US Patent 7797114 Torque measuring apparatus and rotation center measuring apparatus

A front wheel is placed on a lifting table, which is rotated by an actuator together with the front wheel. By rotating the lifting table by the actuator, the front wheel is rotated under constraint of a steering mechanism of an automobile. The rotation angle of an arm with respect to a base is detected by an encoder provided at an end of an extendable rod which pivotally supports the arm in a rotatable manner. The rotation angle of the base is detected by a second encoder to determine the rotation angle θ2−θ1 and rotation radius Lt of the front wheel under constraint of the steering mechanism. Based on reaction force F detected by a load cell, rotation radius Lt, and rotation angle θ2−θ1, friction torque Tt is determined.