Video: SDM Hand
One of the greatest successes of biologically-inspired design has been the development of mechanically robust robots. One promising biomimetic fabrication technique is Shape Deposition Manufacturing (SDM), which alternates material deposition and machining to produce robot structures with compliant joints and embedded sensing and actuation elements. This process, while currently being implemented in only a handful of research laboratories worldwide, is quickly gaining popularity in the robotics and mechatronics community in part because of its simple construction process, the ability to embed sensors and actuators in the structure, and the extremely robust nature of the finished parts.
Much of the reason for the current limitations is that traditional robot hands, which typically involve complex mechanisms, sensing suites, and control, are difficult to use, fragile, and impractical. Alternatively, by carefully designing the mechanical structure of the hand to appropriately incorporate features such as compliance and adaptability, the uncertainty inherent in unstructured grasping tasks can be more easily accommodated. These features can reduce the need for complicated sensing and control by passively adapting to the object properties and positioning, making the hand easier to operate, more robust, and less expensive.
After undertaking design optimization studies to determine the best means of incorporating these features into a robot hand, we built a novel, four-fingered robot hand that is both compliant and highly underactuated (see figure). The hand uses only a single actuator for the eight joints yet is able to passively adapt to large variations in object geometry. Experimental work with the prototype hand showed that even with three positioning degrees of freedom and open loop hand control, target objects spanning a large range of size, shape, and mass could be reliably grasped.
Aaron M. Dollar and Robert D. Howe
Simple, Robust Autonomous Grasping in Unstructured Environments, proceedings of the 2007 IEEE International Conference on Robotics and Automation (ICRA), Rome, Italy, April 10-14, 2007.
Joint Coupling Design of Underactuated Grippers, proceedings of the ASME 30th Annual Mechanisms and Robotics Conference, 2006 International Design Engineering Technical Conferences (IDETC), Philadelphia, PA, Sept. 10-13, 2006.
Towards Grasping in Unstructured Environments: Grasper Compliance and Configuration Optimization, Advanced Robotics, vol. 19(5), pp. 523-543, 2005.
All Robotic Grasping Publications >>