Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2018 Feb 13;18(2):566.
doi: 10.3390/s18020566.

Compact Hip-Force Sensor for a Gait-Assistance Exoskeleton System

Hyundo Choi  1 , Keehong Seo  2 , Seungyong Hyung  3 , Youngbo Shim  4 , Soo-Chul Lim  5
Affiliations

Compact Hip-Force Sensor for a Gait-Assistance Exoskeleton System

Hyundo Choi et al. Sensors (Basel). .

Abstract

In this paper, we propose a compact force sensor system for a hip-mounted exoskeleton for seniors with difficulties in walking due to muscle weakness. It senses and monitors the delivered force and power of the exoskeleton for motion control and taking urgent safety action. Two FSR (force-sensitive resistors) sensors are used to measure the assistance force when the user is walking. The sensor system directly measures the interaction force between the exoskeleton and the lower limb of the user instead of a previously reported force-sensing method, which estimated the hip assistance force from the current of the motor and lookup tables. Furthermore, the sensor system has the advantage of generating torque in the walking-assistant actuator based on directly measuring the hip-assistance force. Thus, the gait-assistance exoskeleton system can control the delivered power and torque to the user. The force sensing structure is designed to decouple the force caused by hip motion from other directional forces to the sensor so as to only measure that force. We confirmed that the hip-assistance force could be measured with the proposed prototype compact force sensor attached to a thigh frame through an experiment with a real system.

Keywords: force sensor; gait assistance; hip exoskeleton; hip force sensor; rehabilitation robotics; wearable sensor.

PubMed Disclaimer

Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Autonomous hip exoskeleton for gait enhancement and thin assistance torque sensor.
Figure 2
Figure 2
(a) Modeling of the assistance force sensor and (b) the structure of the sensor.
Figure 3
Figure 3
(a) The developed sensor system and (b) force measurement and calibration system setup.
Figure 4
Figure 4
Experimental results of the relationship between the input force on the z-axis (a,b), the y-axis (c,d) and x-axis (e) and the voltage variation of each sensor.
Figure 5
Figure 5
Assistance controller architecture.
Figure 6
Figure 6
Relation between applied force and sensor voltage.
Figure 7
Figure 7
Experimental setup with a treadmill.
Figure 8
Figure 8
Assistive torque estimated from the force-sensitive resistor (FSR) sensor and motor current for comparison. The hip joint angle while walking is also presented.
See this image and copyright information in PMC

References

    1. Cruz-Jentoft A.J., Baeyens J.P., Bauer J.M., Boirie Y., Cederholm T., Landi F., Martin F.C., Michel J.-P., Rolland Y., Schneider S.M., et al. Sarcopenia: European consensus on definition and diagnosis: Report of the European working group on Sarcopenia in older people. Age Aging. 2010;39:412–423. doi: 10.1093/ageing/afq034. - DOI - PMC - PubMed
    1. Gullberg B., Johnell O., Kanis J.A. World-wide projections for hip fracture. Osteoporos. Int. 1997;7:407–413. doi: 10.1007/PL00004148. - DOI - PubMed
    1. Verghese J., LeValley A., Hall C.B., Katz M.J., Ambrose A.F., Lipton R.B. Epidemiology of gait disorders in community-residing older adults. J. Am. Geriatr. Soc. 2006;54:255–261. doi: 10.1111/j.1532-5415.2005.00580.x. - DOI - PMC - PubMed
    1. Ferris D.P. The exoskeletons are here. J. Neuroeng. Rehabilit. 2009;6 doi: 10.1186/1743-0003-6-17. - DOI - PMC - PubMed
    1. Collins S.H., Wiggin M.B., Sawicki G.S. Reducing the energy cost of human walking using an unpowered exoskeleton. Nature. 2015;522:212–215. doi: 10.1038/nature14288. - DOI - PMC - PubMed