Limits...
Design of a novel telerehabilitation system with a force-sensing mechanism.

Zhang S, Guo S, Gao B, Hirata H, Ishihara H - Sensors (Basel) (2015)

Bottom Line: Patients' safety is guaranteed by monitoring the motor's current from the exoskeleton device.To compensate for any possible time delay or data loss, a torque-limiter mechanism was also designed in the exoskeleton device for patients' safety.Finally, we successfully performed a system performance test for passive training with transmission control protocol/internet protocol communication.

View Article: PubMed Central - PubMed

Affiliation: Graduate School of Engineering, Kagawa University, 2217-20 Hayashi-cho, Takamatsu, Kagawa 761-0396, Japan. s13d505@stmail.eng.kagawa-u.ac.jp.

ABSTRACT
Many stroke patients are expected to rehabilitate at home, which limits their access to proper rehabilitation equipment, treatment, or assessment by therapists. We have developed a novel telerehabilitation system that incorporates a human-upper-limb-like device and an exoskeleton device. The system is designed to provide the feeling of real therapist-patient contact via telerehabilitation. We applied the principle of a series elastic actuator to both the master and slave devices. On the master side, the therapist can operate the device in a rehabilitation center. When performing passive training, the master device can detect the therapist's motion while controlling the deflection of elastic elements to near-zero, and the patient can receive the motion via the exoskeleton device. When performing active training, the design of the force-sensing mechanism in the master device can detect the assisting force added by the therapist. The force-sensing mechanism also allows force detection with an angle sensor. Patients' safety is guaranteed by monitoring the motor's current from the exoskeleton device. To compensate for any possible time delay or data loss, a torque-limiter mechanism was also designed in the exoskeleton device for patients' safety. Finally, we successfully performed a system performance test for passive training with transmission control protocol/internet protocol communication.

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Calibration results for the force-sensing mechanism.
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sensors-15-11511-f008: Calibration results for the force-sensing mechanism.

Mentions: Without applying any control methods, the master device becomes non-backdrivable after motor excitation; i.e., when a force is added on the master device, the motor will not rotate. Therefore, the added force will deflect the elastic elements. We installed a force sensor (FS03 force sensor; Honeywell, Morristown, NJ, USA) on the front end of the forearm part to perform the calibration. The force sensor is a peizoresistive-based force sensor. The sensor features a laser-trimmed thick ceramic film and an integrated circuit sensor element in small plastic housing. The extremely small size (25.1 × 17.27 × 8.26 mm) and light weight (approximately 3.5 g) was suitable to calibrate our master device. We recorded data from two sensors with a synchronous analog-to-digital board at a 1000-Hz sampling frequency. We performed the curve fitting with MATLAB (MathWorks Co., Natick, MA, USA). We used the root-mean-square error (RMSE) to evaluate the obtained fitting results. The calibration result is shown in Figure 8, where RMSE is 0.004198, and the sensed load Fl can be varied with torque as shown in Equation (13) where lm is equal to 165 mm. The relationship between the data from the angle sensor and the force sensor is described by Equations (14) which was calculated with a curve-fitting method (linear polynomial):(13)τl=ks⋅θ⋅K⋅lm(14)τl=0.3578⋅θ+0.001652


Design of a novel telerehabilitation system with a force-sensing mechanism.

Zhang S, Guo S, Gao B, Hirata H, Ishihara H - Sensors (Basel) (2015)

Calibration results for the force-sensing mechanism.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4481901&req=5

sensors-15-11511-f008: Calibration results for the force-sensing mechanism.
Mentions: Without applying any control methods, the master device becomes non-backdrivable after motor excitation; i.e., when a force is added on the master device, the motor will not rotate. Therefore, the added force will deflect the elastic elements. We installed a force sensor (FS03 force sensor; Honeywell, Morristown, NJ, USA) on the front end of the forearm part to perform the calibration. The force sensor is a peizoresistive-based force sensor. The sensor features a laser-trimmed thick ceramic film and an integrated circuit sensor element in small plastic housing. The extremely small size (25.1 × 17.27 × 8.26 mm) and light weight (approximately 3.5 g) was suitable to calibrate our master device. We recorded data from two sensors with a synchronous analog-to-digital board at a 1000-Hz sampling frequency. We performed the curve fitting with MATLAB (MathWorks Co., Natick, MA, USA). We used the root-mean-square error (RMSE) to evaluate the obtained fitting results. The calibration result is shown in Figure 8, where RMSE is 0.004198, and the sensed load Fl can be varied with torque as shown in Equation (13) where lm is equal to 165 mm. The relationship between the data from the angle sensor and the force sensor is described by Equations (14) which was calculated with a curve-fitting method (linear polynomial):(13)τl=ks⋅θ⋅K⋅lm(14)τl=0.3578⋅θ+0.001652

Bottom Line: Patients' safety is guaranteed by monitoring the motor's current from the exoskeleton device.To compensate for any possible time delay or data loss, a torque-limiter mechanism was also designed in the exoskeleton device for patients' safety.Finally, we successfully performed a system performance test for passive training with transmission control protocol/internet protocol communication.

View Article: PubMed Central - PubMed

Affiliation: Graduate School of Engineering, Kagawa University, 2217-20 Hayashi-cho, Takamatsu, Kagawa 761-0396, Japan. s13d505@stmail.eng.kagawa-u.ac.jp.

ABSTRACT
Many stroke patients are expected to rehabilitate at home, which limits their access to proper rehabilitation equipment, treatment, or assessment by therapists. We have developed a novel telerehabilitation system that incorporates a human-upper-limb-like device and an exoskeleton device. The system is designed to provide the feeling of real therapist-patient contact via telerehabilitation. We applied the principle of a series elastic actuator to both the master and slave devices. On the master side, the therapist can operate the device in a rehabilitation center. When performing passive training, the master device can detect the therapist's motion while controlling the deflection of elastic elements to near-zero, and the patient can receive the motion via the exoskeleton device. When performing active training, the design of the force-sensing mechanism in the master device can detect the assisting force added by the therapist. The force-sensing mechanism also allows force detection with an angle sensor. Patients' safety is guaranteed by monitoring the motor's current from the exoskeleton device. To compensate for any possible time delay or data loss, a torque-limiter mechanism was also designed in the exoskeleton device for patients' safety. Finally, we successfully performed a system performance test for passive training with transmission control protocol/internet protocol communication.

Show MeSH
Related in: MedlinePlus