Resolved Motion Research Articles

Resolved motion rate control of space manipulators with generalized Jacobian matrix

The authors establish a control method for space manipulators taking dynamical interaction between the manipulator arm and the base satellite into account. The kinematics of free-flying multibody systems is investigated by introducing the momentum conservation law into the formulation and a novel Jacobian matrix in generalized form for space robotic arms is derived. The authors develop a control method for space manipulators based on the resolved motion control concept. The proposed method is widely applicable in solving not only free-flying manipulation problems but also attitude-control problems. The validity of the method is demonstrated by computer simulations with a realistic model of a robot satellite.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

一般化ヤコビ行列を用いた宇宙用ロボットマニピュレータの分解速度制御

In recent years, space has attracted special interest as a new application field of robotics. A robotic teleoperator system installed with space manipulators will play an important role in future space projects, such as constructing space structures or servicing satellites. However, in space environment, the lack of a fixed base arises many problems in controlling space robotic systems. In general, any motion of the manipulator arm will induce reaction forces and moments which disturb position and attitude of the supporting base satellite. To establish a control method for space manipulators taking dynamical interaction between the manipulator arm and the base satellite into account, the authors investigate the kinematics of free-flying multi-jointed link systems by introducing the momentum conservation law into the formulation and derive a new Jacobian matrix in generalized form for space robotic arms. By means of the new matrix, they develop a control method for space manipulators based on the resolved motion rate control concept. The proposed method is widely applicable for not only free-flying manipulation problems but also attitude control problems. The validity of the method is demonstrated by computer simulations with a realistic model of robot satellite.

Resolved Motion Adaptive Control for Mechanical Manipulators

This paper presents the development of a resolved motion adaptive control which adopts the ideas of “resolved motion rate control” [8] and “resolved motion acceleration control” [10] to control a manipulator in Cartesian coordinates for various loading conditions. The proposed adaptive control is performed at the hand level and is based on the linearized perturbation system along a desired hand trajectory. The controlled system is characterized by feedforward and feedback components which can be computed separately and simultaneously. The feedforward component resolves the specified positions, velocities, and accelerations of the hand into a set of values of joint positions, velocities, and accelerations from which the nominal joint torques are computed using the Newton-Euler equations of motion to compensate all the interaction forces among the various joints. The feedback component consisting of recursive least square identification scheme and an optimal adaptive self-tuning controller for the linearized system computes the perturbation torques which reduce the manipulator hand position and velocity errors along the nominal hand trajectory. The feasibility of implementing the proposed adaptive control using present day low-cost microprocessors is explored.

Resolved Motion Force Control of Robot Manipulator

A new Cartesian position control called resolved motion force control (RMFC) has been developed for robot manipulator. It adapts force convergence concept to control the Cartesian force and position instead of classical joint control. In this way, the changing configurations, gravity loading, and internal friction of the manipulator can be automatically compensated. Also, the method only uses the Jacobian transpose matrix such that it is applicable to more than six degrees-of-freedom manipulator without increasing the computational burden.

The LEMMA concept: A new manipulator

The LEMMA is a proposed conceptual design of a remote teleoperator manipulator arm with 6 degrees of freedom, exclusive of the end-effector. The bevel gear arrangement in 4 of the 6 degrees of freedom, together with the concentric-tubular arm configuration, requires a unique and a novel drive mechanism. This differential drive assembly, housed in the shoulder, is a self-compensating device and simplifies the matrix solution for the resolved motion rate control system needed to guide the arm in its performances. The article will describe the need for the 6 degrees of freedom as established by the work envelope, the functioning of the differential shoulder drive, the arm and joint configuration, and the anticipated degree of accuracy.

An evaluation of control modes in high gain manipulator systems

The performance of replica master and resolved motion rate control of a large manipulator is evaluated for two tasks. The first task simulates removing parts from a conveyor and stacking them on a pallet. The second task simulates stowing palletized cargo in a container. Related experiments are discussed and the results correlated to this work. Results show the bilateral master to have a distinct performance advantage over resolved motion rate control. The advantage is not as large as reported for small manipulators, however.

Resolved Motion Rate Control of Manipulators and Human Prostheses

The kinematics of remote manipulators and human prostheses is analyzed for the purpose of deriving resolved motion rate control. That is, the operator is enabled to call for the desired hand motion directly along axes relevant to the task environment. The approach suggests solutions to problems of coordination, motion under task constraints, and appreciation of forces encountered by the controlled hand.