Study of active tolerant control for encoder fault in lift stage machinery control systems based on signal reconstruction

For the encoder fault in lift stage machinery control system, an active fault tolerant control method based on signal reconstruction was proposed in the paper. Firstly, multi-scale morphological method was adopted to decompose the encoder fault signals. Considering the DIF filter´s capacity of underlining the fault characteristic, it was used as feature extraction for decomposed signals to achieve fault diagnosis of encoder. Secondly, as incremental encoder and absolute encoder were used to measure the speed and position of the lift stage respectively, redundant function was formed. So when the fault was diagnosed online, the redundancy mentioned above will be utilized by selecting proper numerical integrator and differentiator to substitute reconstructed signal for fault signal, thus an active fault tolerant strategy was implemented with switch strategy.