LocoMan: Advancing Versatile Quadrupedal Dexterity with Lightweight Loco-Manipulators

Abstract

Quadrupedal robots have emerged as versatile agents capable of locomoting and manipulating in complex environments. Traditional designs typically rely on the robot's inherent body parts or incorporate top-mounted arms for manipulation tasks. However, these configurations may limit the robot's operational dexterity, efficiency and adaptability, particularly in cluttered or constrained spaces. In this work, we present LocoMan, a dexterous quadrupedal robot with a novel morphology to perform versatile manipulation in diverse constrained environments. By equipping a Unitree Go1 robot with two low-cost and lightweight modular 3-DoF loco-manipulators on its front calves, LocoMan leverages the combined mobility and functionality of the legs and grippers for complex manipulation tasks that require precise 6D positioning of the end effector in a wide workspace. To harness the loco-manipulation capabilities of LocoMan, we introduce a unified control framework that extends the whole-body controller (WBC) to integrate the dynamics of loco-manipulators. Through experiments, we validate that the proposed whole-body controller can accurately and stably follow desired 6D trajectories of the end effector and torso, which, when combined with the large workspace from our design, facilitates a diverse set of challenging dexterous loco-manipulation tasks in confined spaces, such as opening doors, plugging into sockets, picking objects in narrow and low-lying spaces, and bimanual manipulation.

Figures (13)

• Figure 1: Equipped with loco-manipulators, LocoMan is proficient in handling versatile manipulation tasks. (a) With a single loco-manipulator, LocoMan not only can perform manipulation tasks that require precision and stability, but also excels at operating in extremely narrow space in its compact form. (b) With both loco-manipulators installed on the two front legs, LocoMan is able to perform bimanual manipulation tasks when standing upright. (c) LocoMan is also capable of loco-manipulation, e.g. carrying objects with its loco-manipulators while walking.
• Figure 2: Design of our loco-manipulator. (a) The joint configuration of the legged-arm. The legged-arm has six joints including three from the leg and three from loco-manipulator. (b) The components of a right loco-manipulator shown in an exploded view.
• Figure 3: The unified framework for whole-body loco-manipulation. The robot commander converts the desired action command from user into the standardized robot command based on a specific operation mode ($M$). The unified whole-body controller, including whole-body impulse control and joint-level PD control, computes torques for each joint of LocoMan to track the desired robot command,
• Figure 4: Our loco-manipulator turns the original non-prehensile (in orange) workspace of Go1 to a prehensile workspace (in blue) and expand the reachable area by more than 80%.
• Figure 5: The figure on the left shows trajectory tracking of the end effector position and the torso orientation when drawing a spatial square. The figure on the right depicts the corresponding 3D trajectory tracked by an LED light attached to the gripper.