Reflex-Based Adaptive Locomotion for Biped Robots Using Piezoelectric Sensing on Slippery Terrain

Bipedal robots face many issues with stability through walking on slippery environments, and traction can lead to falls with potential mechanical damage when reduced.These challenges are identified as dangerous conditions in real time due to the complexity of slip behavior and the limited processing capabilities of embedded systems.To address these challenges, a reflexive-based control strategy is employed with piezoelectric sensors within the support polygon of the robot foot to classify the surface type under the robot foot by measuring force response.Surfaces separated and signals filtered using an Exponential Moving Average (EMA) filter for normal (rough) and slippery surfaces.The results show that on standard conditions of terrains (rough), robots maintain balancing with shorter stance duration (≈ 0.2 s) and high joint speed (≈ 125•/s).In contrast, through walking on a slippery environment, the reflex controller increases the stance duration (≈ 0.38 s) and decreases the speed (≈ 53•/s) to enhance balancing.These results demonstrate that a lightweight reflex-based control system can adapt to slip conditions effectively.Furthermore, it offers an economical and simple method to improve the safety of this type of robot in unstructured environments.