralized manner. The main contributions of the current paper are the proposal of a new objective function that considers both collision avoidance and formation requirement for the trajectory generation, and an analytical solution of trajectory parameters in the trajectory optimization. Simulations and experiments on multirobots are performed to demonstrate the effectiveness of the proposed approach to the multirobot formation in a dynamic environment.

Binary-actuated robots offer a discrete workspace with the advantage that no feedback control is needed, as their actuators have two mechanical end-positions. This contribution focuses on a planar parallel robot with a PRRRP structure and driven by rodless pneumatic cylinders. Thus, the robot's workspace only features four destination points, which can be reached quickly and with high repeatability. Because of the fact that there is no possibility to reach in discrete points, an adapted task configuration is essential. The objective of this work is to establish and validate a synthesis and calibration technique for binary parallel robots with a PRRRP structure.

This paper addresses the orientation-singularity analysis and the orientationability evaluation of a special class of the Stewart–Gough parallel manipulators in which the moving and base platforms are two similar semi-symmetrical hexagons. Based on the half-angle transformation, an analytical polynomial of degree 13 that represents the orientation-singularity locus of this special class of parallel manipulators at a given position is derived. Graphical representations of the orientation-singularity locus of this class of manipulators are illustrated with examples to demonstrate the results. Based on the description of the orientation-singularity and nonsingular orientation region of this class of parallel manipulators, a performance index, referred to as orientationability, which describes the orientation capability of this class of manipulators at a given position, is introduced. A discretization algorithm is proposed for computing the orientationability of the special class of parallel manipulators at a given position in the workspace. Moreover, the effects of the design parameters and position parameters on the orientationability are also investigated in detail. Based on the orientationability performance index, another performance index, referred to as practical orientationability, representing the practical orientation capability of the manipulators at a given position, is introduced. In this performance index, singularities, the limitations of active and passive joints and link interferences are all taken into consideration. Furthermore, the practical orientationability of the special class of parallel manipulators studied here is also analyzed over several plane sections of the position-workspace in detail.

This paper presents bimodal mobility actuated by inertial forces with elastic bodies for an exploration robot in a microgravity environment. The proposed bimodal locomotion mechanism can selectively achieve vibration propulsion or rotational hopping mode based on centrifugal force and reaction torque exerted by the control of a single eccentric motor, where the rotational hopping is the primary locomotion mode for practical applications. The bimodal mobility performance under microgravity is experimentally examined using an air-floating testbed. Furthermore, we also present theoretical modeling of the bimodal mobility system, and the model is verified by comparison with the experiments.

As a solution to soft material manipulation, dual-arm robots that are capable of multi-point grasping have become the latest trend due to their higher capability and efficiency. To explore further development in soft material manipulation and go beyond the hardware limit of dual arms, in this paper the robot platform “Quad-SCARA” that consists of four Selective Compliance Assembly Robot Arm (SCARA) is developed and introduced. With the base of hardware platform, a novel collision avoidance system designed for the motion planning of Quad-SCARA in multi-point grasping state is proposed. This system is inspired by the idea of “Buffered Voronoi Cell (BVC),” an algorithm originally proposed for multi-agent collision avoidance. After appropriate adaptation and new proposition in implementation of BVC, the experiments of folding and spreading a handkerchief are performed, and the results in simulation and robot experiments are presented and discussed for the validation and evaluation of entire system.

Each of several speed-limited planar robots is driven by the acceleration, limited in magnitude. There is an unpredictable dynamic complex object, for example, a group of moving targets or an extended moving and deforming body. The robots should reach and then repeatedly trace a certain object-dependent moving and deforming curve that encircles the object and also achieve an effective self-deployment over it. This may be, for example, the locus of points at a desired mean distance or distance from a group of targets or a single extended object, respectively. Every robot has access to the nearest point of the curve and its own velocity and “sees” the objects within a finite sensing range. The robots have no communication facilities, cannot differentiate the peers, and are to be driven by a common law. Necessary conditions for the solvability of the mission are established. Under their slight and partly unavoidable enhancement, a new decentralized control strategy is proposed and shown to solve the mission, while excluding inter-robot collisions, and for the case of a steady curve, to evenly distribute the robots over the curve and to ensure a prespecified speed of their motion over it. These are justified via rigorous global convergence results and confirmed via computer simulations.

Agile bionic leg mechanism (ABLM) has attracted more and more attention in the development of jumping robots and high-speed running robots. However, theoretical study of the global structure for motility characteristics and its evolution is few. By using the modern mathematical tools such as singular theory, geometric topology, and group theory, a global scale analysis method for kinematic performance of mechanisms is proposed. Taking 6-bar with two rings mechanism as an example, a detailed analysis process is studied. The 6-bar ABLM designed by this theory is verified by virtual prototype simulation experiment. The global scale analysis of 4-bar linkage is also carried out by using this method, and the result is compared with the “Grashof criterion” to verify the correctness of this method. It provides a general theory and method for innovative design and global scale analysis of ABLM.

