Hitch raise rate calibration method

• US 20060030989A1
• Filed: 08/03/2004
• Published: 02/09/2006
• Est. Priority Date: 08/03/2004
• Status: Active Grant

• Current Assignee: Deere & Company
• Original Assignee: Deere & Company
• Inventors: Boe, Thomas Eugene, Eagles, Derek Malcolm, Alexander, William Guy, Yu, Jianming
• Granted Patent: US 7,142,968 B2
• Time in Patent Office: Days
• US Class Current: 701/50
• CPC Class Codes: A01B 59/067 the lower arms being lifted or lowered by power actuator means internally incorporated in the tractor
• CPC Class Codes: A01B 63/1117 using a hitch position sensor

Abstract

A method is provided for automatically determining a hitch raise rate calibration value for a hitch control system having a hydraulic actuator for moving the hitch, a valve for controlling flow of hydraulic fluid to the actuator and an electronic hitch control unit. The method includes applying a first control signal to the valve to cause the hitch to raise, determining a first hitch velocity as the hitch moves in response to the first control signal, and repeating these steps for a second control signal. The raise rate calibration value is then calculated as a function of a desired raise velocity, the first and second control signals and the first and second velocities.

Claims

1. In a hitch control system having a hitch mounted on a vehicle, a hydraulic actuator for moving the hitch, a hitch position sensor, a valve for controlling flow of hydraulic fluid to the actuator and an electronic hitch control unit for supplying valve control signals to the valve, a method of determining a hitch raise rate calibration value, the method comprising:

applying a first estimated control signal S1 to the valve to cause the hitch to raise;

determining a first hitch velocity V1 as the hitch moves in response to the first control signal;

applying a second estimated control signal S2 to the valve;

determining a second hitch velocity V2 as the hitch moves in response to the second control signal; and

calculating the raise rate calibration value as a function of the first and second estimated control signals, the first and second hitch velocities, and a desired hitch raise rate.

2. The method of claim 1, wherein:

the raise rate calibration value is calculated according to the following equation;

REVOFFSET=[((Vdesired−

V1)×

S2)/(V2−

V1)]−

[((Vdesired−

V2)×

S1)/(V2−

V1)],

where Vdesired is the desired hitch raise rate.

3. The method of claim 1, further comprising determining the first hitch velocity V1 by:

storing a first hitch start position Ps1 obtained from the position sensor;

after a certain delay time period T storing a first hitch end position Pe1 obtained from the position sensor; and

calculating a first hitch velocity V1=(Pe1−

Ps1)/T.

4. The method of claim 3, further comprising waiting for a certain time period between applying the first estimated control signal and storing the first hitch start position.

5. In a hitch control system having a hitch mounted on a vehicle, a hydraulic actuator for moving the hitch, a hitch position sensor, a valve for controlling flow of hydraulic fluid to the actuator and an electronic hitch control unit for supplying valve control signals to the valve, a method of determining a hitch raise rate calibration value, the method comprising:

applying a first estimated control signal S1 to the valve;

storing a first hitch start position Ps1 obtained from the position sensor;

after a certain delay time period T storing a first hitch end position Pe2 obtained from the position sensor 28;

calculating a first hitch velocity V1=(Pe1−

Ps1)/T;

applying a second estimated control signal S2 to the valve;

storing a second hitch start position Ps2 obtained from the position sensor;

after a certain delay time period T storing a second hitch end position Pe2 obtained from the position sensor;

calculating a second hitch velocity V2=(Pe2−

Pe2)/T; and

calculating the raise rate calibration value according to the following equation.

REVOFFSET=[((Vdesired−

V1)×

S2)/(V2−

V1)]−

[((Vdesired−

V2)×

S1)/(V2−

V1)],

where Vdesired is a desired hitch raise rate.

6. The method of claim 5, further comprising:

waiting for a certain time period between applying the estimated control signal and storing the hitch start position.