Control of Torque-Assisted Bicycle based on Physical Activity during Repetitive Prolonged Cycling Exercise Tohru KIRYU*, Shinya KATO*, Takao MORIYA**, and Yasufumi MIZUNO** *Graduate School of Science and Technology, Niigata University, 8050 Ikarashi-2, Niigata 950-2181, Japan, **Yamaha Motor Co., Ltd., 2500 Shingai, Iwata, Shizuoka 438-0026, Japan
Control of Torque-Assisted Bicycle based on Physical Activity during Repetitive Prolonged Cycling Exercise, ISEK2004 in Boston, June 19, 2004 Introduction Power-Assisted Bicycle is now spreading Numbers of Power-Assisted Bicycles in Japan [ten thousand] 25 20 15 10 5 0 93 94 95 96 97 98 99 00 01 02 03 Easy to climb at steep slope like cycling at flat road year Merit: Facilitate voluntary movement and support degenerate muscle force due to aging or small amount of exercise Demerit: excessive assist reduces amount of exercise, while too small assist causes overload for degenerate muscle force Appropriate power assist based on physical activity is required T. Kiryu, Niigata University
Control of Torque-Assisted Bicycle based on Physical Activity during Repetitive Prolonged Cycling Exercise, ISEK2004 in Boston, June 19, 2004 Background and Purpose Current power-assisted bicycle is controlled by a given torque from a rider - Weak point of torque control: no reflection of pedal torque physical activity including muscle fatigue of a rider. - Ex. Reduction of pedal torque due to muscle Assist System fatigue decreases assist torque at the same time. This will induce progression of fatigue . � driving torque Reflection of physical activity on power-assist control is required during cycling Biosignals Physical Activity Determination of Assist Torque step 1 step 2 step 1: estimation of physical activity from measured biosignals. step 2: determination of appropriate power-assist . T. Kiryu, Niigata University
Control of Torque-Assisted Bicycle based on Physical Activity during Repetitive Prolonged Cycling Exercise, ISEK2004 in Boston, June 19, 2004 Outline 1. Measurement of biosignals during cycling with power-assisted bicycle and evaluation of the correlation between physical activity and power-assist with the progression of fatigue. RSA MPF 2. Designing how to control appropriate power-assist based on the physical activity during cycling. modeling 3. Feasibility experiments for a power-assist bicycle equipped with a new control system. 50 old syste � 40 new system RSA-ratio[%] 30 20 10 control by PLC 0 start rest start climbing finish finish rest T. Kiryu, Niigata University
Control of Torque-Assisted Bicycle based on Physical Activity during Repetitive Prolonged Cycling Exercise, ISEK2004 in Boston, June 19, 2004 Measurement of Vehicle Data pedal torque - torque assist - 20 inch wheel - auto-transmission Assist System - speed limit assist ratio 2 1 driving torque (pedal and assist) YAMAHA PAS PX20 speed 0 Limit-1 Limit-2 http://www.jbpi.or.jp/english/b.news/enews2.html. Vehicle Data - speed [m/sec] at the wheel magnetic sensors - cadence [rpm] at the pedal 60 [rpm] was requested by a tone pace maker - pedal torque [Nm] T. Kiryu, Niigata University
Control of Torque-Assisted Bicycle based on Physical Activity during Repetitive Prolonged Cycling Exercise, ISEK2004 in Boston, June 19, 2004 Measurement of Biosignals Biosignals R-R interval time-series [sec] - ECG - EMG at right/left vastus lateralis MPF: mean power frequency [Hz], ARV: averaged rectified value [ µ V] - Subjective index NASA-TLX f Measurement Conditions Signal processing H f F ( ) f df � � t - ECG gain: 46 [dB] f ( ) MPF t L = time constant: 150 [msec] f H ( ) F f df � t - EMG gain: 60 [dB] f L time constant: 30 [msec] T 1 ARV ( t ) S ( t ) dt = � + � Data Acquisition 2 T T � 12 [bit], sampling frequency f H : low frequency � F t : fft_result of 5000 [Hz] f L : high frequency � f : frequency T. Kiryu, Niigata University
Control of Torque-Assisted Bicycle based on Physical Activity during Repetitive Prolonged Cycling Exercise, ISEK2004 in Boston, June 19, 2004 Route and Time Table 830 [m] long side view start height period climbing period finish period start period finish period -2.5 ˚ 5.7 ˚ -6.3 ˚ top view 3.4 ˚ 237 507 [m] distance climbing period Five or six trials for each experimental set measurement resting 3 [min] 2 [min] NASA-TLX start finish 4th trial 5th trial 6th trial 1st trial 2nd trial 3rd trial [min] 5 10 15 20 25 0 30 T. Kiryu, Niigata University
