Masanobu Koga

Coordinated motion control of robot arms based on the virtual internal model

This paper proposes an alternative coordinated motion control architecture of robot arms manipulating an object. The motion and the internal force of the object are resolved into the motion of each arm. Each arm is controlled based on the virtual internal model so as to operate in coordination even if geometric errors exist in the robot arms and the object. The virtual internal model is a reference model driven by sensory information implemented in the controller. The proposed architecture will keep the state of the system bounded even if the breakage of the manipulated object occurs. The control algorithm is experimentally applied to the coordinated motion control of two planar robot arms, each of which has three degrees of freedom. The results illustrate the validity of the proposed control architecture.

An integrated software environment for the design and real-time implementation of control systems

Abstract This paper introduces the development of a CAD environment for control systems, which supports not only the analysis of control systems, and the design of controllers, but also the real-time implementation of controllers. By utilizing this software, the control engineer is able to repeat the procedure for the modification of both controllers and experiments, without recompiling, to attain better performance. The software also offers a facility to update the parameters of controllers without interrupting the real-time control, which helps in the on-line tuning of controllers. Otherwise, if some of the parameters of a controller are changed on-line, the control input may change in a discontinuous fashion. This would have a serious effect on the control systems. A method for the on-line tuning of a state feedback controller with a state observer is proposed and verified through an experiment with an inverted pendulum.

An adaptive control of a nonholonomic space robot

This paper presents a design method of an adaptive controller based on time-state form for a nonholonomic space robot which consists of a base, an arm and two weights. We assume that the base and the arm are connected at the center of gravity of the base and that the center of the arm and two weights are the same. The weights are assumed to move synchronously.

A numerical computational approach of Hamilton-Jacobi-Isaacs equation in nonlinear H/sub /spl infin// control problems

We propose a new numerical approach to computing an approximate solution of the Hamilton-Jacobi-Isaacs Equation (HJE) developed in nonlinear H/sub /spl infin// control problems. The new method is motivated by a method proposed by Lu and Doyle (1995) that derived a state dependent Riccati equation (sRE) from the HJE under some kinds of integratability constraint. They formulated a NLMI (nonlinear matrix inequality)-problem to solve a numerical solution of the sRE. However, the resulting sRE solution from their method cannot lead us to a promising HJE solution since its integratability assumption is not considered at all. Here, we propose a method to treat the constraints by means of the least-square-error approximation method. Specifically, we realize the problem by choosing the to-be-minimized square-error function in approximating a HJE solution from the sRE solution. Then, minimization of the square-error function provides us with a meaningful approximation method to determine an optimal HJE solution from the sRE solution in the sense of least square-error. We discuss the advantages of the new method in comparison with another approximation approach-Taylor series approximation. Finally, we give numerical examples of a nonlinear H/sub /spl infin//, control problem, and it is verified that a nonlinear H/sub /spl infin// controller derived from the new approach could result more satisfactory system performance than the one from Taylor series approximation method or linear H/sub /spl infin// theory.

A control of underactuated hopping gait systems: acrobot example

While many researchers have been working on hopping gait systems, most of the previous works have focused on the mechanism designed by Raibert (1986) which has two actuators. We consider the acrobot, which has only one actuator as our model of a hopping gait system. In spite of the difficulty of realizing the acrobots hopping gait, it produces more interesting and attractive control problems than Raiberts model. Furthermore, the hopping principle of legged systems can be understood by treating the system which is difficult to control by intuition like the acrobot.

An Integrated Software Environment for Design and Real-Time Implementation of Control Systems

Abstract In this paper development of a CAD of control systems is introduced which enables us to do not only analysis of control systems, design of controllers but also real-time implementation of controllers. By utilizing this software, the control engineer is able to repeat the procedure of modification of controllers and experiments without recompile to attain better performance. The software also offers the facility to update the parameters of controllers without stopping real-time control, which helps on-line tuning of controllers. If some parameters of the controller is changed on-line, the control input may change discontinuously. It has serious effect on the control systems. A method for on-line tuning of state feedback controller with state observer is proposed and verified through the experiment with an inverted pendulum.

Manipulation problem of a ball between two parallel plates based on time-state control form

This paper deals with the ball-plate problem being considered as an effective model for nonholonomic constraints, and gives simultaneous control method for both the position and orientation of the ball based on the time-state control form.

Design of a nonlinear H/sub /spl infin// state feedback controller for bilinear systems with nonlinear weight

This paper gives the design method of a nonlinear H/sub /spl infin// state feedback controller for bilinear systems with nonlinear weights. Generally, in order to derive a nonlinear H/sub /spl infin// controller, we have to solve the Hamilton Jacobi inequality, but it is very difficult to solve. In this paper, it is shown that the Hamilton Jacobi inequality is reduced to the algebraic Riccati inequality, under some constraints on nonlinear weights. Finally, one of the admissible nonlinear weights are derived.

M A TX: A High-Performance Interactive Software Package for Scientific and Engineering Computation

Abstract MaTX is a high-performance interactive software package for scientific and engineering numeric and symbolic Computation. MaTX integrates numerical analysis, matrix computation, and symbolic Computation in an easy-ta-use environment where problems and solutions are expressed just as they are written mathematically. MaTX supports not only interpreter for interactive processing bat also compiler for batch processing. The data in MaTX can be examined graphically using a graphical drawing and editing environment XPLOT.

A control for a class of nonholonomic systems subject to velocity constraints using acceleration inputs

We present a control method to stabilize a class of systems subject to velocity constraints using acceleration inputs. The method is an extension of time-state control form and its control strategy which we have already proposed for a class of nonholonomic systems subject to velocity constraints with velocity inputs. We can also apply this new strategy to stabilizing control for a class of nonholonomic systems. Such a class of systems is broader than those which can be transformed into the chained form.