added sonar filtering page
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5f0ff276e9
commit
e24b957fa0
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278
index.html
278
index.html
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@ -28,6 +28,7 @@
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<button class="tab-btn text-gray-600 hover:text-blue-600" data-target="lesson6">OLED Display</button>
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<button class="tab-btn text-gray-600 hover:text-blue-600" data-target="lesson7">RGB LED(Neopixel)</button>
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<button class="tab-btn text-gray-600 hover:text-blue-600" data-target="lesson8">Sonar</button>
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<button class="tab-btn text-gray-600 hover:text-blue-600" data-target="lesson8b">Sonar Filtering</button>
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<button class="tab-btn text-gray-600 hover:text-blue-600 hidden" data-target="lesson9">Motor
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Encoders</button>
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<button hidden class="tab-btn text-gray-600 hover:text-blue-600" data-target="lesson10">Reciever</button>
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@ -48,13 +49,16 @@
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<!-- Step 1 -->
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<div class="prose">
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<h2>Step 1: Setting up the IDE</h2>
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<p>There are many IDEs that we can use to program MicroPython robot, we'll be using one called "Thonny". So let's begin by downloading it.</p>
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<p>There are many IDEs that we can use to program MicroPython robot, we'll be using one called
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"Thonny". So let's begin by downloading it.</p>
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<h3>Download</h3>
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<ul class="ml-6 list-disc">
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<li><a href="https://github.com/thonny/thonny/releases/download/v4.1.7/thonny-4.1.7.exe" class="text-blue-600 hover:underline">Windows</a>
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<li><a href="https://github.com/thonny/thonny/releases/download/v4.1.7/thonny-4.1.7.exe"
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class="text-blue-600 hover:underline">Windows</a>
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</li>
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<li><a href="https://github.com/thonny/thonny/releases/download/v4.1.7/thonny-4.1.7.pkg" class="text-blue-600 hover:underline">Mac</a></li>
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<li><a href="https://github.com/thonny/thonny/releases/download/v4.1.7/thonny-4.1.7.pkg"
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class="text-blue-600 hover:underline">Mac</a></li>
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</ul>
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<p>You can also get it from the Thonny website, <a
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href="https://thonny.org/">https://thonny.org/</a></p>
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@ -69,13 +73,16 @@
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<ol class="list-decimal ml-6">
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<li>In Thonny, click on the Run->Configure Interpreter buttons at the top of the window.</li>
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<li>Choose "MicroPython (Raspberry Pi Pico) from the first dropdown menu.</li>
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<li>Click the "<u>Install or update MicroPython</u>" button down the bottom-right of the window.</li>
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<li>You need to put your device in FLASH mode, hold down the BOOT button, press and release the RESET button.</li>
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<li>Click the "<u>Install or update MicroPython</u>" button down the bottom-right of the window.
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</li>
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<li>You need to put your device in FLASH mode, hold down the BOOT button, press and release the
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RESET button.</li>
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<li>You should now find a drive called "RPI-RP2". in the Target volume dropdown, shoose it.</li>
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<li>Choose the variant "Raspberry Pi Pico - Pico / Pico H"</li>
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<li>Press Install button to install the firmware.</li>
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<li>Reset the device again with the RESET button.</li>
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<li>Press the cancel button to close the firmware update panel, then press OK to officially begin coding.</li>
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<li>Press the cancel button to close the firmware update panel, then press OK to officially
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begin coding.</li>
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</ol>
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</div>
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<div>
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@ -100,8 +107,10 @@
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<!-- Step 1 -->
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<div class="prose">
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<h2>Step 1: Open/Create the main.py file</h2>
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<p>When your device is plugged into your computer, you should be able to press the File->Load button, and choose "Raspberry Pi Pico" to load from.</p>
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<p>If no such file exists we need to make it, press File->New, and then save it to the Raspberry Pi Pico as "main.py"</p>
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<p>When your device is plugged into your computer, you should be able to press the File->Load
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button, and choose "Raspberry Pi Pico" to load from.</p>
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<p>If no such file exists we need to make it, press File->New, and then save it to the Raspberry Pi
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Pico as "main.py"</p>
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</div>
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<div>
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@ -110,7 +119,8 @@
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<!-- Step 2: Image -->
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<div class="prose">
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<h2>Step 2: Open the Serial Monitor</h2>
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<p>To get messages back from your device, and to read errors, press the view->shellbutton and make sure
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<p>To get messages back from your device, and to read errors, press the view->shellbutton and make
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sure
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you have the shell window open at the bottom.</p>
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</br>
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@ -119,7 +129,8 @@
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<code>print("Hello World")</code> and then save, yuou should see the message appear in the
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Serial monitor.
