Brake control unit

1. A method of controlling braking of a towed vehicle, said method comprising:

receiving a speed signal based on speed of a towing vehicle, or a towed vehicle, or both said towing vehicle and said towed vehicle;

generating a brake output signal based on at least said speed signal;

sending said brake output signal to brakes of said towed vehicle to provide power to said brakes;

applying said brakes of said towed vehicle based on said brake output signal;

determining a relationship between said speed and a speed threshold;

applying a function to modify said brake output signal only when said speed of the towing vehicle is below said speed threshold;

wherein said function modifies said brake output based on said speed; and

wherein said brake output signal is not modified based on speed when said speed of said towing vehicle is above said speed threshold.

2. The method of claim 1 , further comprising receiving a speed signal based on speed of said towed vehicle.

3. The method of claim 1 , further comprising modifying said brake output signal to provide more power to said brakes as a function of pressure.

4. The method of claim 3 , wherein a pressure signal is provided by at least one of a brake pedal sensor, a brake pad sensor, a hydraulic brake system pressure sensor of the towing vehicle, and a signal from a communications bus.

5. The method of claim 1 , further comprising:

determining an actual deceleration of said towed vehicle based upon said speed signal;

determining a characteristic of said towed vehicle based upon said actual deceleration of said towed vehicle in response to a previously determined brake output signal; and

adjusting said brake output signal to achieve a desired deceleration of said towed vehicle.

6. The method of claim 5 , wherein said characteristic of said towed vehicle includes at least one of brake temperature of said towed vehicle, brake pad wear of said towed vehicle, proximity of brake pads to brake drum of said towed vehicle, brake magnet strength of said towed vehicle, brake spring strength of said towed vehicle, brake pad moisture of said towed vehicle, battery voltage of said towed vehicle, number of axles of said towed vehicle, load of said towed vehicle, weight distribution of said towed vehicle, tire conditions of tires of said towed vehicle, speed of said towed vehicle and road conditions as experienced by said towed vehicle.

7. The method of claim 6 , further comprising:

examining said actual deceleration to determine whether said actual deceleration increases when brake pressure increases; and

reducing a gain setting associated with said brake output signal when said actual deceleration does not increase when said pressure increases, wherein said reduced gain setting causes said brake output signal to provide reduced power to brakes of said towed vehicle.

8. The method of claim 6 , further comprising:

examining said actual deceleration to determine whether said actual deceleration is proportional to said previously determined brake output signal;

reducing a gain setting associated with said brake output signal when said actual deceleration is not proportional to said brake output signal; and

reducing said brake output signal to provide reduced power to brakes of said towed vehicle.

9. A method of controlling braking of a towed vehicle, said method comprising:

receiving an input signal based on: i) a pressure in a brake system of a towing vehicle; and ii) speed of a towing vehicle, or a towed vehicle, or both said towing vehicle and said towed vehicle;

generating a brake output signal based on at least said input signal;

sending said brake output signal to brakes of said towed vehicle to provide power to said brakes;

applying said brakes of said towed vehicle based on said brake output signal;

determining a relationship between said speed and a speed threshold;

applying a function to modify said brake output signal only when said speed of the towing vehicle is below said speed threshold;

wherein said function modifies said brake output based on said input signal; and

wherein said brake output signal is not modified based on speed when said speed of said towing vehicle is above said speed threshold.

10. The method of claim 9 , further comprising receiving a speed signal based on speed of said towed vehicle.

11. The method of claim 9 , further comprising modifying said brake output signal to provide more power to said brakes as a function of pressure.

12. The method of claim 11 , wherein said input signal is provided by at least one of a brake pedal sensor, a brake pad sensor, a hydraulic brake system pressure sensor of the towing vehicle, and a signal from a communications bus.

13. The method of claim 9 , further comprising:

determining an actual deceleration of said towed vehicle based upon said speed signal;

determining a characteristic of said towed vehicle based upon said actual deceleration of said towed vehicle in response to a previously determined brake output signal; and

adjusting said brake output signal to achieve a desired deceleration of said towed vehicle.

14. The method of claim 13 , wherein said characteristic of said towed vehicle includes at least one of brake temperature of said towed vehicle, brake pad wear of said towed vehicle, proximity of brake pads to brake drum of said towed vehicle, brake magnet strength of said towed vehicle, brake spring strength of said towed vehicle, brake pad moisture of said towed vehicle, battery voltage of said towed vehicle, number of axles of said towed vehicle, load of said towed vehicle, weight distribution of said towed vehicle, tire conditions of tires of said towed vehicle, speed of said towed vehicle and road conditions as experienced by said towed vehicle.

15. The method of claim 14 , further comprising:

examining said actual deceleration to determine whether said actual deceleration increases when brake pressure increases; and

reducing a gain setting associated with said brake output signal when said actual deceleration does not increase when said pressure increases, wherein said reduced gain setting causes said brake output signal to provide reduced power to brakes of said towed vehicle.

16. The method of claim 14 , further comprising:

examining said actual deceleration to determine whether said actual deceleration is proportional to said previously determined brake output signal;

reducing a gain setting associated with said brake output signal when said actual deceleration is not proportional to said brake output signal; and

reducing said brake output signal to provide reduced power to brakes of said towed vehicle.

17. A method of controlling braking of a towed vehicle, said method comprising:

periodically receiving speed signals based on speed of a towing vehicle, or a towed vehicle, or both said towing vehicle and said towed vehicle;

estimating a gain setting of said towed vehicle based on said speed signals and prevailing conditions of said towed vehicle to determine a maximum braking power before wheels of said towed vehicle lock up;

applying said gain setting to limit said maximum braking power;

providing an initial brake output signal to brakes of said towed vehicle based on said estimated gain setting;

setting a slew rate of said brake output signal based on said estimated gain setting; and

modifying said initial brake output signal based on said estimated gain setting.

18. A method of controlling braking of a towed vehicle, said method comprising:

periodically receiving speed signals based on speed of a towing vehicle, or a towed vehicle, or both said towing vehicle and said towed vehicle;

estimating a gain setting of said towed vehicle based on said speed signals and prevailing conditions of said towed vehicle to determine a maximum braking power before wheels of said towed vehicle lock up;

applying said gain setting to limit said maximum braking power; and

estimating a boost setting of said towed vehicle based on said estimated gain setting; and

modifying said brake output signal to brakes of said towed vehicle based on said estimated boost setting.