TIKL: Development of a Wearable Vibrotactile Feedback Suit for Improved Human Motor Learning

Jeff Lieberman and Cynthia Breazeal

Comments:

Drew’s Blog

Manoj’s Blog

Summary:

The article presents the use of a wearable vibrotactile feedback suit to improve human motor learning. It is proposed that this can be used as an extension of the human teacher whose movements can be analyzed and used as a model to provide real time corrective vibrotactile feedback to the student. This is seen as a more direct and precise real time method of communicating motor movement. The need to map visual cues from the teacher onto oneself is avoided and unlike verbal feedback the vibrotactile system has a very short response latency which is critical in learning. Additionally, the system can be used for rehabilitation, teaching the blind, or as a full time motor skills teacher running in the background.

The use of a virtual reality teacher has been shown in some complex learning tasks to be more robust against distraction than its human counterpart. At the core of the proposed setup is a Vicon tracking system, which enables both teacher and student movements to be analyzed. Calibration for individual conformational differences is performed before testing is conducted. However, this rather bulky and costly system is intended to demonstrate proof of concept and not as a final production implementation. The vibrotactile actuators are of an electromagnetic type which enable control of both frequency and amplitude of stimulation with no spin up latency.

For the purpose of this study joint angles are used to measure position. To induce corrective movement, vibrotactile actuators on the side of the limb that it needs to move away from are triggered. Rotational movements are induced by using a saltation effect.

For the experimental evaluation, 40 subjects were divided into two groups. One group was given visual and vibrotactile cues were as the other was given visual cues alone. The testing consisted of three parts:

The first part consisted of presentations of still images which the subjects were asked to imitate. Each of these was presented for 5 seconds with vibrotactile feedback (depending on the group) where the subjects were asked to assume the positions as quickly as possible.

The second part consisted of a series of videos demonstrating movements which the subjects were again asked to imitate. I am assuming again that vibrotactile feedback (depending on the group) was active immediately for each video.

The final part was a questionnaire.

The vibrotactile group commented that more concentration was required but with time performance would improve. Analysis of their movements revealed that there was a significant frame by frame improvement over their non vibrotactile counterparts. Vibrotactile communication of hinge movements were much clearer than rotations. The vibrotactile group showed 27% improvements on hinge movements and little or no improvement on rotations. Repeated trials showed 7% acquisition improvements on hinge movements as subjects became accustomed to the system.

Discussion:

This is a very novel concept. In particular the use of a more direct line of communication without the use of language for motor movement learning is interesting. In many regards, this is a much more naturalistic paradigm as we are predisposed to process touch while executing motor movements for mid course corrections when dealing with collisions etc. Real time stimulation as a mode of communication during a movement would be far simpler than using language. Ultimately, this should lead to faster acquisition of movements as there should be less repetition.

The article mentions several possible improvements such as the placement of the tracking marks, stimulators and in particular the rotational feedback.

From a learning perspective, a behavioral comparison of movement acquisition between the two test groups would be interesting.