CN / EN
Case Studies - Medical rehabilitation

IROS 2025 | Tianjin Univ Neck Support Exoskeleton - CHINGMU Motion Capture


Research on Neck Support Exoskeleton


In some occupations requiring long-term head-down work, such as surgeons performing operations and assembly line workers conducting assembly tasks, employees often need to maintain a forward-bending posture of the head and neck. The weight of the head imposes significant burden on the neck muscles and bones, leading to a significantly higher probability of neck-related diseases among this group compared to the general population. However, there is a severe lack of ergonomic solutions currently available that can provide head support, effectively reduce neck muscle strain, and not hinder normal operational functions in various environments.


Based on this, the research team from Tianjin University conducted relevant studies and designed a novel variable stiffness cervical exoskeleton equipped with a pneumatically driven tensile actuator. In the flexible state, this cervical support exoskeleton allows the head to move with minimal resistance, ensuring the flexibility and smoothness of the wearer's head movements during work. In the rigid state, it can provide stable head support and effectively alleviate neck muscle burden. This research achievement has been accepted and published at the renowned robotics conference IROS 2025.1. Research SchemeThe research team designed and fabricated a variable stiffness cervical exoskeleton weighing only 520g. By introducing a variable stiffness actuator, this semi-active exoskeleton achieves lighter weight and better wearing comfort.


The cervical exoskeleton has two main degrees of freedom: flexion in the sagittal plane and axial rotation. The flexion degree of freedom in the sagittal plane is affected by the stiffness of the variable stiffness actuator. When the variable stiffness actuator is in the flexible state and the head flexes in the sagittal plane, the L-shaped support rod rotates passively and acts on the variable stiffness actuator, which can extend with minimal resistance without significantly hindering normal movements. When the variable stiffness actuator switches to the rigid state, its elongation resistance is significantly improved. The head weight is transmitted to the variable stiffness actuator through the chin support and L-shaped support rod, allowing the neck extensor muscles to relax and the exoskeleton to provide stable head support. Axial head rotation is achieved through a guide rail and link mechanism, which includes a slide rail, slider, connecting rod, and chin support. During head rotation, the movement is transmitted to the slider through the connecting rod, and the slider slides along the guide rail to adapt to the head movement. In addition, when the head flexes, the chin retracts toward the neck. This mechanism not only enables unobstructed head rotation but also compensates for chin retraction to maintain continuous contact with the chin support, thereby ensuring free head rotation without affecting the support function.


Figure 1 Specific structure of the cervical support exoskeleton


Based on the above structural design, the research team recruited subjects to conduct wearing tests of the exoskeleton system, evaluating the exoskeleton's impact on the range of cervical motion and its auxiliary support performance.


Innovations and Advantages of the Scheme:

  1. The exoskeleton integrates a variable stiffness actuator, enabling active stiffness adjustment to reduce resistance to the user's normal movements while providing appropriate support.
  2. The exoskeleton design considers human physiological characteristics, achieving decoupling of head flexion and rotation movements to ensure support function without restricting head rotation.
  3. The exoskeleton weighs only 520g (excluding the waist-worn control system), making it lighter than most existing neck exoskeletons.
  4. Experimental Verification


The motion information collection adopted the optical motion capture system developed by CHINGMU Shanghai CHINGMU Vision Technology Co., Ltd. This system is equipped with 4 high-speed optical cameras (MC4000) that record head motion information at a sampling frequency of 110Hz, as shown in Figure 2(a). As shown in Figure 2(b), a total of 9 markers were placed on the subjects' trunks and heads. The high-speed cameras capture the time-varying position information of the markers, and the position change data is exported through collection software to calculate the range of head motion.


Figure 2 Optical-based motion capture experimental scenario


This study recruited 5 subjects (age: 25.6±1.4 years, height: 180.4±4.3 cm, weight: 70.1±7.9 kg). Each subject was required to complete three motion tasks shown in Figure 3 at a comfortable and self-determined speed both with and without wearing the exoskeleton (in the flexible state). Each task was repeated 5 times, and the average range of motion from the 5 experiments was calculated.


Figure 3 Schematic diagram of three motion tasks: flexion in the sagittal plane and axial rotation


Figure 4 shows the comparison of the average range of joint motion of the 5 subjects before and after wearing the exoskeleton. The length of the color bars in the figure represents the average range of motion of the 5 subjects, and the error bars represent the standard deviation. To analyze the statistical significance of the results, a paired-samples t-test was performed on the range of motion results, where * indicates p<0.05 and ** indicates p<0.01.


Figure 4 Comparison of the average range of motion of 5 subjects under each action


Experimental results show that when wearing the exoskeleton, the average ranges of motion of the subjects' head flexion, left rotation, and right rotation were 60.4°±4.7°, 28.9°±6.5°, and 32.6°±4.4°, respectively. Compared with the state without wearing the exoskeleton, the ranges of motion of head flexion, left rotation, and right rotation decreased by 7.51±6.2%, 58.51±8.4%, and 56.07±5.0%, respectively. The study indicates that the range of head flexion can meet the actual needs of surgeons during operations. Although the range of left and right axial rotation decreased significantly, most activities only require 20% to 40% of the total cervical range of motion, which the neck exoskeleton proposed in this study can fully satisfy.


