Robotics actuator · Tejas Patel

Industrial robots are rigid, which makes them fast, precise and dangerous to stand next to. Biological joints are not. This was my B.Des degree project, 18 weeks from 17 January 2022 at the sysIDEA Robotics Lab at IIT Gandhinagar, and the report marks it as industry sponsored. The lab’s brief was a table-top robotic manipulator with at least two degrees of freedom and a learning control system.

I started from muscle biomechanics, the series and parallel elastic parts of muscle, and a horse’s leg. Then I drew four concepts: two cable-driven, a belt-driven rolling joint, and remotely driven links. The belt drive was designed so the links can rotate freely in any direction. What I built is a belt-driven arm with series elastic actuators and a clutch that can engage or release the parallel spring. The report’s note on compliance is that it provides safety where humans and robots work together.

The build is 3D-printed gears and pulleys and clear acrylic links, in a three-layer rig of aluminium extrusion. The report puts the electronics on the bottom layer, the spring and clutch stage in the middle and the open arm on top. Controls and mechanisms were tested on an optical breadboard, which goes together and comes apart quickly. A tool made for the arm measures the forces at its tip.

The report describes the testing but gives no safety or efficiency figures, so I’m not quoting any. In its reflection, the hard part was holding engineering and design in one project, and it was my first long stretch away from home.

A white and black 3D-printed gear stage close up on a dark bench, with more printed gears blurred behind it. — Two printed parts, one white and one black, seated together by their notched teeth.

Printed and laser-cut parts laid out on a black bench: black and white gears and pulleys, bearings, and an assembled stage with springs, a shaft and a clear acrylic arm. — Printed gears and pulleys laid out beside a built-up arm with springs, a steel shaft and clear acrylic links.

Tejas sitting on the floor of the lab in a face mask, assembling a three-layer aluminium-extrusion frame with clear acrylic shelves and orange parts. — Me on the floor, fitting parts into the aluminium-extrusion rig.