Control of Torque-Assisted Bicycle based on Physical Activity during Repetitive Prolonged Cycling Exercise, ISEK2004 in Boston, June 19, 2004 Two Types appearing in HRV RR_interval GDRR RR_interval SDRR 1.0 1.0 [sec] [sec] 0.8 0.8 0.6 0.6 0.4 0.4 0.2 0.2 0 50 100 150 200 250 300 0 50 100 150 200 250 300 time [sec] time [sec] start 3rd corner finish start 3rd corner finish RSA_ratio RSA_ratio 2nd corner 2nd corner 60 60 [%] [%] 40 40 20 20 0 0 0 50 100 150 200 250 300 0 50 100 150 200 250 300 time [sec] time [sec] side view height climbing period finish period start period -2.5 ˚ 5.7 ˚ -6.3 ˚ 3.4 ˚ 237 507 [m] distance Representation of the overall behavior as a function of distance from the starting point to compare the results for each phase among trials T. Kiryu, Niigata University
Control of Torque-Assisted Bicycle based on Physical Activity during Repetitive Prolonged Cycling Exercise, ISEK2004 in Boston, June 19, 2004 Autonomic Regulation RSA: Respiratory Sinus Arrhythmia - Frequency band of 0.15 [Hz] ~ 0.5 [Hz] in heart rate variability - Improving gas exchange - Reflection of sympathetic and parasympathetic nervous activities - Increase during rest, while decrease under fatigue or stress. RSA-ratio frequency climbing period 0 . 5 [Hz] W ( f , t ) dfdt � RSA _ ratio ( t ) 0 . 3 = f WH W ( f , t ) dfdt � 0.5 f WL 0.3 f : frequency W: wavelet result f WH : max frequency f WL : min frequency time t start point T. Kiryu, Niigata University
Control of Torque-Assisted Bicycle based on Physical Activity during Repetitive Prolonged Cycling Exercise, ISEK2004 in Boston, June 19, 2004 Grouping by RSA ratio Grouping two types of physical activities at each trial by RSA-ratio - SDRR (Steeply Decreasing in RR interval before climbing) mean of RSA-ratio at start period is greater than 20% - GDRR (Gradually Decreasing in RR interval) otherwise Change in physical activity during an experimental set even in the same subject GDRR and SDRR show the condition of current physical activity and does not show the physical work capacity of each subject T. Kiryu, Niigata University
Control of Torque-Assisted Bicycle based on Physical Activity during Repetitive Prolonged Cycling Exercise, ISEK2004 in Boston, June 19, 2004 Grouping Results by RSA ratio Subjects: healthy 8 male and 5 female students (21–24 yrs. Old) total 103 trials � 22 trials were assist-off trials) assist SDRR GDRR total ON 54(66.7%) 27(33.3%) 81 OFF 7(31.8%) 15(68.2%) 22 total 61(59.2%) 42(40.8%) 103 - SDRR was dominant for assist-on trials, whereas GDRR for assist-off trials. � power assist might be effective - However, there were GDRR even in assist-on trials. � power assist is not a definite factor for increasing RSA-ratio Conventional power assist strategy is not suitable for rider’s physical work capacity or conditions T. Kiryu, Niigata University
Control of Torque-Assisted Bicycle based on Physical Activity during Repetitive Prolonged Cycling Exercise, ISEK2004 in Boston, June 19, 2004 RSA ratio and RR Interval SDRR GDRR LRR SRR RSA ratio RR interval p < 0.05 * * * 35 35 * * [%] * 30 30 * 25 25 20 20 15 15 10 10 5 5 0 0 preceding phases phases phases following rest 1 and 2 3 and 4 5 and 6 rest assist on assist off side view assist on height climbing period finish period assist off start period -2.5 ˚ 5.7 ˚ -6.3 ˚ 3.4 ˚ 237 507 [m] distance T. Kiryu, Niigata University
Control of Torque-Assisted Bicycle based on Physical Activity during Repetitive Prolonged Cycling Exercise, ISEK2004 in Boston, June 19, 2004 RSA ratio before & after the Steep Uphill climbing steep uphill RSA_ratio at climbing period RSA_ratio at finish period after [%] [%] 50 50 40 40 SDRR GDRR GDRR SDRR 30 30 20 20 10 10 0 0 0 10 20 30 40 50 0 10 20 30 40 50 [%] [%] before RSA_ratio at start period RSA_ratio at start period side view height climbing period finish period start period -2.5 ˚ 5.7 ˚ -6.3 ˚ 3.4 ˚ [m] 237 507 distance T. Kiryu, Niigata University
Control of Torque-Assisted Bicycle based on Physical Activity during Repetitive Prolonged Cycling Exercise, ISEK2004 in Boston, June 19, 2004 RR Interval before & after the Steep Uphill climbing steep uphill RRI at climbing period RRI at finish period after [ s e c ] [ s e c ] 0.8 0.8 LRR SRR 0.6 0.6 SRR LRR 0.4 0.4 0.2 0.2 0.2 0.4 0.6 0.8 0.2 0.4 0.6 0.8 [ s e c ] [ s e c ] before RR interval at start period RR interval at start period side view height climbing period finish period start period -2.5 ˚ 5.7 ˚ -6.3 ˚ 3.4 ˚ [m] 237 507 distance T. Kiryu, Niigata University
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