Unique Grip and Adhesion Technologies developed at UCSD
Research labs at the University of California, San Diego are conquering new frontiers in soft and micro-robotics. Bio-inspired Robotics & Design Lab under professor Tolley Michael has made breakthroughs in the grip and adhesion technologies, through the development of clingfish-inspired robotic grippers, gas-lubricated vibration-based adhesion, development of under-actuated gripper to name a few.
1. Gas-lubricated Vibration-based Adhesion
Gas-lubricated vibration-based adhesion is a unique concept that allows controllable adhesion on a variety of surfaces. When we attach a thin membrane with a source of vibration like a pager-motor type actuator (usually found in mobile phones, or an eccentric rotating mass), the vibration creates adhesion when the membrane comes into close contact with a smooth surface. When the membrane vibrates, it moves the fluid between the membrane and the smooth surface, which creates a low-pressure region. This low-pressure region helps in generating adhesion.
This unique adhesion technology has interesting characteristics that make it suitable for mobile robot applications. It provides adhesion in the normal direction only. Gecko-inspired, Electro-static, or glue-based adhesion usually provide adhesion in normal as well as shear direction, so in applications of a mobile robot, to move from one location to another, we need to grip the surface at some initial points, use multiple limbs to stick to another points and remove the adhesion from initial location and then move the body. Interestingly, with gas-lubricated adhesion, we can attach wheels on this membrane to move around while the membrane maintains adhesion in the normal direction. Using this technology, they have designed and built a mobile robot capable of scaling vertical walls, driving along a curved loop, and supporting a payload approximately x10 the weight of the total robotic system.
2. Clingfish inspired reversible underwater adhesion
Clingfish can grip rough surfaces quite firmly due to micro-structures present around the suction disc on her body. These microstructures conform to micro-scale roughness and allow the fluid to channel out of the way to create an intimate contact.
Inspired by this characteristic, Bio-inspired Robotics & Design Lab researchers have developed a suction gripper as shown in the figure to the side.
These grippers have shown better performance as compared to the commercial suction grippers on rough surfaces. Though because the micro-structures creates inadequate sealing on smooth surfaces like glass, these suction grippers lag in performance in comparison to commercial suction cups.
3. Highly Underactuated Grippers
Novel highly underactuated grippers developed in the same lab conform to large arbitrarily shaped objects to create a better grip. This gripper uses tendon-driven linkages. In addition to that, it uses a gecko-inspired adhesive to provide adhesion-controlled friction that helps stabilize the gripper and improves grasp performance without the need of large normal forces. With these high-friction interfaces, highly under-actuated linkages successfully grasp in many configurations without strict stability.
In addition to these projects, Bio-inspired Robotics & Design Lab has worked on some really interesting projects in soft robotics that can also have applications in legged locomotion. Professor Tolley Michael discusses these projects elaborately in a lecture he delivered at SoftTechRehab 2021. Stay tuned for a blog on the same!
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