Dual mode sensing joystick assembly

1. A joystick assembly comprising:

a joystick mounted for rotational movement about a circular area;

at least one pre-load centering spring coupled to the joystick for biasing the joystick to a neutral position, wherein the joystick has a central free-play zone about the neutral position, a transitional zone surrounding the central free-play zone in which the at least one pre-load centering spring begins to act upon the joystick, and a load zone surrounding the transitional zone in which the at least one pre-load centering spring exerts a relatively flat spring rate force upon the joystick;

an angular position sensor system for generating a first signal indicative of a travel angle of the joystick;

a force sensor system for generating a second signal indicative of a force applied to the joystick; and

a controller for receiving the first and second signals, wherein the controller is operative to set start/stop points for control by the joystick approximately synchronously with the joystick moving from the transitional zone to the load zone based upon the second signal.

2. The joystick assembly as recited in claim 1 , wherein the start/stop points are set in the transitional zone at least 10% of the transitional zone from the load zone.

3. The joystick assembly as recited in claim 1 , the controller determines fluid metering in an electro-hydraulic vehicle.

4. The joystick assembly as recited in claim 1 , wherein the controller compares the first and second signals so that an error signal is generated when the first and second signals are different by more than an error threshold.

5. The joystick assembly as recited in claim 1 , wherein the controller is operative to: calculate a slope of a force curve based on the second signal to determine the zones during an auto-calibration routine; and regulate the control based on the first signal between the start/stop points.

6. A joystick assembly comprising:

a joystick;

angular position sensors for generating a first signal indicative of travel angle of the joystick;

force sensors for generating a second signal indicative of a force applied to the joystick; and

a controller for receiving the first and second signals, wherein the controller is operative to evaluate a torque curve for the force applied to the joystick to determine start points based on the second signal so that metering based on the first signal is optimized and synchronized with a haptic feel of the joystick.

7. The joystick assembly as recited in claim 6 , wherein the controller is further operative to perform a calibration data routine to determine the torque curve.

8. The joystick assembly as recited in claim 7 , wherein the controller is further operative to use a slope of the torque curve to determine a transition zone, wherein the transition zone surrounds a centrally located free-play zone, a loaded zone surrounds the transition zone, and the start point is approximately at a junction of the transition zone and the loaded zone.

9. The joystick assembly as recited in claim 8 , wherein the centrally located free-play zone, the transition zone and the loaded zone are determined by analysis of a local slope of the torque curve.

10. The joystick assembly as recited in claim 8 , wherein the start point is approximately 10% of the transition zone into the load zone.

11. The joystick assembly as recited in claim 6 , wherein the controller is further operative to apply a plausibility algorithm based upon comparing the first and second signal to stored position and force sensor value pairs.

12. The joystick assembly as recited in claim 6 , wherein the controller is further operative to calculate a derivative of the torque curve.

13. The joystick assembly as recited in claim 6 , further comprising a switch in communication with the controller so that metering control based upon the first signal can be selected.

14. The joystick assembly as recited in claim 6 , wherein the controller is further operative to calculate an end-of-travel position based upon the first signal during a calibration routine.

15. A dual mode sensing joystick assembly for an electro-hydraulic vehicle comprising:

a joystick;

pre-loaded centering springs coupled to the joystick for biasing the joystick to a neutral position;

angular position sensors for generating a first signal indicative of travel angle of the joystick;

force sensors for generating a second signal indicative of a force applied to the joystick; and

a controller for receiving the first and second signals, wherein the controller is operative to determine initial deflection of the pre-loaded centering springs based upon the second signal so that fluid metering in the electro-hydraulic vehicle is started by the first signal indicating the initial deflection has occurred to trigger the fluid metering being governed by the first signal.