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Notice:

lib_pid.ks has been superseded by the kOS inbuilt PIDloop() function. It is maintained for example purposes only, please see the kOS documentation for more.

lib_pid

A library of routines to implement a simple generic PID controller.

PID_init

args:

  • Kp - number, the tuning gain for the Proportional (position) term.
  • Ki - number, the tuning gain for the Integral term.
  • Kd - number, the tuning gain for the Derivative term.
  • cMin - number, the bottom limit of the control range (to protect against integral windup)
  • cMax - number, the upper limit of the control range (to protect against integral windup)

returns:

  • PID_array - a data structure holding info to be passed to PID_seek.

description:

  • Initialize a PID controller data structure to hold the values used later during calls to PID_seek, given the initial tuning parameters. This is a very simple PID controller that makes no attempts to tune its parameters. You must supply them for it. Call PID_init once before your controlling loop begins.
  • When calling it, set cMin and cMax to define the range of valid values it should be allowed to return for the control input. For example if using it for a LOCK THROTTLE, you should set cMin to 0 and cMax to 1. if using it for, say, a SHIP:CONTROL:YAW, it should be a cMin of -1 and a cMax of +1.

PID_seek

args:

  • PID_array - the structure returned by an earlier call to PID_init
  • seekVal - number, the value you are trying to seek, the "setpoint".
  • curVal - number, the value of the thing you are seeking, as it currently measures right now

returns:

  • newInput - number, the value you should be setting the input controlling mechanism to.

description:

  • After PID_init has been called, you call PID_seek repeatedly in a loop, telling it the value of some property you are trying to seek, and the value that property currently has. It will return a number back to you that you should immediately set the control that influences that property to. An example showing it being used exists in the examples directory, to create a hovering rocket.

Copyright © 2015,2019 KSLib team

This work and any code samples presented herein are licensed under the MIT license.