Closed loop door position control

1. A powered vehicle closure system comprising:

a body structure having an opening;

a closure member movably mounted to the body structure by a connecting structure for movement between a closed position and an open position;

an electrically powered actuator configured to move the closure member relative to the body structure;

a position sensor configured to provide a measured position of the closure member as the closure member moves relative to the body structure; and

a controller configured to utilize measured position to control a force of the electrically powered actuator to cause the closure member to move according to an S-shaped position vs time function having starting and ending positions whereby a velocity of the closure member smoothly transitions from a first minimum at a starting position to a maximum at a central position between the starting and ending positions, and to a second minimum at the ending position.

2. The powered vehicle closure system of claim 1 , wherein:

the S-shaped position vs time function corresponds to an S-shaped commanded door position function;

and wherein the controller is configured to minimize differences between the S-shaped position vs time function and the S-shaped commanded door position function.

3. The powered vehicle closure system of claim 2 , wherein:

the S-shaped commanded door position function is substantially sinusoidal.

4. The powered vehicle closure system of claim 2 , wherein:

the controller is configured to utilize an S-shaped position vs time function during door opening and closing operations.

5. The powered vehicle closure system of claim 1 , wherein:

the first and second minimums comprise zero velocity.

6. The powered vehicle closure system of claim 1 , wherein:

a derivative of the S-shaped position vs time function is S-shaped.

7. The powered vehicle closure system of claim 1 , wherein:

the controller comprises a Proportional-integral-Derivative (PID) controller.

8. The powered vehicle closure system of claim 1 , wherein:

the electrically powered actuator comprises an electric motor having a drive shaft; and

the position sensor comprises an absolute position sensor having first and second components that generate absolute position signals as the first and second components move relative to one another, and wherein the first component of the absolute position sensor is mounted to the drive shaft.

9. The powered vehicle closure system of claim 8 , wherein:

the absolute position sensor comprises an Anisotropic Magneto-Resistive (AMR) sensor.

10. The powered vehicle closure system of claim 1 , including:

an activation switch;

a powered latch configured to selectively retain the closure ember in a closed position; and wherein:

the controller is configured to unlatch the powered latch and cause the electrically powered actuator to open the closure member when the activation switch is actuated.

11. The powered vehicle closure system of claim 1 , wherein:

the closure member comprises a door that is rotatably connected to the body structure by a hinge structure for rotation about a vertical axis.

12. The powered vehicle closure system of claim 1 , wherein:

the controller is configured to move the door in a jerkless, smooth manner such that a third derivative of the position vs time function is substantially zero.

13. The powered vehicle closure system of claim 1 , wherein:

the S-shaped position vs time function is continuously differentiable.

14. A method of controlling movement of a vehicle door relative to a vehicle body structure, the method comprising:

utilizing an angular position sensor to provide measured position data to a controller; and

configuring the controller to utilize the measured position data to generate a signal to a powered actuator to move the door between open and closed positions in a substantially smooth manner by causing the door to follow a position vs time function that is continuously differentiable such that a third derivative of the position vs time function is substantially zero.

15. The method of claim 14 , wherein:

the position vs time function is sinusoidal.

16. The method of claim 14 , wherein:

the position vs time function is non-sinusoidal.

17. The method of claim 14 , including:

configuring the controller to move the door such that the door does not have sudden changes in velocity exceeding about 0.01 radians per second.

18. A powered vehicle door system comprising:

a body structure having an opening;

a door rotatably mounted to the body structure by a connecting structure;

an electrically powered actuator configured to move the door relative to the body structure;

an absolute position sensor configured to provide a measured position of the door as the door moves relative to the body structure; and

a controller configured to utilize measured position to control a force of the electrically powered actuator to cause the door to move according to a position vs time function that is continuously differentiable whereby the door moves from a starting position to an ending position in a continuous, manner that is substantially jerkless such that a third derivative of the position vs time function is substantially zero.

19. The powered vehicle door system of claim 18 , wherein:

the controller moves the door in a manner that prevents changes in velocity exceeding about 0.01 radians per second.

20. The powered vehicle door system of claim 19 , wherein:

the position vs time function is substantially sinusoidal.