Real-time simulation of friction in a flexible space manipulator

This paper describes the development of a real-time simulation model of the European Robot Arm ERA that will be used on the Russian segment of the International Space Station. The simulation model contains a friction model that is not based on the conventional hypothesis that friction is opposite to velocity, but on the new hypothesis that friction tries to stop the system. The conventional hypothesis leads to a strongly non-linear friction model that causes numerical instability. The new hypothesis leads to a new friction model that simulates the effects of the friction accurately in only little computing time.