Velocity control of position-controlled motor controllers

Patent metadata

Field	Value
Publication number	US-9870002-B1
Application number	US-201615257066-A
Country	US
Kind code	B1
Filing date	Sep 6, 2016
Priority date	Sep 6, 2016
Publication date	Jan 16, 2018
Grant date	Jan 16, 2018

Abstract

An example system may include a motor, a position-controlled motor controller configured to drive the motor to a commanded position with a characteristic acceleration profile, and a control system. The control system may be configured to determine a target velocity for the motor. The control system may be additionally configured to determine a target position that, when commanded to the motor controller, is predicted to cause the motor controller to drive the motor with the target velocity at a target time point by driving the motor with the characteristic acceleration profile. Further, the control system may be configured to provide an instruction for execution by the position-controlled motor controller, the instruction may be configured to cause the motor controller to drive the motor to the target position.

First claim

What is claimed is:

1. A method, comprising:
determining a target velocity for a motor, wherein a position-controlled motor controller is configured to drive the motor to a commanded position with a characteristic acceleration profile;
determining a target position that, when commanded to the motor controller, is predicted to cause the motor controller to drive the motor with the target velocity at a target time point by driving the motor with the characteristic acceleration profile; and
providing an instruction for execution by the position-controlled motor controller, the instruction configured to cause the position-controlled motor controller to drive the motor to the target position.

2. The method of claim 1 , wherein determining the target position comprises:
determining an expected velocity profile that the motor is predicted to follow based on the characteristic acceleration profile of the position-controlled motor controller;
determining an integral of the expected velocity profile; and
determining the target position based on (i) the determined integral and (ii) a current position of the motor.

3. The method of claim 1 , wherein the characteristic acceleration profile comprises:
a first maximum acceleration in a first direction; and
a second maximum acceleration in a second direction opposite to the first direction.

4. The method of claim 3 , wherein determining the target position comprises:
determining the target time point at which to reach the target velocity;
determining a first time interval during which the motor controller is predicted to drive the motor with the first maximum acceleration in the first direction; and
determining a second time interval during which the motor controller is predicted to drive the motor with the second maximum acceleration in the second direction, wherein (i) driving the motor with the first acceleration in the first direction during the first time interval and (ii) driving the motor with the second acceleration in the second direction during the second time interval is predicted to cause the motor to reach the target velocity at the target time point.

5. The method of claim 4 , wherein determining the target position comprises:
determining a first double integral of the first maximum acceleration over the first time interval;
determining a second double integral of the second maximum acceleration over the second time interval; and
determining the target position based on the sum of (i) the first double integral and (ii) the second double integral.

6. The method of claim 3 , wherein determining the target position comprises:
determining a starting velocity of the motor, wherein the starting velocity corresponds to a starting time point;
determining a target time point at which to reach the target velocity;
determining an intersection point between (i) a first line through a point corresponding to the starting velocity and the starting time point, the first line having a slope corresponding to the first maximum acceleration and (ii) a second line through a point corresponding to the target velocity and the target time point, the second line having a slope corresponding to the second maximum acceleration;
determining an integral of the first line between the starting time point and a time point corresponding to the intersection point;
determining an integral of the second line between the time point corresponding to the intersection point and the target time point; and
determining the target position based on the sum of the integral of the first line and the integral of the second line.

7. The method of claim 3 , wherein the characteristic acceleration profile additionally comprises (i) a first transition profile between zero acceleration and the first maximum acceleration and (ii) a second transition profile between the first maximum acceleration and the second maximum acceleration, wherein determining the target position comprises:
determining a first time interval during which the motor controller is predicted to drive the motor with the first maximum acceleration in the first direction;
determining a second time interval during which the motor controller is predicted to drive the motor with the second maximum acceleration in the first direction;
determining a third time interval during which the motor controller is predicted to drive the motor according to the first transition profile;
determining a fourth time interval during which the motor controller is predicted to drive the motor according to the second transition profile;
determining a first double integral of the first maximum acceleration over the first time interval;
determining a second double integral of the second maximum acceleration over the second time interval;
determining a third double integral of the first transition profile over the third time interval;
determining a fourth double integral of the second transition profile over the fourth time interval;
determining the target position based on the sum of (i) the first double integral, (ii) the second double integral, (iii) the third double integral, and (iv) the fourth double integral.

8. A non-transitory computer readable storage medium having stored thereon instructions that, when executed by a computing device, cause the computing device to perform operation comprising:
determining a target velocity for a motor, wherein a position-controlled motor controller is configured to drive the motor to a commanded position with a characteristic acceleration profile;
determining a target position that, when commanded to the motor controller, is predicted to cause the motor controller to drive the motor with the target velocity at a target time point by driving the motor with the characteristic acceleration profile; and
providing an instruction for execution by the position-controlled motor controller, the instruction configured to cause the position-controlled motor controller to drive the motor to the target position.

9. A system comprising:
a motor;
a position-controlled motor controller configured to drive the motor to a commanded position with a characteristic acceleration profile; and
a control system configured to:
determine a target velocity for the motor;
determine a target position that, when commanded to the motor controller, is predicted to cause the motor controller to drive the motor with the target velocity at a target time point by driving the motor with the characteristic acceleration profile; and
provide an instruction for execution by the position-controlled motor controller, the instruction configured to cause the position-controlled motor controller to drive the motor to the target position.

10. The system of claim 9 , wherein the control system is configured to determine the target position by:
determining an expected velocity profile that the motor is predicted to follow based on the characteristic acceleration profile of the position-controlled motor controller;
determining an integral of the expected velocity profile; and
determining the target position based on (i) the determined integral and (ii) a current position of the motor.

11. The system of claim 9 , wherein the characteristic acceleration profile comprises:
a first maximum acceleration in a first direction; and
a second maximum acceleration in a second direction opposite to the first direction.

12. The system of claim 11 , wherein the control system is configured to determine the target position by:
determining the target time point at which to reach the target velocity;
determining a first time interval during which the motor controller is predicted to drive the motor

Assignees

• X Dev Llc

Inventors

• Holmberg Robert
• Russell Jared
• Rublee Ethan

Classifications

• G05B19/416

  characterised by control of velocity, acceleration or deceleration (G05B19/19 takes precedence) · CPC title

• G05B6/02

  electric · CPC title

• G05B19/00

  Program-control systems · CPC title

• Y10S901/01

  Mobile robot · CPC title

• G05B19/18

  Numerical control [NC], i.e. automatically operating machines, in particular machine tools, e.g. in a manufacturing environment, so as to execute positioning, movement or co-ordinated operations by means of program data in numerical form (G05B19/418 takes precedence) · CPC title