Dynamic model based friction compensation on the Furuta pendulum

The Furuta pendulum is used to evaluate a friction compensator based on the dynamic LuGre friction model. The effect of friction compensation is very well illustrated by reduction of limit cycles when stabilising the pendulum. The observer based LuGre friction compensator is compared with classical Coulomb and stiction compensator schemes. Existing analysis of the LuGre observer is extended to observer based friction compensation in general linear state feedback control of linear time invariant systems where friction enters the system at the input. In particular this observer based friction compensation is applicable on the pendulum. The performance of the LuGre compensator was found to be similar to that of the stiction compensator. Important differences is the smooth control signal obtained from the LuGre observer, and that it uses less prior information.