US 5,216,342 AGranted

Sliding mode control method with a feedforward compensation function

AssigneeFanuc Corporation

InventorsNobutoshi Torii, Ryo Nihei, Tetsuaki Kato

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Abstract

A sliding mode control method with a feedforward compensation function achieves a control response characteristic adapted to varying system parameters and properly maintains a manipulated variable affecting a controlled object. A position deviation (.epsilon.), speed deviation (.epsilon.), predicted maximum and minimum inertias (Jmax, J0), predicted maximum and minimum gravity loads (GRmax, GRmin), switching variable (s), integral element (.intg.(.epsilon.+C.multidot..epsilon.)), second differential (.theta.r) of the command position, and actual speed (.theta.) are periodically calculated on the basis of a command position (.theta.r), actual position (.theta.), inertia data, and gravity load data (100-102, 104, 107, 110, 114, 117, 120, 123, 127). Even when a nonlinear system parameter such as inertia varies, a proper torque command (T) is periodically calculated, as a manipulated variable, on the basis of a switching amount (T1) obtained by adding together five terms calculated in accordance with respective positive or negative signs of the switching variable, position deviation, integral element, second differential, and actual speed (105, 106, 108, 109, 111-113, 115, 116, 118, 119, 121, 122, 124 to 126, 128-131).

Claims2

Dependent claims

A sliding mode control method with a feedforward compensation function for controlling a controlled object, comprising the steps of:

(a) obtaining position deviation and speed deviation values of an operation parameter representative of an operating state of the controlled object and gravitational and inertial values, corresponding thereto, of a nonlinear system parameter, which vary in dependence on the operating state of the controlled object, said obtaining including the steps of:
(a1) periodically detecting a command position in a command from a host processor and an actual position in feedback from a position detector;
(a2) receiving inertia data and gravity load data as the inertial and gravitational values of nonlinear system parameters;
and
(a3) periodically calculating the position deviation and the speed deviation values in dependence upon the command and actual positions;
(b) calculating a value for a manipulated variable to converge a characteristic of a control system on a switching plane in accordance with the position and speed deviation values of the operation parameter and the gravitational and inertial values of the nonlinear system parameter, said calculating including the steps of:
(b1) periodically calculating a predicted maximum inertia, a predicted minimum inertia, a predicted maximum gravity load, and a predicted minimum gravity load, in dependence upon the command position, the actual position, the inertia data, and the gravity load data detected in step (a);
and
(b2) periodically calculating the manipulated variable in dependence upon the position deviation, the speed deviation, the predicted maximum inertia, the predicted minimum inertia, the predicted maximum gravity load, and the predicted minimum gravity load calculated in step (b1);
and
(c) controlling operation of the controlled object in dependence upon the manipulated variable.

8 more elements

Dependencies are inferred from the claim text.