Shinichi Sagara

Digital RAC for underwater vehicle-manipulator systems considering singular configuration

We have proposed continuous-time and discrete-time resolved acceleration control methods for underwater vehicle-manipulator systems and the effectiveness of the control methods has been shown by experiments. In this article, we propose a digital control method considering the singular configuration of manipulator. Experimental results show the effectiveness of the proposed method.

Digital type disturbance compensation control of a floating underwater robot with 2 link manipulator

We have proposed continuous and discrete time resolved acceleration control methods for underwater vehicle-manipulator systems and the effectiveness of the control methods have been shown by experiments. In this paper, we propose a digital type disturbance compensation control method based on the RAC method considering singular configuration of manipulator. Experimental results show the effectiveness of the proposed method.

A design of digital adaptive control systems for space robot manipulators using a transpose of the generalized Jacobian matrix

We propose a digital control method for space robot manipulators using the transpose of the generalized Jacobian matrix. The method, however, is developed on the supposition that all the physical parameters of the robot manipulator are known. Therefore, if the end-effector of the manipulator captures an object whose mass is unknown, the stability of the control system cannot be maintained because the physical parameters are changed. This article presents the adaptive control version.

A master-slave control system for a semi-autonomous underwater vehicle-manipulator system

Underwater vehicle-manipulator systems (UVMS) are expected to play an important role in ocean exploration. It is considered that UVMS will be operated by both automatic and manual control. We have proposed an automatic control method. In this article, we propose a master-slave system for a UVMS. The effectiveness of the proposed master-slave control system is demonstrated by using a floating underwater robot with a 2-link manipulator.

Digital adaptive control of space robot manipulators using transpose of generalized Jacobian matrix

We have proposed a digital control method of space robot manipulators using the transpose of a generalized Jacobian matrix. The trajectory of the end-effector, however, is generally curved, because a desired trajectory is not defined in the control method. Furthermore, the method is based on the supposition that all physical parameters of the robot manipulator are known; therefore, if the end-effector captures an unknown mass object, the physical parameters are changed, and the control performance gets worse. In the paper, setting a desired trajectory and parameter identification are applied to the control method so as to overcome the drawbacks. Computer simulation, where a 3 DOF planar manipulator mounted on a free-floating robot base is selected, is performed. The simulation result demonstrates the effectiveness of the combination of setting the desired trajectory and parameter identification.

Manipulation of a floating object by two space manipulators

This paper deals with manipulation of a floating object by two space robots with manipulators. It is shown in this paper that a total system consisting of two robots and a floating object could be treated as a distributed system, and then a new generalized Jacobian matrix (GJM) is defined. Moreover, it is confirmed that this type of GJM is effective for using adaptive control for decreasing the amount of calculation for the control algorithm.

Cooperative manipulation of a floating object by some space robots: application of a tracking control method using the transpose of the generalized Jacobian matrix

In future space missions, it is considered that many tasks will be achieved by cooperative motions of space robots. For free-floating space robots with manipulators, we have proposed a digital tracking control method using the transpose of the generalized Jacobian matrix (GJM). In this paper, the tracking control method using the transpose of the GJM is applied to cooperative manipulations of a floating object by space robots. Simulation results show the effectiveness of the control method.

Digital adaptive control for servo system with unknown nonlinear friction

The authors consider the design of a discrete time model reference adaptive control system (MRACS) for motion control systems with unknown nonlinear friction. From a control system viewpoint, the static and Coulomb frictions are characterized by a nonlinear dead-zone element and constant value disturbance for the control input signal, respectively. The discrete MRACS is considered for a nonlinear system which is a cascade combination of an unknown dead-zone block and a linear dynamic block with disturbance. In order to verify the validity of the theory, the design method described is applied to a servo system influenced by friction. Experimental results show the high control performance of the constructed MRACS and the effectiveness of the proposed method.<<ETX>>

Digital RAC with a disturbance observer for underwater vehicle-manipulator systems

Most control methods of underwater vehiclemanipulator systems (UVMS) are based on the computed torque method that is used for underwater robotic vehicles. We have proposed a resolved acceleration control (RAC) method for UVMS. In this article, we propose a disturbance compensation control method for both vehicle and manipulator based on the RAC method. Experimental results using an underwater robot with a vertical planar 2-link manipulator show that the proposed control method has good control performance.

Adaptive RMRC for cooperative manipulation of a floating object by two free-based space robots

This paper deals with an adaptive resolved motion rate control (RMRC) method for a cooperative manipulation of a floating object by two free-based space robots with manipulators. Discussions as for the adaptive estimation are done on the divided generalized Jacobi matrices, which can be derived by system partition of the whole robot system. The method proposed here has an advantage that control algorithm of each robot is same even if a number of robots increases. The validity of the method was successfully confirmed by computer simulation.