Posts Tagged Force control

[Abstract] Impaired force control contributes to car steering dysfunction in chronic stroke

Purpose: Precise control of a car steering wheel requires adequate motor capability. Deficits in grip strength and force control after stroke could influence the ability steer a car. Our study aimed to determine the impact of stroke on car steering and identify the relative contribution of grip strength and grip force control to steering performance.

Methods: Twelve chronic stroke survivors and 12 controls performed three gripping tasks with each hand: maximum voluntary contraction, dynamic force tracking, and steering a car on a winding road in a simulated driving environment. We quantified grip strength, grip force variability, and deviation of the car from the center of the lane.

Results: The paretic hand exhibited reduced grip strength, increased grip force variability, and increased lane deviation compared with the non-dominant hand in controls. Grip force variability, but not grip strength, significantly predicted (R2 = 0.49, p < 0.05) lane deviation with the paretic hand.

Conclusion: Stroke impairs the steering ability of the paretic hand. Although grip strength and force control of the paretic hand are diminished after stroke, only grip force control predicts steering accuracy. Deficits in grip force control after stroke contribute to functional limitations in performing skilled tasks with the paretic hand.

  1. Implications for rehabilitation
  2. Driving is an important goal for independent mobility after stroke that requires motor capability to manipulate hand and foot controls.

  3. Two prominent stroke-related motor impairments that may impact precise car steering are reduced grip strength and grip force control.

  4. In individuals with mild-moderate impairments, deficits in grip force modulation rather than grip strength contribute to compromised steering performance with the paretic hand.

  5. We recommend that driving rehabilitation should consider re-educating grip force modulation for successful driving outcomes post stroke.

via Impaired force control contributes to car steering dysfunction in chronic stroke: Disability and Rehabilitation: Vol 0, No 0

, , , , , , ,

Leave a comment

[Abstract + References] 4 DOF Exoskeleton Robotic Arm System for Rehabilitation and Training – Conference paper


This paper presents a rehabilitation and training system with 4 DOF exoskeleton robotic arm. This proposed system can record a posture of physiotherapist and playback that posture to the patients. For the posture playback, the exoskeleton arm’s motion was controlled with the recorded gesture and adjusted the level of an assistive motion. The GRNN method was used for predicting the static gravity compensation of each joint with accuracy of 94.66%, 97.63%, 87.02%, and 97.32%, respectively. Hence, the exact system modelling was not required in this system. The force controller with admittance control method was applied to control this exoskeleton robotic arm. The results of the usability test showed that the proposed system had an ability to enhance the muscle’s strength and indicated that the purposed exoskeleton arm could be applied to the rehabilitation or training task.


  1. 1.
    World Health Organization: World Health Organization disability assessment schedule: WHODAS II. Phase 2 field trials. Health services research (2000)Google Scholar
  2. 2.
    Gordon, N.F., et al.: Physical activity and exercise recommendations for stroke survivors: an American Heart Association scientific statement from the Council on Clinical Cardiology, Subcommittee on Exercise, Cardiac Rehabilitation, and Prevention; the Council on Cardiovascular Nursing; the Council on Nutrition, Physical Activity, and Metabolism; and the Stroke Council. Stroke 35(5), 1230–1240 (2004)CrossRefGoogle Scholar
  3. 3.
    Perry, J.C., Rosen, J., Burns, S.: Upper-limb powered exoskeleton design. IEEE/ASME Trans. Mechatron. 12(4), 408–417 (2007)CrossRefGoogle Scholar
  4. 4.
    Guidali, M., et al.: Assessment and training of synergies with an arm rehabilitation robot. In: IEEE International Conference on Rehabilitation Robotics, ICORR 2009. IEEE (2009)Google Scholar
  5. 5.
    Balasubramanian, S., et al.: RUPERT: an exoskeleton robot for assisting rehabilitation of arm functions. In: Virtual Rehabilitation. IEEE (2008)Google Scholar
  6. 6.
    Gupta, A., O’Malley, M.K.: Design of a haptic arm exoskeleton for training and rehabilitation. IEEE/ASME Trans. Mechatron. 11(3), 280–289 (2006)CrossRefGoogle Scholar
  7. 7.
    Pehlivan, A.U., Celik, O., O’Malley, M.K.: Mechanical design of a distal arm exoskeleton for stroke and spinal cord injury rehabilitation. In: 2011 IEEE International Conference on Rehabilitation Robotics (ICORR). IEEE (2011)Google Scholar
  8. 8.
    Dellon, B., Matsuoka, Y.: Prosthetics, exoskeletons, and rehabilitation [grand challenges of robotics]. IEEE Robot. Autom. Mag. 14(1), 30–34 (2007)CrossRefGoogle Scholar
  9. 9.
    Mao, Y., Agrawal, S.K.: A cable driven upper arm exoskeleton for upper extremity rehabilitation. In: 2011 IEEE International Conference on Robotics and Automation (ICRA). IEEE (2011)Google Scholar
  10. 10.
    Panjan, S., Charoenseang, S.: Design and development of a robotic arm for rehabilitation and training. In: Park, J.J.(Jong Hyuk), Pan, Y., Yi, G., Loia, V. (eds.) CSA/CUTE/UCAWSN-2016. LNEE, vol. 421, pp. 3–8. Springer, Singapore (2017). Scholar
  11. 11.
    Yu, W., Rosen, J., Li, X.: PID admittance control for an upper limb exoskeleton. In: American Control Conference (ACC). IEEE (2011)Google Scholar

via 4 DOF Exoskeleton Robotic Arm System for Rehabilitation and Training | SpringerLink

, , , , , , , ,

Leave a comment

[ARTICLE] Force control in chronic stroke


  • Post stroke motor impairments involving force control capabilities are devastating.
  • Bimanual motor synergies provide robust data on coordinating forces between hands.
  • Low-force frequency patterns reveal fine motor control strategies in paretic hands.
  • Analyzing both novel approaches advance understanding of post stroke force control.


Force control deficits are common dysfunctions after a stroke. This review concentrates on various force control variables associated with motor impairments and suggests new approaches to quantifying force control production and modulation. Moreover, related neurophysiological mechanisms were addressed to determine variables that affect force control capabilities. Typically, post stroke force control impairments include:

(a) decreased force magnitude and asymmetrical forces between hands,

(b) higher task error,

(c) greater force variability,

(d) increased force regularity, and

(e) greater time-lag between muscular forces.

Recent advances in force control analyses post stroke indicated less bimanual motor synergies and impaired low-force frequency structure.Brain imaging studies demonstrate possible neurophysiological mechanisms underlying force control impairments:

(a) decreased activation in motor areas of the ipsilesional hemisphere,

(b) increased activation in secondary motor areas between hemispheres,

(c) cerebellum involvement absence, and

(d) relatively greater interhemispheric inhibition from the contralesional hemisphere.

Consistent with identifying neurophysiological mechanisms, analyzing bimanual motor synergies as well as low-force frequency structure will advance our understanding of post stroke force control.

via Force control in chronic stroke.

, , , , , , , , , , , ,

Leave a comment

%d bloggers like this: