1 / 55

Portable Haptic Aids for Training and Rehabilitation

Portable Haptic Aids for Training and Rehabilitation. Li Jiang April 4 th 2008. Emergency personnel training. Stroke Rehabilitation. Presentation Outline. Background Portable haptic aids for emergency personnel virtual reality (VR) training

bliss
Download Presentation

Portable Haptic Aids for Training and Rehabilitation

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Portable Haptic Aids for Training and Rehabilitation Li Jiang April 4th 2008

  2. Emergency personnel training Stroke Rehabilitation Presentation Outline • Background • Portable haptic aids for emergency personnel virtual reality (VR) training • Portable haptic aids for stroke and multiple sclerosis • Conclusion • Future work

  3. Portable Device Grounded Device Portable vs Grounded

  4. Force Cybergrasp Cyberforce Vibration Pager motors “Rumble” joystick Haptic Devices Grounded Portable Design Tradeoffs: Performance Price Portability …….. ?

  5. Event-Cue vs Amplitude-Based Feedback Amplitude-BasedFeedback (ABF) Event-CueFeedback (ECF) ECF: symbolic information ABF: analog information

  6. Portable Haptic Aid for Emergency Personnel Virtual Reality (VR) Training

  7. Haptic Devices for Emergency Personnel VR Training “Immersive” training systems withhaptic feedback have been expensive and encumbering

  8. Portable Haptic Aids for VR Emergency Personnel Training Unlike motor-skill related VR training, VR emergency personnel training focuses on high level abstract skill training such as team procedures and collaborations in dangerous and confusing environments.

  9. Questions to Answer through First Set of Experiments • Can low-cost, portable vibrational feedback improve trainees’ training performance in emergency procedures? • How does vibrational “event-cue” feedback compare with amplitude-based force feedback?

  10. VR for Experiment I Virtual environment generated by Half-Life videogame engine *Half-life: a science fiction first-person shooter computer game.

  11. Experiment I Scenario The task given to users was to go through a dark, cluttered and potentially hazardous corridor in the aftermath of an explosion. 15 random-order obstacles in the corridor, A dim red light indicates the direction of the exit.

  12. Portable Haptic Feedback

  13. Experiment Procedure and Metrics Two Feedback Modes: ECF (event cue) and no-haptic feedback 8 Subjects (5 male, 3 female) Experiment order was randomized and counterbalanced *Subjects were told that time is not a metric in the memory trials

  14. F(1,7) = 14 P<0.01 • (significant) Experiment Results: Memory Paired T test: ECF Moderecorded No-Haptic Moderecorded

  15. F(1,7) =8.75 P<0.01(significant) Experiment Results: Memory Paired T test: ECF Moderecordedcorrectly No-Haptic ModerecordedCorrectly

  16. Speed Trials Memory Trials Time without vibration feedback Time without vibration feedback Time with ECF vibration feedback Time with ECF vibration feedback Experiment Results: Speed

  17. Experiment II: Event-Cue Vibration Feedback (ECF) vs Amplitude-Based Force Feedback (ABF) Commercial vibration, force joysticks Modified by Immersion Studio. VR generated by Half-Life Game engine:a dark and confusing building with rooms to navigate and clear.

  18. Subject Hostage Experiment Metrics While soldiers are clearing the building layout, they should stop at each door before entering each rooms to make sure there is no potential danger in the rooms. [Holifield, Leonard., “Close-Quarter Combat: A Soldier's Guide to Hand-To-Hand Fighting,” Paladin Press, May 1997.] Subjects were asked to stop at each door to mimic this event. A contact between the subject’s body and the wall beside the door was counted as the completion of the check. The number of times a subject failed to execute this check is counted as an error metric.

  19. Building Layouts and Feedback Methods Feedback Methods: Amplitude-Based Force Feedback (ABF) Event-Cue Vibration Feedback (ECF) No Haptic Feedback (NHF) Error metric: Number of missed safety checks Typical building layout (layouts were chosen randomly from a variations on the one shown above)

  20. F(1,11) = 19.85 P<0.01 (significant) Experiment II Results 12 subjects, experiment order counterbalanced • Bonferroni Corrected Paired T test: • F(1,11) = 14.86 P<0.01 (significant)

  21. VR Emergency Personnel Training Experiment Results • Can portable event-cue vibrational feedback improve trainees’ training performance? Yes, Significantly ! • How does vibrational event-cue feedback compare with amplitude-based force feedback in VR emergency personnel training scenarios? Event-cue vibrational feedback can improve subjects’ performance as well as amplitude-based force feedback.

  22. Portable Haptic Aids for Stroke and Multiple Sclerosis

  23. Previous Haptic Feedback Devices The ARCMIME system and MIME system

  24. Force Sensor Haptic Feedback Strategy Framework Force information collected by sensors on the impaired hand are rendered to the healthy hand through small vibrational tactors

  25. Three Feedback Modes Provided • NHF mode: No-Haptic Feedback • ABF mode: Amplitude-Based Feedback • ECF mode: Event-Cue Feedback

  26. Stroke and MS Experiment Goals • Can vibrational feedback improve patients’ ability in manual force control? • How does the event-cue feedback (ECF) strategy compare with the amplitude-based feedback (ABF) strategy? vs.

  27. Comparison of Impairments Stroke Patients Multiple Sclerosis Patients Sensory loss Sensory loss Poor Hand Motor Skill Better Hand Motor Skill Not able to open impaired hand Able to open impaired hand Conclusion: First, we need a device to help stroke patients to open their impaired hands

  28. Impaired Side Healthy Side Hand-Opening Device Design Design Goal: A passive mechanical system that can transfer power from healthy hand to the impaired hand to help the impaired hand open. Design Process: Six design iterations and prototypes (details in the thesis) Each prototype was evaluated by stroke patients and therapists.

