PTB News 2/2000 (209 kB) PTB News 2/2000, English edition, Issue August 2000Ergometers for foot crank work are used to induce a defined physical stress on patients in medical checks of the cardiovascular system known as «exercise ECG» and as a means of therapy control during rehabilitation and in sports medicine. In order to ensure the legally required measurement accuracy a facility for the measurement of dynamic power was installed at PTB.
The exact diagnosis of the fitness of patients requires measurements of dynamic power as a product of torque and rotational frequency with an error of less than 5%. This metrological requirement cannot be met by the manufacturers if only static checks of the torque sensor are performed and the power losses caused by the mechanical measurement parts like crank bearings, chains and transmissions are only estimated and corrected. Therefore, PTB has installed an ergometer driven by an electric motor as a national standard of dynamic torque measurement. In addition, a transfer standard simulating an ergometer with very small measurement error was developed.
The exact diagnosis of the fitness of patients requires measurements of dynamic power as a product of torque and rotational frequency with an error of less than 5%. This metrological requirement cannot be met by the manufacturers if only static checks of the torque sensor are performed and the power losses caused by the mechanical measurement parts like crank bearings, chains and transmissions are only estimated and corrected. Therefore, PTB has installed an ergometer driven by an electric motor as a national standard of dynamic torque measurement. In addition, a transfer standard simulating an ergometer with very small measurement error was developed.