Yuichiro Taira

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.

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.

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.

Adaptive control of underwater vehicle-manipulator systems using radial basis function networks

This paper deals with a control scheme for underwater vehicle-manipulator systems with the dynamics of thrusters in the presence of uncertainties in system parameters. We have developed two controllers that overcome thruster nonlinearities, which cause an uncontrollable system: one is a regressor-based adaptive controller and the other is a robust controller. However, the structure of the adaptive controller is very complex due to the feedforward terms including the regressors of dynamic system models, and the error feedback gains of the robust controller with a good control performance are excessively high due to the lack of feedforward terms. In this paper we develop an adaptive controller that uses radial basis function networks instead of the feedforward terms. The replacement leads to a moderately high gain controller whose structure is simpler than that of the regressor-based adaptive controller.

Digital tracking control of space robots using a transpose of the generalized Jacobian matrix

We have proposed discrete time-control methods using the transpose of the generalized Jacobian matrix (GJM) for free-floating space robots having manipulators. The control methods are robust for singular configurations of robots. Since the methods belong to a class of constant-value control, in this article we propose a digital trajectory tracking control method using the transpose of the GJM. Computer simulations show the effectiveness of the proposed method.

Digital adaptive control of space robot manipulator having input constraints

This paper deals with a digital adaptive control for a manipulator mounted on a space robot. Most control methods are based on the supposition that all physical parameters of the space robot are known. However, if the end-effector catches an unknown object, the physical parameters of the robot are changed. Furthermore, joint actuators of a manipulator generally have input constraints. Even though the end-effector does not catch any objects, if the inputs of the actuators become saturated, the control performance gets worse. In this paper, we propose a digital adaptive control method for a manipulator having input constraints. Experimental results from a Space Manipulator Robot Testbed demonstrate the effectiveness of the proposed method.

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

We have studied the cooperative manipulation of floating object by several space robots. For these cooperative motions, we have reported that a tracking control method using the transpose of the generalized Jacobian matrix (GJM) can be utilized for robots with joint torque controllers. For cooperative motions by some robots with joint velocity controllers, we proposed a tracking control method using the transpose of the GJM. Simulation results show the effectiveness of the proposed control method.

Digital control of space robot manipulators with velocity type joint controller using transpose of generalized Jacobian matrix

For free floating space robots having manipulators, we have proposed a discrete-time tracking control method using the transpose of Generalized Jacobian Matrix (GJM). Control inputs of the control method are joint torques of the manipulator. In this paper, the control method is augmented for angular velocity inputs of the joints. Computer simulations have shown the effectiveness of the augmented method.

Digital Control of Free Floating Space Robot Manipulators Using Transpose of Generalized Jacobian Matrix

Space robots having manipulators are expected to work in future space missions (Xu & Kanade, 1993). Since it is difficult to supply fuel to the robots equipped with rocket motors during manipulation, control methods for free-floating space robots consisting of a base and a manipulator have been proposed (Dubowsky & Papadopulos, 1993; Masutani et al., 1989a;b; Sagara et al., 1998a;b; Shin et al., 1995; Umetani & Yoshida, 1989; Yamamoto et al., 1995). Most of them use the inverse of the Generalized Jacobian Matrix (GJM) which is a coefficient matrix between the velocity of the end-effector of the manipulator and the manipulator’s joint velocity (Umetani & Yoshida, 1989). Therefore, in a case that the robot manipulator gets into a singular configuration, the inverse of the GJM does not exist and the manipulator is out of control. For this problem, a continuous-time control method using the transpose of the GJM has been proposed for manipulators equipped with joint torque controllers (Masutani et al., 1989a;b). In practical systems digital computers are utilized for controllers. So, we have proposed a discrete-time control method using the transpose of the GJM (Taira et al, 2001). The control method using the transpose of the GJM uses position and orientation errors between the desired and actual values of the end-effector. Namely, the control method belongs to a class of constant value control such as PID control. Therefore, the value of the errors depends on the desired linear and angular velocities of the end-effector based on the desired trajectory. To obtain higher control performance we have proposed a digital trajectory tracking control method that has variable feedback gains depending on the desired linear and angular velocities of the end-effector (Sagara & Taira, 2007). Moreover, we have also proposed the control method for manipulators with velocity type joint controllers (Sagara & Taira, 2008b). In addition, it is considered that many tasks will be achieved by cooperative motions of several space robots in future space missions. We have studied control problems for realizing cooperative manipulations, and reported that a system consisting of space robots with manipulators and a floating object can be treated as a kind of distributed system (Katoh et al., 1997; Sagara et al., 1998b). Using the distributed system representation, each robot consisting of the distributed system can be designed by the control system individually, and we have reported a cooperative manipulation of a floating object by some space robots with the control methods using the transpose of the GJM (Sagara & Taira, 2008a; 2009). 2

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

Deals with a digital kinematic control method of space robot manipulators. The method uses not the inverse of the generalized Jacobian matrix but its transpose and guarantees the kinematic stability of the system in the discrete time domain by using Lyapunovs direct method for difference equations. Computer simulation, where a 3 DOF manipulator mounted on a robot base is selected, is performed. Simulation result demonstrates the effectiveness of the proposed method.