Method of controlling a prosthesis
The present invention relates to a method of controlling a movable component of a prosthesis or orthosis. The method ( 100 ) comprises moving the component by means of a motor ( 102 ) and determining when movement of the component is arrested when the component bears against a surface ( 104, 106 ). Thereafter a plurality of driving electrical pulses are applied to the motor ( 110 ) in dependence on the determination and when movement of the component is arrested to thereby drive the motor so as to cause the component to bear against the surface with greater force.
1. A method of increasing the force applied by a movable component of a prosthesis or orthosis against a surface, the method comprising:
moving the component by providing a plurality of spaced apart electrical motive pulses supplied to a motor driving a worm gear having a plurality of teeth that extend at an angle greater than 2° and less than 10° as measured from a line perpendicular to the axis of rotation of the worm and configured to drive the movable component;
determining when movement of the component is arrested when the component bears against the surface; and
providing a plurality of driving electrical pulses to the motor in response to the determination that the movement of the component is arrested,
wherein the plurality of motive electrical pulses have a frequency more than 1000 times higher than the frequency of the driving pulses, to thereby drive the motor so as to cause the component to bear against the surface with greater force.
2. The method according to claim 1 , in which the motor is contained in the component being moved.
3. The method according to claim 1 , in which the component is a digit of a hand prosthesis.
4. The method according to claim 1 , in which the first of the plurality of driving electrical pulses are provided to the motor when movement of the component has substantially stopped.
5. The method according to claim 1 , in which determining when movement of the component is arrested comprises measuring an electrical signal passing through the motor.
6. The method according to claim 5 , in which determining when movement of the component is arrested comprises comparing the measured electrical signal with a threshold value.
7. The method according to claim 1 , in which the step of determining when movement of the component is arrested comprises determining when movement is arrested after a period during which the component is moved by the motor.
8. The method according to claim 1 , in which the motor comprises a direct current motor.
9. The method according to claim 1 , in which each of the plurality of spaced apart electrical motive pulses has a period of less than 1 mS.
10. The method according to claim 1 , in which no motive pulse is provided to the motor when the at least one driving electrical pulse is provided to the motor.
11. The method according to claim 1 , further comprising the step of delaying the provision of the at least one driving electrical pulse to the motor for a predetermined delay period after completion of the step of determining when movement of the component is arrested.
12. The method according to claim 11 , in which the predetermined delay period is between substantially 10 mS and substantially 4 seconds.
13. The method according to claim 1 , in which the plurality of driving electrical pulses are provided to the motor for at least substantially 0.5 seconds.
14. The method according to claim 1 , in which the driving electrical pulses have a period of between substantially 1 second and substantially 2 mS.
15. The method according to claim 14 , in which the driving electrical pulses have a period of between substantially 50 mS and substantially 20 mS.
16. The method according to claim 1 , in which a space between driving electrical pulses is greater than an on time of at least one of the driving electrical pulses.
17. The method according to claim 1 , in which the on time of at least one of the driving electrical pulses is substantially 50% of the period of the driving electrical pulses.
18. The method according to claim 1 , in which a driving electrical pulse comprises a constant portion and a decaying portion, the constant portion being at substantially a same voltage over time and the decaying portion changing from the level of the constant portion to substantially zero over time.
19. The method according to claim 18 , in which the constant portion is substantially 50% of the driving electrical pulse on time and the decaying portion is substantially 50% of the driving electrical pulse on time.
20. The method according to claim 1 , in which the method comprises arresting, by means of a counter movement arrangement, movement of the component in a direction opposite the direction in which the component is moved by the motor.
21. The method according to claim 20 , in which the counter movement arrangement comprises first and second gear components that are configured such that when they mesh with each other they present a greater resistance to movement in relation to each in one direction than in another.
22. The method according to claim 21 , in which one of the first and second gear components comprises a plurality of teeth with each tooth being asymmetric.
23. The method according to claim 1 , in which the component is mechanically coupled to the motor by a mechanical coupling such that, in use, the component is moved by the motor by way of the mechanical coupling, the mechanical coupling comprising at least one of: a gearbox; a first bevel gear and a second bevel gear that mesh with each other; and a gear wheel and a worm that mesh with each other.