Overview
The cable tension switch sensor for the Open Tentacle robot project is designed to detect when the cable is slack (binary yes/no detection). This allows the control software to determine when motors need to move to tighten specific cables.
Design Concept
The sensor switch consists of two main components that slide relative to each other, held together by a spring. Metal contacts on the touching surfaces complete an electrical circuit when the cable is slack.
To the right is the original design drawing showing the concept and dimensions of the tension switch.
How It Works
A cable is threaded through the hollow center of the sensor. When the two pieces are spread apart slightly and the ends are tightened, the cable bunches up when the pieces are brought together, indicating slack. As tension increases in the cable, the two pieces are pulled apart, breaking the circuit to the Arduino analog input.
Design Note
The original design used aluminum foil as the conductive metal contact, but this was later revised to ensure a continuous conductive path to the wire connection points. The insulating adhesive on the foil needed to be removed in some areas to ensure proper conductivity.