Patent ID: 9075399
Filing Date: 2015-07-07
Classification: F16H,G05B,H02P

Abstract:
1. A positioning system for controlling driving of an actuator which reduces in speed of rotation of a motor via a wave gear device and transmits the reduced-speed rotation to a load shaft, so as to control positioning of the load shaft; the system comprising: a semi-closed loop feedback controller for feeding back a motor shaft position θ a feedforward linearization compensator for compensating positioning errors in the load shaft due to at least relative rotation-synchronous component or nonlinear friction among nonlinear spring characteristics, relative rotation-synchronous component and nonlinear friction which are nonlinear elements of the actuator, wherein the nonlinear elements for which compensation is to be performed is: only a relative rotation-synchronous component; only nonlinear friction; both a relative rotation-synchronous component and nonlinear friction; or nonlinear spring characteristics, a relative rotation-synchronous component and nonlinear friction; the feedforward linearization compensator is obtained from an equivalent conversion of a feedback linearization compensator into a feedforward compensator, by incorporating a nonlinear plant model representing the actuator to be controlled into the feedback linearization compensator based on an exact linearization method; the nonlinear plant model is defined by the nonlinear state equation shown in formula (6), the state quantity being x=[θ wherein J D J D T D N: reduction ratio, K θ ω θ ω θ θ τ τ i: motor torque current command value; by adding linearization feedback α(x) and an input variable β(x), with the state quantity x as an argument, to the nonlinear plant model, the feedback linearization compensator brings the characteristic from the input v to the output y of the expanded system to d the feedforward linearization compensator uses a load jerk command j the nonlinear spring characteristics in the present invention are nonlinear spring characteristics of the wave gear device relative to load torque defined by formula (1), and the coefficients K among the angular transmission errors of the wave gear device, the relative rotation-synchronous component is an angular transmission error defined by formula (3), the relative rotation-synchronous component being the motor shaft synchronous component θ  and of the nonlinear friction of the wave gear device, the nonlinear friction comprises the motor shaft friction τ where