Design of an Untethered Multi-Mode Swimming Robot Driven by Electromagnetic Actuators
Jinchun Yan, Yiyi Lu, Qifan Li, Oncay Yasa
AI summary
Problem
Most electromagnetically actuated underwater robots are confined to fixed swimming modes due to rigid or overly simple designs, limiting their adaptability in unstructured aquatic environments.
Approach
The robot integrates four 2-degree-of-freedom electromagnetic modules connected by optimized silicone connectors and membranes. By symmetrically arranging these modules and varying activation signals, it generates diverse undulatory and translational motions without tethers or mechanical joints.
Key results
- Achieved five distinct swimming modes via simple signal sequencing
- Reached a maximum backward swimming speed of 87.8 mm/s at 3 Hz
- Optimized Ecoflex 00-30 connectors to balance 19° bending range with structural stability
- Enabled fully untethered operation with onboard electronics and passive buoyancy control
Why it matters
Provides a scalable, untethered platform for adaptive underwater exploration and search-and-rescue missions in complex environments.
Abstract
Underwater robots have significant potential for a wide range of applications, including deep-sea exploration, hydrocarbon extraction, marine biodiversity observation, and waste retrieval. A hybrid actuation system that combines electromagnets and permanent magnets preserves the main benefits of magnetic-driven robots, addressing the issues of bulky coil systems and limited mobility. However, most electro- magnetically actuated underwater robots are limited to a fixed swimming mode due to their relatively simple designs, which restrict their adaptability to unpredictable and unstructured aquatic environments. In this work, we present an unteth- ered multi-mode swimming robot driven by four 2-degrees- of-freedom (DoF) electromagnetic actuators, each with a rigid shell interconnected by flexible connectors and covered with silicone membranes. Initially, we conducted tests to determine the optimal hardness of the flexible connector by validating the module’s range of motion across different activation times. Next, we demonstrated that the robot can swim forward and backward in a water tank, exhibiting snake-inspired motion, front- and rear-undulation, and wave-shaped motion, and reaching a maximum speed of 87.8 mm s−1. Finally, we showed the lateral translation and steering motions achieved with different control signals, resulting in an average turning speed of 3 ◦s−1. This approach enables a novel robot design strategy based on compact multi-DoF electromagnetic modules, facilitating potential applications in search-and-rescue missions and environmental inspections.