Kuei-Shu Hsu

Haptic Direct-Drive Robot Control Scheme in Virtual Reality

This paper explores the use of a 2-D (Direct-Drive Arm) manipulator for mechanism design applications based on virtual reality (VR). This article reviews the system include a user interface, a simulator, and a robot control scheme. The user interface is a combination of a virtual clay environment and human arm dynamics via robot effector handler. The model of the VR system is built based on a haptic interface device behavior that enables the operator to feel the actual force feedback from the virtual environment just as s/he 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 are 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 and that the designed controller is robust to constrained/unconstrained environment.

Design and control of a two-dimensional telerobotic system with a haptic interface

Abstract A model for a ‘master-slave’ two-dimensional telerobotic dynamic system with a haptic interface device is derived. The telerobotic system consists of a ‘master’ robot, which is a direct-drive robot operated by a human arm, and a ‘slave’ robot, which is an x-y type pallet located at a remote site. When the active handle of the master is moved along an arbitrary trajectory, the remote slave duplicates the motion in a constrained or unconstrained environment. The behaviour of the environment is felt by the operator through the active handle of the master. This is achieved by feeding back the disturbance and reaction forces from the environment and the loads to the active handle. Consequently, the operator gets a feel of the task being performed without being physically at the location of the task. A control scheme is devised for the telerobotic system to establish smooth communication between the master and slave robots. This control scheme integrates the dynamics of the human arm, actuators and the environment in the closed-loop system. It was shown that the experimental and the theoretical results are in good agreement and that the design controller is robust to constrained/unconstrained environments.

Design and analysis of a 2-D haptic interface device in virtual reality

Analysis and design of a telerobotics device with a haptic interface, based on the virtual reality (VR) approach for simulating the cutting clay system, is proposed. The force feedback device is built using an x-y table and a multi-degree-of-freedom joystick and an equivalent computer model is computed. A virtual reality model for cutting oil clay using a haptic interface device is subsequently obtained. The VR model for the cutting tool system and the environment is simulated by the virtual haptic model that enables the operator to feel the actual force feedback from the virtual environment just as she/he would from the real environment. A control law for the virtual reality closed-loop model is derived. The stability and performance of the system are studied. Experiments on cutting virtual oil clay are used to validate the theoretical developments. It was shown that the experimental and theoretical results are in good agreement and that the designed controller is robust to constrained/unconstrained environment and load disturbances.

The visual tracking system using a stereo vision robot

Purpose – The purpose of this paper is to use vision stereo to simultaneously acquire image pairs under a normal environment. Then the methods of moving edges detection and moving target shifting are applied to reduce noise error in order to position a target efficiently. The target is then double confirmed via image merge and alignment. After positioning, the visual difference between the target and the image created by the stereo vision system is measured for alignment. Finally, the image depth of the target is calculated followed by real-time target tracking. Design/methodology/approach – This study mainly applies Sobel image principle. In addition, moving edges detection and moving target shifting are also used to work with system multi-threading for improving image identification efficiency. Findings – The results of the experiment suggest that real-time image tracking and positioning under a pre-set environment can be effectively improved. On the other hand, tracking and positioning are slightly aff...

Neural-net tuned PID control of a parallel type mechanism with force feedback for virtual reality applications

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.

Modeling and index analysis of the hexaglide type mechanism

Interest in the analysis and application of a parallel robot system is arising in the automation industry. A new type of 3D (three-dimensional) parallel robot arm manipulator with human interface, as well as the parallel motion control of a platform manipulator actuated by three AC servomotors are introduced in this paper. To comprehensively realize the performance of the parallel robot, the forward kinematics, inverse kinematics, Jacobian and singularity are theoretically derived for the application of quantified and graphical performance synthesis tools presented in by Gosselin (1990). In addition, the computer simulation of the parallel robot with MATLAB program is also proposed for the telerobotic system, and the experimental results of the telerobotic system showed good workability in the remote control. Moreover, the discussions and suggestions from the experiments are fully prepared. Through this study, the capability of this parallel robot in its applications as well as its future research and development are thus approached.

Remote monitoring of an omnidirectional smoke detection system using texture features image processing techniques

Purpose – The purpose of this paper is to develop an early fire-alarm raising system based on video processing, and combine it with the omnidirectional projecting system. It not only gives alarm immediately in early fire so that people can be able to strive for more time to escape from the spot, but also solves problem of discontinued screen which was presented fire scene. Design/methodology/approach – The smoke detection system is made by image processing. The flowchart of smoke detection is improved, which the method of background updating can filter out the moving objects that only stay for a short time in the image; and avoids these objects being determined to be the background. Moreover, the authors extract the flickering area to separate the non-smoke and smoke from the candidate of smoke regions. Finally, the image processing is applied in omnidirectional projecting system, then presented the 360-degree fire scene. Findings – The results show that the smoke detection system can accurately detect th...

The application and development of the distance measurement and tracking system using a video camera

In, this research, the binocular vision effect is used to simulate the neck motion of a man. The exact distance between camera and object can be calculated by using a vision algorithm as well as focus correction. Here, the image error can be corrected by the servomotor. In addition, the object will be placed in the center of the binocular vision frame. If the object can be observed by a single vision only, the monocular method will be also used to estimate its distance. The result reveals that this monocular system can instantaneously determine the distance between the object and lens using treated image data as well as the vision algorithm even though the binocular vision system is not available. We can trace the movement of an object under general condition by using the binocular vision system. The comparison of system error between the monocular and binocular vision systems is also investigated.

A reinforced learning control using iterative error compensation for uncertain dynamical systems

This paper investigates a learning control using iterative error compensation for uncertain systems to enhance the precision of a high speed, computer-controlled machining process. It is specially useful in mass-produced parts produced by a high-speed machine tool system. This method uses an iterative learning technique which adopts machine commands and cutting errors experienced from previous manoeuvres as references for compensation actions in the current manoeuvre. Non-repetitive disturbances and nonlinear dynamics of the cutting processes and servo systems of the machine which greatly affect the convergence of the learning control systems were studied in this research. State feedback and output feedback methods were used for controller design. Stability and performance of learning control systems designed via the proposed method were verified by simulations on a single degree of freedom servo positioning system.

Elastic Balancer Design Using Motion and Energy Synthesis

The actuator of a mechanical/mechanism system often wastes a lot of energy to overcome the gravitational potential energy of the system in order to perform the essential work by the external circumstances. In this study, the motion and energy method are introduced and utilized to simulate the linkage design of a mechanical system. An appropriate elastic-balancer is additionally proposed to support the actuator in counteracting the gravitational force of a traditional elevator to save energy. The elasticbalancer composed of a four-bar linkage and a spring is considered through motion and energy synthesis. It also permits the total potential energy of the original system to remain constant. There is no significant influence to the dynamic characteristics when add a much lighter elastic-balancer to the original system. With the simulated results through the computerized program proposed, it is found that the two balancers connected to the actuator reduced 64% in peak torque as well as the overshoot from the range. The desired elastic potential energy curve of a system is often irregular and not easy to fit. This paper not only fits the desired elastic potential energy curve to the summation curve of generated elastic potential energies by the balancer, but also provides a concrete design approach in synthesizing the four-bar linkage elastic balancers to modify the dynamics of the original system and therefore reduce actuator torque and force.