An exoskeleton joint output force control technology based on improved ADRC

The exoskeleton robot is a kind of typical multivariable, strong coupling and time-varying nonlinear control system. When the joint is composed of a hydraulic pump control system, it is hard to get an accurate exoskeleton single joint force control model, due to the presence of nonlinear factors, such as friction and pressure fluctuation. Being unable to use a model-based control strategy, we propose applying the theory of active disturbance rejection controller (ADRC) to suppress various disturbances on the joint and improve the dynamic performance of single joint. First of all, we build a state equation model, using the principle of hydraulic system. Secondly, we introduce the joint output force control method of ADRC. Finally, we experiment and compare the joint output force control effect between ADRC and PID control strategies. The experimental results show that proposed ADRC has a good control effect.