uBot-7: A dynamically balancing mobile manipulator with series elastic actuators

Abstract

We present the next generation of the uBot series: the uBot-7 mobile manipulator with 14 degrees of freedom, 95 cm tall, weighing about 27 kg. The robot is a new, unique mobile manipulator with great versatility to solve tasks in mobility and manipulation. The design is based on experiences from previous uBot generations. We detail the mechanical and electrical layout and highlight the improvements with regards to its predecessor uBot-6. All arm and torso joints are driven by series elastic actuators (SEAs) for better sensing and safer interaction around humans. This makes it the first wheeled dynamic balancer with SEAs. Upgrades to stronger brushless DC motors improve the strength of the robot more than twofold. The head has been extended with two additional motors and now offers independent viewpoint control of the RGB-D camera for all postural configurations of the robot. Finally, a new drive train removes backlash from the base wheels while providing more torque and speed. The design of the robot will be released as open-source.