This paper presents a simple identification method of the actual kinematic parameters for a robot with parallel joints. It is known that Denavit–Hartenberg's coordinate System is not useful for nearly parallel joints. In this paper, the coordinate frames are reassigned to model the kinematic parameter between nearly parallel joints by four parameters. The proposed identification method uses a straight ruler about 1 m long. A robot hand is placed by using a teaching pendant at the prescribed points on the ruler, and the corresponding error function is defined. The identified kinematic parameters, which make the error function zero, are obtained by the iterative least square method based on the singular value decomposition. In the compensation of joint angles, only the position is considered because the usual applications of robot do not require a precise orientation control.

A new neural network (NN) control technique for robot manipulators is introduced in this paper. The fundamental robot control technique is the model-based computed-torque control which is subjected to performance degradation due. to model uncertainty. NN controllers have been traditionally used to generate a compensating joint torque to account for the effects of the uncertainties. The proposed NN control approach is conceptually different in that it is aimed at prefiltering the desired joint trajectories before they are used to command the computed-torque-controlled robot system (the plant) to counteract performance degradation due to plant uncertainties. In this framework, the NN controller serves as the inverse model of the plant, which can be trained on-line using joint tracking error. Several variations of this basic technique is introduced; Back-propagation training algorithms for the NN controller have been developed. Simulation results have demonstrated the excellent tracking performance of the proposed control technique.

An implementation of a real-time scheme suitable for coordinated-motion control of a class of teleoperated industrial machines with redundancy is presented. An efficient gradient projection technique is adopted for the numerical solution. The scheme utilizes the redundancy to avoid the joint limits by minimizing a hyperbolic function of the joint distances from the mid-range. This new performance criterion is shown to be advantageous over similar criteria; both the joint-limit avoidance capability and the resulting joint velocity profiles can be adjusted by the appropriate choice of parameters introduced in the criterion. Previous criteria are shown to be special cases of the new criterion. Furthermore, the scheme includes a novel algorithm which incorporates the bounded joint velocities. The joint motions are determined considering both the required task in terms of the desired end-effector speed and the dynamic considerations, such as hydraulic circuit interdependency and power limitations.

The feasibility and effectiveness of the implementation of the scheme is first tested through simulations of a Kaiser Spyder-like excavator machine on a PC-486 micro-computer. The robustness and real-time response of the scheme are then validated on a real-time excavator-based graphics simulator interfaced to a human operator through a joystick.

In regard to work-space controller design, a derivation of the relationships between the operational approach and the decoupling method is introduced. The given generating rules, which are valid for nonredundant robots, permit the design of a Position-Speed-Acceleration controller or hybrid Force-PSA controllers.

A practical architecture, using a four-bar-linkage, is considered for the University of Minnesota direct drive rotot. This statically-balanced direct drive robot has been constructed for stability analysis of the robot in constrained maneuvers.2–6 As a result of the elimination of the gravity forces (without any counter weights), smaller actuators and consequently smaller amplifiers were chosen. The motors yield acceleration of 5 g at the robot end point without overheating. High torque, low speed, brush-less AC synchronous motors are used to power the robot. Graphite-epoxy composite material is used for the construction of the robot links. A 4-node parallel processor has been used to control the robot. The dynamic tracking accuracy-with the feedforward torque method as a control law- has been derived experimentally.

The main objective of this paper is a presentation of an experimental identification of a non-direct drive robot and load dynamic parameters, which appear in the integral model. The last one is based on the energy theorem formulation. In the robotics literature there are not many experimental results known to the authors, concerning the identification of the dynamic parameters of different models. In order to satisfy this, the experimental system has been built around an industrial ASEA IRp-6 robot. In this paper we propose to precompute the friction characteristics which are separated in the integral model. Various aspects of the exciting trajectories are considered. It is shown how to identify the friction coefficients using a short integral model. The experimental results are presented, including comparison of the results for both integral and differential identification. The identified models are verified by computing the predicted torques and trajectories

In a 1985 issue of this journal, Kusiak presented a formulation of the single period station loading problem related to planning of Flexible Manufacturing Systems. This note makes several observations about this formulation and the linear programming solution technique used. Possible variations and some structural properties of the fomulation are highlighted.