Figure P8.1: Completed Robotic Arm
This final design included a spring to aid the shoulder servo in lifting the arm. This was necessary because we decided to make the arm longer than originally proposed to be more realistic and proportional, this increased the torque needed to lift the arm.
The elbow joint was damaged during testing. The lifting or the shoulder would cause bouncing of the rest of the arm. This placed an unexpected force on the elbow servo and stripped teeth off one of the internal gears. Further development of the arm should include a method of reducing strain on the internal components of the motors.
Video P8.1: Video Demo
This video was taken after the damage to the elbow joint's motor, this caused us to remove the motor as we had no replacement. In different clips of this demo varying delays can be seen between the motion of the operators arm. This was due to different tweaks in the code that improved the speed of the response. The electrodes that controlled the lift of the arm did not produce a dependable signal. We attempted several placements of the electrodes and found a more dependable signal but still not quite dependable enough for actual use within industry. Further development is necessary in finding an appropriate placement for electrodes or possibly exploring other sensors to control the lifting of the shoulder. The flexion sensors were both dependable and easy to mount within a sleeve that the operator wore. Electrodes did not stick well to the skin, required more setup time as well as amplification, and produced signals that did not necessarily correlate with the position of the operators arm. For these reasons other sensors may be explored.
