How to control the servo motor

To move the servo the PCA9685 library inside the python folder must be implemented, an example of which can be found in the TestScript.py file. Inside the PCA9685 class there are only two methods that should be used:

• calibrate() - takes no arguments, returns the servos to their base position.
• stutterRotation(channel, angle) - channel refers to the pan (represented by 0) or the tilt (1) servo and angle refers to the angle to be moved to.

Ensure that calibrate is called after powering up servo, and between tests. This needed because the stutterRotation function requires the position of the servos to be accurate to the values that are stored in servo_values.txt, which can become missaligned if the servo jutters on start up or is moved by hand.

Inside TestScript.py two methods have been created to implement a more complete implementation of this functionality through the commands:

• tilt(range, increment) - range represents the final angle to be moved to and increment referes to the size of the steps to be moved through. This command takes no channel as it only works on the tilt servo. use the pan(range, increment) function to control the pan servo.
• calibrate() - no arguments, functions simply as a wrapper to unify the nescassary commands under a single instance of the TestScript class

When using the TestScript.py class, if it is required to switch between calibration and testing, comment out the command you do not want to run. Its best not to run both commands at once as it has not been tested.

The time.sleep(x) value will need changing inside TestScript.py if the time between intervals of movement need changing. Ensure the value for time.sleep(x) is a multiple of the sample rate inside Iris minus 0.5

Data Converter Script notes

The DataConverterScript.py find the newest .csv file inside its current directory, detects the Iris detection type, and normalizes and averages the values retrieved from the detector, by Iris, by angle - based on the distance traveled by the rotating servo. The output of this will be put in a file called output - [filename].csv.

To use this, DataConverterScript.py must be placed in the same directory as the Iris output .csv files. When the script has generated a file, said generated file must be removed from the directory, or Iris must capture more data, before the script should be used again (because the script saves needing inputs by automatically working on the newest .csv file inside its directory).
Because of this time saving technique, it is reccomended that between each Iris run, the DataConverterScript.py be run

The values in the script will need changing if:

• A different sensor is placed on the servos that has a different height (change radius),
• The source position is changed relative to the sensor (change distance),
• The Iris data capture rate is changed from the tested 1 capture per 10s (change dataPointsPerRotation).
  Ensure nescassary modules are installed (os, glob, math, csv).

How to run a complete test:

• Set up Iris
• Ensure the PiHat is connected to the servos and the Pi, and that it is powered
• Open TestScript.py inside the Thonny editor on the Pi and press Run
• Press start on Iris within 5 seconds.

It is currently set up to capture 6 data points (1 every 10s) between servo movements, if this is changed update the values as required inside Iris and inside TestScript.py. Ensure the value inside the sleep in TestScript.py is a multiple of the value of data capture in Iris (- 0.5 to account for servo move time). The DataConverterScript.py would also needed to be changed to reflect this change by adjusting the "dataPointsPerRotation" variable to be equal to the number of data points that are to be captured between servo movements.

Pi setup (if Pi needs to be reset)

• Ensure I2C is enabled in "raspi-config".
• Ensure Pi hat is powered through the external powersupply.
• Follow instuctions for BCM2835 install in the docs at https://www.waveshare.com/wiki/Pan-Tilt_HAT.
• If any issues are encountered consult the docs.