Comparative Evaluation of LQR and LQT for VD-49.15-K1-B00 Brushless DC Servomotor Tracking Under Noise

Anisa Fitri Santosa (Bio-Industrial Mechatronics Engineering, National Chung Hsing University)
Anggara Trisna Nugraha (Marine Electrical Engineering, Shipbuilding Institute of Polytechnic Surabaya, Indonesia)
Rama Arya Sobhita (Marine Electrical Engineering, Shipbuilding Institute of Polytechnic Surabaya)
Dimas Eka Saputra (Design and Manufacture Engineering, Shipbuilding Institute of Polytechnic Surabaya)

Sainstech Nusantara
Vol. 3 No. 1 (2026): February 2026

Compact brushless direct-current servomotors require controllers that combine rapid reference tracking, low transient error, and tolerance to measurement disturbance. This study presents a harmonized simulation-based comparison of linear quadratic regulator (LQR) and linear quadratic tracking (LQT) control for the VD-49.15-K1-B00 three-phase external-rotor servomotor. Manufacturer specifications were revalidated, the plant was represented in state-space form, and both optimal-control structures were assessed in MATLAB/Simulink under nominal and additive-noise conditions. Performance was quantified using 10–90% rise time, 2% settling time, percentage overshoot, and normalized root-mean-square error (RMSE) over a common evaluation interval. Without noise, LQT reduced rise time from 0.45 to 0.30 s, settling time from 0.80 to 0.65 s, and RMSE from 2.5% to 2.0%, while overshoot increased from 1.0% to 3.0%. With noise, RMSE increased to 4.5% for LQR and 4.0% for LQT. The results therefore indicate a practical speed–overshoot trade-off: LQT provides faster and more accurate tracking in the evaluated conditions, whereas LQR limits the nominal peak excursion.