LocoMan Lends Robots a Hand

As the state of the art has advanced, quadrupedal robots have proven to be an important innovation in the world of robotics, offering unique capabilities that make them well-suited for traversing difficult terrain and fitting into tight spaces. These robots mimic the locomotion of animals with four legs, which gives them stability and balance on rough or uneven surfaces. Their ability to adapt to various environments allows them to navigate through areas that wheeled or tracked robots may struggle with, such as rocky landscapes, rubble, or even muddy and slippery conditions.

However, one of the major weaknesses of quadrupedal robots is their limited ability to interact with their environment. Unlike humanoid robots, quadrupedal robots lack arms and hands for precise manipulation of objects. Their legs and heads can only perform coarse actions, such as pushing or kicking objects, which limits their usefulness in tasks that require fine motor skills.

To address this limitation, some quadrupedal robots have been equipped with a robotic arm on their back. This addition allows them to perform more complex tasks such as picking up or manipulating objects with greater precision. However, incorporating a robotic arm also comes with trade-offs. It increases the overall weight of the robot, which can hinder its agility and mobility. Additionally, the arm may restrict the robot's ability to fit into tight spaces, reducing its effectiveness in certain scenarios.

Drawing on inspiration from animals like the great apes and bears, a group led by researchers at Carnegie Mellon University has developed an add-on system for quadrupedal robots that gives them dual-purpose legs and hands. With these robotic hands, called LocoMan, attached to the existing legs, they can pull double duty as arms. Due to the unique design of these manipulators, payload is only nominally increased, and the robot does not lose any agility or the ability to squeeze into tight spaces.

LocoMan consists of custom-designed, lightweight 3-DoF manipulators that can be attached to the calves of an existing quadrupedal robot. This arrangement allows the robot to maintain its normal ability to traverse challenging terrain, but also can repurpose the leg joints and actuators to treat them as arms. The LocoMan hands are then utilized for precision interactions with their environment, from picking up objects to pressing buttons.

Since traditional four-legged robots do not factor hands into their control systems, the researchers designed their own unified whole-body control framework. This system allows the LocoMan-equipped robot to operate in a number of modes, from standard locomotion to bi-manual manipulation, single-gripper manipulation, or even performing manipulations while on the move.

The team’s system was attached to an off-the-shelf Unitree Go1 robot in order to evaluate its performance. It was demonstrated that the enhanced robot could perform precise manipulations, like opening cupboards and pouring drinks. It was also shown that the robot did not sacrifice any agility by having LocoMan installed, and that the robot could still squeeze into tight spaces.

Looking ahead, the team intends to further enhance the utility of their system by incorporating vision-language machine learning models into the control framework. By adding visual perception of environments and the ability to process verbal instructions, they believe they can make it more intuitive to give the robot instructions.