Performance measurement of mobile manipulators

Abstract

This paper describes a concept for measuring the reproducible performance of mobile manipulators to be used for assembly or other similar tasks. An automatic guided vehicle with an onboard robot arm was programmed to repeatedly move to and stop at a novel, reconfigurable mobile manipulator artifact (RMMA), sense the RMMA, and detect targets on the RMMA. The manipulator moved a laser retroreflective sensor to detect small reflectors that can be reconfigured to measure various manipulator positions and orientations (poses). This paper describes calibration of a multi-camera, motion capture system using a 6 degree-of-freedom metrology bar and then using the camera system as a ground truth measurement device for validation of the reproducible mobile manipulator's experiments and test method. Static performance measurement of a mobile manipulator using the RMMA has proved useful for relatively high tolerance pose estimation and other metrics that support standard test method development for indexed and dynamic mobile manipulator applications.

Mobile robot and mobile manipulator research towards ASTM standards development

“…The mobile manipulator shown in Figure 3 was used for onboard equipment docking experiments building on previous research [12, 13]. Three recent indexing experiments were performed, as described in section 3.2.2 Vehicle with Onboard Equipment Docking.…”

“…NIST developed a test apparatus for measuring mobile manipulator performance [13]. The apparatus, shown in Figure 3, is called the Reconfigurable Mobile Manipulator Apparatus-1 (RMMA-1).…”

“…In [13], a calibrated vehicle carried the onboard manipulator to a point with 5 mm position uncertainty. The manipulator was able to register (determine its position with respect to the artifact) using a circular-spiral search and repeatedly locate 6 mm diameter targets when the manipulator was positioned by the AGV at a static location and next to the square pattern on the RMMA-1.…”

Mobile manipulator performance measurement data

“…NIST has been developing a mobile manipulator, performance measurement concept over the past two years [3,4,5]. This concept, which evolved from the experiments described in [6], consists of using 1) a NIST-developed, reconfigurable, mobile manipulator artifact (RMMA) (see Figure 1) with 2) interchangeable and varying sized fiducials to be detected by a sensor carried by the mobile manipulator.…”

“…The current location and orientation of the AGV were recorded. The arm was repositioned manually until the sensor detected alignment [3,5,6] with each of the index fiducials, and the manipulator position was recorded. This information, along with the position of the manipulator base relative to the vehicle's coordinate system, allowed the correct manipulator coordinates for the index fiducials to be calculated for an arbitrary AGV location.…”