Programmable logic design for an encoder-based velocity sensor in a DSP-controlled motion system

The paper presents a dedicated hardware interfacing an optical incremental encoder and DSP-controlled motion system. Different velocity sensing techniques and methods are discussed. One of them is chosen and implemented, fulfilling the main objectives proposed. The first objective is to reserve the computational power of the DSP for control tasks, avoiding the processor's use for sensing tasks like velocity sensing. The second objective is to get the maximum accuracy over a wide velocity range. There are two error sources: quantification effects due the digital system and errors in the encoder channels due to encoder mechanical and/or electronic imperfections. Both error sources have been considered, obtaining an improved accuracy compared with other actual methods based only on quantification effect reduction.