Modular platforms for Advanced Inspection, Locomotion, and Manipulation

Abstract

Robots can provide remote access, manipulation, and inspection capabilities to augment human workers and improve safety in potentially dangerous decommissioning, radioactive waste management, and emergency response operations. However, such activities may require navigating challenging and unstructured environments, such as those with uneven terrain, obstacles, or loose debris. This remains a difficult task, even for modern robots. What’s more, a robot’s physical design can inhibit it from accessing hard-to-reach areas such as the tight spaces around, underneath, or inside piping and equipment. To address these challenges, we have developed a series of physically robust hardware modules that can be configured into a variety of robot morphologies, specialized to support different operational needs. Each hardware module consists of a number of onboard sensors and a high performance actuator with a series elastic element to sense and control interaction forces for improved locomotion and manipulation. Using this hardware, we have designed several robotic platforms that support the access, manipulation, and inspection requirements of decommissioning and radioactive waste management. To highlight current capabilities and potential opportunities for technological improvement, we present the outcomes from field demonstrations of our modular platforms at the Office of Environmental Management’s Science of Safety Portsmouth Gaseous Diffusion Plant Robotics Challenge. Specifically, results include a serpentine robot climbing vertical structures such as pipes, posts, and supports to demonstrate advanced inspection. Additionally, we discuss field trials of a similar modular configuration that yields a highly dexterous manipulator arm and camera system capable of adding manipulation and inspection functionality to existing structures. Results are presented from inspection tasks in which the manipulator is installed on another mobile robotic platform. Finally, we show our hardware modules can be reconfigured into platforms capable of withstanding significant impacts and of alternative means of locomotion, as may be required to cross terrain too challenging for traditional wheeled robots. Results describe the performance of a hexapod robot that uses proprioceptive feedback to locomote in outdoor trials reminiscent of emergency response conditions. INTRODUCTION Nuclear decommissioning involves a number of activities that may be restrictive or otherwise dangerous for human workers. For instance, workers need to inspect in WM2017 Conference, March 5 – 9, 2017, Phoenix, Arizona, USA 2 or around dense facility piping, equipment, and environments with hazardous materials. In such situations, robots can serve as vital tools, facilitating access and remote manipulation in dangerous areas, while their operators remain safely out of harm’s way. However, traditional industrial robots are often expensive, bulky, and relatively inflexible. That is, the inherent physical (hardware) constraints of such robots prohibit access to tight spaces and limit them to specific tasks, with highlyspecialized technical staff required to adapt “canned” behaviors. To develop more flexible and adaptable robots, our lab, the Carnegie Mellon’s Biorobotics lab, and HEBI robotics, a startup founded by former lab members, have designed a series of physically robust hardware modules that can be rapidly assembled into different robot morphologies to support different task needs. The modules can, for example, form highly-dexterous serial-chain manipulator arms that can be installed on any base (or mobile platform). The same modules can be re-assembled into wheeled, tracked, legged, or undulatory (snake-like) platforms that can locomote over rough, outdoor terrain for mobile sensing and manipulation, e.g, in disaster response scenarios [1,2,3] (see Fig. 1). While physical adaptability is ultimately essential to the development of robots that can support humans in different scenarios, it is of little use if teams of engineers are required to re-program and develop new behaviors for each new robot, i.e., each customized modular configuration. To address this concern, we emphasize principles of modularity and scalability not only in physical design, but in control. The following section will describe a tiered control scheme that is easy to adapt to new robots and behaviors, and computational tools that we have devised to simplify or automate motion planning for relatively complex tasks such as gait design [4,5]. To demonstrate these capabilities in action, the DISCUSSION section describes results from the Office of Environmental Management’s Science of Safety Portsmouth Gaseous Diffusion Plant Robotics Challenge. The CONCLUSIONS section discusses future potential and current limitations of modular robots to support tasks such as nuclear decommissioning. METHODS The following section describes the modular hardware used to construct the different platforms demonstrated during the robotics challenge. Additionally, we provide an overview of the tiered control system and computational tools we use to simplify the design and planning of new behaviors on new robots.