SUMMARYThe paper presents an educational system for teaching and research in robotics which consists of a manipulator, controller and a PC compatible host computer. The advanced design of host-computer user-interface software makes the system very suitable for teaching. It allows the user not only to follow the system states but also to change the control structure on-line. In the first part of this paper the architecture of the system, window-oriented user interface, specially designed robot language and several build-in students lessons will be described as well as the data acquisition system and advanced graphical capabilities.In the second part of this paper the executive controller architecture is described. Besides the manipulator control function and IO operations, the controller supports communication with the host-computer. The controller is programmable, i.e. it executes various tasks within user-defined and build-in students lessons. By the use of simple host-computer commands the controller can execute various algorithms both for trajectory generation and dynamically compensated digital servo control. The dynamic model components in the feed-forward and feed-back control loop can be selectively included and changed during the manipulator's motion. Experimental results with a 4-link educational robot are presented.
Efficient parallel processing algorithms have been used in a wide variety of applications such as simulation, robot control, and image synthesis. This paper presents two novel parallel algorithms f o r computing robot inverse dynamics (as well as control laws) starting f r o m the customized symbolic robot models. The first algorithm resolves the scheduling problem f o r an array of pipelined processors. The second one is devoted t o parallel processors connected by a complete crossbar in!erconnection network. The main feature of the proposed algorithms is that they take into account the communication delays between processors and minimize both the execution time and the communication cost. The algorithms are verified by experiments on an INMOS T800 transputer based system. The experimental results show that the most complicated dynamic control laws can be executed in a submilisecond range.
One of the problems in real-time control of reduntlant manipulators is considerably increased computational complexity comparing with nonredundant robots. The main idea in this paper is to reduce computational complexity by combining analytical and pseudoinverw solution. In this way the dimensions of Jacobian arc' ronsiderably reduced yielding several times less computational complexity. Further reduction of computat ioiial time is achieved by applying the gradient projection method [6] to the actually redundant subrobot. At the end, a simple performance criterion for avoiding wrist singularity is proposed.
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