Burst Stimulation for Enhanced Locomotion Control of Terrestrial Cyborg Insects

Terrestrial cyborg insects are biohybrid systems integrating living insects as mobile platforms. The insects' locomotion is controlled by the electrical stimulation of their sensory, muscular, or neural systems, in which continuous pulse trains are usually chosen as the stimulation waveform. Although this waveform is easy to generate and can elicit graded responses from the insects, its locomotion control efficiency has not been consistent among existing literature. This study demonstrates an improvement in locomotion control by using a new stimulation protocol, named Burst Stimulation, to stimulate a cyborg beetle's antennae (Zophobas morio). Modulating the continuous pulse train into multiple bursts enhanced the beetle's turning responses. At the same stimulation intensity (amplitude, pulse width, and active duration), the Burst Stimulation improved the turning angle by up to 50% compared to the continuous waveform. Moreover, the beetle's graded response was preserved. Increasing the stimulation frequency from 10 Hz to 40 Hz raised the turning rate by 40 deg/s. In addition, the initial implementation of this protocol in the feedback control-based navigation achieved a success rate of 81%, suggesting its potential use to optimize further the autonomous navigation of terrestrial cyborg insects.