T. C. de Oliveira, R. Gaino, M. R. Covacic, M. C. M. Teixeira, and A. A. de Carvalho, “LQR control applied to the movement of the knee of paraplegic patients”, Semin., Exact Tech. Scienc., vol. 35, no. 2, pp. 231–246, Oct. 2014.