This paper discusses a cooperative control problem by two one-link flexible Timoshenko arms. The goal is to control a grasping force to collect an object with the two flexible arms, and to simultaneously suppress the vibrations of the arms. To solve this problem, we propose a boundary controller that is based on a dynamic model represented by a hybrid PDE-ODE model; the exponential stability of the closed-loop system is then proven by the frequency domain method. Finally, several numerical simulations are carried out to investigate the validity of the proposed boundary cooperative controller.
This paper presents the design and characteristics of a five-fingered haptic interface robot named HIRO III. The aim of the development of HIRO III is to provide a high-precision three-directional force at the five human fingertips. HIRO III consists of a 15-degrees-of-freedom (DOF) haptic hand, a 6-DOF interface arm, and a control system. The haptic interface, which consists of a robot arm and hand, can be used in a large workspace and can provide multipoint contact between the user and a virtual environment. However, the following problems peculiar to a multi-DOF robot have arisen: a large amount of friction, a backlash, and the presence of many wires for many motors and sensors. To solve these problems, a new mechanism and a wire-saving control system have been designed and developed. Furthermore, several experiments have been carried out to investigate the performance of HIRO III. These results show the high-precision force display and great potential of HIRO III.
Abstract-This paper discusses a contact-force control problem for a flexible arm. This flexible arm includes a Timoshenko beam, and thus we call it the flexible Timoshenko arm. The aim of the force control is to control the contact force at the contact point. To solve this problem, we propose a simple boundary controller and show the exponential stability of the closed-loop system by the frequency domain method. Finally, we describe simulation results carried out to investigate the validity of the proposed controller for the force control problem.
This paper addresses the adaptive synchronization problem of networked mechanical systems in task space with time-varying communication delays, where both kinematic and dynamic uncertainties are considered and the information flow in the networks is represented by a directed graph. Based on a novel coordination auxiliary system, we first extend existing feedback architecture to achieve synchronization of networked mechanical systems in task space with slow-varying delays. Given that abrupt turns arise for the delays sometimes, we then propose a delay-independent adaptive synchronization control scheme which removes the requirement of the slow-varying condition. Both of the two control schemes are established with time-domain approaches by using Lyapunov-Krasovskii functions. Simulation results are provided to demonstrate the effectiveness of the proposed control schemes.
This paper discusses a contact-force control problem of a one-link flexible arm. This flexible arm includes a Timoshenko beam, and thus we call it the flexible Timoshenko arm. The primary aim is to control the contact force at the contact point. To do so, we first apply our previously proposed force controller, which exponentially stabilizes the closed-loop system of a flexible Euler-Bernoulli arm, to the force-control problem of the flexible Timoshenko arm. We then show that our previously proposed force controller cannot exponentially stabilize the flexible Timoshenko arm. Next, we consider the flexible Timoshenko arm, which is making contact with a soft environment. By utilizing the damping force in the soft environment, as well as the controller, we try to overcome the problem. We then prove the exponential stability of the closed-loop system. Finally, we provide simulation results, and consider the validity of our force controller.
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