Dynamic system control method

Abstract

Techniques are provided herein for reducing vibrations in various modes of a dynamic system. One such technique comprises incorporating vibration limiting and sensitivity constraints into a partial fraction expansion equation model of the system so as to reduce vibrations to specific levels. Another technique comprises shaping a command determined using the partial fraction expansion equation model to produce a desired output. The entire command may be shaped or only selected portions thereof which produce vibrations. Another technique involves commanding in current to produce saturation in voltage. By doing this, it is possible to command voltage switches. The times at which the switches occur can be set to reduce system vibrations. Other techniques are also provided. These include varying transient portions at the beginning, middle and/or end of a move and using Posicast inputs, among others.

1 . A method of controlling movement in a dynamic system which can be expressed in terms of both rigid and flexible modes, the method comprising the steps of:
 generating a rigid body input for the dynamic system;   processing the rigid body input so as to produce a processed input which compensates for vibrations in the flexible mode of the system; and   applying the processed input to control the dynamic system.   
   
   
       2 . A method according to  claim 1 , wherein the generating step comprises (i) creating a model of the rigid mode of the dynamic system based on a modal analysis, and (ii) determining the rigid body input based on the modal analysis. 
   
   
       3 . A method according to  claim 1 , wherein the rigid body input corresponds to a fundamental limiting parameter of the system, the fundamental limiting parameter of the system comprising a first parameter of the system to enter into saturation. 
   
   
       4 . A method according to  claim 3 , wherein the processing step processes the rigid body input in accordance with a system vibration limiting constraint and a system sensitivity constraint. 
   
   
       5 . A method according to  claim 4 , wherein the system vibration limiting and sensitivity constraints reduce vibration during movement of a component of the dynamic system by less than 100%. 
   
   
       6 . A method according to  claim 1 , wherein the processing step processes the rigid body input in accordance with one or more constraints that are a function of a movement distance of a component of the dynamic system. 
   
   
       7 . A method according to  claim 1 , wherein the processing step processes the rigid body input in accordance with a system vibration limiting constraint only. 
   
   
       8 . A method according to  claim 1 , wherein the processing step shapes the rigid body input using a predetermined shaping function. 
   
   
       9 . A method according to  claim 8 , wherein the rigid body input includes both transient portions and a steady state portion; and
 wherein only the transient portions of the rigid body input are shaped in accordance with the predetermined shaping function.   
   
   
       10 . A method according to  claim 1 , wherein the processing step processes the rigid body input by filtering the input using filters having zeros which are substantially near poles of the system. 
   
   
       11 . A method according to  claim 1 , wherein the processing step processes the rigid body input in accordance with at least one of constraints relating to system thermal limits, system current limits, and system duty cycle. 
   
   
       12 . A method according to  claim 1 , wherein the processing step processes the rigid body input by determining a movement distance of a component of the dynamic system and modifying the rigid body input based on the movement distance. 
   
   
       13 . A method according to  claim 1 , wherein the rigid body input comprises a Posicast input. 
   
   
       14 . A method according to  claim 1 , wherein the rigid body input comprises a symmetric input. 
   
   
       15 . A method according to  claim 1 , wherein the processing step processes the rigid body input in accordance with a symmetric constraint that varies as a function of at least one of time and position of a component of the dynamic system. 
   
   
       16 . A method according to  claim 1 , wherein the rigid body input comprises a voltage which has been controlled by controlling current.