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Results Methods 1. Two healthy young, six healthy middle-aged and older adults, and three stroke patients participated in the study (Table 1). 2. Examples of tracking performance curves (Fig. 6). 3. The subjects reduced tracking errors over time whether as individuals or as groups (Table 2.)(Fig. 7). • The Motor Sequence Learning Paradigm: • The design: a baseline test, five-day training period, and a retention test • Set-up: The IMU was fastened to the dorsal-anterior aspect of the non-dominant foot of the subject (Fig. 4); the subject was sitting in front of the monitor equipped with the interface and analysis software (Fig. 5) • Procedures: each subject performed ankle dorsiflexion /plantarflexion movements to track the upward/downward trajectories of the target. On each day of training, 12 blocks of ten 12-sec repeated/random sequence trials were practiced. • Dependent measure: RMSEbaseline, RMSEretention, and normalized change (∆) of RMSE after training • Normalized ∆ of RMSE = (RMSEbaseline - RMSEretention)/RMSEbaseline x 100% • The ankle tracking device: The system consisted of a wireless inertial measurement unit (IMU) (InvenSense® )(Fig. 1), a computer monitor, interface software, and analysis software. • The IMU: Equipped with a 3-DoF accelerometer, a 3-DoF gyro sensor, a 3-DoF magnetometer, and a microprocessor; can precisely and reliably measure roll, yaw, and pitch angles with less than 0.8° of errors as validated by a standard potentiometer encoder. • The interface: developed by using C++ Builder (Borland® ), used for producing and displaying target tracking trajectories (Fig. 2), which were derived from polynomial equations, and for displaying subject’s ankle position (Fig. 2) • The analysis software: to record tracking performance and calculate the root mean square errors (RMSE) between target position and subject’s ankle position, normalized to subject’s maximal ankle range of motion (Fig. 3). Ko Chiao 1 An-Chih Tsai 2 Tsung-Han Hsieh 2 Meng-Tien Wu 1,3 Ta-Te Lin 2 Pei-Fang Tang 1 * 1 School and Graduate Institute of Physical Therapy, National Taiwan University, Taipei, Taiwan, ROC 2 Department of Bio-Industrial Mechatronics Engineering, National Taiwan University, Taipei, Taiwan, ROC 3 Rehabilitation Center, Cardinal Tien Hospital Yunghe Branch, Taipei, Taiwan, ROC Conclusions Fig. 2 Target and ankle position displayed on the monitor Fig. 1 IMU 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0.10 1 2 3 4 5 6 7 RMSE Repeated Sequence Young aver. Older aver. Stroke_aver. 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0.10 1 2 3 4 5 6 7 RMSE Random Sequence Young aver. Older aver. Stroke_aver. 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 1 2 3 4 5 6 7 RMSE Day Y01 Repeated Random 0.02 0.03 0.04 0.05 1 2 3 4 5 6 7 RMSE Day H06 Repeated Random 0.06 0.07 0.08 0.09 0.10 0.11 0.12 0.13 1 2 3 4 5 6 7 RMSE Day S02 Repeated Random Young Subjects Baseline test Retention test Normalized ∆ Y01 0.0800 0.0500 37.50% Y02 0.0600 0.0500 16.67% Mean 0.0700 0.0500 27.08% Older Subjects Baseline test Retention test Normalized ∆ H02 0.0486 0.0338 30.42% H03 0.0788 0.0493 37.41% H04 0.0688 0.0257 62.69% H05 0.0401 0.0276 31.20% H06 0.0443 0.0274 38.10% H07 0.0658 0.0418 36.51% Mean 0.0577 0.0343 39.39% Stroke Subjects Baseline test Retention test Normalized ∆ S01 0.0707 0.0546 22.75% S02 0.1193 0.0671 43.78% S03 0.0649 0.0474 26.93% Mean 0.0850 0.0564 31.15% Young Subjects Baseline test Retention test Normalized ∆ Y01 0.0500 0.0300 40.00% Y02 0.0500 0.0200 60.00% Mean 0.0500 0.0250 50.00% Older Subjects Baseline test Retention test Normalized ∆ H02 0.0490 0.0338 31.03% H03 0.0791 0.0477 39.75% H04 0.0642 0.0294 54.20% H05 0.0412 0.0270 34.35% H06 0.0428 0.0270 36.86% H07 0.0570 0.0391 31.44% Mean 0.0556 0.0340 37.94% Stroke Subjects Baseline test Retention test Normalized ∆ St01 0.0634 0.0601 5.32% St02 0.1130 0.0733 35.08% St03 0.1048 0.0491 53.17% Mean 0.0937 0.0608 31.19% Table 2. The RMSE and normalized ∆ of RMSE of the ankle tracking performance of young, older and stroke groups (Left: Repeated sequence; Right: Random sequence) Repeated sequence Random sequence Background and Purpose Fig. 6 Performance curves of 3 subjects. Fig. 3 Examples of repeated and random sequences of ankle tracking trajectories with subject’s tracking performance (green) being superimposed on the target trajectories (red). Fig. 4 Placement of IMU • Ankle motor control is crucial for balance and walking. Few portable devices are available for the assessment and training of ankle motor control. • We invented a new portable wireless device and tested its feasibility to be used for the assessment and training of ankle tracking performance in healthy and clinical populations using a motor sequence learning paradigm. Subject Target Max. dorsiflexion Max. plantarflexion • Preliminary results support that the devise is applicable to the assessment and training of ankle plantarflexion/dorsiflexion tracking movements. Further studies will be needed using larger samples of different populations. Acknowledgments NSC 101–2314–B–002–009 awarded to Dr. Tang; Advanced Biomedical MRI Lab at NTUH Subject Age Gender Footed- ness Hemiplegic side MMSE Muscle strength (kg) Fugl- Meyer score Fugl-Meyer score of ankle motion Y01 24.4 F R -- 30 23.60 -- -- Y02 22.2 F R -- 30 17.43 -- -- H02 67.9 M R -- 28 23.60 -- -- H03 64.3 F R -- 30 13.20 -- -- H04 49.0 F R -- 30 21.90 -- -- H05 52.2 F R -- 30 20.57 -- -- H06 58.0 F R -- 30 17.40 -- -- H07 61.2 F R -- 28 16.87 -- -- S01 76.1 F R L 29 13.07 30/34 8/8 S02 66.8 M R L 30 -- 30/34 8/8 S03 27.2 F R R 28 -- 27/34 5/8 Table 1. Demographics of all subjects Fig. 7 Mean performance curves of 3 subject groups for repeated and random sequence learning. Fig. 5 Experimental setting
