Grip as Needed, Glide on Demand: Ultrasonic Lubrication for Robotic Locomotion
Mostafa A. Atalla, Jack Cumming, Daan van Bemmel, Paul Breedveld, Michael Wiertlewski, Aimee Sakes
AI summary
Problem
Robotic locomotion traditionally relies on passive friction or complex mechanical systems to anchor and release, limiting adaptability in confined or fragile environments.
Approach
The method uses transverse ultrasonic vibrations to generate a pressurized fluid film at contact interfaces, dynamically switching between high-friction grip and low-friction glide states independently of normal load or surface texture.
Key results
- Designed cylindrical and flat-plate ultrasonic friction modules operating at ~21–23 kHz
- Integrated modules into inchworm and wasp ovipositor-inspired locomotion prototypes
- Achieved bidirectional locomotion with over 90% efficiency across rigid, soft, granular, and biological surfaces
- Demonstrated substantial, controllable friction reduction under dry and wet conditions
Why it matters
Offers a mechanically simple, versatile friction-control mechanism that can reduce design complexity and improve locomotion efficiency in confined or challenging robotic applications.
Abstract
Friction is the essential mediator of terrestrial locomotion, yet in robotic systems it is almost always treated as a passive property fixed by surface materials and conditions. Here, we introduce ultrasonic lubrication as a method to actively control friction in robotic locomotion. By exciting resonant structures at ultrasonic frequencies, contact interfaces can dynamically switch between ”grip” and ”glide” states, en- abling locomotion. We developed two friction control modules: a cylindrical design for lumen-like environments and a flat- plate design for external surfaces, and integrated them into bio- inspired systems modeled after inchworm and wasp ovipositor locomotion. Both systems achieved bidirectional locomotion with nearly perfect locomotion efficiencies that exceeded 90%. Friction characterization experiments further demonstrated substantial friction reduction across various surfaces, including rigid, soft, granular, and biological tissue interfaces, under dry and wet conditions, and on surfaces with different levels of roughness, confirming the versatility of ultrasonic lubrication for locomotion applications. These findings establish ultrasonic lubrication as a viable active friction control mechanism for robotic locomotion, with the potential to reduce design complex- ity and improve the efficiency of robotic locomotion systems.