Transputer control of a flexible robot link

The applicability of transputers in control systems is investigated. This is done by implementing a controller for a flexible robot arm with one degree of freedom on a system consisting of an IBM-AT and four transputers. It is found that a control system with transputers offers a great improvement compared with conventional digital control systems. Transputers can solve the common problem in control practice, Le. having very sophisticted controllers but not being able to implement them because they need too much computing time. However, transputers are not an optimal solution for more sophisticated control systems because of shortcomings in the scheduling mechanism. control systems transputers robots Today's robots, although built to huge sizes, are only able to manipulate masses that are small compared with their own weight. In some applications, as in automotive robots, light arms are preferred. A relatively low mass can be driven by small motors and higher accelerations can be achieved. However, because of the inherent flexibility of light arms it is much more difficult to position the end-effector accurately. To study the problems in controlling light, flexible robot links, a 'robot' was constructed as a long aluminium strip (190 x 6 x 0.4 cm) driven by a DC motor. Until recently this robot was controlled by a Z80 microprocessor system with a floating-point coprocessor, but it was soon found that this system was too slow for accurate control of the robot arm. Evidently, more processing power was needed. This could be obtained by faster processors like the Motorola 68020. However, with the increasing complexity of control algorithms, the limits of these processors will soon be reached as well. Parallelism is the key to the solution of this problem: a parallel system can be expanded gradually to a high capacity, although one has to be aware that not even/problem can be solved in parallel without introducing a large communication overhead. The transputer has been designed for building concurrent systems, so we have investigated whether trans-purer networks can be useful in complex robot control applications. Digital control systems have a specific quality; the plant to be controlled has to be sampled at specific equidistant moments. It is this strict equidistant sampling that distinguishes digital control systems from other realtime systems. Generally speaking, two types of tasks exist in such a system, i.e. time-bounded and time-limited tasks 1. Time-bounded tasks (the sample and control actions) have to be executed …