Quadruped robots are usually equipped with additional arms for manipulation,
negatively impacting price and weight. On the other hand, the requirements of
legged locomotion mean that the legs of such robots often possess the needed
torque and precision to perform manipulation. In this paper, we present a novel
design for a small-scale quadruped robot equipped with two leg-mounted
manipulators inspired by crustacean chelipeds and knuckle-walker forelimbs. By
making use of the actuators already present in the legs, we can achieve
manipulation using only 3 additional motors per limb. The design enables the
use of small and inexpensive actuators relative to the leg motors, further
reducing cost and weight. The moment of inertia impact on the leg is small
thanks to an integrated cable/pulley system. As we show in a suite of
tele-operation experiments, the robot is capable of performing single- and
dual-limb manipulation, as well as transitioning between manipulation modes.
The proposed design performs similarly to an additional arm while weighing and
costing 5 times less per manipulator and enabling the completion of tasks
requiring 2 manipulators.Comment: 6 pages, 10 figures, updated layout to fit in margins and corrected
typos, accepted to the 2022 IEEE/RSJ International Conference on Intelligent
Robots and Systems (IROS 2022
