2G "Velo" Gripper
At Willow Garage we are constantly engaged in exploration and research work aiming to advance towards future personal robots. In this context, an ongoing project explores novel gripper designs and grasping strategies using them. The Velo 2G Gripper is a result of this exploratory project. Starting from early research prototypes, we have taken the current design to what we refer to as Alpha prototypes, which we are describing here. Based on 3D printing technology, the Alphas can be manufactured in small batches and used for application research and exploration, as well as integration on exploratory mobile manipulation platforms.
Parallel grippers are effective on a wide range of objects and tasks, executing fingertip grasps between two perfectly opposing pads. However, adding the ability to envelop objects can greatly increase the stability of the grasp in many situations. We explored the design space aiming to achieve both of these capabilities.The Velo has two fingers with two joints each, and is tendon-driven. Aiming to reduce the complexity and potential cost, we used a single actuator, resulting in an underactuated design. The gripper executes fingertip or enveloping grasps by passively adapting to the shape of the grasped object. Extension is passive, provided by springs.
The route of the tendons and the magnitude of the extension forces are optimized to execute both types of grasps, and to passively transition from one to the other based on the shape of the grasped object. The forces applied to the target object are also optimized to result in stable grasps in a large set of possible configurations. Passive adaptation also allows the gripper to conform to asymmetric or irregular shapes.
The dimensions of the palm and the links are optimized to execute enveloping grasps on a large set of common household objects.
- Dimensions of grasped objects
- parallel fingertip grasps: from arbitrarily thin objects (e.g. sheet of paper) up to 13.5cm object width
- enveloping grasps:
- circular objects up to 10cm in diameter
- rectangular objects of various sizes and aspect ratios
- Maximum grasping force: up to 10N contact force on each finger.
- Impact resistance: 2J impact energy (survive collision if attached at the end of a 3kg arm and traveling at 2m/s)
- Lifetime testing: up to 60K open/close cycles under load
- Integration: EtherCAT interface
- Is the Velo available for sale?
- The Velo is currently not mass-produced or available for sale. The Alpha prototypes are manufactured based primarily on 3D printing technology, and meant primarily for research work. However, we are exploring the possibility of offering a limited number of them for sale in the future. If you would be interested, please send an email to the contact address below, and specify the following: your application/research domain, the system you would like to integrate the Velo on, and any particular requirements.
- What robots have you mounted the Velo on?
- We have tested the Velo on the PR2 robot, integrated it with ROS grasipng and manipulation software, and used to grasp a wide variety of objects both under teleoperation and under manual control.