Speed limiting in electric vehicles
A controller and methods for controlling the speed of a vehicle having an electric motorized drive is provided. In one embodiment, a method involves determining a steady state average torque and a torque during acceleration or deceleration of the vehicle traveling over an underlying surface. Speed of the vehicle is controlled based on the steady state average torque, the torque during acceleration or deceleration the measured regeneration current generated by a motorized drive arrangement of the vehicle that applies torque to at least one ground-contacting element of the vehicle for traveling over the underlying surface, weight of the vehicle and payload, the torque applied to the ground-contacting element, acceleration of the vehicle and the speed of the vehicle.
1. A method for controlling the speed of a vehicle having an electric motorized drive, the method comprising:
determining a steady-state torque signal and acceleration or deceleration torque signal of the vehicle traveling down a sloped surface; and
controlling speed of the vehicle when traveling down the sloped surface and when a measured actuator regeneration current exceeds a threshold, the actuator current being generated by a motorized drive arrangement of the vehicle that applies torque to at least one ground-contacting element of the vehicle for braking;
wherein the speed of the vehicle is controlled based on:
the steady-state torque signal;
the acceleration or deceleration torque signal of the vehicle;
a measured actuator regeneration current;
weight of the vehicle and a payload;
the torque applied to the ground-contacting element;
acceleration of the vehicle; and
the speed of the vehicle.
2. The method of claim 1 , wherein controlling speed of the vehicle comprises determining an acceleration-compensated average current.
3. The method of claim 1 , wherein controlling the speed of the vehicle comprises determining an amount of actuator current required for accelerating or decelerating the vehicle.
4. The method of claim 1 , wherein determining the amount of actuator current required for accelerating or decelerating the vehicle is based on the speed of the vehicle and slope of the surface.
5. The method of claim 2 , wherein the acceleration-compensated average current is determined by subtracting actuator current caused by deceleration from the measured actuator current of the vehicle.
6. The method of claim 2 , wherein the acceleration-compensated average current is determined by subtracting actuator current caused by acceleration from the measured actuator current of the vehicle.
7. The method of claim 1 , wherein the vehicle is a dynamically stabilized transporter and maximum allowable speed of the vehicle is controlled by modulating a pitch component of the vehicle.
8. The method of claim 7 , wherein a pitch controller modulates the maximum allowable speed of the vehicle based on the acceleration-compensated average current.
9. The method of claim 8 , comprising decreasing the maximum allowable speed of the vehicle if a regeneration current is increasing.
10. The method of claim 8 , comprising increasing the maximum allowable speed of the vehicle if a regeneration current is decreasing.
11. The method of claim 1 , wherein acceleration and deceleration of the vehicle is achieved at least primarily by operation of the motorized drive arrangement.
12. The method of claim 1 , wherein the speed of the vehicle is limited when the measured current exceeds an overall current threshold.
13. The method of claim 12 , wherein the overall current threshold is based on experience level of a user.
14. The method of claim 1 , wherein the vehicle is a statically-stable transporter.
15. The method of claim 1 , wherein the weight of the vehicle and a payload is an estimate.