X-3D Parameters

From UfoWiki

Below is a description of the user configurable X-3D parameters. This information was extracted from the (now obsolete) X3DControl-program, which was used to configure an X-3D placed on a China board. For X-3Ds placed on an X-Base the description may not be fully accurate anymore.

Contents 1 Introduction 2 General information about the used controllers 3 The parameters 4 Meaning of the parameters 4.1 Kp, Kp_Yaw 4.2 Kd,Kd_Yaw 4.3 angle_max 4.4 K_stick 4.5 K_expo 4.6 K_expo_edge 4.7 K_stick_direct 4.8 Temp compensation

[edit] Introduction

Here, you can read an overview over the controlling parameters of the X-3D gyro and their effects on the behavior of the Ufo. For getting in touch with controller design we recommend to read this wikipeda article: (no link was given here, the german version referred to http://de.wikipedia.org/Regelungstechnik)

[edit] General information about the used controllers

The controllers running on the X-3D are so called PD controllers. The controlled value is the angle in nick and roll axis. As the gyros on the X-3D are only able to measure angular velocity, the angle is calculated as the integral over the angle velocitys. Every integral calculation lags the information about the starting value. Thus, the angle is not the absolute, but the relative angle to the start of the Ufo.

With the remote control, the desired value of nick, roll and yaw is set. Due to effects like temperature drift, the raw gyro values and also the integrated are not exact. Thus the Ufo starts drifting slowly in random directions. Practically, this drift is no big issue, as small corrections with the remote control can compensate it. Big temperature drifts are also compensated by the X-3D gyro automatically.

As the nick and the roll axis are aquivalent, all parameters are the same for both. Only the yaw controller has a different set of parameters.

[edit] The parameters

The parameters can be roughly diveded into two categories:

• Controller parameters: Kp,Kd,angle_,max, Kp_yaw,Kd_yaw, fast_yaw_margin
• Stick parameters: K_stick, K_expo, K_expo_edge, K_stick_direct, K_stick_yaw,K_expo_yaw

The controller parameters are only dependend on the Ufo itself and its weight including the battery. No matter if you hover inside or do loopings outside, in theorie all controllers parameters stay the same. Practically spoken, controller settings for outdoor flying are set to higher controller values, as a little bit shaking while hovering is acaptable as long as the controller stabilizes the ufo quicker in extrem situations. These adaptions are in the region <10%. In general the relation between the P and D value should not be changed!

The stick parameters are used to adapt the behavior of the Ufo to the pilot: From easy and smooth to agressive and powerful.

[edit] Meaning of the parameters

[edit] Kp, Kp_Yaw

The P value (=propotional) of the controller sets the speed of the Ufo getting back to its desired angle value. If Kp is too big, the Ufo starts to swing around the desired value. If its much too big, it gets instable. A very small Kp value results in a Ufo that's not able to get back to its desired angle.

[edit] Kd,Kd_Yaw

The Kd (=differential) value compensates for fast glitches and slows down the P part to prevent overshoots. If Kd is too big, the Ufo start shaking. If its to small compared to P, the Ufo starts to swing or if both are to small, it gets unstable.

[edit] angle_max

angle_max is a virtual border for the difference between actual value and desired value in nick and roll. Normally, you don't have to change this value.

[edit] K_stick

K_stick is the direct proportianal stick gain for nick and roll.

[edit] K_expo

This is the exponential stick gain. Its added to the stick value after K_stick and accelerates the angle increasing as the stick leaves the middle position.

[edit] K_expo_edge

This parameter sets an edge gain for the stick. This gain is added ontop of K_stick and K_stick_expo, when the nick or roll stick is at the maximum.

[edit] K_stick_direct

To hover very precise, this parameter sets the direct stick to outmix mixer. Keep this value low, as it's the same as a glitch for the controller.

[edit] Temp compensation

This value sets the speed of the temperature calibration. Normally, there is no need to change this value.