Robotic Prosthetic Hand With Claw or 3d Printed Hand
by tankapotamus in Circuits > Assistive Tech
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Robotic Prosthetic Hand With Claw or 3d Printed Hand
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Making a muscle controlled robotic hand. Using an Arduino, a Myoware biometric EMG sensor, and a robotic claw, or 3D printed hand.
Parts
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1)Pro Trinket
2)USB Isolator
3)Myoware Muscle Sensor
4)Robotic claw
5)Power cable
Wiring
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MyoWare "+" to Pro Trinket 5V
MyoWare "-" to Pro Trinket GND
MyoWare "SIG" to Pro Trinket A0
Orange Servo Wire to Pro Trinket #3
Red Servo Wire to 5V
Brown Servo Wire to Ground
Code
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#include
Servo myservo;
// constants
const int iServoPin = 3; // servo pin number
const int iSensorPin = A3; // muscle sensor pin number
const int iMaxServoVal = 1140; // HS-7940's fully extracted claw servo position PWM value (in microseconds)
const int iMinServoVal = 1800; // HS-7940's fully retracted claw servo position PWM value (in microseconds)
const int iMinThreshVal = 200; // muscle sensor threshold value to begin controlled extension
const int iServoStep = 10; // controls claw extension speed - increase to speed up
const unsigned long lLockOut = 2000L; // duration to hold max threshval to toggle the lock state (in milliseconds)//
// global variables
unsigned long lStartTime = 0L; // variable to store the time the timer was started
bool bStartLockTimer = false; // if true, the timer has been started; false otherwise
bool bActiveLock = false; // if true, the claws have been locked in fully extended state; unlocked otherwise.
void setup()
{
myservo.attach(iServoPin); // attaches the pin to the servo object
delay(10000); // 10 second delay to give you time to plug in the battery, stow it, and get clear
}
void loop()
{
// read muscle sensor value
int iSensorVal = analogRead(iSensorPin);
int iServoVal = iMinServoVal; // intialize to min value
// determine what state to put the claws in based on the sensor value
// three possible states
if(iSensorVal < iMinThreshVal)
{
// state 1 - below threshold - fully retract claws
iServoVal = iMinServoVal;
}
else
{
// state 2 - above max threshold - fully extend claws
iServoVal = iMaxServoVal;
}
// if sensor is in state 2, start timer to trigger lLockOut
if(iServoVal == iMaxServoVal)
{
// if the timer hasn't been started, then start it.
if(!bStartLockTimer) { lStartTime = millis(); bStartLockTimer = true;
}
}
else
{
// reset timer variables
lStartTime = 0L; bStartLockTimer = false;
}
// check to see if the timer was started and it runs for the amount of time required to trigger lock/unlock
if(bStartLockTimer && millis()-lStartTime >= lLockOut)
{
// toggle lock state
bActiveLock = !bActiveLock;
// reset timer variables
lStartTime = 0L;
bStartLockTimer = false;
// set servo value to max when locking
if(bActiveLock)
{
myservo.writeMicroseconds(iMaxServoVal);
iServoVal = iMaxServoVal;
}
else // reset servo value to min when unlocking
{
myservo.writeMicroseconds(iMinServoVal);
iServoVal = iMinServoVal;
}
// pause for a second to allow the user to adjust to the new setting
delay(1000);
}
// move the servo to the desired postion
if(bActiveLock)
myservo.writeMicroseconds(iMaxServoVal);
else
myservo.writeMicroseconds(iServoVal);
// delay to not overload the ADC
delay(100);
}
Mount to Arm
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this will depend on the type of prosthetic you have. I had to use a bolt and dremel.