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Topic: Robotic thumb mover (continuous passive motion) Linear actuator with H-bridge (Read 182 times) previous topic - next topic


Hi guys.... First post here/ New to adruino

Parts bag=  Adrunino Uno, an L298P motor driver shield ( Ive been calling it a H-bridge hat) , 12v dewalt battery, 12v 75mm linear actuator (2-wire) with built in limit switches

Several years ago I had my thumb ripped off and it was re-attached.  The top and middle joins scars down (flexor tendon) inside the thumb to other parts (pulleys/sheaths).  I can occasionally tear it loose from those parts using a joint jack which it like a small vice and then a frap strap the pull it down towards my wrist. The issue is once I tear it loose from the inside .... when I sleep, it scars back down.  Every other joint including other fingers you can buy or rent a continuous passive motion machine.  However none is made for the thumb.  

I believe I have the mechanics of this worked out by using a 3D printed thumb mold with a mounting tab on the tip of the last joint, which attaches to a triangle lever (might not be the correct name- but looks the triangle in a pull rod swing arm) the 2nd tip of the triangle would have a strap that goes around the back of thumb and the 3rd would attach to the linear actuator.  When fulling extending it would actually pull the middle of my thumb in and press the tip out.   When contracting it would bend all 3 thumb joints.   Obviously the bottom of the actuator will mount below my wrist.

For the adriono/ hat.   The uno and the L298P slide together which connect all the pins.  My plan is to wire this 12v dewalt battery to the VMS (+) and Gnd (-) and put the OPT jumper on and wire the actuator to motor A on the P298P board.   I think this will power the Uno and the motor drive by itself.... I'm guessing that I can also hook a 12dcv supply to the uno DC jack while the battery is attached during the night. If not I will set an alarm and switch the batteries out every few hours.

What I would like the Uno to do is run the motor out which should take 2-3 seconds then wait 8-10 seconds and reverse the motor all the way wait 8-10 seconds..... loop   The speed isn't all that important so I dont really need PMW

I tried to use someone else's code but its was for a linear servo and would accept a 2ms pulse to run in/out.  Ive never programed an Adriano and pretty much have no idea what im doing.  None the less I have windows10/ arduino IDE, python and a USB cable

#include <actuator.h>

Servo actuator; // create a actuator object named "actuator"

void setup() {
  actuator.attach(9); // attach the actuator to Arduino pin 9 (PWM)
  actuator.writeMicroseconds(4000); // )
  delay(8000); // delay a few seconds to give the arm time to retract

void loop() {
  // Extend and retract the actuator arm on a12 second interval
  actuator.writeMicroseconds(4000); // 
  delay(8000); // the actuator takes >3s to extend/retract when loaded - give it plenty of time
  actuator.writeMicroseconds(4000); // 2ms pulse to retract the arm

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