Development and evaluation of a handheld type 6 DoF midair haptic device using asymmetric vibration and a presentation force vectoring mechanism

This paper describes a handheld type aerial haptic device with 6 DoF (degree of freedom) using pseudo-haptics by asymmetric vibration. By introducing a original presentation force vectoring mechanism, 6 DoF force sense presentation and compactness suitable for handheld use with a small number of vibrators are realized together. In addition, a relationship between the drive input and output (presentation force sense) of the developed device is formulated, and its inverse problem solving method for obtaining the drive input that realizes a desired presentation force sense is derived. Furthermore, a user test clarified the direction in which this device can / cannot effectively exert force.

Effects of 2 Different External Loads on Joint Position Sense and the Relationship Between Muscle Strength and Force Sense

Context: Joint position sense (JPS) tests of proprioception lack ecological validity because the testing conditions are so different from the normal function that they can contribute little to understanding the role proprioception plays in daily and sporting activities. Objective: To evaluate the effect of low and high external load on the knee JPS and to investigate the relationship between maximum voluntary isometric contraction and force sense (FS). Design: Experimental study. Setting: Research laboratory. Participants: A total of 47 volunteers with no history of knee pathology. Interventions: Three active JPS tests performed with no load, low load, and high load were compared at the 45° target angle. For isometric FS test, 50% load was used. For isotonic low load and high load JPS tests, 30% and 70% loads were applied, respectively. Main Outcome Measures: To analyze obtained data set 2-way multiple analysis of variance, repeated measures of analysis of variance, paired sample t test, and the Pearson correlation coefficient were used. Results: JPS was not affected by gender (male and female) and activity levels (sedentary, recreational, and trained). Results of the repeated measure of analysis of variance demonstrated the significant main effect of loads (P = .001). Significant differences were found between no load, low load, and high load JPS (P = .001). A positive and significant correlation was found between maximum voluntary isometric contraction and FS error values (r = .41, P = .001). Conclusions: The results suggest that as the load level increases, the knee JPS improves. Knee JPS assessed under external load may be a more appropriate alternative to the nature of the sport. Those with higher muscle strength have a worse FS.

Evaluation of proprioception in denervated and healthy wrist joints

We recruited 25 patients after complete wrist denervation and 60 healthy adults to investigate conscious and unconscious proprioception of the wrist. Ipsi- and contralateral joint-position sense, force sense, and wrist reflexes were measured. The latter were triggered by a trapdoor, recording electromyographic signals from the extensor carpi radialis brevis, extensor carpi ulnaris, flexor carpi radialis, and flexor carpi ulnaris muscles. No significant differences were found for joint position sense, force sense, and wrist reflexes between both groups, except for reflex time of the flexor carpi ulnaris after denervation of the left wrist as compared with the left flexor carpi ulnaris in controls or in right operated wrists. At a mean follow-up of 32 months (range 8 to 133), we found no proprioceptive deficit of the conscious proprioceptive qualities of joint position sense, force sense, and the unconscious proprioceptive neuromuscular control of wrist reflex time for most muscles after complete wrist denervation. We conclude from this study that complete wrist denervation does not affect the proprioceptive senses of joint position, force sense, and reflex time of the wrist.