Control system and vehicle steering control system

Abstract

A control system calculates inputs to a control target that has m inputs and n outputs (m=n, each of m and n is a natural number that is more than one), while designating a plurality of combinations of the inputs and the outputs. A feedback controller calculates, with respect to each designated combination, a control input to a non-interference controller based on a difference between a target value and a current value of the control quantity to make the current value follow the target value. The non-interference controller executes, with respect to each designated combination, a non-interference control to reduce influence due to mutual interference between n control quantities. This reduces the number of combinations of the inputs and the outputs, the combinations whose mutual interference needs considering; thereby, the non-interference control may be easily achieved.

What is claimed is: 
     
         1 . A control system that controls a control target that provides a plurality of n outputs of control quantities based on a plurality of m inputs of operation quantities, wherein m=n and each of m and n is a natural number that is more than one, the control system comprising:
 a plurality of feedback controllers, each of which calculates the operation quantity based on a difference between (i) a target value, which is generated by a target value generator, the target value corresponding to the control quantity and, and (ii) a current value of the output provided by the control target; and   a non-interference controller provided between (i) the plurality of feedback controllers and (ii) the control target, the non-interference controller executing a non-interference control to reduce influence due to mutual interference between the outputs provided by the control target, wherein:   combinations of the inputs and the outputs in the control target are designated; and   the non-interference control by the non-interference controller and the feedback control by the feedback controllers are executed with respect to each of the designated combinations of the inputs and the outputs.   
     
     
         2 . The control system according to  claim 1 , wherein:
 when designating the combinations of the inputs and the outputs in the control target, a priority is given to a subject combination of (i) an input among the plurality of inputs and (ii) an output among the plurality of outputs, the subject combination providing a maximum gain.   
     
     
         3 . The control system according to  claim 1 , wherein:
 each combination is of (i) one input among the plurality of inputs and (ii) one output among the plurality of outputs; and   a number of the designated combinations is equal to n being a number of the outputs, n being equal to m being a number of the inputs.   
     
     
         4 . A vehicle steering control system to which the control system according to  claim 1  is applied,
 the vehicle steering control system controlling steering of a vehicle while providing, as the outputs of the control target, at least two control quantities among three control quantities that are (i) a steering angle, (ii) a yaw angle velocity, and (iii) a lateral acceleration,
 the three control quantities being vehicle properties generated based on a driver's steering torque. 
 
 
     
     
         5 . The vehicle steering control system according to  claim 4 , wherein:
 the control target includes a variable gear transfer steering motor which controls an actual steering angle of a front wheel; and   the designated combination is of (i) a motor voltage of the variable gear transfer steering motor that serves as an input and (ii) a steering angle of the vehicle that serves as an output.   
     
     
         6 . The vehicle steering control system according to  claim 4 , wherein:
 the control target includes an electric power steering motor which assists a steering force by a driver; and   the designated combination is of (i) a motor voltage of the electric power steering motor that serves as an input and (ii) a yaw angle velocity of the vehicle that serves as an output.   
     
     
         7 . The vehicle steering control system according to  claim 4 , wherein:
 the control target includes an active rear steering motor which controls an actual steering angle of a rear wheel; and   the designated combination is of (i) a motor voltage of the active rear steering motor that serves as an input and (ii) a lateral acceleration of the vehicle that serves as an output.