Digital Control of Micro-Systems using On-Line Arithmetic

The integration of control micro-electronics within mechanical mini and micro-systems is a current trend in the design of high-performance mechatronic systems. However, implementing controllers of higher complexity, while still decreasing the size of the system implies difficult demands on the control electronics. In order to maintain a high computational speed and to reduce controller size, implementation complexity and power consumption, often custom electronics become necessary. Actually, there are two trends towards a progressive miniaturization. One is a pure technological optimization (shrinking of transistor and interconnection dimensions) which is based on existing algorithms. The other consists of efforts to change the signal processing structure. In this thesis, the latter approach is followed and it is demonstrated that serial computations with most significant digits first (MSDF), that is online arithmetic, offer an important potential for real-time control. They allow combination of traditional functions, such as analog to digital converters and control data computations. This introduces a parallelism between sequential operations by overlapping these in a digit-pipelined fashion. Additionally, a parallelism at the operator level becomes possible because of the small size and low interconnection bandwidth of on-line arithmetic operations. This makes controller construction very modular and leads to very efficient controller implementations with small size, high speed and low power consumption. In this thesis the use of on-line arithmetic for real-time control is presented in comparison with classical methods like digit-parallel approaches or least significant digit first (LSDF) arithmetic. Theoretical aspects of on-line arithmetic have already been known for about 20 years in the computer science literature, but they were never applied to realtime control. Therefore, most control engineers are not familiar with this method and a short introduction to the basic concepts of on-line