The Design of Stretch: A Compact, Lightweight Mobile Manipulator for Indoor Human Environments
Charles C. Kemp, Aaron Edsinger, Henry M. Clever, Blaine Matulevich
TL;DR
The paper tackles the limited adoption of indoor mobile manipulators by introducing Stretch, a compact, lightweight, and cost-effective design that achieves Cartesian end-effector motion using a two-wheeled base, a lift, and a telescoping arm. It couples anthropometric analysis with static stability modeling to define safe, maneuverable workspace and demonstrates the design through the Stretch RE1 in real homes, including teleoperation and autonomous task programs. The key contributions are the minimalist four-actuator architecture, modular wrist and gripper options, comprehensive stability analysis (including planar and triangular base models), and extensive real-home validation. The work suggests that such designs can accelerate adoption of mobile manipulation in daily environments and lays groundwork for future modular enhancements and broader deployment.
Abstract
Mobile manipulators for indoor human environments can serve as versatile devices that perform a variety of tasks, yet adoption of this technology has been limited. Reducing size, weight, and cost could facilitate adoption, but risks restricting capabilities. We present a novel design that reduces size, weight, and cost, while supporting a variety of tasks. The core design consists of a two-wheeled differential-drive mobile base, a lift, and a telescoping arm configured to achieve Cartesian motion at the end of the arm. Design extensions include a 1 degree-of-freedom (DOF) wrist to stow a tool, a 2-DOF dexterous wrist to pitch and roll a tool, and a compliant gripper. We justify our design with anthropometry and mathematical models of static stability. We also provide empirical support from teleoperating and autonomously controlling a commercial robot based on our design (the Stretch RE1 from Hello Robot Inc.) to perform tasks in real homes.