Linear Identification of a Combined System of an Iso-power Controlled Bicycle Ergometer and a Human

• Published in: Iyo denshi to seitai kogaku. Japanese journal of medical electronics and biological engineering Vol. 26; no. 1; pp. 8 - 14
• Main Authors: MOKUSHI, Koichi, YAMAMOTO, Yoshiharu, NAKAMURA, Yoshio
• Format: Journal Article
• Language: Japanese
• Published: Japan Japanese Society for Medical and Biological Engineering 01.03.1988
• Subjects: Adult; Bioelectric Energy Sources; Exercise Test; Feedback; Humans; Male; Microcomputers; Physical Exertion
• ISSN: 0021-3292; 2185-5498
• DOI: 10.11239/jsmbe1963.26.8

The purpose of this study was to identify a bicycle-human system during moderate exercise. Four male subjects performed pedalling exercises on an electrically controlled ergometer which had a feedback loop to maintain the power value given by the other computer. Work load was varied for 9.6 sec as a pseudorandom binary sequence (dt=0.05 sec, 6 bit, 3 cycle) which enable us to calculate the frequency response and the transfer function of the system, after dead time correction. Three trials were performed with a set load of 40-80, 80-120, and 40-120W, respectively. The transfer function could be described as the fourth-order rational function when calculated by least squares on time domain as follows: G(jω)=[0.46-0.0030(jω)+0.00098(jω)2-0.0000024(jω)3+0.00000052(jω)4]/[1.0+0.018(jω)+0.0050(jω)2+0.000013(jω)3+0.0000031(jω)4] The parameters of these transfer functions had no significant differences among the subjects nor the work load settings (p>0.05). The characteristics of Bode diagrams showed the resonance on the average to be approximately 2.2 and 6.4Hz. The resonance of 6.4Hz was unstable. It is necessary for identification of a human body system to design a control system that tracks rapid changes of work load.