Tohoku University researchers have built a mechanical reflex module that reproduces a knee-jerk response without electronic sensors or circuits in the module itself. The university reported on November 4 that the mechanism also helped a musculoskeletal robot generate a walking gait.
The device responds when an artificial muscle stretches beyond an adjustable threshold, triggering contraction through its physical structure. It takes inspiration from muscle spindles, which help the nervous system detect changes in muscle length and coordinate movement.
The team first recreated the patellar tendon reflex, the response seen when a doctor taps below a patient’s kneecap. To produce bipedal walking, the researchers added a higher-level controller that changed the activation threshold with the movement phase. The walking system therefore still uses additional control.
The study, by Shunsuke Koseki, Mitsuhiro Hayashibe and Dai Owaki, appears in Advanced Intelligent Systems. Its mechanical approach offers a useful contrast with conventional robot actuators, where sensing, software and drive components usually work together to regulate motion.
The researchers see potential to reduce control complexity, computational demands and power consumption, rather than reporting a quantified efficiency improvement. Their next step is to combine mechanical reflexes with minimal electronic control in robots containing more artificial muscles.
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