Patent ID: 8427094

Claim:
A method for controlling by a processor, positioning of an actuator which reduces a rotational output of a motor via a wave gear device and transmitting the output from a load shaft, and controlling positioning of the load shaft based on a rotational position and speed of a motor shaft of the motor, the processor arranged to: perform non-linear spring compensation for inhibiting a reduction in the accuracy with which positioning of the load shaft is controlled, as caused by non-linear elastic deformation in relation to a load torque of the wave gear device; and in the non-linear spring compensation, construct a plant model that has been linearized using an exact linearization technique from the actuator to be controlled, and defining the linearization feedback α(x) and input conversion β(x) as well as the characteristics of the expansion system from input v to output y according to formulae (A), (B), and (C), respectively; ⁢ [ FORMULA ⁢ ⁢ A ] α ⁡ ( x ) · x = - J m ⁢ J l ⁢ N D g ⁢ K t ⁢ { 1 J l ⁢ ⅆ ⅆ t ⁢ τ g ⁡ ( θ tw ) - ( D l + D g J l 2 + D g J m ⁢ J l ⁢ N 2 ) ⁢ τ g ⁡ ( θ tw ) + ( ( D l + D g ) 2 J l 2 + D g 2 J m ⁢ J l ⁢ N 2 ) ⁢ ω l - ( D l ⁢ D g + D g 2 J l 2 ⁢ N + D m ⁢ D g ⁢ N 2 + D g 2 J m ⁢ J l ⁢ N 3 ) ⁢ ω m } ( A ) ⁢ [ FORMULA ⁢ ⁢ B ] ⁢ β ⁡ ( x ) · υ = J m ⁢ J l ⁢ N D g ⁢ K t ⁢ υ ( B ) ⁢ [ FORMULA ⁢ ⁢ C ] ⁢ ⅆ 3 ⁢ y ⅆ t 3 = υ ( C ) measure the non-linear elastic deformation in relation to the load torque of the wave gear device; define the non-linear spring model τg(θtw) using a cubic polynomial as shown in formula (D), with the constant defined as zero, to be able to recreate the measurement results; and [FORMULA D] τ g (θ tw )= K g3 θ tw 3 +K g2 θ 2 +K g1 θ tw (D) respectively input into the processor arranged as a semi-closed loop control system for controlling the positioning of the load shaft, as a feed-forward current command and a feed-forward motor position command, the current input into the plant model and the motor position of the plant model when a load acceleration command is a command value.