Myoelectrically controlled prothesis

Claim 2

A control system for actuating a prosthesis from myoelectric potentials, comprising: a prosthesis; electrode means for sensing myoelectric potentials developed by the body, said electrode means being adapted to engage over a single muscle area of the body; means actuating said prosthesis in response to said sensed myoelectric potential; means for providing a position feedback signal to said actuating means for identifying the degree of actuation imparted to said prosthesis; and, means for delaying in time said position feedback signal.

Claim 3

The control system as claimed in claim 1 wherein said electrode sensing means comprise spaced first and second electrodes each formed of a metal biologically compatible with the skin and capable of making a low resistance contact therewith.

Claim 4

The control system of claim 2, wherein said means for minimizing said interference noise signals comprises a guard ring assembly encircling said sensing electrodes, the assembly being connected to signal ground and adapted to contact the skin surface, a mounting plate adapted to be spaced from the skin surface and forming the base of the guard ring assembly and having the electrodes positioned on one side thereof, and a preamplifier positioned on the mounting plate on the side thereof opposite the electrodes, the mounting plate serving as a shield between the preamplifier and the electrodes to prevent electrical feedback and to minimize direct pickup from stray electric fields.

Claim 5

The control system as claimed in claim 1 and further comprising: means for converting said sensed myoelectric potential into a DC level signal; and means for providing interfacing between said converting means and said actuating means.

Claim 6

The control system as claimed in claim 4, wherein said converting means is a detector and said interfacing means is a buffer amplifier.

Claim 7

The control system as recited in claim 5 wherein said means for providing said position feedback signal comprises a potentiometer whose wiper arm is mechanically actuated in direct proportion to the degree of actuation imparted to said prosthesis, the voltage sensed by said wiper arm being received by said actuating means.

Claim 8

The control system as claimed in claim 6 wherein said actuating means comprises: means for determining the error difference signal between said position feedback signal and said DC level signal; means for applying electrical energy to said prosthesis only when said error difference signal is of a predetermined amplitude; and means for converting said electrical energy into mechanical energy for actuating said prosthesis.

Claim 9

The control system set forth in claim 7 wherein said means for determining said error difference signal is a summing amplifier comprising: a first input terminal for receiving said DC level signal; a second input terminal for receiving said pOsition feedback signal; means for providing a fixed threshold signal; and means for obtaining the difference between said DC level signal and said fixed threshold signal and producing a difference error signal when the difference signal is of an amplitude greater or less than said position feedback signal.

Claim 10

The control system as claimed in claim 8, wherein said means for converting said electrical energy into mechanical energy for actuating said prosthetic device is a DC torque motor.

Claim 11

The control system of claim 1 and further comprising; means for minimizing interference noise signals; means for amplifying said myoelectric potentials; and means for attaching said electrode means to the body.

Claim 12

A control system for actuating a prosthesis from muscle myoelectric potentials comprising: a prosthesis, means for sensing myoelectric potentials comprising electrode sensing means adapted to engage over a muscle area of the body, means for amplifying said sensed myoelectric potentials, means for converting amplified myoelectric potentials into a DC level signal having an amplitude proportional to the intensity of said generated myoelectric potentials, means for identifying the exact physical position of said prosthetic device and for producing therefrom a position feedback signal, means for actuating said prosthesis in response to said sensed myoelectric potentials, said actuation means providing an electrical signal sufficient to actuate said prosthesis and including a summing amplifier for producing such electrical actuation signal when the resultant threshold output amplitude of said means for converting the amplified myoelectric potentials into a DC level signal is greater than the amplitude of said position feedback signal, means for converting said electrical signal into mechanical energy; and, means for producing a control signal effective to actuate said prosthetic device only when sensed myoelectric potentials are above a predetermined threshold level, said degree of prosthetic actuation being proportional to the amplitude of said sensed myoelectric potentials, said means for producing said control signal comprising a standard waveform generator having a predetermined amplitude, said electrical actuation signal being generated when said output amplitude of said summing amplifier is greater than said predetermined amplitude of the standard waveform.

Claim 13

A control system for actuating a prosthesis from muscle myoelectric potentials comprising: a prosthesis, means for sensing myoelectric potentials comprising electrode sensing means adapted to engage over a muscle area of the body, means for amplifying said sensed myoelectric potentials, means for converting amplified myoelectric potentials into a DC level signal having an amplitude proportional to the intensity of said generated myoelectric potentials, means for identifying the exact physical position of said prosthetic device and for producing therefrom a position feedback signal, means for actuating said prosthesis in response to said sensed myoelectric potentials, said actuation means providing an electrical signal sufficient to actuate said prosthesis and including a summing amplifier for producing such electrical actuation signal when the resultant threshold output amplitude of said means for converting the amplified myoelectric potentials into a DC level signal is greater than the amplitude of said position feedback signal, means for converting said electrical signal into mechanical energy; and, means for producing a control signal effective to actuate said prosthetic device only when sensed myoelectric potentials are above a predetermined threshold level, said degree of prosthetic actuation being proportional to the amplitude of said sensed myoelectric potentials, said means for producing said control signal comprising a standard waveform generator having a predetermined amplitude, said electrical actuation signal being generated when said output amplitude of said summing amplifier is greater than said predetermined amplitude of the standard waveform.

Claim 14

The control system as claimed in claim 11, wherein said sensing means comprises electrode means adapted to a single muscle site.

Claim 15

The control system as claimed in claim 12, wherein said electrode means comprises first and second electrodes.

Claim 16

The control system as claimed in claim 11, wherein said means for converting said amplified myoelectric potential into a DC level signal is a DC detector.

Claim 17

The control system as claimed in claim 11, wherein said means for converting said electrical signal into mechanical energy comprises a DC torque motor.

Claim 18

The control system as claimed in claim 15, and further including gear means between said DC torque motor and said prosthesis, actuation of said DC torque motor causing said prosthesis to operate at a speed determined by the final ratio of said gear means.

Claim 19

The control system as claimed in claim 16, wherein said means for producing said position feedback signal comprises a potentiometer having a wiper arm, said wiper arm being operably connected to the output of said gear means.

Claim 20

The control system as claimed in claim 15, and further including means for suppressing spurious responses generated by the actuation and subsequent non-actuation of said DC torque motor.

Claim 21

The control system as claimed in claim 18, wherein said spurious response suppression means comprises a plurality of serially connected zener diodes all connected in parallel with said DC torque motor.

Claim 22

The control system as claimed in claim 11, wherein said means for generating said standard waveform is a triangular wave generator.

Claim 23

The control system as claimed in claim 20, wherein said means for generating said electrical actuation signal is a pulse width modulator.

Claim 24

The control system as claimed in claim 11, and further including means for delaying in time said position feedback signal.