Using Stereo Vision to Operate Mobile Telepresence Robots

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The use of mobile telepresence robots (MTRs) is increasing. Very few MTRs have autonomous navigation systems. Thus teleoperation is usually still a manual task, and often has user experience problems. We believe that this may be due to (1) the fixed viewpoint and limited field of view of a 2D camera system and (2) the capability of judging distances due to lack of depth perception.

To improve the experience of teleoperating the robot, we evaluated the use of stereo video coupled with a head-tracked and head-mounted display.

To do this, we installed a brushless gimbal with a stereo camera pair on a robot platform. We used an Oculus Rift (DK1) device for visualization and head tracking.

StereoBot and Gimbal.

Stereobot telepresence robot (left) and stereo gimbal system (right).

We conducted a preliminary user study to gather qualitative feedback about telepresence navigation tasks using stereo vs. a 2D camera feed, and high vs. low camera placement. In a simulated telepresence scenario, participants were asked to drive the robot from an office to a meeting location, have conversation with a tester, then drive back to the starting location.

An ANOVA on System Usability Scale (SUS) scores with visualization type and camera placement as factors results in a significant effect of visualization type on the score. However, we observed a higher SUS score for navigation based on a 2D camera feed. The camera placement height did not show a significant effect.

The following two main reasons could have caused the lower ratings for stereo: (1) about half of the users experienced at least some form of disorientation. This might have been due to their unfamiliarity with immersive VR headsets but also due the sensory distortion effect of being immersed visually in a moving environment while other bodily senses report sitting still. (2) the video transmission quality was not optimal due to interference of the analog video transmission signal by objects in the building and due to the relatively low display resolution of the Oculus Rift DK1 device.

In the future we intend to work on improving the visual quality of the stereo output by using better video transmission and head-worn display. We furthermore intend to evaluate robot navigation tasks using a full VR view. This view will make use of the robot’s sensors and localization system in order to display the robot correctly within a virtual representation of our building.