This paper presents the control system of a chess-playing robot developed by the Research Institute of Robots at the Shanghai Jiaotong University. Thanks to the Windows NT operation system and the RTX (Real-Time eXtension), the whole system can achieve good real-time performance. The control system, which is supported by a standard PC hardware platform and a modularized structure of system software, is open-ended and easily expansible.

This paper explores and experimentally compares the effectiveness of robot-stopping approaches based on the speed and separation monitoring for improving fluency in collaborative robotics. In the compared approaches, a supervisory controller checks the distance between the bounding volumes enclosing human operator and robot and prevents potential collisions by determining the robot’s stop time and triggering a stop trajectory if necessary. The methods are tested on a Franka Emika robot with 7 degrees of freedom, involving 27 volunteer participants, who are asked to walk along assigned paths to cyclically intrude the robot workspace, while the manipulator is working. The experimental results show that scaling online the dynamic safety zones is beneficial for improving fluency of human-robot collaboration, showing significant statistical differences with respect to alternative approaches.

The paper presents an approach to automatic synthesis of program for robots in a flexible manufacturing cell (FMC). The system of program generation consists of two layers: Task-Level Programming Layer and Program Interpretation and Verification Layer. The first layer uses robot-independent planning techniques to create a work plan for robots (set of elementary actions) and program for each elementary action. The second layer uses robot-dependent planning methods to plan robot's trajectories and calculate the robot's motion times. A simulation model of whole FMC, which is created based on a description of FMC and program for robots, makes possible evaluation of efficiency of FMC work.

This paper investigates the contributions of each joint in perturbed balance by employing multiple balance strategies and exploring gain scheduling. Hybrid controllers are developed for sagittal standing in response to constant pushes, and a hypothesis is then investigated that postural feedback gains in standing balance should change with perturbation size via an optimization approach. Related research indicates the roles of each joint: the ankles apply torque to the ground, the hips and/or arms generate horizontal ground forces, and the knees and hips squat. To investigate it from an optimization point of view, this paper uses a horizontal push of a given size, direction, and location as a perturbation, and optimizes controllers for different push sizes, directions, and locations. It applies to the ankle, hip, squat, and arm swinging strategies in standing balance. By comparing the capability of handling disturbances and investigating the feedback gains of each strategy, this paper quantitatively analyzes the contributions of each joint to perturbed balance. We believe this work is also instructive to study the progressive behavioral changes as the model gets more and more complex.

At the end of the 20th century robot technology became well established as a reliable and economic source in industrial automation. On the other hand, it is claimed that even a general six or seven degree of freedom robot arm or a multifingered robot hand designed carefully and manufactured with very high precision lacks versatility in its use in a variety of tasks that must be done instead of a human. The lack of versatility or the clumsiness of present industrial robots is not due to the fine mechanism of such robots. Rather, the clumsiness shows a lack of our knowledge of everyday physics, in particular, a lack of knowledge of physics involving grasping and handling of various kinds of things and manipulating them with certain dexterity, in which tactile and vision sensings must be well coordinated.

A work cell with multiple robots increases manufacturing flexibility and productivity. Robots in the work cell equipped in a sparse area usually share a motion path, resources and workspace. In this paper, an embedded Markov chain model for a multi-robot system that has a common workspace is constructed on the basis of the concept of a multi-processor system. With the presented model, we measure the performance of error recovery schemes under different workloads and analyze the sensitivity of the execution time with respect to the robot speed. We verify the presented model with an experimental multi-robot work cell. This study is useful in evaluating the performance of a robotic work cell and presents a guide for designing a complex work cell.

An eight-legged walking machine with purely mechanical control of leg motion has been built, based on an old design by Space-General Corporation. The paper describes its mechanical design, and experiments with it on a variety of surfaces.

The design of control laws for flexible manipulators is known to be a challenging problem, when using a conventional actuator, i.e., a motor with gear. This is due to the friction of the nonlinear actuator, which causes torque dead zone and stick-slip behavior, thereby hampering the good performance of the control system. The torque needed to attenuate the vibrations, although calculated by the control law, is consumed by the friction inside the actuator, rendering it ineffective to the flexible structure control. Nonlinear friction varies with different operational conditions of the actuator and a friction compensation mechanism based on these models cannot always keep a good performance. This study proposes a new control strategy using wavelet network to friction compensation. Experimental results obtained with a flexible manipulator attest to the good performance of the proposed control law.

