Transcript Myoelectric Signal Control System Myoelectric Prosthesis Johns Hopkins Applied Physics Lab, Baltimore, MD Alexander Sollie |Callie Wentling | Michael LoNigro | Kerry Schmidt |

Myoelectric Signal Control System
Myoelectric
Prosthesis
Johns Hopkins Applied Physics Lab, Baltimore, MD
Alexander Sollie |Callie Wentling | Michael LoNigro | Kerry Schmidt | Elizabeth DeVito | Brian Do
Overview
Brian
Signal Collection and Processing
Myoelectric
Signals
FPGA
Microprocessor:
C2000
Brian
Mechanical Output
Base Level
• No Amputation (1:1) arm mimic
• Output to simple display system
Transradial
• Amputation “Below Elbow”
• Output to simple mechanical arm
Transhumeral
Forequarter
• Amputation “Above Elbow”
• Output to higher level mechanical arm
• Amputation of shoulder
• Output to highest level of prosthetic
Brian
Application – Medical Prosthesis
Kinematic Coupling
• Pro: Predetermine movements
• Cons: Limits prosthetic freedom
Heuristic Rules
• Pro: Reach, Move, Orient, Grasping/Releasing
• Cons: Reduces prosthetic control
Sensor Systems
• Pro: Sense environment for motion
• Cons: High variability, incorrect control
Pulse Control
• Pro: Direct control of movements
• Cons: Limited control points, higher level of dexterity
Brian
Analog Signal Block Diagram (1st)
E1
Analog
Low Pass
FIlter
E6
Analog
RF Receiver
Analog
Analog
Active
Summer
Analog
RF Transmitter
Analog
A/D Converter
Callie
Active Summer Circuit
Callie
Low Pass Filter
Callie
Active Summer Simulation
Elizabeth
Active Summer Simulation
Elizabeth
Low Pass Filter Simulation
Elizabeth
Callie
Callie
Analog Signal Block Diagram
E1
Analog
Analog
Filter
Analog
RF Receiver
Analog
E2
Instrumentational
Amplifier
Analog
RF Transmitter
Analog
A/D Converter
Callie
BiPolar Filter
E Ref
Bandpass Filter
Circuit
ECG
PreAmplifier
Low Pass w/ Gain
Rg
Rg/2
Rg/2
INA128/INA149
Instrumentational
Amplifier
E1
Full Wave Rectifier
E2
Brian
ECG Amplifier
Brian
INA129
Brian
Filter Circuit
Brian
Fullwave Rectifier & BP Filter
Brian
Milestones
Milestone 1
• Amplitude thresholds
• Electrode placement
• Initial Analog signal processing
• PCB Rev 1
Elizabeth
Milestones
Milestone 2
• Multi Electrode system
• Amplitude Differentiation
• PCB Final Rev
Expo
• Mounting Cuff
• Consistent Signal Capture
Elizabeth
Computing
• Settled on using the FPGA with the DE2
• Experimented with C2000 but decided against
it
• FPGA will connect to a board via a ribbon
cable
• Most difficult part of software will be
processing multiple ADC signals in parallel
ADC and Parallel processing
Control Systems and Device Driver
FPGA Details
FPGA: Input/Output Signals
• Implement a circular buffer to hold incoming
samples.
• If the amplitude doesn’t meet a certain
threshold value, the samples will be overwritten.
Michael
FPGA: Input/Output Signals
Michael
FPGA: Calibration
• The previously mentioned “threshold” value
will be determined by a calibration step.
• We will implement this using one of the push
keys on the DE2 board.
– While the key is pressed, the values being stored
in the circular buffer will be saved and the
amplitude will be averaged and saved.
Michael
FPGA: Analog-to-Digital Conversion
• We would like to eventually implement 4+
channels of A/D conversion.
– The DE2 board only has a one channel ADC.
– We will use an external multi-channel ADC
plugged into the D.O.U.G.L.E board.
Michael
FPGA: Additional Signal Processing
• Time permitting, we would also like to use an
FFT algorithm for more precise arm control.
