An actuator system.

摘要

A railway vehicle brake actuator employs an electric motor driving through a step-down gearbox to mechanically move the brake blocks. After the initial rubbing contact point the response of the system is non-linear and the motor feedback control involves compensation for said non-linearity. The motor output shaft is connected to a rotary shaft encoder so that the position of the actuator output member, and thus also the brake force applied, can be determined by pulse counting. The ideal relationship between a brake demand signal and brake force is linear. The actual relationship between actuator position and brake force is non-linear. Correction factors covering the whole operating range are stored in a memory against pulse count numbers and used as a look-up table in the feedback circuit to compensate either the feedback signal or the demand signal for the non-linearity of the response.