GUIDANCE SYSTEM BY CONTROL OF DERIVATIVE

• US 20140207257A1
• Filed: 05/04/2012
• Published: 07/24/2014
• Est. Priority Date: 06/30/2011
• Status: Active Grant

• Current Assignee: Universidad Nacional de Educación a Distancia
• Original Assignee: Universidad Nacional de Educación a Distancia
• Inventors: Viudez Moreiras, Daniel, Nevado Reviriego, Antonio, Martin Sanchez, Juan Manuel
• Granted Patent: US 9,665,075 B2
• Time in Patent Office: Days
• US Class Current: 700/29
• CPC Class Codes: G05B 13/04 involving the use of models or simulators
• CPC Class Codes: G05B 13/048 using a predictor
• CPC Class Codes: G05D 1/00 Control of position, course, altitude or attitude of land, water, air or space vehicles, e.g. using automatic pilots drive control systems specially adapted for autonomous road vehicles B60W60/00

Abstract

Guidance System for controlling output variables of single-input single-output or multi-input multi-output processes, where the process parameters are known or unknown and time-varying. The guidance system of the present invention generates a desired trajectory for a process output variable, and based on said desired trajectory, computes a set point for the derivative variable of said process output variable. This set point is then applied to a model based advanced controller for said derivative variable and the control action generated by said model based advanced controller is applied to the process and guides the process evolution in such a way that said process output variable converges towards said desired trajectory.

Claims

1. A method for generating a control variable during each of a plurality of control instants k, said control variable to be applied to an apparatus which carries out a process with at least one input variable and at least one output variable, said apparatus varying one of said variables, at least one input variable according with the value of said control variable, said method guiding said output variable towards an output set point, said method comprising the steps of:

(A) Generating a derivative variable from said output variable;

(B) Generating a future desired trajectory for driving said output variable towards said output set point with a desired dynamic;

(C) Computing from said desired trajectory a derivative set point for said derivative variable;

(D) Using a model based advanced controller for said derivative variable for computing said control variable that will drive said derivative variable to said derivative set point and, as a consequence, said output variable towards said desired trajectory.

(E) Applying said control variable in a manner which will cause said apparatus to vary one of said variables, at least one input variable in accordance therewith.

2. The method of claim 1, wherein said variable, at least one input variable defining an input vector, at least one said output variable defining an output vector, said control variable is replaced by a control vector, said output set point is replaced by an output set point vector, said derivative variable is replaced by a derivative vector, and said model based advanced controller is replaced by a multi-input multi-output model based advanced controller, generating each one of the components of said derivative vector from each one of the components of said output vector in accordance with step (A), computing a future desired trajectory for each one of said components of the output vector and for each one of the components of said derivative vector a derivative set point in accordance with steps (B) and (C), using said multi-input multi-output model based advanced controller for computing, from said components of the derivative vector and their corresponding derivative set points, said control vector in accordance with step (D) and said apparatus varying said input vector taking into account said control vector in accordance with step (E).

3. The method of claim 2, wherein the steps (B) and (C) update said desired trajectory for each one of the components of said output vector and said derivative set point for each one of the components of said derivative vector at control instants separated by an updating period which is a multiple of the control period.

4. The method of claim 3, wherein said multivariable model based advanced controller is an adaptive predictive controller such as those described in U.S. Pat. Nos. 4,197,576, 4,358,822 and 6,662,058 B1.

5. The method of claim 4, wherein said desired trajectory for one of the components of said output vector is determined by an approaching increment towards the corresponding component of the output set point vector within the next updating period, when one of the said components of the output vector differs more than a certain distance from said corresponding component of the output set point vector, since said variable approaching increment is progressively reduced when one of the said components of the output vector approaches said corresponding component of the output set point vector within said certain distance.

6. A guidance system for controlling during each of a plurality of control instants k a process having at least one input variable and at least one output variable, at least one of said output variables defining an output vector and at least one of said input variables defining an input vector, said guidance system generating a control vector that varies said input vector to guide said output vector towards an output set point vector, said guidance systems comprising:

a. Computation block means responsive to said output vector for generating a derivative vector.

b. Guidance block means responsive;

(i) to said output vector and said output set point vector for generating a desired output trajectory for each one of the components of said output vector, this set of desired output trajectories driving said output vector towards said output set point vector with desired dynamics, and (ii) to each one of said desired output trajectories for generating a set point value for each one of the corresponding components of said derivative vector.

c. Multi-input multi-output model based advanced controller means responsive to said components of said derivative vector and their corresponding set point values for generating a control vector which must be applied to the process at control instant k varying said input vector to drive said components of said derivative vector towards their corresponding set point values and, consequently, said components of said output vector towards their corresponding desired trajectories.