Experimental Achievements


This study demonstrates that the variable stiffness cervical exoskeleton can provide the expected head flexion support without significantly restricting normal head movements. It can reduce the physical burden on neck muscles, and with its light weight and minimal restriction on head movements, it can meet the needs of long-term head-down work in scenarios such as surgical operations. This research provides an effective technical solution for addressing neck health issues among relevant occupational groups.


References

  1. E Tetteh, M S Hallbeck, G A Mirka, “Effects of passive exoskeleton support on EMG measures of the neck, shoulder and trunk muscles while holding simulated surgical postures and performing a simulated surgical procedure,” Appl Ergon, vol. 100, Apr. 2022.

  2. G P Y Szeto, P Ho, A C W Ting, et al, “Work-related musculoskeletal symptoms in surgeons,” J. Occup. Rehabil, vol. 19, pp. 175-184, Apr. 2009.

  3. I Dianat, A Bazazan, M A S Azad, et al, “Work-related physical, psychosocial and individual factors associated with musculoskeletal symptoms among surgeons: Implications for ergonomic interventions,” Appl Ergon, vol. 67, pp. 115-124, Feb. 2018.

  4. T A Plerhoples, T Hernandez-Boussard, S M Wren, “The aching surgeon: a survey of physical discomfort and symptoms following open, laparoscopic, and robotic surgery,” J. Robot. Surg, vol. 6, pp. 65-72, Dec. 2012.

  5. M Wohlauer, D M Coleman, M Sheahan, et al, “SS12. I feel your pain—a day in the life of a vascular surgeon: results of a national survey,” J. Vasc. Surg, vol. 69, Jun. 2019.

  6. P Gorce, J Jacquier-Bret, “Effect of assisted surgery on work-related musculoskeletal disorder prevalence by body area among surgeons: systematic review and meta-analysis,” Int. J. Environ. Res. Public Health, vol. 20, Jul. 2023.

  7. E Nutz, J S Jarvers, J Theopold, et al, “Effect of an upper body exoskeleton for surgeons on postoperative neck, back and shoulder complaints,” J Occup Health Psychol, vol. 66, Apr. 2024.

  8. A M Geers, E C Prinsen, D J Van Der Pijl, et al, “Head support in wheelchairs (scoping review): state-of-the-art and beyond,” Disabil. rehabilitation. Assist. Technol, vol. 18, pp. 564-587, May. 2023.

  9. A S A Doss, P K Lingampally, G M T Nguyen, et al, “A comprehensive review of wearable assistive robotic devices used for head and neck rehabilitation,” Results Eng, vol. 19, Sep. 2023.

  10. C A Yee, H Kazerooni, “Reducing occupational neck pain with a passive neck orthosis,” IEEE T-ACES, vol. 13, pp. 403-406, Nov. 2015.

  11. C Zhang, J M Hijmans, C Greve, et al, “A novel passive neck and trunk exoskeleton for surgeons: design and validation,” J. Bionic Eng, pp. 1-12, Dec. 2024.

  12. H Zhang, K Albee, S K Agrawal, “A spring-loaded compliant neck brace with adjustable supports,” Mech Mach Theory, vol. 125, pp. 34-44, Jul 2018.

  13. S P Torrendell, H Kadone, M Hassan, et al, “A neck orthosis with multi-directional variable stiffness for persons with dropped head syndrome,” IEEE Rob. Autom. Lett, vol. 9, pp. 6224-6231, Jul 2024.

  14. B C Chang, H Zhang, S Long, et al, “A novel neck brace to characterize neck mobility impairments following neck dissection in head and neck cancer patients,” Wearable Technologies, vol. 2, Jul. 2021.

  15. L Yang, T Wang, T K Weidner, et al, “Intraoperative musculoskeletal discomfort and risk for surgeons during open and laparoscopic surgery,” Surg Endosc, vol. 35, pp. 6335-6343, Nov. 2021.

  16. D G Cobian, N S Daehn, P A Anderson, et al, “Active cervical and lumbar range of motion during performance of activities of daily living in healthy young adults,” Spine, vol. 38, pp. 1754-1763, Sep. 2013.

  17. H Yajima, R Nobe, M Takayama, et al, “The mode of activity of cervical extensors and flexors in healthy adults: A cross-sectional study,” Medicina, vol. 58, May. 2022.

  18. M N Mahmood, A Tabasi, I Kingma, et al, “A novel passive neck orthosis for patients with degenerative muscle diseases: development & evaluation,” J Electromyogr Kinesiol, vol. 57, Apr. 2021.

  19. E A Keshner, D Campbell, R T Katz, et al, “Neck muscle activation patterns in humans during isometric head stabilization,” Exp Brain Res, vol. 75, pp. 335-344, Apr. 1989.

  20. H Zhang, S K Agrawal, “Kinematic design of a dynamic brace for measurement of head/neck motion,” IEEE Rob. Autom. Lett, vol. 2, pp. 1428-1435, Jul 2017.
  • Prev:No Prev
  • Back
  • Next:No Next
Contact us

CHINGMU is here to support your motion capture journey. We are happy to help you find the solution you need.

Contact our experts immediately