  29. Hand Opening Device Demo With the help from the healthy side Without the help from the healthy side

  30. Microcontroller and circuits Force Data Box with Force Sensors Feedback Strategy for Stroke Impaired hand grasps an instrumented box, with help of vibration feedback applied to the back of the opposite hand. Vibration Tactor Impaired Hand Healthy Hand

  31. Pulse Width V 5V …. Period t Tactor: A Low-Cost, Small, Wearable Vibrational Feedback Device Pager motor output (magnitude of vibratory force) is a nonlinear function of applied voltage or current. Best results are obtained by creating a pulse train with varying frequency andduty cycle.

  32. grasp force is below desired threshold grasp force exceeds desired threshold Event-Cue Feedback Mode Event-Cue Feedback (ECF)

  33. Amplitude-Based Feedback Mode Vibration pattern: Period varies Reciprocal to measured grasp force. Pulse width increases with the increase of grasp force.

  34. Perceived magnitude Measured Grasping Force ABF mode Perception Test Based on data of 6 subjects R2 = 0.9909 Slope = 13.7887

  35. ForceSensor Grasp Force Force Sensing Experiment with Stroke Patients Force Sensor Instrumented object with force sensors to measure the grasping forces that subjects provided with their impaired hand.

  36. Pilot Experiment with Stroke Patients • Three Subjects (2 male, 1 female). • Task:Subjects were asked to grasp an object and try to use minimum force to maintain a stable grasp without dropping the object for 10 seconds and then replace it. • Two metrics: Force Failure rate • Three feedback modes: NHF ABF ECF

  37. Experiment Data Analysis ANOVA test: p=0.0005 Bonferroni corrected paired T test: NHF vs ABF: p<0.005, NHF vs ECF: p<0.0002. ABF vs ECF p<0.905 No significant results were found in Failure Rate

  38. Masku Neurological Rehabilitation Center

  39. Microcontroller and circuits Feedback Strategy for Multiple Sclerosis Vibrational tactorattached to fingernail Force Sensorattached to fingerpad Impaired Hand Healthy Hand

  40. Force SensorsExperiment with Multiple Sclerosis patients

  41. Experiment Design Goal:Determine whether portable haptic feedback can improve patients’ finger force control ability. Task:Grab an object and raise it up from the desk. Subjects were asked to balance the forces they applied on the index, middle and ring finger. When they feel the force is balanced, they should hold the object for 5 seconds and then put it back to the desk. Feedback Modes:NHF Mode, ABF Mode, ECF Mode ECF: users alerted whenever one finger apply too much or too less force. ABF: vibration pattern (intensity) is in proportion to the measured force

  42. Experiment Procedure • Every user completed the task under all three modes in one of the six possible orderings (NHF-ABF-ECF, NHF-ECF-ABF, ABF-ECF-NHF, etc…). • Ample time was provided for pre-test practice to minimize learning effects. • Practice trials were provided every time the mode was switched. 24 Subjects (8 male, 16 female, age range: 33 to 64 with a mean of 56.4). The recruited subjects all have reduced sensation in one hand and good sensation in the other hand.

  43. Force Data Analysis Average force : Fa = (Fi+Fm+Fr)/3;Fi: Index finger force Fm: Middle finger force Fr: Ring finger force The metric:sum of the force differences with respect to the average force:Force_sum = abs(Fi – Fa)+abs(Fm – Fa)+abs(Fr – Fa) Analysis uses the last 5 seconds of force data before subjects released the box. (Subjects were asked to maintain force balance for 5 seconds before replacing the box)

  44. Sum of Force Differences in 3 Different modes 2.5 2 1.5 Sum of force differences to the average force 1 0.5 0 NHF ABF ECF Sum of Force Differences for 24 Subjects Bonferroni corrected PairedT test: NHF vs ECF, p < NHF vs ABF, p < ABF vs ECF, p < 0.27

  45. Impairment Level: IL = (Subject’s completion time/Normal completion time*) - 1 *for subject’s age group Nine-Hole-Peg Test Looking for evidence of correlation between impairment level and most useful type of feedback Task: placing 9 dowels in 9 holes. Subjects are scored on the amount of time it takes to place and remove all 9 pegs. It is widely used in MS clinical trials to quantitatively assess upper extremity function.

  46. R2 = 0.53 Difference in Improvement for ABF vs ECF, with Respect to NHF Baseline Difference in Percent Improvement for ABF vs ECF ABF better ECF better Impairment Level (IL) less impaired more impaired

  47. Sum of Force Difference for More and Less Impaired Groups ABF vs ECF: p < 0.00001 ABF vs ECF: p < 0.00001 Less impaired group (10 subjects ) More impaired group (14 subjects)

  48. Event-Cue Feedback vs Amplitude-Based Feedback Mildly impaired patients performed better with event-cue feedback (ECF), while severely impaired patients performed better with amplitude-based feedback (ABF).

  49. Failure Rates for the Different Modes Significance found: NHF vs ECF, p < 0.0006; NHF vs ABF, p < 7·10-8; ABF vs ECF, p < 0.002;

  50. Summary of Stroke and MS Studies • Can portable vibrational feedback (ECF or ABF) improve patients’ ability in grasping force control? Yes! For stroke: 15% For multiple sclerosis: 60% They both result in reduced failures. • How does the amplitude-based feedback strategy compare with the event-cue feedback strategy? For mildly impaired patients: ECF > ABFFor severely impaired patients: ABF > ECF ABF results in less failures than ECF overall.

More Related