Force control method based on disturbance load estimation

• US 5,734,242 A
• Filed: 12/01/1994
• Issued: 03/31/1998
• Est. Priority Date: 04/02/1993
• Status: Expired due to Fees

• Current Assignee: Fanuc Ltd (Fanuc Corporation)
• Original Assignee: Fanuc Ltd (Fanuc Corporation)
• Inventors: Iwashita, Yasusuke
• Primary Examiner(s): Cabeca, John W.
• Application Number:
  US08/347,301
• Time in Patent Office: 1,216 Days
• Field of Search: 364/148, 364/149, 364/150, 364/151, 318/432, 318/433, 318/601, 318/632, 318/603, 318/609, 318/606, 318/649, 318/608, 318/607, 318/434
• US Class Current: 318/434
• CPC Class Codes: G05B 13/04 involving the use of models or simulators
• CPC Class Codes: G05B 19/19 characterised by positioning or contouring control systems, e.g. to control position from one programmed point to another or to control movement along a programmed continuous path
• CPC Class Codes: G05D 17/02 characterised by the use of electric means

Abstract

A disturbance estimation observer estimates a disturbance load torque applied to a motor. The estimated disturbance load torque is fed back so that the feedback control is carried out by making the torque corresponds to a commanded force value which is a target value. According to the feedback control, the estimated disturbance load torque is controlled to correspond to the target value, and when the estimated disturbance load torque approximates to an actual load torque, the actual load torque is controlled to the target value. Thus, force control by the motor can readily be carried out on the basis of the disturbance load estimated without using force sensors.

Claims

1. A force control method based on a disturbance load estimation comprising the steps of:

estimating an external load acting on a controlled system driven by a motor by a disturbance estimation observer and outputting an estimated disturbance load torque based thereon;

feeding back said estimated disturbance load torque; and

carrying out feedback control so that said estimated disturbance load torque corresponds to a commanded force value, wherein a value obtained by adding a product of a velocity of the motor and a coefficient to said estimated disturbance load torque determines a force feedback value.

2. A force control method based on a disturbance load estimation according to claim 1, wherein said disturbance estimation observer estimates a disturbance load torque based on a torque value commanded to the motor and an actual velocity of the motor.

3. A force control method based on a disturbance load estimation, comprising the steps of:

estimating an external load acting on a controlled system driven by a motor by a disturbance estimation observer and outputting an estimated disturbance load torque based thereon;

feeding back said estimated disturbance load torque; and

carrying out feedback control so that said estimated disturbance load torque corresponds to a commanded force value,

wherein a force feedback value is clamped according to a value obtained by adding a product of a maximum permissible velocity of the motor and a coefficient to said estimated disturbance load torque, thereby controlling a rotational velocity of the motor so that the rotational velocity of the motor is less than the maximum permissible velocity.

4. A force control method based on a disturbance load estimation according to claim 3, wherein said disturbance estimation observer estimates a disturbance load torque based on a torque value commanded to the motor and an actual velocity of the motor.