Comparison of methods for estimation and compensation of friction applied to an inverted pendulum

The inverted pendulum contains non-negligible nonlinearities due to friction, causing limit cycles. In this paper, a recently proposed method is applied to estimate friction using only data from the closed loop operation. The estimate is compared with the results of open loop tests, showing their similarity. The friction compensation is carried out via two different approaches. First, Karnopp and LuGre friction models are used to estimate and compensate friction force. Then knocker and dead band compensators are applied using friction estimates. Both performance and information required for compensation techniques implementation are compared through a real inverted pendulum application.