Using Motion Capture to Test Robot Movement

Source: University of Michigan 3D Lab

At the end of every year, seniors in the College of Engineering are working hard to finish their capstone design projects. These projects are guided by a professor but built entirely by students. Keteki Saoji, a mechanical engineer focusing on manufacturing, took inspiration from Professor Revzen who studies legged locomotion in both insects and robots. Earlier in the year Professor Revzen published the results of experiments with tripping cockroaches which indicated that insects can use their body mechanics and momentum to stabilize their motions, rather than relying on their nervous system interpreting their environment and sending electrical messages to the muscles. The study predicts that robots which similarly lack feedback can be designed to be remarkably stable while running.

Saoji and her three teammates took on the challenge of creating a robot that would maintain such stability on very rough terrains. They worked with a hexapedal robot designed at the University of Pennsylvania that was shown to follow the same mechanically stabilizing dynamics as cockroaches. The team had to design new legs with sensors allowing the robot to detect when its feet hit the ground. The changes in motion introduced by sensing were so subtle that they needed special equipment to see the change. Using the 3D Lab’s eight-camera Motion Capturesystem, the team was able to track the intricacies of how the robot moved when sensory information is used and when it is not used. They took the data collected from the Motion Capture session to track how the robot moved with their mechanical and programming revisions, establishing that ground contact sensing allows robot motions to adapt more effectively to rougher ground.

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