A preliminary review on metrics for modular snake robots locomotion

Without changing its mechanical structure, a modular snake robot (MSR) can move using different gaits. In order to evaluate their locomotion, different metrics according to specific research goals have been developed in the last decades. However, there is a lack of homogeneity in the use of these metrics between robot types and the tasks executed. In this paper, a set of metrics is presented. These metrics were divided in performance and efficiency metrics to capture such characteristics in a MSR. Related work on metrics for this kind of robots was reviewed in detail. A description of each metric was provided. Friction coefficients, translational speed, orientation of the velocity vector and a stability margin, define the first set of metrics aimed to measuring the robot's performance. On the other hand, energy efficiency, mechanical energy efficiency and dissipated power conform the set of efficiency metrics. Hence, a metric framework for MSR's locomotion was presented. The use of this framework is oriented to spatial motion of modular snake robots.