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</p>
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<p>Note that the code won't persist on the robot after a reset unless you also SAVE it to the device, RUN just runs it once</p>
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<p>Note that the code won't persist on the robot after a reset unless you also SAVE it to the
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device, RUN just runs it once</p>
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</br>
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<h2>Step 4: Code all the things!</h2>
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@ -132,7 +143,7 @@
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<img src="images/thonny_code.png" alt="Robot turning right"
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class="rounded shadow w-full max-w-xs md:max-w-full" />
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</div>
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</div>
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</section>
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@ -908,10 +919,13 @@ while True:
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<!-- Step 2 -->
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<div class="prose">
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<h2>Step 2: Coding</h2>
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<p>We'll use a library to handle sending and listening for the pulses. Put this module on your device.</p>
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<p>We'll use a library to handle sending and listening for the pulses. Put this module on your
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device.</p>
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</br>
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<p>When the "distance()" function is called, it sends a short pulse on the trigger pin, then waits for a response on the echo pin. The time it takes for the echo to return is used to calculate the distance.</p>
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<p>When the "distance()" function is called, it sends a short pulse on the trigger pin, then waits
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for a response on the echo pin. The time it takes for the echo to return is used to calculate
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the distance.</p>
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</div>
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<div>
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<pre class="bg-gray-100 p-4 rounded shadow text-sm"><code class="language-python">
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@ -955,7 +969,8 @@ class Sonar:
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<!-- Step 3 -->
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<div class="prose">
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<h2>Step 3: Call it in the main.py</h2>
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<p>Now all we need to do is create the object and call the distance function in the main.py file.</p>
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<p>Now all we need to do is create the object and call the distance function in the main.py file.
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</p>
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</div>
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<div>
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<pre class="bg-gray-100 p-4 rounded shadow text-sm"><code class="language-python">
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@ -1076,6 +1091,237 @@ while True:
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</section>
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<!-- Lesson 6 (hidden initially) -->
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<section id="lesson8b" class="lesson-content hidden">
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<h1 class="text-3xl font-bold mb-6">Sonar Filtering</h1>
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<div class="grid grid-cols-1 md:grid-cols-2 gap-6">
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<!-- Step 1 -->
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<div class="prose">
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<h2>Step 1: Understand the problem</h2>
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<p>Like most inputs, the sonar data is noisy, and there are different types of noise.</p>
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<p>On the right you can see a fairly fixed output, but with sudden spikes of irregular data.</p>
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</br>
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<p>So we need code that will filter our spikes like that, the easiest is to just throw them away. To
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do this we'll use a simple moving average filter.</p>
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</div>
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<div>
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<img src="images/sonar_noise.png" alt="Robot turning right"
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class="rounded shadow w-full max-w-xs md:max-w-full" />
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</div>
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<!-- Step 2 -->
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<div class="prose">
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<h2>Step 2: Coding a moving average filter</h2>
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<p>Instead of just taking single data points and making decisions, we'll keep an array of the last 8
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readings.</p>
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</br>
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<p>First we need to start keeping a rolling buffer of the last 8 readings.</p>
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<p>We'll use a list to store the readings, and we'll use the <code>append()</code> method to add new
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readings to the end of the list.</p>
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<p>We'll use the <code>pop(0)</code> method to remove the oldest reading from the start of the list.
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</p>
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<p>We'll use the <code>len()</code> method to check the size of the list.</p>
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<p>We'll use the <code>print()</code> method to print the list.</p>
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</br>
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<p><b>NOTE:</b> We can get smoother results by using a larger buffer size, but this can also start
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to introduce lag.</p>
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</div>
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<div>
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<pre class="bg-gray-100 p-4 rounded shadow text-sm"><code class="language-python">
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BUFFER_SIZE = 8 # The size of the buffer
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buffer = [] # Create an empty array to hold
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# the readings (this is the rolling buffer)
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while True:
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dist = sonar.distance() # Get a new reading
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buffer.append(dist) # Add it to the buffer
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# If the buffer is too big, remove the oldest reading
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if len(buffer) > BUFFER_SIZE:
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buffer.pop(0)
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print(buffer) # Print the buffer
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</code></pre>
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</div>
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<!-- Step 3 -->
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<div class="prose">
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<h2>Step 3: Take the average</h2>
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<p>Now all we need to do is create the object and call the distance function in the main.py file.
