Robot Fish Inclination Control for Narrow-Space Swimming

The robotic fish uses a movable weight mechanism that can dynamically adjust the position of weights along the longitudinal axis of the body. This allows rapid change in the center of gravity position, enabling quick inclination adjustment without the delays inherent in buoyancy adjustment systems. The weight can be moved forward or backward to quickly pitch the fish nose up or down, achieving fast inclination changes while maintaining submergence control.

The robotic fish employs a movable weight mechanism that serves multiple functions: it controls inclination for submergence and upward swimming, and also enables rotational movement for obstacle avoidance. By shifting the weight laterally or asymmetrically, the fish can generate rotational torque to navigate around obstacles. This single mechanism provides both depth control and directional control, making the fish adaptable to various swimming scenarios including narrow spaces where rotation is limited.

The robotic fish uses a movable counterweight mechanism to generate backward propulsive force. By rapidly shifting the weight to the rear and then forward in a controlled manner, the fish creates reactive forces that propel it backward. This counterweight system allows the fish to reverse direction without requiring a separate backward propulsion mechanism, enabling escape from obstacles by generating backward thrust through controlled weight movement and body oscillation.

The movable weight mechanism serves as a universal control system that performs multiple functions: it adjusts inclination for depth control, enables rotational movement for obstacle avoidance, and generates both forward and backward propulsive forces. By using this single multi-functional mechanism instead of separate propulsion devices for forward and backward movement, the robotic fish achieves backward capability without increasing structural complexity or size.