Motion control of a motion device

Patent metadata

Field	Value
Publication number	US-12443187-B2
Application number	US-202118258946-A
Country	US
Kind code	B2
Filing date	Dec 21, 2021
Priority date	Dec 24, 2020
Publication date	Oct 14, 2025
Grant date	Oct 14, 2025

Abstract

A method for generating a trajectory to control movement of a motion device, by: i) receiving a specification of the trajectory; ii) receiving at least one jerk constraint; and iii) generating a sequence of one or more trajectory segments based on the at least one jerk constraint. The generating includes applying a velocity transition algorithm including moving the magnitude of a velocity reference of the trajectory segments in a given time to a desired final velocity reference, the difference between the desired final velocity reference and the velocity reference defining a velocity delta. The velocity transition algorithm includes computing a peak acceleration having a magnitude being a function of the velocity delta.

First claim

The invention claimed is:

1. A method for generating a trajectory to control movement of a motion device, the method comprising:
i) receiving a specification of the trajectory, the specification including a commanded position;
ii) receiving at least one jerk constraint; and
iii) generating a sequence of one or more trajectory segments based on the at least one jerk constraint, each of the one or more trajectory segments being a respective portion of the trajectory prescribing at least one of a jerk reference, an acceleration reference, a velocity reference and a position reference as a function of time;
wherein the one or more trajectory segments of the sequence of trajectory segments is generated by applying a velocity transition algorithm including moving a magnitude of the velocity reference of the one or more trajectory segments in a given time to a desired final velocity reference, a difference between the desired final velocity reference and the velocity reference defining a velocity delta;
wherein the velocity transition algorithm includes computing a peak acceleration having a magnitude being a function of the velocity delta; and
wherein the at least one jerk constraint defines a plurality of constraints for generating a sequence of one or more trajectory segments, the plurality of constraints including:
an acceleration constraint, and the generating the one or more trajectory segments is based on whether:
i) a magnitude of the acceleration reference of the trajectory is substantially equal to a computed peak acceleration, and/or
ii) the computed peak acceleration is smaller than or substantially equal to the acceleration constraint, and/or
iii) the computed peak acceleration exceeds the acceleration constraint.

2. The method of claim 1 , comprising:
receiving at least one velocity constraint, at least one acceleration constraint, and/or at least one deceleration constraint, said at least one velocity constraint, at least one acceleration constraint, at least one deceleration constraint.

3. The method of claim 2 , wherein a value of at least one of the plurality of constraints is a function of a total mass of the motion device, configured as a load handling device.

4. The method of claim 3 , wherein the value of any one of the at least one velocity constraint, at least one acceleration constraint, and/or at least one deceleration constraint is inversely proportional to the total mass of the load handling device.

5. The method of claim 1 , wherein each of the one or more trajectory segments comprises:
a respective start point and a respective endpoint such that the start point of each of the one or more trajectory segments includes an initial position reference, initial velocity reference and an initial acceleration reference, and the endpoint of each of the one or more trajectory segments includes an endpoint position reference, an endpoint velocity reference and an endpoint acceleration reference.

6. The method of claim 5 , wherein the velocity delta is based on a difference between the desired final velocity reference and either the initial or endpoint velocity reference of the one or more trajectory segments.

7. The method of claim 1 , comprising:
generating the one or more trajectory segments are generated by applying the at least one jerk constraint such that the desired final velocity reference is substantially zero.

8. The method of claim 1 , wherein in response to the acceleration reference being substantially equal to the computed peak acceleration, generating the one or more trajectory segments comprises:
i) applying the at least one jerk constraint such that the initial acceleration reference of the one or more trajectory segments has a magnitude substantially equal to the computed peak acceleration, and the respective endpoint acceleration of the one or more trajectory segments has a magnitude of substantially equal to zero and the endpoint velocity reference is substantially equal to the desired final velocity reference.

9. The method of claim 1 , wherein in response to the computed peak acceleration being smaller than or equal to the acceleration constraint, generating one or more trajectory segments comprises:
i) generating a first trajectory segment by applying the at least one jerk constraint such that an endpoint acceleration reference of a first trajectory segment has a magnitude substantially equal to the computed peak acceleration; and
ii) generating a second trajectory segment by applying the at least one jerk constraint such that an endpoint of the first trajectory segment is assigned to a start point of the second trajectory segment and a magnitude of the endpoint acceleration of the second trajectory segment is substantially equal to zero and an endpoint velocity reference of the second trajectory segment is substantially equal to the desired final velocity reference.

10. The method of claim 1 , wherein in response to the magnitude of the computed peak acceleration exceeding the acceleration constraint, generating one or more trajectory segments comprises:
i) generating a first trajectory segment by applying at least one jerk constraint such that an endpoint acceleration reference of the first trajectory segment has a magnitude substantially equal to the acceleration constraint;
ii) generating a second trajectory segment by applying at least one jerk constraint having a magnitude of substantially zero such that an endpoint of the first trajectory segment is assigned to a start point of the second trajectory segment and a magnitude of an endpoint acceleration reference of the second trajectory segment is substantially equal to the acceleration constraint; and
iii) generating a third trajectory segment by applying at least one jerk constraint such that an endpoint of the second trajectory segment is assigned to a start point of the third trajectory segment and a magnitude of the endpoint acceleration reference of the third trajectory segment is substantially equal to zero and an endpoint velocity reference of the third trajectory segment is substantially equal to the desired final velocity reference.

11. The method of claim 10 , comprising:
generating the one or more trajectory segments in response to the magnitude of the endpoint acceleration reference being substantially less than the acceleration constraint.

12. The method of claim 1 , wherein in response to the magnitude of the computed peak acceleration exceeding the acceleration constraint, generating one or more trajectory segments comprises:
i) generating a first trajectory segment by applying at least one jerk constraint having a magnitude of substantially zero such that an endpoint acceleration reference of the first trajectory segment has a magnitude substantially equal to the acceleration constraint;
ii) generating a second trajectory segment by applying at least one jerk constraint such that an endpoint of the first trajectory segment is assigned to a start point of the second trajectory segment and a magnitude of the endpoint acceleration reference of the second trajectory segment is substantially equal to zero and an endpoint velocity of the second trajectory segment is substantially equal to the desired final velocity reference.

13. The method of claim 12 , comprising:
generating the one or more trajectory segments in response to a magnitude of the trajectory acceleration reference being substantially equal to the acceleration constraint.

14. The method of claim 1 , wherein applying the velocity transition algorithm comprises:
generating one or more trajectory segments in response to:
i) a magnitude of the accele

Assignees

• Ocado Innovation Ltd

Inventors

• Jorge Tiago Miguens Rijo Branco

Classifications

• G05D1/00

  Control of position, course, altitude or attitude of land, water, air or space vehicles, e.g. using automatic pilots (drive control systems specially adapted for autonomous road vehicles B60W60/00) · CPC title

• G05D1/65 Primary

  Following a desired speed profile · CPC title

• B65G1/0478

  for matrix-arrangements · CPC title

• G05D2107/70

  Industrial sites, e.g. warehouses or factories · CPC title

• G05D2101/10

  using artificial intelligence [AI] techniques · CPC title