Traction speed recovery based on steer wheel dynamic

• US 10,414,288 B2
• Filed: 11/10/2017
• Issued: 09/17/2019
• Est. Priority Date: 01/13/2017
• Status: Active Grant

• Current Assignee: Crown Equipment Corporation
• Original Assignee: Crown Equipment Corporation
• Inventors: Mangette, Stephen
• Primary Examiner(s): Kan, Yuri
• Application Number:
  US15/808,949
• Publication Number:
  US 20180201156A1
• Time in Patent Office: 676 Days
• CPC Class Codes: B60L 15/20 for control of the vehicle or its driving motor to achieve a desired performance, e.g. speed, torque, programmed variation of speed
• CPC Class Codes: B60L 15/2036 Electric differentials, e.g. for supporting steering vehicles
• CPC Class Codes: B60L 2200/42 Fork lift trucks
• CPC Class Codes: B60L 2240/12 Speed
• CPC Class Codes: B60L 2240/24 Steering angle
• CPC Class Codes: B60L 2250/24 by lever actuation
• CPC Class Codes: B60L 3/08 Means for preventing excessive speed of the vehicle
• CPC Class Codes: B60W 10/08 including control of electric propulsion units, e.g. motors or generators
• CPC Class Codes: B60W 10/20 including control of steering systems
• CPC Class Codes: B60W 2300/121 Fork lift trucks, Clarks
• CPC Class Codes: B60W 2710/081 Speed
• CPC Class Codes: B60W 2710/083 Torque
• CPC Class Codes: B60W 2710/207 Steering angle of wheels
• CPC Class Codes: B60W 30/18172 Preventing, or responsive to skidding of wheels
• CPC Class Codes: B60Y 2200/15 Fork lift trucks, Industrial trucks
• CPC Class Codes: B66F 17/003 for fork-lift trucks
• CPC Class Codes: B66F 9/07568 Steering arrangements
• CPC Class Codes: B66F 9/07572 Propulsion arrangements
• CPC Class Codes: Y02T 10/64 Electric machine technologies in electromobility
• CPC Class Codes: Y02T 10/72 Electric energy management in electromobility

Abstract

Calculating a current target position value for controlling a traction speed of a materials handling vehicle, that includes receiving steering command signals; generating an output value proportional to a rate of change of the steering command signals; determining whether the output value is greater than or equal to a predetermined threshold; determining a raw target position value for controlling the traction speed of the materials handling vehicle; and calculating the current target position value based on: whether the output value is greater than or equal to a predetermined threshold, and whether the raw target position value is less than or equal to a previously calculated target position value for controlling the traction speed.

Claims

1. A computer-implemented method for controlling a traction motor of a materials handling vehicle, the method comprising:

receiving, by a processor, steering command signals from a steering control input sensor of the materials handling vehicle;

generating, by the processor, a current output value proportional to a rate of change of the steering command signals;

determining, by the processor, a raw target steering angle value;

calculating, by the processor, a current target steering angle value based on;

the current output value compared to a predetermined threshold, and

the raw target steering angle value compared to a previously calculated target steering angle value;

calculating, by the processor, a traction speed limit based on the calculated current target steering angle value;

calculating, by the processor, a traction setpoint based on the traction speed limit; and

controlling the traction motor of the materials handling vehicle based on the traction setpoint.

2. The method of claim 1, wherein the calculated current target steering angle value equals the raw target steering angle value when the raw target steering angle value is greater than the previously calculated target steering angle value.

3. The method of claim 1, wherein the calculated current target steering angle value equals the previously calculated target steering angle value when:

the current output value is greater than or equal to the predetermined threshold; and

the raw target steering angle value is less than or equal to the previously calculated target steering angle value.

4. The method of claim 1, wherein the calculated current target steering angle value equals a value that is closer to the raw target steering angle value than the previously calculated target steering angle value when:

the current output value is less than the predetermined threshold; and

the raw target steering angle value is less than or equal to the previously calculated target steering angle value.

5. The method of claim 4, wherein the calculated current target steering angle value is calculated by applying a smoothing filter function to the raw target steering angle value.

6. The method of claim 5, wherein the smoothing filter function comprises an adjustable multiplier coefficient.

7. The method of claim 1, wherein generating the current output value proportional to the rate of change of the steering command signals comprises:

calculating, by the processor, a current input value proportional to the rate of change of the steering command signals;

comparing the current input value to a previous output value;

if the current input value is equal to or less than the previous output value, calculating by the processor the current output value by multiplying the previous output value by a predetermined decay rate of a filter; and

if the input value is greater than the previous output value, setting the current output value equal to the current input value.

8. The method of claim 1, comprising:

determining, by the processor, whether the current output value is greater than or equal to the predetermined threshold.

9. The method of claim 8, wherein the current target steering angle value is calculated based on:

whether the current output value is greater than or equal to the predetermined threshold, and

whether the raw target steering angle value is less than or equal to the previously calculated target steering angle value.

10. The method of claim 1, wherein controlling the traction motor comprises controlling at least one of a speed of the traction motor or a torque of the traction motor.

11. A system for controlling a traction motor of a materials handling vehicle, the system comprising:

a steering control input sensor of the materials handling vehicle;

a processor coupled to memory, wherein the memory stores program code that is executed by the processor to;

receive steering command signals from the steering control input sensor of the materials handling vehicle;

generate a current output value proportional to a rate of change of the steering command signals;

determine a raw target steering angle value;

calculate a current target steering angle value based on;

the current output value compared to a predetermined threshold, and

the raw target steering angle value compared to a previously calculated target steering angle value;

calculate a traction speed limit based on the calculated current target steering angle value; and

calculate a traction setpoint based on the traction speed limit; and

a traction controller that controls the traction motor of the materials handling vehicle based on the traction setpoint.

12. The system of claim 11, wherein the calculated current target steering angle value equals the raw target steering angle value when the raw target steering angle value is greater than the previously calculated target steering angle value.

13. The system of claim 11, wherein the calculated current target steering angle value equals the previously calculated target steering angle value when:

the current output value is greater than or equal to the predetermined threshold; and

the raw target steering angle value is less than or equal to the previously calculated target steering angle value.

14. The system of claim 11, wherein the calculated current target steering angle value equals a value that is closer to the raw target steering angle value than the previously calculated target steering angle value when:

the current output value is less than the predetermined threshold; and

the raw target steering angle value is less than or equal to the previously calculated target steering angle value.

15. The system of claim 14, wherein the calculated current target steering angle value is calculated by applying a smoothing filter function to the raw target steering angle value.

16. The system of claim 15, wherein the smoothing filter function comprises an adjustable multiplier coefficient.

17. The system of claim 11, wherein the processor when executing the program code to generate the current output value proportional to the rate of change of the steering command signals:

calculates a current input value proportional to the rate of change of the steering command signals;

compares the current input value to a previous output value; and

if the current input value is equal to or less than the previous output value, calculates the current output value by multiplying the previous output value by a predetermined decay rate of a filter; and

if the input value is greater than the previous output value, sets the current output value equal to the current input value.

18. The system of claim 11, wherein the memory stores program code that is executed by the processor to:

determine whether the current output value is greater than or equal to the predetermined threshold.

19. The system of claim 18, wherein the current target steering angle value is calculated based on:

whether the current output value is greater than or equal to the predetermined threshold, and

whether the raw target steering angle value is less than or equal to the previously calculated target steering angle value.

20. The system of claim 11, wherein the traction controller controls at least one of a speed of the traction motor or a torque of the traction motor.