Soft robotics is rapidly advancing, particularly in medical device applications. A particular miniaturized manipulator design that offers high dexterity, multiple degrees-of-freedom, and better lateral force rendering than competing designs, has great potential for minimally invasive surgery. However, it faces challenges such as the tendency to suddenly and unpredictably deviate in bending plane orientation at higher pressures. In this work, we identified the cause of this deviation as the buckling of the partition wall and proposed design alternatives along with their manufacturing process to address the problem without compromising the original design features. In both simulation and experiment, the novel design managed to achieve a better bending performance in terms of stiffness and reduced deviation of the bending plane. We also developed an artificial neural network-based inverse kinematics model to further improve the performance of the prototype during vectorization. This approach yielded mean absolute errors in orientation of the bending plane below $5^{\circ }$.

While initially conceived for human motion augmentation, wearable robots have gradually evolved as technological aids in motion assistance and rehabilitation. There are increasing real-world applications in industrial and medical scenarios. Though efforts have been made on wearable robotic systems, e.g. robotic prostheses and exoskeletons, there are still several challenges in kinematics and actuation solutions, dynamic analysis and control of human-robot systems, neuro-control and human-robot interfaces; ergonomics and human-in-the-loop optimization. Meanwhile, real-world applications in industrial or medical scenarios are facing difficulties considering effectiveness.

To remove humans from hazardous environments “good” teleoperated robotic systems are needed. “Good” is defined here to mean a system which is task centred and which is transparent to the user-in other words, a system you can see through. A teleoperated robotic system which strives towards this goal is described by way of illustration. The fundamentals that have helped to achieve this are: design and build from a task centred viewpoint, careful design of the Human Computer Interface(HCI) and special consideration for the systems integration task.

Prosthetics presents a challenge for engineers, they must balance user needs with practicalities. In the past the compromises made have been towards simpler devices. Recently this has begun to change, new microprocessors, powerful motors and novel batteries make it possible to conceive of different solutions. These papers give an overview of what is now possible.

The dynamic model of a new class of underwater robot is derived and the validity of the model is checked experimentally. Close agreements between theory and experiment are attained. The interaction between the buoyancy and gravity forces acting on the robot arm, present in the underwater environment, is used to generate torques necessary to move the arm. The mathematical model of a multi-arm robot is developed to define the interaction between the dynamics of the moving weight and the robot links under the action of the resisting water drag and other external forces. The Lagrangian method is used in the formulation of the arm dynamics. The developed dynamic equations serve as means for designing the control laws necessary for controlling the position of the different joints of the robots. The study indicates that the buoyancy and gravity-driven robot can position a payload accurately as well as at a fairly fast speed of response. It is indicated from the theoretical and experimental study that the arm motion is created by a small displacement of moving weight on the power screw. Therefore, power requirement of this type of robot is just as enough to overcome the friction between the power screw and the moving weight. This features emphasize the potential of the concept as a viable means for driving underwater robots

In this paper we present an experimental comparison between different decentralized controllers for industrial robot manipulators. In spite of the fact that robot manipulators are highly nonlinear and coupled multivariable systems, decentralized controllers have been widely adopted in industrial environments for trajectory tracking, because of their simplicity and their fault tolerance feature. Different kinds of controllers have been investigated: the typical PID-based controller, a nonlinear three-term controller devised by Tarokh, and a variable structure control law, a discontinuous integral control, both in the continuous and in the discretised version. Allowances are made for the tuning of the parameters in order to obtain low tracking errors. Results show that better performances are obtained by controllers other than PID, especially by the discontinuous integral control, so that they appear to be particularly appropriate for the use in industrial robots.

In the original version of this paper the email of the corresponding author, Reza Mahboobi Esfanjani, was given incorrectly. The correct email is [email protected].

The publisher apologises for this error.