PID Control Experiment – Tuning the Controller

PID_FCIn the first part of this blog I described building a test apparatus that allows me to experiment with tuning a PID loop controlling a levitating pin pong ball in a tube.

This second installment is about trying different hands-on methods of tuning the loop, understanding how they are derived, and how well they perform compared to each other.

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PID Control Experiment – Making the Testing Rig

PID_FCPID (Proportional, Integral, Derivative) control is a classic control algorithm that I have used for a few projects, ending with ‘good enough’ control, without really spending time learning how to properly tune the PID constants.

Time for me to fill in the gap in my knowledge, so in this two part blog I want to capture my learning. Hopefully it is useful for someone else. In this first part I will document the learning and testing rig and software. The next part will be about tuning the control loop.

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Reliable Bluetooth LE Comms Between Arduino and MIT App Inventor (AI2)

MIT_AI2_IconIn a previous post, I looked at creating reliable communications using Classic Bluetooth. While that approach works well, and is a reliable way to connect devices, there may be circumstances when a Bluetooth Low Energy (BLE) connection is preferable.

As it turns out, Bluetooth and BLE are about as similar as apples and oranges. The change in transmission protocol technology is more than a trivial change in the code and its structure.

In this article I explore the difference between BT and BLE and how the previous BT AI2 app needs to be adapted.

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Reliable Bluetooth Comms Between Arduino and MIT App Inventor (AI2)

MIT_AI2_IconI recently needed to develop a Bluetooth application between an Arduino and a controlling App running on Android. App Inventor 2 was used to simplify development of the Android App .

MIT App Inventor (AI2) is a web-based online graphical mobile application development environment for Android devices, where you can create an application by simply dragging and connecting a series of function blocks.

When researching the task, I found a lot of disparate information about how to write the Bluetooth management code for AI2. This information (some good, some wrong, and a lot repetitive) was synthesized it into a set of functions, described here, that provide a reliable communications interface to my project.

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Simple Debugging for Arduino Sketches

Bug_TrackingDespite the advent of source level debuggers for Arduino code, one of the most accessible ways to debug Arduino projects is still the Serial.print() statement. It is how most beginners will start when trying to debug their code.

But what do you do with all the print() statements sprinkled through the code once your application is working?

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