Series Elastic Actuator · ME 495 Mechatronics Capstone

A series-elastic actuator for safer human-robot interaction

Designed and built a tabletop MARIONET-style Series Elastic Actuator with a dual-loop control architecture - designed and simulated in MATLAB, then implemented in embedded C on an NI myRIO. Hardware testing demonstrated stable position tracking, disturbance rejection, and torque control.

Validated on hardware: stable tracking, disturbance rejection, torque control

Role

Controls + Embedded Systems

Applied

Control SystemsMATLABEmbedded CNI myRIOMechatronicsHuman-Robot Interaction

Reference

Capstone report ↗

Series Elastic Actuator - full system CAD render showing the complete tabletop MARIONET mechanism with springs, pulleys, and motor — FIG 01Full system CAD render - the complete tabletop Series Elastic Actuator with elastic elements, pulley mechanism, and drive motor.

My contribution

Designed and built a tabletop MARIONET-style Series Elastic Actuator for safer human-robot interaction.
Implemented a dual-loop control architecture - an inner torque loop with a custom lead controller and an outer position loop with PIDF.
Simulated the controllers in MATLAB, then implemented them in embedded C on an NI myRIO.
Validated on hardware: stable position reference tracking, disturbance rejection, and torque control.

Objective

Series elastic actuators put a spring between motor and load so a robot can sense and limit the force it applies - the basis for safer physical human-robot interaction. This senior mechatronics capstone set out to design, build, and control one on the tabletop, taking it from a MATLAB model to validated hardware.

Series Elastic Actuator lever arm - CAD render of the 3D-printed pulley and lever subassembly — FIG 02Lever and pulley subassembly - 3D-printed in yellow PLA, carries the wire through the elastic element.

Series Elastic Actuator physical prototype on test bench - yellow 3D-printed parts, springs, wiring, and NI myRIO controller — FIG 03Built prototype on the test bench - NI myRIO controller mounted above, wired to the motor driver and encoder. Hardware used for control validation.

Technical details

Control is split into two nested loops. The inner loop regulates torque through the elastic element with a custom lead controller; the outer loop regulates position with PIDF wrapped around it. Both were designed and simulated in MATLAB before being implemented in embedded C on a National Instruments myRIO. On hardware, the actuator tracked position references stably, rejected disturbances, and held torque control as designed.