FPGA Implementation of Velocity Estimation Method Using Chebyshev Expansion

In motion control, velocity is required to be estimated with less delay and less error, but the two are trade-offs because of an encoder's quantization noise, and they are difficult to make both small simultaneously. This paper aims to overcome the trade-off when conventional methods are used. This paper proposes an FPGA (Field Programmable Gate Array) implementation method for a model-free velocity estimation using Chebyshev expansion. The use of Chebyshev expansion enables better rejection of quantization noise from the measured data than using a frequency-domain filter. The estimation method is realized by a single inner product calculation, which takes 3μs of computation time on FPGA. The performance of the proposed method is validated by a velocity estimation from actual encoder data.