As a fatigable part of industrial products, cable is a valuable research topic to predict the product lifetime. Since the cable fatigue is related to the bending radius in motion, this paper presents a cable motion capture and bending radius calculation method based on optical tracking system. In particular, a marker sorting algorithm is developed for further spline interpolation in cable motion tracking. The cable bending radius calculation precision is analysed as well. The Results show that the proposed method can successfully track cable motion with an acceptable error for cable lifetime prediction.

A computational derivation of valid kinematic limbs for spatial 3-DOF parallel mechanisms (PMs) without redundant constraint is studied based on contracted graphs, topological graphs, and basic joints. First, some contracted graphs without any binary links are constructed, some curves with only binary links are distributed over contracted graphs and many valid topological graphs are derived. Second, a software is developed in Visual Basic for deriving the kinematic limb, and some basic chain structures are constructed by connecting various basic joints in series. Third, all valid kinematic limbs of the 3-DOF PMs without redundant constraint are derived computationally from the basic chain structures and some novel 3-DOF PMs are synthesized using this approach. Finally, the number of the different 3-DOF PMs without redundant constraint are determined based on the topological graphs and valid chain structures of the limb.

In this paper, we present a passive lower extremity exoskeleton with a simple structure and a light weight. The exoskeleton does not require any external energy source and can achieve energy transfer only by human body’s own gravity. The exoskeleton is self-adaptive to human gait to achieve basic matching therewith. During walking, pulling forces are generated through Bowden cables by pressing plantar power output devices by feet, and the forces are transmitted to the exoskeleton through a crank-slider mechanism to enable the exoskeleton to provide torques for the ankle and knee joints as required by the human body during the stance phase and the swing phase. Our self-developed gait detection system is used to perform experiments on kinematics, dynamics and metabolic cost during walking of the human body wearing the exoskeleton in different states. The experimental results show that the exoskeleton has the greatest influence on motion of the ankle joint and has the least influence on hip joint. With the increase in elastic coefficient of the spring, the torques generated at the joints by the exoskeleton increase. When walking with wearing k3EF exoskeleton at a speed of 0.5 m/s, it can save the most metabolic cost, reaching 13.63%.

In this paper, a novel robust model reference adaptive impedance control (RMRAIC) scheme is presented for an active transtibial ankle prosthesis. The controller makes the closed loop dynamics of the prosthesis similar to a reference impedance model and provides asymptotic tracking of the response trajectory of this impedance model. The interactions between human and prosthesis are taken into account by designing a second-order reference impedance model. The proposed controller is robust against parametric uncertainties in the nonlinear dynamic model of the prosthesis. Also, the controller has robustness against bounded uncertainties due to unavailable ground reaction forces and unmeasurable feedbacks of accelerations at the socket place. Moreover, an appropriate Series Elastic Actuator (SEA) mechanism for the prosthetic ankle is included in this work and its effects are discussed. Tracking performance and stability of the closed-loop system are proven via the Lyapunov stability analysis. Using simulations on an overall amputee prosthetic foot system, the effectiveness of the proposed RMRAIC controller is investigated for the task of level ground walking.

In our previous work, a novel force control actuator, called series damper actuator (SDA), has been proposed. This paper proposes a general design procedure for the SDA system. From design requirements, several key parameters of the SDA plant can be determined. Based on these parameters, the selection or design of the series damper and the motor can be carried out. A case study is included to illustrate the effectiveness of the procedure. As there could be more than one feasible solutions from the procedure, the mechatronic design quotient (MDQ) method can be adopted to select the best solution from a feasible solution space.

We propose the N-learning practical approach for teaching and learning behaviors in a multirobot system, which is performed through mandatory behavior acquisition based on interactions between the robots at execution time. The proposed methodology can be used to self-program the robots of a team by programming only a single robot with a set of codes that contain behaviors to be transferred and used by other robots as necessary. These codes are implemented in a modular fashion. An advantage of our approach is that when a team of robots is required to perform a specific mission, the set of behaviors required to accomplish that mission can be implemented only once in a single robot or in a distributed fashion. Then, these distributed behaviors are transferred to each of the other robots in the team according to their demand, without the need to reprogram them by hand since the robots in the team can share them autonomously. As an application example, a human critic can teach (or program) only one or a few robots, and these robots are thus able to exchange knowledge with the other team members since they have been preinstalled to run the N-learning system basics. Simulated and real robot experiments are performed to demonstrate the feasibility and validation of our approach.