Aiming at the non-linear friction problem of spatial robotic arm joints

non-linear friction modeling and compensation methods are proposed.Firstly

the relationships between the non-linear friction and the motor current and the non-linear friction and the angular acceleration are derived based on the established dynamics equations of robotic arm joints.Then

the angular acceleration is estimated based on the Kalman-Newton prediction machine which is designed through the sampled angle signal.Through the angular acceleration and sampling current

the friction torque is calculated

and an exponential friction model is established.Finally

based on the friction model

a feed-forward compensation controller is designed to compensate the non-linear friction.The suitability of this methods is verified via a series of robotic arm joint driving experiments.