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</p>
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<pre class="bg-gray-100 p-4 rounded shadow text-sm"><code class="language-python">
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def average_filter(values):
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total = 0
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for i in range(len(values)):
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total = total + values[i]
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return total / len(values)
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# Call in the main loop
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filtered = average_filter(values)
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print(filtered)
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</code>
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</pre>
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</div>
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<div>
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<img src="images/sonar_noise_averaged.png" alt="Robot turning right"
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class="rounded shadow w-full max-w-xs md:max-w-full" />
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</div>
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<div class="prose">
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<h2>Step 4: Take the median</h2>
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<p>That's better, but those large peaks are still throwing our average off quite a bit. We can improve this by taking the MEDIAN of the buffer rather than the average.
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</p>
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<pre class="bg-gray-100 p-4 rounded shadow text-sm"><code class="language-python">
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def median_filter(values):
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sorted_vals = sorted(values) # sort the values from low->high
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mid = int(len(sorted_vals) / 2) # get the middle index
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return sorted_vals[mid] # return the value of the median
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# Call in the main loop
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filtered = median_filter(values)
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print(filtered)
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</code>
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</pre>
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</div>
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<div>
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<img src="images/sonar_noise_median.png" alt="Robot turning right"
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class="rounded shadow w-full max-w-xs md:max-w-full" />
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</div>
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<div class="prose">
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<h2>Step 5: Fine tuning</h2>
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<p>Before moving on, play with the buffer size to see how it effects the results AND the responsiveness to changes.</p>
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<p>Try and find a good balance with the time.sleep() value as well</p>
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</div>
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</section>
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<!-- Lesson 6 (hidden initially) -->
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<section id="lesson10" class="lesson-content hidden">
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<h1 class="text-3xl font-bold mb-6">Receiver</h1>
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<div class="grid grid-cols-1 md:grid-cols-2 gap-6">
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<!-- Step 2 -->
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<div class="prose">
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<h2>Step 1: Coding</h2>
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<p>Create a new file called <code>remote.py</code> and add the code to the right.</p>
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</div>
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<div>
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<pre class="bg-gray-100 p-4 rounded shadow text-sm"><code class="language-python">
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# remote.py
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import board
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import busio
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START_BYTE = 0xAA
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END_BYTE = 0xBB
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PACKET_LENGTH = 8
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# Calibration values
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LEFT_MIN = 0
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LEFT_MID = 131
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LEFT_MAX = 203
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RIGHT_MIN = 51
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RIGHT_MID = 120
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RIGHT_MAX = 255
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class ThumbInput:
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def __init__(self, tx=board.GP0, rx=board.GP1, baudrate=115200):
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self.uart = busio.UART(tx=tx, rx=rx, baudrate=baudrate, timeout=0.1)
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self.buffer = bytearray()
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def read(self):
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"""Returns (left_percent, right_percent) in range [-100, 100], or None if packet incomplete."""
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data = self.uart.read(1)
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if data:
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byte = data[0]
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self.buffer.append(byte)
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if len(self.buffer) > PACKET_LENGTH:
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self.buffer = self.buffer[-PACKET_LENGTH:]
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if len(self.buffer) == PACKET_LENGTH and self.buffer[0] == START_BYTE and self.buffer[-1] == END_BYTE:
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payload = self.buffer[1:7]
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self.buffer = bytearray()
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left_raw = payload[1]
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right_raw = payload[3]
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left = self._map_thumbstick(left_raw, LEFT_MIN, LEFT_MID, LEFT_MAX)
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right = self._map_thumbstick(right_raw, RIGHT_MIN, RIGHT_MID, RIGHT_MAX)
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return (int(left), int(right))
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return None
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def _map_thumbstick(self, x, min_val, mid_val, max_val):
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if x < mid_val:
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return (x - mid_val) / (mid_val - min_val) * 100
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else:
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return (x - mid_val) / (max_val - mid_val) * 100
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</code></pre>
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</div>
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<!-- Step 3 -->
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<div class="prose">
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<h2>Step 2: Using the recieved signal</h2>
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<p>Import just the <code>ThumbInput</code> part of the library.</p>
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</br>
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<p>Initialize the receiver with <code>receiver = ThumbInput()</code></p>
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</br>
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<p>Create a new loop as this won't work nicely with any i2c, this loop should be placed after the
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motors are created, and before the i2c is initialized.</p>
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</div>
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<div>
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<pre class="bg-gray-100 p-4 rounded shadow text-sm"><code class="language-python">
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from remote import ThumbInput
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receiver = ThumbInput()
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while True:
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result = receiver.read()
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if result:
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left_motor.move(result[0])
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right_motor.move(result[1])
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#print("Left:", result[0], "Right:", result[1])
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time.sleep(0.001)
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</code></pre>
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</div>
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</section>
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<!-- Lesson 6 (hidden initially) -->
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<section id="lesson11" class="lesson-content hidden">
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<h1 class="text-3xl font-bold mb-6">PID</h1>
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