Skip to main content Accessibility help

Human Evaluation of Wheelchair Robot for Active Postural Support (WRAPS)

  • Chawin Ophaswongse (a1), Rosemarie C. Murray (a1), Victor Santamaria (a1), Qining Wang (a2) and Sunil K. Agrawal (a1)...


People with severe neuromuscular trunk impairment cannot maintain or control upright posture of the upper body in sitting while reaching. Passive orthoses are clinically available to provide support and promote the use of upper extremities in this population. However, these orthoses only position the torso passively without any degree of trunk movement.

We introduce for the first time a novel active-assistive torso brace called Wheelchair Robot for Active Postural Support (WRAPS). It consists of two rings over the hips and chest connected by a 2RPS-2UPS parallel robotic device. WRAPS can modulate the displacement of the upper ring and/or the forces applied on the torso through the ring in four degrees-of-freedom (DOF), including rotations and translation in the sagittal and frontal planes.

In the present study, we evaluate the design of WRAPS and its functions. Moreover, we discuss the potential effectiveness of WRAPS as a therapeutic robotic tool in people with severe trunk control deficits. The performance of WRAPS was evaluated in seated healthy subjects. Kinematics and surface electromyography (sEMG) were collected when the participants performed selective trunk movements. First, the torso range of motion (tROM) was calculated with WRAPS in transparent mode—zero-force control mode—which was compared with free-guided tROM (no WRAPS) with motion capture system. Second, a position control mode was configured to mobilize the torso along the trajectories obtained with the transparent mode.

Our results show that the design of WRAPS suited well the subject’s anthropometrics while supporting the weight of the torso. Importantly, WRAPS can be programmed to replicate the subject’s tROM, without the full activation of torso muscles. This can be critical in individuals with no trunk control. Altogether, these preliminary results indicate the potential applicability of WRAPS to promote active-assistive trunk mobility in people who cannot sit independently because of trunk dysfunction.


Corresponding author

*Corresponding author. E-mail:


Hide All
1.“Spinal Cord Injury Facts and Figures at a Glance 2018,” National SCI Statistical Center, Birmingham, AL (2018).
2. Forslund, E. B., Roaldsen, K. S., Hultling, C., Wahman, K. and Franzén, E., “Concerns about falling in wheelchair users with spinal cord injury-validation of the swedish version of the spinal cord injury falls concern scale,Spinal Cord 54(2), 115119 (2016).
3. Forslund, E. B., Jørgensen, V., Franzén, E., Opheim, A., Seiger, Å., Ståhle, A., Hultling, C., Stanghelle, J. K., Roaldsen, K. S. and Wahman, K., “High incidence of falls and fall-related injuries in wheelchair users with spinal cord injury: A prospective study of risk indicators,J. Rehabil. Med. 49(2), 144151 (2017).
4. Sezer, N., “S. Akku¸s and F. G. U˘gurlu, “Chronic complications of spinal cord injury,World J. Orthop . 6(1), 24 (2015).
5. Ogura, T., Itami, T., Yano, K., Mori, I. and Kameda, K., “An Assistance Device to Help People with Trunk Impairment Maintain Posture,” In: Proceedings of the IEEE International Conference on Rehabilitation Robotics, London, UK (2017) pp. 358363.
6. Mahmood, M. N., Peeters, L. H. C., Paalman, M., Verkerke, G. J., Kingma, I. and van Dieën, J. H., “development and evaluation of a passive trunk support system for duchenne muscular dystrophy patients,J. Neuroeng. Rehabil. 15, 22 (2018).
7. Murray, R. C., Ophaswongse, C. and Agrawal, S. K., “Design of a Wheelchair Robot for Active Postural Support,” In: Proceedings of the ASME International Design Engineering Technical Conferences and Computers and Information in Engineering Conference, Anaheim, CA (2018) pp. V05AT07A059.
8. Nguyen, C. C., Antrazi, S. C., Zhou, Z. L. and Campbell, C. E., “Analysis and implementation of a 6 DOF stewart platform-based robotic wrist,Comput. Electr. Eng. 17(3), 191203 (1991).
9. Tsai, L. W., Robot Analysis: The Mechanics of Serial and Parallel Manipulators (John Wiley & Sons, Inc., New York, NY, 1999).
10. Gan, D., Dai, J. S., Dias, J., Umer, R. and Seneviratne, L., “Singularity-free workspace aimed optimal design of a 2T2R parallel mechanism for automated fiber placement,J. Mech. Robot. 7(4), 4102241029 (2015).
11. Wu, G., Van der Helm, F. C., Veeger, H. D.,Makhsous, M., Van Roy, P., Anglin, C., Nagels, J., Karduna, A. R., McQuade, K., Wang, X. and Werner, F. W., “ISB recommendation on definitions of joint coordinate systems of various joints for the reporting of human joint motion–Part II: shoulder, elbow, wrist and hand,J. Biomech. 38(5), 981992 (2005).
12. McGill, M. S., “Electromyographic activity of the abdominal and low back musculature during the generation of isometric and dynamic axial trunk torque: implications for lumbar mechanics,J. Orthop. Res. 9(1), 91103 (2005).
13. Danneels, L., Coorevits, P., Cools, A., Vanderstraeten, G., Cambier, D., Witvrouw, E. and De Cuyper, H., “Differences in electromyographic activity in the multifidus muscle and the iliocostalis lumborum between healthy subjects and patients with sub-acute and chronic low back pain,Eur. Spine J. 11(1), 1319 (2002).
14. O’Sullivan, K., McCarthy, R., White, A., O’Sullivan, L. and Dankaerts, W., “Lumbar posture and trunk muscle activation during a typing task when sitting on a novel dynamic ergonomic chair,Ergonomics 55(120),15861595 (2012).
15. Redfern, M. S., Hughes, R. E. and Chaffin, D. B., “High-pass filtering to remove electrocardiographic Interference from torso EMG recordings,Clin. Biomech. 8(1), 4448 (1993).
16. Konrad, P., The ABC of EMG: A Practical Introduction to Kinesiological Electromyography ver 1.4, (Noraxon U.S.A. Inc., 2006) pp. 161.
17. Panjabi, M., Abumi, K., Duranceau, J. and Oxland, T., “Spinal stability and intersegmental muscle forces. A Biomechanical model,Spine (Phila Pa 1976) 14(2), 194200 (1989).
18. Kinoshita, H., “Pathology of hyperextension injuries of the cervical spine,Spinal Cord 32(6), 367 (1994).
19. Sun, P. S., Mai, J., Zhou, Z., Agrawal, S. K. and Wang, Q., “Upper-Body Motion Mode Recognition Based on IMUs for a Dynamic Spine Brace,” In: Proceedings of the IEEE International Conference on Cyborg and Bionic Systems, Shenzhen, China (2018) pp. 167170.


Human Evaluation of Wheelchair Robot for Active Postural Support (WRAPS)

  • Chawin Ophaswongse (a1), Rosemarie C. Murray (a1), Victor Santamaria (a1), Qining Wang (a2) and Sunil K. Agrawal (a1)...


Full text views

Total number of HTML views: 0
Total number of PDF views: 0 *
Loading metrics...

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed