| Summary: | Force feedback during teleoperation and in Virtual Reality (VR) environments is becoming increasingly common. We are interested in understanding the impact of motion on the directional accuracy of force perception, as observed in a VR environment. We used a custom force-feedback system that pulled a handle with a force of 1.87N at various angles in front of N=14 subjects. The virtual environment showed a curved wall, which corresponded to the locations from which the force could physically originate. Subjects selected where they perceived the force to originate from with a virtual laser pointer and by orienting their head. We compared several conditions: the subject held the handle still; the subject moved the handle back and forth toward the center of the wall; the subject moved the handle back and forth across their body; and the subject moved the handle back and forth toward where they thought the force was originating. Subjects were able to localize the force with an average accuracy of 1-10 degrees depending on the force's location, which is better than previous studies. All conditions had similiar accuracies. Subjects had the best precision when they followed the force as compared to either of the other conditions with movement. === Master of Science === In recent years, robots combined with teleoperation, operating in a remote safe environment, has become a popular choice for replacing human workers in dangerous environments. Visual feedback and a sense of touch and motion, are two of the most common feedback modalities. Thus, Virtual Reality (VR) and force rendering are two main ways of conveying information to the operator during teleoperation.\newline
Previous studies have investigated the effects of force feedback on the fingers, wrist, and arms but with limited movements and joint combinations. In this paper, we answered the question of how the planar arm movement impacts the force-directional perception accuracy by using a Virtual Reality (VR) system. To put in other words, we want to find out how accurate and precise a robot operator can feel the physical world through joysticks. If they are asked to do this many times in a row, how repeatable are their guesses? To study this, We asked subjects holding a handle made out of PVC pipe with a position sensor on it. The handle was attached to a motor, which pulled the handle away from the subjects during the experiment trial. The experiment consisted of four different conditions, which studied both stationary, when subjects holding the handle stationary and resist the pull by our motor, and movement, when subjects moving the handle in a certain direction while the handle was pulled by our motor. In each trial, subjects were first asked to resist the force according to the experiment condition, then use a laser pointer and head to both point and look at where they think the motor was pulling the handle from. Because of the use of the VR environment and position sensor, subjects reported their guesses intuitively by pointing and looking at, which eliminated the potential of misreporting guesses. The result of this study is important for designing an effective force feedback system for teleoperation. With this information, a force feedback system in a VR environment could be altered to convey information to a user more accurately, for example to correct any biases that the user may have in where they expect forces to originate.\newline
Our results show that arm movements enhanced the force feedback precision without sacrificing the accuracy. Arm movements also improved the subjects' confidence level in how well they thought they could localize a force. The results also suggest that pointing with the head is significantly more precise compared with the hand. Such results can be used to implement a more effective force feedback system combined with a VR environment. Finally, our data also shows that hand had an opposite accuracy pattern compared with the head. Future works are needed to explain this opposite accuracy pattern.
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