review comments

Author: 8BitJosh

tutorials/basic_motor_control.md

@@ -6,27 +6,22 @@ title: Basic Motor Control
 # Basic Motor Control
 
 The aim of this tutorial is to get a motor turning with your kit.
-To complete this tutorial, you'll need the following:
 
-* The [Power Board](/docs/kit/power_board)
-* A battery (charged, of course)
-* A [Motor Board](/docs/kit/motor_board)
-* 2 large (7.5mm) green _CamCon_ connectors to connect power between the Power Board and Motor Board
-* 2 lengths of thicker gauge wire for powering the Motor Board from the Power Board (one should be black)
+To complete this tutorial, you'll need the following items from the kit:
+
+* A charged battery
+* An assembled kit according to the [assembly guide]({{ site.baseurl }}/tutorials/assembly)
+* A small (5mm) green CamCon connector to plug the motor into the Motor Board
+* 2 lengths of wire for your motor
+* A small slotted/flat blade screwdriver (for the CamCon screws)
+
+And additionally you will need to provide the following:
 * A motor (see specification below)
-* A small (5mm) green _CamCon_ connector to plug the motor into the Motor Board
-* 2 lengths of a suitable gauge of wire for your motor
-* 2 Micro USB cables
-* A USB hub
-* A USB A to B cable (used to connect to the USB hub to the brain)
-* The memory stick
 * A soldering Iron
 * Some solder wire
 * Wire strippers
-* A small slotted/flat blade screwdriver (for the _CamCon_ screws)
 
-You should be familiar with the setup for most of the above now, so it's just the motor-related parts that need explaining.
-If you need help assembling the rest of the kit please look at the [guide]({{ site.baseurl }}/tutorials/assembly) on assembling the kit
+Before continuing with this guide, if you have yet to setup your kit, first follow the instructions on the [kit assembly]({{ site.baseurl }}/tutorials/assembly) page.
 
 
 ## Motor Specification
@@ -35,7 +30,7 @@ There is a certain specification the motor(s) you use must meet.
 The criteria are as follows:
 
 * 12V motor
-* A stall current of less than 10A (this is the current limit for the [Motor Boards](/docs/kit/motor_board))
+* A stall current of less than 10A (this is the maximum current a motor will draw when it can't turn)
 
 <div class="info">
 When designing your robot you should bear in mind that while each Motor Board can deliver 10A on each output, all the power needs to go through the Power Board, which is limited to a combined total of 30A.
@@ -45,32 +40,19 @@ This means that across all the outputs for all the motors (as well as the rest o
 
 ## Connecting a Motor
 
-To plug the motor into the kit, you'll need to solder an appropriate gauge of wire to the terminals on the motor, and connect the other ends to the _CamCon_ connector.
+To plug the motor into the kit, you'll need to solder two wires to the terminals on the motor, and connect the other ends to the CamCon connector.
+
 Like so:
 
 ![Motor connected to CamCon]({{ site.baseurl }}/images/content/kit/motor_and_camcon.png)
 
 <div class="info">
 You may want to insulate the motor's terminals with some insulation tape (or heat shrink tubing if you've got it) like in the image above.
+This will stop the wires accidentally touching and shorting out the power.
 </div>
 
-Now you need to connect the motor to one of your Motor Boards.
-You'll need to connect the following:
-
-* Your motor plugged into the motor 0 socket on the Motor Board
-* The micro USB cable from the Motor Board to the USB hub
-* The USB A to B cable from the USB hub to the Brain Board
-
-This is almost ready, but the Motor Board also needs the power that it will be delivering to the motor.
-This is done by connecting together the two larger _CamCon_ connectors, using the other two lengths of wire.
-Be sure that the cable connects the positive output ("+") of the Power Board to the positive power input of the Motor Board, and likewise for the ground ("-") output &mdash;
-see the [Power Board](/docs/kit/power_board) and [Motor Board](/docs/kit/motor_board) documentation to see which is which.
-
-<div class="info">
-You must always use black for ground (0V) connections (and only for these), so that it's clear which these are.
-</div>
-
-You can now connect this into the Power Board on one end, and the Motor Board power connection on the other.
+This motor should then be connected to motor 0 socket on the Motor Board.
+To see which output is number 0, look at the [Motor Board]({{ site.baseurl }}/kit/motor_board) page.
 
 
 ## Some Code
@@ -80,101 +62,108 @@ You will want to ensure the motor is secured when testing.
 A motor suddenly starting up during testing and moving across the table could cause a potential hazard.
 </div>
 
-The example program we'll write will do a number of things with the motor:
-forwards and backwards, and different power settings, for example.
-Let's begin.
-
-To start off with, we'll just make a motor move forwards, then backwards, and then repeat.
+The following sections will lead you through running some code on your robot which will cause your motor to spin.
+By combining these examples you should be able to achieve movement with your robot.
 
