Iteration 1 / V1

This initial version of the rotary actuator was created for the Risk Reduction part of the project. At this point, we primarily aimed to validate the potiential of a cable-driven linear to rotary conversion mechanism.

The prototype successfully confirmed this key design decision, and it also highlighted many areas of concern that would be tackled in future iterations. For instance, the tolerancing for press fits, the limit on range of motion for the rotary pillar from the actuator stroke distance, and the difficulty in tensioning the system, were all significant concerns discovered as a result of inspection of the V1 prototype

Iteration 2 / V2

In this iteration, we began to implement additional components of the design which we knew would be necessary for a thought-out design.

• Helical cable wrap and angled tensioners

• Motion was smooth and low friction with added bushings

• Machined vented screws improved cable concentricity, aids tensioning

Iteration 3 / V3

The third iteration focused on structural and DFM improvements, but was not manufactured in the interest of maintaining our outlined project timeline.

• Slot-in core and rolling diaphragm actuator for ease of assembly

• Added lid to maintain structural integrity of the frame

• Improved rotary pillar geometries

Iteration 4 / V4

The fourth iteration involved an overhaul of the frame design, and the adoption of 35mm diameter rolling diaphragm actuators for increased force and travel distance. A pair of actuators of this iteration were the last to be manufactured during the project and were used for testing.

• Direct mounting points between the diaphragm cylinder housings and the outer plates

• Separate bearing mounts for improved concentricity and ease of manufacturing

• Rotary sensor stack for redundant position tracking

Test Setup

The first test setup of the fluid transmission system validated our selection of Arduino and pressure transducer for the project. At this stage, an LED displayed the system's state at ambient pressures.

As the system progressed, we began to implement pressure control hardware with actuators previously developed by the sponsor. This served to validate the capabilities of the pressurization system hardware.

Final Setup

In the system's usual operating state, all solenoid valves remain closed and the pressure regulator maintains a constant pressure. This creates two distinct, closed transmission systems. Transmission between the two actuators is accomplished solely through the water and air being pushed through the tubes, and the electronics are used for pressurizing the system and refilling the water line.

This system is further detailed in our Final Report.