Contact Detection and Manipulation with a Shape-Memory Alloy Based Soft Gripper
Louis Plottel, Richard Desatnik, Dinesh K. Patel, Philip LeDuc, Carmel Majidi
AI summary
Problem
Soft robotic grippers struggle with reliable contact sensing and control, limiting their ability to safely manipulate fragile objects or perform complex tasks like twisting.
Approach
The researchers built a multi-axis bending soft gripper with shape-memory alloy actuators and integrated capacitive bend sensors, using real-time acceleration data from the sensors to dynamically adjust control waypoints upon contact.
Key results
- Multi-axis bending soft gripper actuated by lightweight shape-memory alloy coils
- Real-time contact detection algorithm using bend sensor acceleration thresholds
- Successful grasping of diverse objects (ball, chip bag, bottle, egg) with simple waypoint control
- Improved success rate and consistent grasping force for delicate tasks like unscrewing bottle caps when contact detection is enabled
Why it matters
Enables safer, more precise manipulation of fragile or irregular objects in manufacturing and human-robot interaction without bulky external sensors or complex control systems.
Abstract
Soft robotics offers the opportunity to create dexter- ous machines that can safely handle delicate objects. Grippers made from deformable actuators and compliant materials can deform around the objects with which they come in contact. The continuum mechanics of flexible manipulators can be leveraged for safe manipulation tasks such as twisting and grasping during manufacturing. However, to achieve this goal, contact sensing and controls for manipulators in these soft systems still remain a chal- lenge in the field. This letter demonstrates a shape-memory alloy actuated soft gripper, with each finger able to bend about multiple axes. This enables the soft gripper to perform twisting tasks and handle various and fragile objects. Using capacitive bend sensors, we also demonstrate that the measured impedance of motion can be used as a proxy for contact, greatly increasing performance in a delicate manipulation task.