Long-Reach Robotic Manipulation for Assembly and Outfitting of Lunar Structures

Abstract

Future infrastructure construction on the lunar surface will require semi- or fully-autonomous operation from robots deployed at the build site. In particular, tasks such as electrical outfitting necessitate transport, routing, and fine manipulation of cables across large structures. To address this need, we present a compact and long-reach manipulator incorporating a deployable composite boom, capable of performing manipulation tasks across large structures and workspaces. We characterize the deflection, vibration, and blossoming characteristics inherent to the deployable structure, and present a manipulation control strategy to mitigate these effects. Experiments indicate an average endpoint accuracy error of less than 15 mm for boom lengths up to 1.8 m. We demonstrate the approach with a cable routing task to illustrate the potential for lunar outfitting applications that benefit from long reach.

Figures (6)

• Figure 3: Small mobile robots (green) equipped with long, extendable booms (red) can perform tasks that require a large workspace---such as cable stringing and assembly for lunar construction.
• Figure 4: (A) Overview of key hardware components in the long-reach manipulator design: shoulder base, deployable boom arm (0.2 - 3m), and dexterous wrist. (B) Mechanical characterizations of the boom's uniaxial bending and free vibration effects. (C) Boom deployment blossoming effects.
• Figure 5: (A) Rigid kinematic model of the robot manipulator following an R-R-P-R-R-R architecture. (B) Additional augmentation transformation used to compensate for elastic boom deflection.
• Figure 6: Overview of the control framework. The robot follows task trajectories using visual end-effector localization and an augmented task-space kinematic model for closed-loop position control.
• Figure 7: Summary of tracking error across the robot workspace. (A) A $10\,\text{cm} \times 10\,\text{cm}$ square reference trajectory. The robot’s executed trajectories across trials are overlaid, and the maximum spatial error is visualized as a task tube. (B) All trajectories executed at $\theta = 0^\circ$ for varying boom lengths (horizontal axis) and task speeds (vertical axis). Error increases with both parameters. (C) Interpolated 95th percentile isoline plot for $\theta = 0^\circ$. (D) Total robot workspace schematic showing boom length $d_3$, pitch angle $\theta_2$, and yaw $\theta_1$ with an error slice at 50 mm/s. (E) Interpolated error slices at $\theta \in [0^\circ, 90^\circ]$ for two speeds: 17 mm/s (slow) and 80 mm/s (fast). Errors increase with both pitch angle and extension, especially at higher speeds.