Self-Positionning Horizontal Device

Before talking about horizontality, we need to calculate an angle. To do so, we start with the formula previously discussed:
  • read value,
  • convert from integer to real,
  • rest a base value, corresponding to the origin 0 g (or optionally to the Normal Earth attraction 1 g to skip it) 
  • divide by the gain, 333 mV / g
and 
  • calculate asin to get the angle
  • use the Text instruction for formatting
  • display the angle

The Device

The horizontal axis is moved:
  • on the right side, by a manual handle on top
  • on the left side, by a motor.
The sensor is placed in the middle of the horizontal axis:

Usage

On usage, one clear issue is the hysteresis. 
  • With a resolution of 10 mV for the TX-C A/D inputs, a 10 mV difference corresponds to a 2° angle.
  • The accelerometer records both static (here, the gravity to deduct the angle) and dynamic (here, the speed implied by the motor) acceleration. 
The first cause is illustrated with the table on the right. 

I tried to minimise the second cause by placing the accelerometer as close as possible to the center of gravity of the axis.

Download

The attached file is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License. 
angle_x.rpp.zip
File Size: 4 kb
File Type: zip
Download File

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Simple Measures

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X-Y Joystick Remote-Controlled Device