 
 ### Forwards & Backwards
 
-Doing this is actually very easy; the only thing you need to realise is that a positive number is forwards and a negative number is backwards.
+To start off with, we'll make a motor move forwards, then backwards, and then repeat.
+
+The way we control motors is by providing a number between `-1` and `1` to describe its power and direction.
 
 <div class="info">
 The actual direction of travel of a motor, when mounted on a robot, will depend on its orientation and the way in which the wires are connected to the Motor Board.
 If the motor appears to be going in the wrong direction, just swap the motor's positive and negative wires over.
 </div>
 
-Here's the code:
+As a first example:
 
 ~~~~~ python
 from sr.robot3 import *
-import time
 
 robot = Robot()
 
 while True:
     robot.motor_board.motors[0].power = 0.5
-    time.sleep(3.0)
+    robot.sleep(3.0)
 
     robot.motor_board.motors[0].power = 0
-    time.sleep(5)
+    robot.sleep(5)
 
     robot.motor_board.motors[0].power = -0.5
-    time.sleep(3.0)
+    robot.sleep(3.0)
 
     robot.motor_board.motors[0].power = 0
-    time.sleep(5)
+    robot.sleep(5)
 ~~~~~
 
-You're familiar with the first few lines; in fact, the only lines you may not be familiar with are the `robot.motor_board...` lines.
-For a comprehensive reference to the `motor` object, see the `sr.robot3` module's [Motors]({{ site.baseurl }}/programming/motors) page.
-But, to summarise:
-
-<div class="info" markdown="1">
-`robot.motor_board.motors[0].power = x` will set the power of the motor connected to output 0 on the first [Motor Board]({{ site.baseurl }}/kit/motor_board) to `x`, where `x` is a value between `-1` and `1`.
-</div>
+The first few lines in this example are repeated throughout the docs, they import our `sr.robot3` library and then create our `robot`.
 
-So, `robot.motor_board.motors[0].power = 0.5` sets the target power of the motor connected to output 0 to 50% forwards.
+The line:
+~~~~~ python
+robot.motor_board.motors[0].power = 0.5
+~~~~~
+sets the target power of the motor connected to output 0 to 50% forwards.
 
-As you would expect, then, `robot.motor_board.motors[0].power = -0.5` will put the this motor into reverse at 50% power.
+Equally, the line:
+~~~~~ python
+robot.motor_board.motors[0].power = -0.5
+~~~~~
+will put the this motor into reverse at 50% power.
 
-`robot.motor_board.motors[0].power = 0` will output no power to the motor and stop it.
+Finally setting the power to 0 will output no power and stop the motor.
 
-So, if you put the above code on your robot, you should be able to see a motor spin forwards, stop, spin backwards, stop, and then repeat...
+So, if you put the above code on your robot, you should be able to see a motor spin forwards, stop, spin backwards, stop, and then repeat.
 
 <div class="info" markdown="1">
-If you find that the motor doesn't turn when you run the above code, check that you've got all the cables connected to the right places, in particular note that the Motor Board has _two_ outputs.
+If you find that the motor doesn't turn when you run the above code, check that you've got all the cables connected to the right places, in particular note that the Motor Board has two outputs.
 </div>
 
+For a comprehensive reference to the `motor` object, see the `sr.robot3` module's [Motors]({{ site.baseurl }}/programming/motors) page.
+
 
 ### Changing the Speed
 
-Now we're going to modify the program to vary the ramp (go from 0% to 100% slowly) the speed of the motor.
-Our aim is to do the forwards and backwards bit (as above), but, instead of setting the power to a fixed value we will ramp the power from 10% up to 50%, then back down to 10%, and then back to 0 (all in steps of 10%).
+Now we're going to modify the program to ramp (go from 0% to 100% slowly) the speed of the motor.
+Our aim is to do the forwards and backwards bit (as above), but, instead of setting the power to a fixed value we will gradually increase the power from 0% up to 50%, then back down to 0%.
 
