Development of Neuromorphic Integrated Circuit with Light-Stimulated Gait Switching Function for Insect-Type Microrobots

抄録

Many researchers expect to apply microrobots in narrow environments for tasks such as exploration and maintenance. However, digital control, which is the primary robot control method, faces computational cost and circuit miniaturization challenges. The authors have been studying neuromorphic circuits, which mimic biological neural functions for robot control, acting as a central pattern generator (CPG) as a driving circuit to perform the walking motion. Previously, we constructed a neuromorphic circuit on an integrated circuit and we successfully implemented the neuromorphic integrated circuit in millimeter-scale microrobots. However, the microrobot lacked sensory input, which prevented the robot from adapting to the robot's movement in response to external environmental changes. This paper proposes a neuromorphic integrated circuit capable of adaptively switching the gait of an insect-type microrobot in response to light stimuli. The proposed circuit incorporates a receptor cell model that mimics biological sensory neurons, enabling the transformation of external light input into electrical signals using photovoltaic cells (PV cells). The electrical signals are processed through synaptic and CPG models to switch locomotion patterns. The authors systematically measured gait patterns to evaluate the operating range while varying the power supply voltage of the receptor cell model and the output voltage of PV cells. We observed the results, which clarified the regions where stable wave gait, tripod gait, or unstable outputs. Furthermore, we measured the I-V characteristics of a PV cell. Also, we confirmed that its output voltage matches the designed switching threshold of the proposed circuit, enabling optical control without additional signal conditioning. These findings demonstrate that the proposed circuit can be a low-power, sensor-responsive gait controller for future autonomous microrobots.