1.2: Remote Control and Conditionals

Now that you understand drive commands, you can write your own remote control! First, import the Zumi library and create the object before you begin.

To make a remote control, you need a way to register your input and translate it to motor commands. Python includes a function input() that reads the keyboard input and saves it as a variable. To see how this works, run the following code, type in your name, and hit enter. Any input that you entered will be saved in my_name.

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my_name = input("What is your name? ")
print("Hello,",my_name)

Now that you have all the tools you need, put it together in pseudocode, which is a program that’s written in plain language that a human can understand. Pseudocode is a good way to figure out how your program will work before translating it to Python. One small problem: input() can’t read arrow key controls, so your remote control code will be checking for letter inputs “w”, “a”, “s”, and “d”. Look at the pseudocode below to see what we mean.

get input from user
if input is “w”, go forward
if input is “s”, reverse
if input is “a”, turn left
if input is “d”, turn right

• If my alarm goes off, then I will wake up. Else, I will stay asleep.
• If I am hungry, I will eat something.
• If it’s sunny out, I will wear sunscreen.
• If my room is clean, I will get my allowance. Else, I will make no money.

If statements are written like this in Python:

if insert condition here:
Insert statements here
else:
Insert statements here

if alarm goes off:
I will wake up
else:
Stay asleep

The condition is what the computer checks to know if it is true or false.

• If the condition is true, the computer will execute, or carry out, the statements underneath it.
• If the condition is false, the computer will NOT execute the statements underneath it.
• “Else” has no condition! This is because “else” is the last option when using if-else statements. When a computer reaches the “else” option after checking all the other conditions, then the else condition is automatically true and will run its statements.
• One way to use “else” would be when something needs to happen when a condition is false. When the “if” condition is false and nothing needs to happen, don’t use an “else”.

Indentation is very important in the Python programming language. The indentations indicate which statements belong to a particular section in the code.

You may have noticed that the statements below the if and else statements are indented 4 spaces or one tab space. Even if the indent is off by one space, you will get an error! Try to stick to either tabs or spaces, and don’t combine the two.

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X= 10
Y = 100
Z = 200

if X != Y:
    print("X is not equal to Y")

if Z > Y:
    print("Z is greater than Y")

Now you have all the tools to write out the rest of the missing conditionals. Use if statements, comparators, and print statements to write code for the “s”, “a”, and “d” keys.

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#TODO Finish the rest of the missing if statements

while True:
    direction = input("Please enter a command: ")

    if direction == "w":
        print("Go forward")

Did you notice the code is running forever? Because this is a remote control code, you want to be able to continuously tell Zumi what to do. To do this, you need to use a while loop that runs forever. Currently, the only way to stop the code is by clicking the “stop” icon in the toolbar. To safely quit from this loop, it is better to include an if statement that checks for “q” input to break from the loop.

if direction =="q":
    break

Add this code to your code above and test that you can exit your code without errors.

Now that you have the logic down, add the drive commands with the correct command. Remember you can change the parameters for these controls or choose different keys to customize your remote control!

Lombard Street

Lombard Street is one of the most crooked streets in San Francisco. What would Zumi need to do to be able to drive down it? Construct your own model of Lombard Street with whatever materials you choose to use. Walls should be used around the street, and Lombard Street itself is at a 27% slope. Next, measure the turn degree of each hairpin turn to emulate on the model. After streets are finished, test it out with your remote code, noting how many degrees you had to turn their Zumi in order to navigate it safely.