Benchmarking Variable-Stiffness Grippers

Designs for grippers using variable-stiffness principles have become common in recent years. Researchers have developed various tests and setups to measure and validate the properties of their designs. However, there are no clear standards or benchmarks to analyse, categorise and compare this type of grippers. This paper proposes a set of benchmarks to evaluate and categorise variable-stiffness grippers. After reviewing the tests commonly applied to evaluate existing variable-stiffness and generic grippers, we propose four tests to measure different properties of a gripper. The tests are independent of one another and allow to classify each gripper in a three-category taxonomy. In order to validate the benchmark tests, three simple variable-stiffness grippers have been built and analysed with the benchmark. The results show that the grippers can be easily analysed with our benchmarks.