Gyroscope

Gyro sensors are a lot like compasses — they sense rotational motion and detect orientation to figure out what direction something is facing. They’re used in everything from space shuttles to cell phones, and your CoDrone! Gyroscopes are necessary to stabilize your drone while you are flying, since many factors could cause your drone to drih off course. A gyroscope can measure how far and in which direction your drone is tilting or rotating. Using some math and algorithms, a drone can try and correct any unwanted displacements to remain stable. Displacement is a movement from one position to another position.

There are three orientations that we are concerned with when we are flying a drone for stability: roll, pitch, and yaw. The gyro sensor in your CoDrone will return values from 0 to 359 degrees that correspond to the degrees the drone turned in each direction. At 360 degrees, when a full rotation is completed, it starts back over at 0.

Did you notice that throttle is not included? When a drone flies straight up or down, the change in position is not an angular (turning) displacement but a vertical displacement, which is measured by the height sensor.

Like a lot of things, this can be better explained through observation. You will learn how to get the degrees that the drone tilted left or right (roll), tilted forward or backward (pitch), and turned left or right (yaw) from its original position when you turned it on.

Since there are 3 directions, you need a special kind of variable that can hold three values at the same time! This is done for you when you call the method.

angles = drone.get_gyro_angles()

The variable angles now holds three values representing degrees. To access them, we use notation similar to accessing methods from a class:

print(angles.ROLL, angles.PITCH, angles.YAW)

Finally, since we want live updates of the drone’s current position, you should be requesting the angles in a loop. Which kind of loop do you think is best for this test?

Run the code! Your drone will not fly so try picking it up and moving it in different directions to see the numbers change. You will notice that sometimes the numbers are positive and sometimes they are negative. Remember that leh roll, backward pitch, or leh yaw will result in negative degrees:

import CoDrone
import time
drone = CoDrone.CoDrone()
drone.pair(drone.Nearest)
while True:
    angles = drone.get_gyro_angles()
    print(angles.ROLL, angles.PITCH, angles.YAW)

Since you are using a while loop that goes on forever, the only way to exit is to manually terminate the program. Using timers, write a program that will only measure the data for 10 seconds. Start counting AFTER the drone has paired.

See below for an example if you get stuck!

import CoDrone
import time
drone = CoDrone.CoDrone()
drone.pair()
init_time = time.process_time()
timer = init_time
while timer < 10:
    angles = drone.get_gyro_angles()
    print(angles.ROLL, angles.PITCH, angles.YAW)
    timer = time.process_time() - init_time
print("finished!")

The CoDrone library has a function so that you can program your drone to turn a certain number of degrees to the left or right and then stop. This function is useful for more precise turns, or for making shapes! It uses information from the gyro sensor to make more accurate turns. The turn_degree() function takes in two parameters: the direction and the angle degree. Here is how you would make a 90 degree turn to the right:

drone.turn degree(Direction.RIGHT, Degree.ANGLE 90)

The following degree values are defined in the library, meaning you can use only these degrees with this function: 0, 30, 45, 60, 90, 120, 135, 150, 180, 210, 225, 240, 270, 300, 315, and 330.

With your new knowledge, let’s make the drone fly away from you, then turn around and come straight back. You can use drone.set_yaw()for this assignment, but practice using the gyroscope functions. Make sure you include your library, create a drone object, and pair:

drone.takeoff()
drone.set_pitch(50)
drone.move(2)
drone.turn_degree(Direction.LEFT, Degree.ANGLE_180)
drone.set_pitch(50)
drone.move(2)
drone.land()

Program your drone to fly in a square using the turn_degree function. Notice that each side of the square uses the same repeated code a finite, or limited, number of times. For an extra challenge, use a for loop.

Example without a for loop:

import CoDrone
from CoDrone import Direction, Degree

drone = CoDrone.CoDrone()
drone.pair(drone.Nearest)
drone.takeoff()

drone.set_pitch(20)
drone.move(3)
drone.turn_degree(Direction.RIGHT, Degree.ANGLE_90)
drone.set_pitch(20)
drone.move(3) 
drone.turn_degree(Direction.RIGHT, Degree.ANGLE_90)
drone.set_pitch(20)
drone.move(3)
drone.turn_degree(Direction.RIGHT, Degree.ANGLE_90)
drone.set_pitch(20)
drone.move(3)
drone.turn_degree(Direction.RIGHT, Degree.ANGLE_90)
drone.land()

Example with a for loop:

import CoDrone
from CoDrone import Direction, Degree

drone = CoDrone.CoDrone()
drone.pair(drone.Nearest)
drone.takeoff()

for x in range(0, 4, 1):
    drone.set_pitch(20)
    drone.move(3)
    drone.turn_degree(Direction.RIGHT, Degree.ANGLE_90)
    print(x)
drone.land()

Try to fly your drone in the shape of an equilateral triangle or hexagon using turn_degree(). Use a for loop!

Triangle example:

import CoDrone
from CoDrone import Direction, Degree

drone = CoDrone.CoDrone()
drone.pair(drone.Nearest)
drone.takeoff()

for x in range(0, 3, 1):
    drone.set_pitch(20)
    drone.move(3)
    drone.turn_degree(Direction.RIGHT, Degree.ANGLE_120)
    print(x)

drone.land()

Hexagon example:

import CoDrone
from CoDrone import Direction, Degree

drone = CoDrone.CoDrone()
drone.pair(drone.Nearest)
drone.takeoff()

for x in range(0, 6, 1):
    drone.set_pitch(20)
    drone.move(3)
    drone.turn_degree(Direction.RIGHT, Degree.ANGLE_60)
    print(x)
drone.land()

Define your own “turn_degree” functions. For example, using set_yaw()and move(), define a function turn_90that will turn the right amount of seconds to make a 90-degree turn. Then use your custom functions and compare them to the CoDrone library functions! Challenge your friends to make designs.