– Altera MegaCore FFT algorithms would be very
useful here.
• It will also be possible to control the arm
based solely on signal threshold levels – no
frequency spectrum analysis required!
Michael
FPGA: Output and the Motor Interface
• We’ve already successfully outputted multiple
frequency square waves from the FPGA using
the D.O.U.G.L.E board.
– A square wave is easily created using the FPGA
and no special Digital to Analog converter is
necessary.
– There are more than enough pins connected to
the D.O.U.G.L.E to output different signals to
multiple motors.
Michael
FPGA: Milestones
• Milestone 1
– Ability to output multiple frequencies of square
wave (just one output).
– Ability to sample an incoming analog waveform.
• Milestone 2
– Implementation of a calibration step.
– Ability to sample multiple input waveforms.
– Ability to output multiple square waves of varying
frequencies.
Michael
Mechanical Module
Input
• Frequency controlled
square wave from
FPGA
Functionality
• Motor driver controls the stepping
and supplies holding current
• Magnetic energy spins the rotor
Output
• Motor swings the
forearm appropriately
Kerry
Mechanical Module
12-42V
Power
FPGA
Motor
Driver
Motor
Kerry
Mechanical Module - Motor
SureStep™ Stepper Motor
• Moves the rotor discrete
angles (steps)
• 1.8 degrees per step
• Holding current 2.0 A
– Holds arm in place when
not in motion
– Supplies enough power to
hold a small baby
EX For a 90° bicep curl:
50 Hz*1 sec*1.8°=
90°
Kerry
Prosthetic Arm (Higher Level Design)
Clamping motion
Fore-arm twisting motion
Kerry
Milestones
Milestone 1
• Bones of Arm Prototype
• Motor Driver
Milestone 2
• Working Arm Prototype
Expo
• Prosthetic with Multiple Degrees of Freedom
Kerry
Bill of Materials
Item Name / Description
Unit Price
Quantity
Total Amount
Surface Electrodes
12.20
5
61.00
Electrode Gel (4.oz)
20.00
2
40.00
INA116 IC chips
10.25
10
102.50
Electrical Hardware (Op Amps, Resistors,
Capacitors, etc)
150
1
150.00
Hitec RCD Inc. 35990r HSR-5990TG Digital
Servo Motor
108
4
432.00
Mechanical Hardware (Motor mounts,
aluminum framing, Packaging,
Prototyping)
400
1
400.00
66
4
264
175
1
175.00
102.5
1
102.50
130
1
130.00
PCB fabrication
Wireless transmitters and receivers
> RFM12B-S2 Wireless Transceivers
Altera DE0 Board and Cyclone
Microprocessor
Printing
Total
1859.00
Kerry
Division Of Labor
Signals
PCB Designing
Brian/Callie
Bipolar electrode design
Elizabeth/Callie
Analog Signals Board
Brian/Callie
Analog Filtering system
Elizabeth/Callie
Mechanical Driver Board
Computer
Independent Subsystems
Board Interfacing
Elizabeth/Callie/Brian
Brian/Kerry
Signal PCB
Mechanical Driver Board
Independent Subsystems Part 2
Alex/Michael
FPGA - Initial A/D Signal Analysis
Alex/Michael
Basic Heuristic Laws
Alex/Michael
Basic Sensory Systems
Alex/Michael
FPGA - Output pulse signal to Motor Driver
Alex/Michael
Calibration
Alex/Michael
Advanced analog control
Mechanical
Prosthetic Designing
Prosthetic Interfacing
Elizabeth/Kerry
Motor Driver Interface
Kerry/Brian
Aluminum Framing/Mounting
Kerry/Brian
Interfacing
Elizabeth/Kerry
Prototype one: Prosthetic
Kerry/Brian
Motor Gearing System
Kerry/Brian
Wireless Design
Schedule
Schedule (continued)
Questions?
Claudia Mitchell:
Myoelectric Arm developed by Todd Kulken
Lance Cpl. Brandon Mendez:
Myoelectric Arm, below elbow amputation
Patrick Kane, 13, is the youngest person to
be fitted with a myoelectric prothetic