Gyro tutorials (#930)
* gyro tutorials * tutorials * fix gyro simulator * images * updated image * fix svg errors
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docs/static/tutorials/calibrate-gyro.png
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docs/static/tutorials/move-straight-with-gyro.png
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@ -25,6 +25,11 @@ Step by step guides to coding your @boardname@.
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"description": "Use the color sensor to follow line or detect colors",
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"url":"/tutorials/color-sensor",
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"imageUrl":"/static/tutorials/what-color.png"
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}, {
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"name": "Gyro",
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"description": "Drive straight or turn more precisely with the gyro",
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"url":"/tutorials/gyro",
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"imageUrl":"/static/tutorials/calibrate-gyro.png"
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}, {
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"name": "Ultrasonic Sensor",
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"description": "Use the ultrasonic sensor to detect obstacles",
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docs/tutorials/calibrate-gyro.md
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docs/tutorials/calibrate-gyro.md
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# Calibrate Gyro
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## Introduction @fullscreen
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The gyroscope is a very useful sensor in the EV3 system. It detects the rotation rate
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which can be very useful to correct the trajectory of the robot and do precise turns.
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However, the sensor can be imprecise and subject to drifting. It is recommend to
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calibrate your sensor at least once after starting your brick. You don't have to
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recalibrate on every run.
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* [EV3 Driving Base](https://le-www-live-s.legocdn.com/sc/media/lessons/mindstorms-ev3/building-instructions/ev3-rem-driving-base-79bebfc16bd491186ea9c9069842155e.pdf)
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* [EV3 Driving Base with Gyro](https://le-www-live-s.legocdn.com/sc/media/lessons/mindstorms-ev3/building-instructions/ev3-gyro-sensor-driving-base-a521f8ebe355c281c006418395309e15.pdf)
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## Step 1 Show ports
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Add the ``||brick:show ports||`` to see the status of the gyroscope.
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```blocks
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brick.showPorts()
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```
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## Step 2 Calibration
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Add a ``||sensors:calibrate gyro||`` block to calibrate the gyro. The block
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detects if the sensor is present and does a full reset of the sensor if necessary.
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```blocks
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brick.showPorts()
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sensors.gyro2.calibrate()
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```
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## Step 3 Download and run @fullscreen
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Download this program to your brick and press the ENTER button.
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docs/tutorials/gyro.md
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docs/tutorials/gyro.md
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# Gyro tutorials
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## Tutorials
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```codecard
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[{
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"name": "Calibrate",
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"description": "Make sure you gyro sensor is ready to use",
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"cardType": "tutorial",
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"url":"/tutorials/calibrate-gyro",
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"imageUrl":"/static/tutorials/calibrate-gyro.png"
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}, {
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"name": "Move Straight",
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"description": "Use the gyro to correct the trajectory of the robot",
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"cardType": "tutorial",
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"url":"/tutorials/move-straight-with-gyro",
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"imageUrl":"/static/tutorials/move-straight-with-gyro.png"
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}]
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```
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docs/tutorials/move-straight-with-gyro.md
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docs/tutorials/move-straight-with-gyro.md
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# Move Straight With Gyro
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## Introduction @fullscreen
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Rotating using a wheel is not precise. The wheel can slip or the motors
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can be slightly different.
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With the help of the gyro you can detect and correct deviations in your trajectory.
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* [EV3 Driving Base](https://le-www-live-s.legocdn.com/sc/media/lessons/mindstorms-ev3/building-instructions/ev3-rem-driving-base-79bebfc16bd491186ea9c9069842155e.pdf)
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* [EV3 Driving Base with Gyro](https://le-www-live-s.legocdn.com/sc/media/lessons/mindstorms-ev3/building-instructions/ev3-gyro-sensor-driving-base-a521f8ebe355c281c006418395309e15.pdf)
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## Step 1 Calibration
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Add a ``||sensors:calibrate gyro||`` block in a ``||brick:on button enter pressed||`` block so that you can manually start a calibration process. Run the calibration
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at least once after connecting the gyro.
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```blocks
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brick.showPorts()
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sensors.gyro2.calibrate()
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```
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## Step 2 Compute the error
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Make a new **error** variable and drag the ``||sensors:gyro rate||``
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and multiply it by -1. Since the rate shows the rotation rate, we will
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counter it by negating it.
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```blocks
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let error = 0
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brick.showPorts()
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sensors.gyro2.calibrate()
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while (true) {
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error = sensors.gyro2.rate() * -1
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}
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```
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## Step 3 Steer with feedback
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Drag a ``||motors:steer motors||`` block under the variable and pass
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the **error** variable into the turn ratio section.
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If the robot is turning right, the gyro will report a positive rotation rate
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and the turn ratio will be negative which will the turn the robot left!
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```blocks
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let error = 0
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brick.showPorts()
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sensors.gyro2.calibrate()
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while (true) {
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error = sensors.gyro2.rate() * -1
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motors.largeBC.steer(error, 50)
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}
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```
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## Step 4 Run it!
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Download to your brick and test out if the robot is going straight.
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This kind of technique is called a proportional controller;
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it corrects the inputs (motor speed) with a feedback proportional to the output (rotation rate).
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