Control device and speed reducer system

A control device for controlling a motor configured to drive an oscillatory cyclo-speed reducer including an oscillatory gear portion which is provided with at least one hole at an eccentric position, the control device comprising:

• an angle acquirer configured to acquire input information about an input rotational angle which indicates a rotational angle of the motor;
• an estimator configured to estimate an angular error between the input rotational angle and an output rotational angle indicating a rotational angle of the oscillatory cyclo-speed reducer based on a hole number which indicates a quantity of the at least one hole;
• and
• a corrector configured to determine a compensation current value in correspondence to the angular error, the corrector using the compensation current value to correct a command current value and set a magnitude of a current, which is supplied to the motor,
• wherein the oscillatory cyclo-speed reducer includes Np internal teeth which are meshed with the oscillatory gear portion and decelerates an angular velocity ωM of the motor by using a reduction ratio Rg of the oscillatory cyclo-speed reducer;
• wherein the hole number is expressed by a natural number k;
• and
• wherein the estimator calculates an angular frequency ωd of an angular transmission error resulting from elastic deformation inside the oscillatory cyclo-speed reducer from Equation 1, the estimator using a discrete-time state-space model, which includes the angular frequency ωd as a matrix component, to estimate the angular error:
• ω
• d
• =
• kN
• p
• ⁢
• ω
• M
• R
• g
• .
• [
• Equation
• ⁢
• ⁢
• 1
• ]

A speed reducer system, comprising:

• an oscillatory cyclo-speed reducer including an oscillatory gear portion which is provided with at least one hole at an eccentric position;
• a motor configured to drive the oscillatory cyclo-speed reducer;
• and
• a control device configured to control the motor,
• wherein the control device includes an angle acquirer, which acquires input information about an input rotational angle indicating a rotational angle of the motor, an estimator, which estimates an angular error between the input rotational angle and an output rotational angle, which indicates a rotational angle of the oscillatory cyclo-speed reducer based on a hole number indicating a quantity of the at least one hole, and a corrector, which determines a compensation current value in correspondence to the angular error, the corrector using the compensation current value to correct a command current value and set a magnitude of a current, which is supplied to the motor,
• wherein the oscillatory cyclo-speed reducer includes NP Internal teeth which are meshed with the oscillatory gear portion and decelerates an angular velocity COM of the motor by using a reduction ratio Rg of the oscillatory cyclo-speed reducer;
• wherein the hole number is expressed by a natural number k;
• and
• wherein the estimator calculates an angular frequency ωd of an angular transmission error resulting from elastic deformation inside the oscillatory cyclo-speed reducer from Equation 1, the estimator using a discrete-time state-space model, which includes the angular frequency ωd as a matrix component, to estimate the angular error:
• ω
• d
• =
• kN
• p
• ⁢
• ω
• M
• R
• g
• .
• [
• Equation
• ⁢
• ⁢
• 1
• ]