Robot dog runs much more energy-efficiently with passive mechanics

A research team from Delft University of Technology (TU Delft) and the École Polytechnique Fédérale de Lausanne (EPFL) has developed a robotic dog with passive mechanics that can run more energy-efficiently than other walking robots. The scientists analyzed the running behaviour of a biological dog in order to optimize the running mechanics. The robotic dog ran on a treadmill without its own motor drive.

Robotic dogs need a lot of energy to run. In principle, this applies to all walking robots that use electric motors to propel their legs. However, robotic dogs should be able to carry out their work for as long as possible without interruption, for example in surveillance tasks. The scientists at TU Delft and EPFL therefore wanted to make the running of a robot dog more energy-efficient, as they write in the study "Synergy-based robotic quadruped leveraging passivity for natural intelligence and behavioral diversity", which has been published in Nature Machine Intelligence.

The researchers came up with the mechanical optimization of walking based on various examples from nature. For example, they noticed that fish can still swim in a current even when they are dead. The necessary movement of the fish is then achieved exclusively through the passive mechanics of its body, not through a conscious movement, the scientists explain. This shows that optimized body mechanics can result in efficient movement.

The team took advantage of this and analyzed the running movements of dogs in order to incorporate the results of their biomechanics into the development of the robot dog. They used machine learning methods for the analysis and transferred the findings to the structure of the robot by arranging mechanical components such as springs, cables and joints accordingly.

Walking on the treadmill without its own motor

As a result, the scientists obtained a walking robot that can walk on a treadmill and adapt to different speeds without being driven by one or more of its own motors. The robot's running is generated solely by the propulsion of the treadmill and is therefore based on the passive mechanics of the robot.

The researchers then built electric motors into the robot dog to drive its legs in order to overcome possible obstacles. The researchers found that the motors had to perform less than in comparably constructed robot dogs without passive mechanics.

The scientists see their work as a step towards holistically intelligent robots that have improved mechanical and cognitive abilities, work more efficiently and are better able to adapt to complex environments.

(olb)