Design and application of the Reconfigurable Mobile Manipulator Artifact (RMMA)

Abstract

Robot arms onboard mobile bases, or mobile manipulators, are advancing and measurement of these systems is critical for robust safety and performance. As mobile manipulators flexibly fixture (i.e., do not fasten) to a worktable or object, they require advanced systems to measure how well they can perform tasks, such as assembly or inspection. The National Institute of Standards and Technology (NIST) has developed a measurement concept that uses the NIST-designed, Reconfigurable Mobile Manipulator Artifact (RMMA) as the worktable/object. The RMMA includes fiducials with relatively high uncertainty, as compared to the mobile manipulator pose performance, that are measured using a mobile manipulator wielded camera or laser retroreflector sensor as the end-effector. The intent of developing the RMMA is for mobile manipulator manufacturers, users, and researchers to perform in-situ measurement during production or research for frequent system calibration. This paper describes the RMMA design and past RMMA evaluation using an automatic guided vehicle and a mobile robot, each supporting a six degree-of-freedom industrial robot arm, and RMMA/mobile manipulator ground truth measurement using an optical tracking system, also with relatively high uncertainty as compared to the mobile manipulator.

Design and implementation of a closed-loop mobile manipulator control system

“…Additionally, the same Retrorefective Laser Sensor and Emitter (RLS) from prior work was used to digitally detect the retro-refective mock-assembly targets mounted to the CMMA, which represented peg-inhole assembly performance (see also Sec. 3.3) [19,21,61]. The custom mount for fxturing the RLS to the EOAT was modifed with additional threaded M4 screw holes to rigidly attach OTS markers.…”

“…Additionally, these test methods can be used to verify the suitability of a mobile manipulator platform to their specifc manufacturing application domain and environment. Towards this goal, NIST has developed a set of re-confgurable, cost-effcient test artifacts, called the Confgurable Mobile Manipulator Apparatus (CMMA) (previously referred to as the Re-confgurable Mobile Manipulator Artifact (RMMA)) 1 [16][17][18][19]. The CMMA, outftted with machined confgurations of aluminum surfaces and tapped holes, can be used as a mock workspace or work piece to simulate a variety of potential mobile manipulator manufacturing capabilities.…”

“…However, for indexed tasks, the mobile base docks the manipulator in sequence amongst a fnite set of intended poses. In past work, two variants of the CMMA were developed and used for evaluations: The Type A CMMA (formerly called the static RMMA) represented non-curved and smaller work-pieces, while the Type B CMMA served as a more direct analogue to large-scale components with complex shapes [19,20].…”

“…A more comprehensive summary of previous development milestones and evaluation activities can be found in Ref. [19].…”

“…[44] to encompass the multi-robot cooperation of two mobile manipulators to transfer a baton, and the OTS was used primarily to assist in navigating to the handover region and motion synchronization between the two robots. Since the software architecture was the main focus, evaluation of the system task performance was limited to whether or not the handover was accomplished, whereas the CMMA, as a test artifact, can provide a standardized method to evaluate quantitative assembly performance in addition to pass/fail metrics [19].…”