Motion Control

Robotic servicing of a satellite in low earth orbit (LEO) or geosynchronous Earth orbit (GEO) requires advanced systems capable of meeting the harsh environments of space. To support this effort, the Goddard Space Flight Center Satellite Servicing Capabilities Office (SSCO) has developed a camera positioning mechanism that will be capable of viewing features on a client satellite. Application of the CPM technology would be in multiple areas of spaceflight requiring robotic servicing including space exploration, planetary science, Earth science, and manned spaceflight.

The CPM is an electromechanical device that will be used in conjunction with the Advanced Tool Drive System (ATDS) and robotic tools to support the satellite servicing activities performed on a client satellite. Tool functions, such as gripping, refueling, cutting wires, etc., may be performed tele-robotically by using the camera to view robot operations. During robotic servicing of a client satellite, the servicer spacecraft performs various tasks through the robotic manipulation of a variety of tools. The purpose of the CPM is to provide the visual images of the robotic tools and the worksite; for example, the satellite area to be repaired or the refueling ports of a client's satellite. The visual acuity and extent of tele-operations required to perform a satellite repair or refuel is significant and involves grasping a tool at the most basic level; removing the tool from its stowage location; maneuvering the tool by robotic arm to the client satellite; actuating the tool's function to grip, cut, or refuel; and returning the tool to its stowage location. This basic sequence is then repeated as different tasks are required during the servicing.

The CPM operates as part of the robotic arm via commanding from the robot system and ground operators. As a modular design with multiple degrees of freedom, the CPM is installed near the end of the robot arm, as part of the ATDS. The camera/lens assembly is housed in a carrier that can be extended to a point beyond the end of the robot arm where a tool is located. Additionally, the camera/lens assembly can be pointed towards the tool and worksite by a pitching mechanism, which rotates the camera field of view. The camera is paired with a motorized zoom lens (MZL) — an optical zoom lens with adjustable focal length and focus point. These operational degrees of freedom enable optimal viewing of the tool and worksite for each unique servicing task. Actuation of the extension and pitch mechanisms, as well as control of the motorized zoom lens focal length and focus point, is performed by stepper gearmotors. To support the visual imaging of a variety of worksites, the CPM includes integral LED lighting with adjustable intensity.

The novelty of the CPM lies in its capability to provide robotic tele-operators with adjustable views of a client satellite worksite. By being able to extend and pitch the camera/lens assembly, the view provided can be adjusted for each unique situation, whether using a short or long tool. If the worksite is approached by the robot at an off angle, the CPM can move and adjust to meet each particular situation. As a modular design, the CPM can also be used in other locations on the robot arm or elsewhere on the servicing payload.

This work was done by Jonathan Kraeuter of Orbital ATK and Edward Cheung of Jackson & Tull for Goddard Space Flight Center. NASA is seeking partners to further develop this technology through joint cooperative research and development. For more information about this technology and to explore opportunities, please contact Scott Leonardi at This email address is being protected from spambots. You need JavaScript enabled to view it. . GSC-16873-1

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