WaveTouch: Active Tactile Sensing Using Vibro-Feedback for Classification of Variable Stiffness and Infill Density Objects

TL;DR

WaveTouch introduces an active vibro-feedback tactile sensor enabling robots to classify object stiffness during gripping, improving manipulation safety and efficiency by distinguishing between soft and rigid objects through vibration analysis.

Contribution

The paper presents a novel active vibro-feedback tactile sensor that classifies object stiffness during gripping, reducing damage risk and improving manipulation accuracy.

Findings

Rigid objects show low vibration absorption and signal enhancement.

Soft objects absorb vibrations more, indicating different physical properties.

Active vibro-feedback outperforms passive sensing in classification tasks.

Abstract

The perception and recognition of the surroundings is one of the essential tasks for a robot. With preliminary knowledge about a target object, it can perform various manipulation tasks such as rolling motion, palpation, and force control. Minimizing possible damage to the sensing system and testing objects during manipulation are significant concerns that persist in existing research solutions. To address this need, we designed a new type of tactile sensor based on the active vibro-feedback for object stiffness classification. With this approach, the classification can be performed during the gripping process, enabling the robot to quickly estimate the appropriate level of gripping force required to avoid damaging or dropping the object. This contrasts with passive vibration sensing, which requires to be triggered by object movement and is often inefficient for establishing a secure grip. The main idea is to observe the received changes in artificially injected vibrations that propagate through objects with different physical properties and molecular structures. The experiments with soft subjects demonstrated higher absorption of the received vibrations, while the opposite is true for the rigid subjects that not only demonstrated low absorption but also enhancement of the vibration signal.