UCLA

Climbing robots are a growing area of interest for tasks that involve vertical mobility in locations that are difficult or dangerous to access for humans. These robots are often designed for inspection, surveillance, or maintenance tasks, but have not been widely deployed due to key limitations with existing designs. Wheeled climbers have little to no adaptability to surface variations, and can generally only climb a single flat, featureless surface with no obstacles. Legged climbers possess better adaptability with their additional degrees of freedom, but can only step over small obstacles and are also heavy, slow, and expensive.

This dissertation details the development of a novel climbing robot that overcomes these problems with an innovative limb that utilizes tape springs. Like the common tape measure, tape springs can be used for a lightweight, long-reach, low-cost structure that spools into a compact package. This research resulted in two major innovations: the robotic limb EEMMMa (Elastic Extending Mechanism for Mobility and Manipulation) and the climbing robot EEWOC (Extended-reach Enhanced Wheeled Orb for Climbing).

The EEMMMa extendable limb can exhibit controlled bending using only a single primary motor through mechanical multiplexing. With this additional degree of freedom, it can bend its end effector to reach over ledges and around corners or obstacles. EEWOC combines this novel limb with additional magnetic grippers, actuators, and wheels to allow it to freely traverse 3D surfaces. EEWOC weighs 2.1 kg and is only 26 cm tall, and its limb can extend up to 1.2 m.

To better understand the impact of EEWOC’s novel design, several performance tests were carried out in controlled lab and outdoor settings. Compared to existing robots, EEWOC’s climbing performance was found to be equal or superior, with a climbing speed of 4.4 m/min and payload capacity of 3.4 kg. Simplified kinematic models were developed for the limb’s bending mode and for swinging across gaps, which were verified using visual tracking markers and video capture of real bending and swinging maneuvers while climbing.