André Bakkers

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, i.e. 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.

Automatic generation of scheduling and communication code in real-time parallel programs

Inter-process communication and scheduling are notorious problem areas in the design of real-time systems. Using CASE tools, the system design phase will in general result in a system description in the form of parallel processes. Manual allocation of these processes to processors may result in error prone and/or slow communication code. Scheduling of the processes, necessary to meet timing constraints, is also a tedious task that takes many iterations. The described design tools result in code that is comparable in quality and performance with expert manual realization. Many network layers have been implemented to relieve the user from the low-level programming of communication software. However, the increase in user-friendliness is usually paid with performance degradation. The proposed approach combines user-friendliness with high performance by generating communication software that is tailor-made for the application. A similar approach is followed with the scheduling software. Schedulers in the form of a built-in a kernel are available all the time and cause overhead all the time. The proposed preprocessor tool generates scheduling software after analyzing the timing requirements of the particular application. This results in simple code for simple timing requirements and more complicated code for complex timing requirements. The tools have been implemented in Occam for use on a transputer. However, the results are valid for any distributed memory machine.