 Here's the code:
 
 ~~~~~ python
 from sr.robot3 import *
-import time
 
 robot = Robot()
 
 while True:
 
-    # ramp from 10% to 50%
-    for pwr in range(20, 60, 10):
+    # ramp from 0% to 50%
+    for pwr in range(0, 60, 10):
         robot.motor_board.motors[0].power = pwr / 100  # Convert from percentage
-        time.sleep(0.1)
+        robot.sleep(0.1)
 
-    # ramp from 50% to 10%
-    for pwr in range(50, 0, -10):
+    # Drive at 50% power for a second
+    robot.sleep(1)
+
+    # ramp from 50% to 0%
+    for pwr in range(50, -10, -10):
         robot.motor_board.motors[0].power = pwr / 100  # Convert from percentage
-        time.sleep(0.1)
+        robot.sleep(0.1)
+
+    # Stop for a second
+    robot.sleep(1)
 
-    # set power to 0 for a second
-    robot.motor_board.motors[0].power = 0
-    time.sleep(1)
 ~~~~~
 
-You have seen some of those bits of code before but the thing that may be new is the `for` loop.
+You have seen most of these lines of code in the previous example but we have now added a `for` loop.
+
+The [`for`](https://docs.python.org/tutorial/controlflow.html#for-statements) loop accepts anything that has multiple items that Python can step through to get multiple values.
+One example of this is a `list`, which when printed appears in square brackets like so: `[1, 2, 3]`.
+This is called iteration.
 
-The [`for`](https://docs.python.org/tutorial/controlflow.html#for-statements) loop accepts anything that Python can iterate over to get multiple values, such as a `list` (a `list`, when `print`ed, appears in square brackets like so: `[1, 2, 3]`).
+For a comprehensive introduction to to `list`s, have a look at [this tutorial](https://www.w3schools.com/python/python_lists.asp).
 
-For a comprehensive introduction to to `list`s, have a look at [this WikiBooks article](https://en.wikibooks.org/wiki/Python_Programming/Lists).
-The `for` loop will iterate over the `list` (i.e. take each element in turn) and make it available in the loop's body as the variable after the the `for` keyword.
+The `for` loop will iterate over the `list`, taking each element in turn and making it available in the loop.
 Here's an example:
 
 ~~~~~ python
@@ -190,39 +179,48 @@ The above would output:
 3
 ~~~~~
 
-Then there's the [`range()`](https://docs.python.org/3/library/stdtypes.html#typesseq-range) object.
+Then there's the [`range()`](https://docs.python.org/3/library/stdtypes.html#typesseq-range) function.
 
-`range()` objects represent a sequence of numbers.
-They can be constructed with one, two or three arguments to describe what the sequence of numbers should be.
+The `range()` function returns a sequence of numbers.
+The function has three forms that take one, two or three arguments to describe what the sequence of numbers should be.
 
 The general format is:
 ~~~~~ python
 range(start, stop, step)
 ~~~~~
-If only one argument is provided then two of the arguments have default values, the sequence starts at `0` and the step is set to `1`.
-The provided argument only defines the stop point.
+
+start
+:   The value to start your sequence at
+
+stop
+:   The value which stops the sequence if the next step passes or equals this
+
+step
+:   The value which is added on each step of the sequence
+
+If only one argument is provided, this defines the stop point. The other two arguments are set to default values, which is a sequence starting at `0` with a step size of `1`.
 
 For example:
 ~~~~~ python
 range(5)  # [0, 1, 2, 3, 4]
 ~~~~~
 
+<div class="info">
+Note that the stop value is not included in the sequence.
+</div>
+
 If two arguments are provided, then these represent the start and stop with the step being set to `1`.
 
 For example:
 ~~~~~ python
 range(2, 6)  # [2, 3, 4, 5]
 ~~~~~
 
-Taking `range(10, 60, 10)`, as an example of all three arguments:
-
-* Start at 10
-* Go up in steps of 10
-* For all values less than 60
+Taking `range(0, 60, 10)`, as an example of all three arguments:
+Starts at 0, going up in steps of 10, for all values less than 60.
 
-Gives:
 ~~~~~ python
-range(10, 60, 10) # [10, 20, 30, 40, 50]
+range(0, 60, 10) # [0, 10, 20, 30, 40, 50]
 ~~~~~
 
 Putting all of that together; in the motor control example we iterate over that sequence of numbers setting the motor power to each of those values in turn, with a delay of 100ms between.
@@ -232,8 +230,8 @@ You might want to run the code on your kit to see if it does what you expect it
 
 ## Next Steps
 
-From here, you should be able to make your robot move about in a controlled manner.
+From here, you should be able to make your robot move about.
 See if you can make your robot drive forwards to a given point, stop, turn around and then return to its starting point.
 
 You might also like to see if you can make the code example above more concise by creating functions for different types of movement, such as moving and turning.
-[This](https://www.tutorialspoint.com/python3/python_functions.htm) tutorial is good if you want to learn about how functions work.
+[This tutorial](https://www.tutorialspoint.com/python3/python_functions.htm) is good if you want to learn about how functions work.