Dynamically Extensible and Retractable Robotic Leg Linkages for Multi-Task Execution in Search and Rescue Scenarios
William Harris, Lucas Yager, Syler Sylvester, Lizzie Peiros, Michael C. Yip
AI summary
Problem
Search and rescue robots must rapidly traverse uneven terrain while also generating high forces for casualty extraction, but existing legged platforms are typically specialized for only one of these tasks. This specialization leaves a critical gap in creating versatile ground robots capable of handling both mobility and heavy-load rescue operations.
Approach
The authors developed a morphing leg architecture using a parallel five-bar linkage that dynamically extends and retracts its links via capstan-driven actuators. This geometric transformation mechanically shifts the robot between a height-advantaged configuration for fast navigation and a force-advantaged configuration for heavy pulling.
Key results
- Design of a dynamically extensible five-bar linkage leg with mechanical mode switching
- Kinematic modeling and simulation framework mapping link lengths to workspace and force trade-offs
- Experimental validation of static horizontal pushing forces using a custom rail-mounted testbed
- Bipedal prototype demonstration of dynamic configuration transitions and walking performance
Why it matters
Enables the development of versatile SAR robots that can quickly navigate disaster zones and effectively perform physically demanding rescue tasks, reducing risk to human responders.
Abstract
Search and rescue (SAR) robots are required to quickly traverse terrain and perform high-force rescue tasks, necessitating both terrain adaptability and controlled high-force output. Few platforms exist today for SAR, and fewer still have the ability to cover both tasks of terrain adaptability and high- force output when performing extraction. While legged robots offer significant ability to traverse uneven terrain, they typically are unable to incorporate mechanisms that provide variable high-force outputs, unlike traditional wheel-based drive trains. This work introduces a novel concept for a dynamically extensible and retractable robot leg. Leveraging a dynamically extensible and retractable five-bar linkage design, it allows for mechanically switching between height-advantaged and force- advantaged configurations via a geometric transformation. A testbed evaluated leg performance across linkage geometries and operating modes, with empirical and analytical analyses conducted on stride length, force output, and stability. The results demonstrate that the morphing leg offers a promising path toward SAR robots that can both navigate terrain quickly and perform rescue tasks effectively.