Tree Climbing Robot

Step 13 Backbone Motor

To move up and down a tree, the robot extends and contracts by spinning a threaded rod that is fixed to the top segment.  When the rod is spun clockwise, the two segments are pulled together, and the are pushed apart when it spins counter clockwise.  To spin the rod, I needed a relatively high-torque low-speed motor that would run at 12V, and I happened to find just such a motor in my box of parts.  This particular motor came fitted with a brass gear.  To assist with coupling the motor to the threaded shaft, I filed two sides of the gear flat.

To mount the motor to the robot, I bent a short length of aluminum to an "L" shape.  I drilled a large hole out of the center of one of the faces (for the motor shaft and gear) and two small holes in both faces for bolting the motor to the metal and bolting the metal to the robot.  I drilled corresponding holes into the back of one end of the segment of the robot without the electronics, so that the motor was positioned between the two legs.