Exo Arm Work Day 5.23.17

Exo Arm Work Day 

Date: 5.20.17
Location: Logan HS
Time: 3 hours
Goal: Clean up wiring and work on linear actuator switch.

All test connections from Thursday night were soldered together and shrink wrapped to ensure connectivity. Additionally, a platform for the motor driver was fabricated and installed in the control box.

We placed an image of the initial motor driver circuit toward the bottom of this post to show how streamlined and efficient the initial circuit looked. It was unfortunate that the driver chip would only support 1 amp. We did look for a replacement  chip that would fit in that socket, but were unable to locate any that would output up to 3 amps. Using a full H-Bridge would support the amperage, but require a total redesign of the circuit. This we do not have time for.

Also below you will see a picture of a DPDT switch that is wired to act as a center off rocker switch. We used this to test the linear actuator to see if it had an adequate amount of torque to move the arm up and down the linear rail. We wired it directly into the 12 v line and to our surprise it did lift the arm with no problem. This is in spite of no bearings being used on the rail. Reversing the actuator down caused some jerking which we feel is due to how the arm is balanced on the rail system. Overall, we are pleased that the actuator has enough torque to do the job.

Next we need to wire the momentary switch into a motor driver. The switch is giving us some problem because it is a 3 pole momentary switch. If it was a standard DPDT with 6 pins we would be better off as far as the wiring is concerned.

Wiring getting cleaned up in the control box.

DPDT center off switch ready to be wired in for a test.

Original motor driver circuit. It worked great as long as the actuator did not pull more that 1 amp.