Control systems recommendations, from investigations

The restricted-unrestricted approach not only improves results from the unrestricted approach, but also allows to rigorously describe the effect of spin polarization for tlie hyperfine coupling constants as well as to provide ways to analyze the behavior of spin polarization (response term in RU approach, see fheory part) in problematic cases. The RU approach therefore provides a higher degree of control over the calculation and its analysis compared to the unrestricted formalism. It can consequently be recommended for investigations of hyperfine coupling constants in various molecular systems. 

These complex systems were investigated in a European "TE)E" project for mobile medical manipulator systems, in which the author was concerned with safety issues ( 10). The TIDE project specified an international bus structure for a collection of sub-systems, (powered wheelchairs, manipulator and environmental controller). It also highlighted the particular problems for medical manipulators in this role. For the wheelchair and other systems a Dead Mans Switch ( DMS) has been recommended whereby for any prime mover to continue to act, a switch has to be positively held in an on-position. The moment that the DMS is released the power is removed from the local prime mover power relays. However, such a severe stop would be disadvantageous for the smooth control of a manipulator, so instead it is proposed for die manipulator to have a DMS linked to a zero velocity command, fed into the normal control system. This has the disadvantage that the DMS is now reliant upon the integrity of the control system, but is probably the best overall compromise. 

These recommendations and those resulting from other thoroughly investigated accidents also provide an excellent resource to assist in generating the system safety requirements and constraints for similar types of systems and in designing improved safety control structures. 

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