Myoelectric Prosthetics and TMR-TSR Control Flashcards
How does a myoelectric prosthesis work?
Uses electromyography (EMG) signals from voluntarily contracted muscles in the residual limb to control the movement of the prosthesis.
How do you control a transradial prosthetic? Transhumeral? Shoulder disarticulation?
Transradial: activation of residual wrist flexor and extensors to control
Transhumeral: activation of remaining biceps and triceps to control
SD: May use traps, lats, pecs or delts to control
Original Myoelectric Arm Prosthetic
-Developed in 1964 by USSR and distributed in the UK
-Simple pinch-grasp
-No wrist action
-Good speed, quiet motor
Components required for myoelectric prosthetic (6)
- Electrode
- Signal Acquisition and Processing Instrument
- Controller/Microprocessor
- Actuator/Motor
- Prosthetic
- Sensor (for feedback)
What are the pros of myoelectric? (4)
- Little to no harnessing
- Operate in more planes of movement
- Generate more force
- Better cosmesis
What are the cons of myoelectric? (7)
- Heavy
- Not waterproof
- Needs to be charged
- Maintenance
- Cost more
- More complex
- Needs proper electrode placement
What is the ideal scenario for myoelectric?
Collect several muscles EMG, AI would interpret what action, movement would be generated, and feedback would be provided
What did Atkins and colleagues find as concerns for using myoelectric?
Better control that required less visual attention, ability to co-ordinate two or more joints, too costly, too heavy
What complaints were found by Salminger and colleagues? (Most - Least)
Comfort (60%), weight (52%), function (50%), cosmesis (26%)
What is the death cycle of prosthetic arms?
Non-disabled people feel bad and make too complex arms that amputees stop wearing and the market shrinks, so non-disabled people feel bad…
i-LIMB
First prosthetic with 5 individually powered digits by Touch Bionics
Bebionic Hand
Hand programmed with 14 different grips, have life-like silicone glove, designed by Ottobock
Boston Digital Arm
Introduced first microcontroller arm/hand prosthetic in 2001 by Liberating Technologies, has simultaneous control
DARPA
Defense Advanced Research Projects Agency.
Designed the Luke Arm and Modular Prosthetic limb
What is targeted muscle reinnervation (TMR)?
Involves transfer of residual nerves from an amputated limb to unused muscle region near the injury. Allows regain of sensory feedback.
Pattern Recognition in TMR
PR uses a computer algorithm to look for common patterns in movements.
PR allows for more DoF to be used simultaneously by collecting EMG via a grid located over the muscles where TMR has been implemented
Sensory feedback in prosthetic control
Targeted sensory reinnervation - using tactile signals to give feedback
What is Direct Control?
EMG signals from specific antagonistic muscles are used to control specific opposing actions, (ex. biceps - closing; triceps - opening)
