Assistive driving system for a wheelchair and method for controlling assistive driving system

1. A method for activating an assistive drive force to a wheelchair, comprising:

providing a user with an element configured to be worn on the user's hand or wrist and comprising a sensor configured to detect acceleration;

activating the assistive drive force in response to a detection of at least a first acceleration and a second acceleration, each of the first and second accelerations having

(i) an axis that is substantially normal to the user's palm, and

(ii) a threshold magnitude,

and wherein

(iii) the second acceleration occurs within a predefined time interval after the first acceleration.

2. The method of claim 1 , wherein the second acceleration occurs within 2 seconds after the first acceleration.

3. The method of claim 2 , wherein the threshold magnitude is between about 2 g and about 4 g.

4. The method of claim 1 , wherein the threshold magnitude is set by the user.

5. The method of claim 1 , wherein each of the first and second accelerations is in a direction away from the user.

6. The method of claim 1 , wherein the sensor is a three-axis accelerometer.

7. The method of claim 1 , wherein the element comprises a wristband and a screen.

8. The method of claim 7 , wherein the screen is a touchscreen and wherein the level of the assistive drive force is controlled through the touchscreen.

9. The method of claim 1 , wherein, upon activation of the assistive drive force, the level of the assistive drive force gradually increases until a third acceleration is detected, the third acceleration having at least

(i) an axis that is substantially normal to the user's palm, and

(ii) a threshold magnitude.

10. The method of claim 1 , further comprising deactivating the assistive drive force in response to the detection of at least a first acceleration and a second acceleration, each of the first and second accelerations having

(i) a direction along an axis that is substantially normal to the user's palm, and

(ii) a threshold magnitude,

and wherein

(iii) the second acceleration occurs within a predefined time interval after the first acceleration.

11. The method of claim 10 , wherein the second acceleration occurs within 2 seconds after the first acceleration.

12. The method of claim 10 , wherein each of the first and second accelerations is in a direction away from the user.

13. The method of claim 10 , wherein after deactivating the assistive drive force, the assistive drive force cannot be activated in response to the detection of accelerations if those accelerations occur within 5 seconds of deactivation.

14. The method of claim 1 , wherein the assistive drive force is provided by a power assist system.

15. The method of claim 14 , wherein data from the sensor is wirelessly sent to the power assist system.

16. The method of claim 1 , wherein the combination of the first and second accelerations indicate that the user has double-tapped a hand against a hand rim of the wheelchair.

17. A wheelchair configured to deliver an assistive drive force in response to the detection of at least a first acceleration and a second acceleration by a sensor provided on an element that is worn on a user's hand or wrist

wherein each of the first and second accelerations have

(i) an axis that is substantially normal to the user's palm, and

(ii) a threshold magnitude,

and wherein

(iii) the second acceleration occurs within a predefined time interval after the first acceleration.

18. A system for providing an assistive driving force to a wheelchair, comprising:

(a) a power assist drive system;

(b) an element configured to be worn on a user's hand or wrist, the element comprising a sensor configured to detect acceleration;

(c) a processor configured to receive data from the sensor, process the data, and activate or deactivate the power assist drive system;

wherein the processor is configured to activate the power assist drive system in response to a detection of at least a first acceleration and a second acceleration, the first and second accelerations each having

(i) an axis that is substantially normal to the user's palm, and

(ii) a threshold magnitude,

and wherein the second acceleration occurs within a defined time interval after the first acceleration.