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Quickstart-Robot

Let's make a robot drive forward:

Click on the cell below, and press `SHIFT` + `ENTER` to run

In [1]:
import lbot, time, IPython, sys, time
r = lbot.Robot()
r.drive(.1, .1) # range [-1.0 ... 1.0]

The robot should now be driving forward!

Stop the robot by running the cell below:


In [2]:
import lbot, time, IPython, sys, time
r = lbot.Robot()
r.drive(0.0,1.0)

Robot Commands

In the empty cell below, try making the robot spin to the right:

Click on the cell below ("Your code goes here!~") and start typing code!

In [3]:
r.drive(0,1)

Then, in the empty cell below, try to make the robot stop.


In [7]:
r.drive(0.0,0.0)

In [5]:
now, try making the robot drive backwards:


  File "<ipython-input-5-d86cda5b6f40>", line 1
    now, try making the robot drive backwards:
           ^
SyntaxError: invalid syntax

In [6]:
r.drive(-1.0,-1.0)

How to use this interface


In [ ]:

These code blocks are called cells.

The menu and toolbar:

Try clicking on Insert ==> Insert Cell Below.

Fancy Robot Commands

By making new cells below this one, try commanding the robot to drive in different radius circles.

Make a cell below here that spins the robot in ~5 inch diameter circles. (Don't spend too much time tuning)


In [8]:
r.drive(0.,0.0)

In [9]:
r.drive(0.0,0.0)

Make a cell below here that spins the robot in ~10 inch diameter circles. (Don't spend too much time tuning)


In [ ]:
# Your code goes here!~

In [ ]:
# Your code goes here!~

Robot Trajectories

Commands can be strung together to make a robot follow paths.

Compare the behavior of the two cells, and try to record an explaination:


In [10]:
r.drive(0,.2)
r.drive(0,0)
Double click on the cell below ("What happened: Why:") to record your thoughts. Press `SHIFT` + `ENTER` to render the text.

What happened:code overrides the previous code as it goes through

Why:Jesus


In [58]:
r.drive(.15,.15)
time.sleep(1.0)
r.drive(0,0)

What happened: sleep time made it follow that code for a second

Why: magic

Using Robot Trajectories with Sleep

Try making the robot turn 90 degrees using what you've learned (hint: time.sleep might help!)


In [12]:
r.drive(-0.25,0.25)
time.sleep(1.0)
r.drive(0.0,0.0)

Try making the robot drive 5 inches.


In [13]:
r.drive(0.1,0.1)
time.sleep(5)
r.drive(0.0,0.0)

Now, use these together to make the robot drive forwards, turn 180 degrees, drive back, and then turn back to the original angle.


In [26]:
r.drive(0.2,0.2)
time.sleep(1.0)
r.drive(0,0)
r.drive(0.5,-0.25)
time.sleep(1.0)
r.drive(0.0,0.0)
r.drive(-0.25,-0.25)
time.sleep(0.5)
r.drive(0.5,-0.25)
time.sleep(1.0)
r.drive(0.0,0.0)

Variables

We can pass variables to functions:


In [24]:
left = .1
right = .1

r.drive(left, right)

We can also assign variables:


In [29]:
left = .1
right = .1

print left
print right

left = left * 2

print left
print right

r.drive(left, right)
r.drive(0,0)


0.1
0.1
0.2
0.1

In [ ]:
r.drive(0,0)

In [30]:
for i in range(10):
    value = i*5
    print i
    print value


0
0
1
5
2
10
3
15
4
20
5
25
6
30
7
35
8
40
9
45

Using Robot Trajectories With loops

Now, using the for loop, make a robot drive in a square:


In [ ]:
# Your code goes here!~

Sensors

Run the cell below a couple times under various lighting conditions. For example, try:

  • facing up
  • on retro-reflective tape
  • on carpet
  • on the table surface
Press `CTRL` + `ENTER` to run a cell repeatedly while the cell is selected

In [ ]:
reflectances = r.read_sensors()
print reflectances
print len(reflectances)

The output of read_sensors is a tuple: a group of values.


In [ ]:
tups = (12, -1)
print tups
print len(tups)

In [ ]:
print tups[0]
print tups[1]

Use the examples above to print out the value of the third reflectance sensor.


In [ ]:
# Your code goes here!~

Use your knowlege of loops and tuples to print all the values of read_sensors.


In [ ]:
# Your code goes here!~

Streaming data


In [ ]:
for i in range(5):
    print i
    time.sleep(1)

In [ ]:
for i in range(5):
    IPython.display.clear_output()
    print i
    sys.stdout.flush()
    time.sleep(1)

Streaming the reflectance values

Try this:

(To stop it remember that there is a stop button in the toolbar ar the top)


In [ ]:
while True:
    values = r.read_sensors()
    IPython.display.clear_output()
    for val in values:
        print '='*int(30*val) + int(30*(1.-val))*' ' + str(val)
    sys.stdout.flush()
    time.sleep(.01)

Let's explore comparisons!


In [ ]:
5 < 4

In [ ]:
5 > 4

In [ ]:
5 >= 4

In [ ]:
4 >= 4

In [ ]:
4 <= 3

In [ ]:
5 == 4

In [ ]:
5 == 5.0

In [ ]:
5 != 4

In [ ]:
2 + 2 == 4

In [ ]:
2 >= 3

What do the following comparison operators do?

  1. ">":

  2. "<":

  3. ">=":

  4. "<=":

  5. "!=":

Playing with logicals

See if the value read in by the first sensor is greater than or equal to .3

Store the result in variable boo


In [ ]:
# Your code goes here!~

Conditionals

Play with the code below to understand conditionals.


In [ ]:
temp = 0

if temp > 8:
    print "hello"
else:
    if temp > 4:
        print "bye"
    else:
        print "Your number is too small"

Try printing a tuple of Booleans (True or False) that indicates if a sensor is on the tape line.


In [ ]:
# Your code goes here!~

Now let's use sensors while driving the robot

Try to do the following:

  • Set the robot to be perpendicular to some retro reflective tape a few inches away

  • Let the robot drive until the robot reaches the tape

  • Run the cell multiple times for varrying distance from the reflective tape.

Think about your tests under different lighting conditions and logical operators.


In [ ]:
# Your code goes here!~

In [ ]:
# Your code goes here!~

Now put the robot on reflective tape parallel to it and have it drive until it is off the reflective tape.


In [ ]:
# Your code goes here!~

Congratulations, you are on your way to follow a line!

Reading Joysticks

Run the cell below, and try graphing the values using examples above.

You will need to jiggle the joysticks to read values.


In [ ]:
r.read_joysticks()

Try making the robot drive using joysticks.


In [ ]:
# Your code goes here!~