Quadrupedal Locomotion with Passive Ventral Wheels: A Data-Driven Approach to Energy Efficiency Analysis

In this paper, a hybrid locomotion approach is proposed and experimentally validated for a quadrupedal robot to enhance energy efficiency on mixed terrains. A mechanical solution was implemented by adding passive wheels on the robot’s abdomen, to allow for gliding on flat portions of the faced terrains. This strategy aims to reduce the use of the legs, decreasing the overall energy consumption. To allow an efficient use of simulations, a data-driven approach was developed to estimate motor power consumption from joint dynamics on the real robot and subsequently applied within the simulation environment. The neural network achieved a coefficient of determination of R2 = 0.97, ensuring accurate estimation of energy consumption under both simulated and real conditions. Experimental and simulated results show that the proposed sliding gait reduces the average Cost of Transport from approximately 4.5–6.0 during trotting to 0.8–1.1 during sliding, corresponding to a four–five-fold improvement in energy efficiency. Overall, the results demonstrate that a simple mechanical upgrade of the robot’s body structure can significantly enhance locomotion efficiency and versatility on flat or slightly descending terrains.