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Step 18Limit Switches
Because I used a regular DC motor instead of a servo or a stepper to spin the threaded rod that is the spine, the robot can not know the degree of extension of the spine at all times. Therefore, limit switches must be used to prevent it from extending or contracting too much.
The spine has two limit switches. One is pressed in when the two segments of the robot are pulled close together, and the other becomes un-pressed when the threaded rod retracts past it. The latter is a switch like this glued parrallel to the threaded rod, on the segment of the robot with the electronics. When the spine retracts, it pushes down the lever of the switch, and when it retracts, the switch opens.
The second limit switch is a push button switch that requires very little force to actuate. I mounted it on a strip of aluminum from the front of the electronics segment.
Both the switches are connected to the same 5V and ground lines as the potentiometers on the legs, and their signals go to inputs A4 and A5, which the Arduino is set to read as digital inputs rather than analog.
The spine has two limit switches. One is pressed in when the two segments of the robot are pulled close together, and the other becomes un-pressed when the threaded rod retracts past it. The latter is a switch like this glued parrallel to the threaded rod, on the segment of the robot with the electronics. When the spine retracts, it pushes down the lever of the switch, and when it retracts, the switch opens.
The second limit switch is a push button switch that requires very little force to actuate. I mounted it on a strip of aluminum from the front of the electronics segment.
Both the switches are connected to the same 5V and ground lines as the potentiometers on the legs, and their signals go to inputs A4 and A5, which the Arduino is set to read as digital inputs rather than analog.
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