Patent ID: 6825631
Filing Date: 2004-11-30
Classification: G05B

Abstract:
A prediction controlling device outputting a control input and feedforward signal to the controlled object, so that the output of the controlled object is reconciled with a target command, comprising:a feedforward signal generation command filter that receives a target command signal which is information of a future target command as an input and outputs a future command increment which is an increment from one sampling period to the next sampling period of a target command signal from the present sampling time to a multiple-sampling future and the feedforward signal from the future target command signal; and a prediction controller that receives the future command increment, the feedforward signal and a controlled object output at the past sampling time over zero sampling as inputs, acquires the future error prediction value by using a transfer function model from the feedforward signal and the control input to the controlled object output, determines the control input so that the performance function of the error prediction value and the control input becomes minimal, and applies the control input to the controlled object; and wherein said prediction controller includes: an integrator that receives the future command increment as an input and calculates said target command from the present sampling time to a multiple-sampling future; a memory section that stores constants for prediction control in advance and receives as inputs said target command calculated by said integrator, two feedforward signals, controlled object output, and control input, and stores the past target command, past feedforward signals, past controlled object output and past control input; a subtracter that subtracts said controlled object output from said past target command and acquires the past error; and an operational unit that receives as inputs the target command acquired by said integrator, the past feedforward signals, the past controlled object output, the past control input and constants for prediction control, which are stored by the memory section, and the error obtained by the subtracter, obtains a future error prediction value by using a discrete-time transfer function model, which is: Y(z)={(b1zâˆ’1+ . . . +bNbzâˆ’Nb)U(z)+(d1zâˆ’1+ . . . +dNdzâˆ’Nd)FF1(z)+(c1zâˆ’1+ . . . +cNczâˆ’Nc)FF2(z)}/(1âˆ’a1zâˆ’1âˆ’ . . . âˆ’aNazâˆ’Na), from the feedforward signal and the control input to the controlled object output where FF1(z) and FF2(z) are z-transform of the two feedforward signals, U(z) is z-transform of the above control input, Y(z) is z-transform of the controlled object output, Na, Nb, Nc, and Nd are natural numbers, and a1, a2, . . . , aNa, b1, b2, . . . , bNb, c1, c2, . . . , cNc, d1, d2, . . . , dNd are prescribed coefficients, and determines and outputs the control input so that the performance function of said corresponding future error prediction value and control input is minimized; and furtherwherein, where x is an integer indicating a sampling time, FF1(x) and FF2 (x) are said two feedforward signals, u(x) is said control input, y(x) is said controlled object output, r(x) is said target command, M, Na, Nb, Nc, and Nd are natural numbers, K is an integer of K&gE;0, qm, pn, E, gn, xn, and tn are said constants for prediction control, and i is the present sampling time, said operational unit calculates said control input, which is: u&af;(i)=&Sum;m=1M&it;qm&it;r&af;(i+m)-&Sum;n=0Na&it;pn&it;y&af;(i-K-n)+Ee&af;(i-K)-&Sum;n=1Nb+K&it;gn&it;u&af;(i-n)-&Sum;n=0Nd+K&it;xn&it;FF1&af;(i-n)-&Sum;n=0Nc+K&it;tn&it;FF2&af;(i-n)and outputs the same.