Feldman Project Log

  • Strain gauge amplifiers need to have ground attached to negative on the power supply not V-
  • Attached is a Better Diagram for straing gauge amplifer set up
  • Increasing the gain on the amp and decreasing the offset makes strain gauges more sensitive but they tend to loose calibration easier so a higher deadzone is required
  • Pushing on bar right on motor1 makes motor 2 go clockwise, pushing left makes it go counter-clockwise
  • Motion is currently very jerky because it simply goes to angle and has to stop for a cycle before going again.  This is a problem in the stepper controller which needs to be changed anyways so that we can have a more analog input of speed.
  • Since there is no set velocity method we will probably have to set max velocity and change it on the fly.  I think setting it to a position that it will never be able to get to and changing max speed will give it a servo motor type functionality while still having accurate stop points if we need them later.  Need to add a set max_pos command to stepper controller and set max_speed so that it can be changed to negative when force is couter clockwise and positive for clockwise.  Max_speed will very proportionally to the amount of voltage registered.   The same principle will work for the controller motor(assuming it works at all) except max_pos will change depending on the force of the collision motor 2 encounters.
  • Calibrating the strain gauges is a little tricky.  Seems some combination of settings hold the calibration better.  There is a problem when the power cuts off that it doesn’t reset to what it shut off at.  Once its been on and off a couple times it seems to hold better.  This may be due to the difference in resistance between the strain gauges and the resistors or that the gain is set too high because of the resistance of the strain gauges. Might try using the the variable resistors to lower the resistances not sure if that will help.