Wireless-Controlled Capsule Robots: A Novel Design and Experimental Validation

Wireless capsule robots represent a rapidly advancing area of biomedical engineering, with various designs targeting challenges in movement control, power transmission, and functionality within the gastrointestinal tract. This paper presents a wireless-controlled capsubot by integrating an internal lithium battery and a Bluetooth amplification circuit, enabling wireless communication with an external USB Bluetooth transmitter to eliminate physical signal wires. New physical and mathematical models were developed by incorporating drag and buoyant force when capsubot moves in the fluid environment. An experimental system was built to verify the wireless control capabilities of capsubot in the dry friction condition. Comparative analysis of experimental results and numerical simulation data by the XPPauto software revealed a consistent correlation, indicating the accuracy of the mathematical model and the reliability of Bluetooth wireless control solutions for the proposed capsule. Experimental investigations demonstrated that the excitation frequency directly affects the capsubot’s movement speed. The capsubot can completely reverse its direction by altering the external excitation signals from sine waves to square wave and vice versa or change the control parameters including frequency f and excitation force intensity Fm from outside the capsule. Bifurcation diagram analysis, phase trajectory, and Poincaré section techniques were employed to evaluate the dynamic behavior and stability of the capsule system. The influence of frequency, excitation signal type and fluids properties on capsule performance was also evaluated by numerical method. These results serve as a foundation for optimizing operational parameters and conducting experiments for the capsule under more realistic conditions in the future.