Gyro Sensor

QikEasy Adapter enables your existing EV3 Gyro Sensor to appear as a Spike Prime Distance Sensor to the Spike Prime hub.  The main axis angle and rotation rate are encoded into the returned distance data.  This data value ranges from 0 to 200.  We managed by encode both angle and rate into a single data value by alternating between them during data streaming.   When data value is between 0 and 99, it represents Rate.  When data value is between 100 and 200, it represents angle.  Below are the formulas for decoding these data readings:

When SensorValue < 100:

Angle = SensorValue * 3.6      (calculated result would be in the range of 0 to 360)

When SensorValue >= 100:

Rate = SensorValue – 150      (calculated result would be in the range of -50 to 50)

The following example program shows how one would retrieve these readings in Word Blocks.  When this program is run, it will set the variables GyroAngle (ranged from 0 to 360) and GyroRate (ranged from -50 to 50) to the angular position and rotation rate of the gyro in real time.

Notes:

• The EV3 Gyro sensor recalibrates itself and reset its zero position when it powers up.  When using QikEasy Adapter, there is a special feature that allows the user to programmatically force EV3 Gyro to “reset” and recalibrate.   To perform this forced “reset”, you only need to turn on the emulated sensor’s  light control (even though the physical gyro doesn’t have any light).
• During the “reset” process, the detected Spike Prime Distance Sensor will disappear on the App for 5 to 10 seconds, and then it will reappear.   The “wait until” control block is used to detect when the “reset” is finished.
• IMPORTANT: Before the “reset” begins, you should keep the gyro stationary on a flat surface to allow the gyro to properly calibrate itself.  You should only touch and move it after the Applause ring tone is played.
• The following Word Block program provides an example of how to perform Gyro reset at the starting of the program.  It also demonstrates how to decode the data read from the Gyro.
  • The GetAngle&Rate custom block is defined for converting Distance Sensor’s distance data into Angle & Rate, and save them into the variables GyroAngle (ranged from 0 to 360) and GyroRate (ranged from -50 to 50).
  • Its main program has a Forever loop that continuously calls the GetAngle&Rate custom block to read from the sensor and to decode the angle and rate values into the global variables GyroAngle and GyroRate.  To use this values, one may access these global variables in another event loop.

EV3 Tilt Angle and Tilt Rate can only be accessed through Python, and they are only available in newer models of EV3 Gyro sensor.  If you try the following program and it doesn’t work, it most likely means you have an older version of the sensor that doesn’t support this feature.

Tilt Angle data is returned in Mode 4 of the emulated Distance Sensor.  The data range is from 0 to 360, representing 0 to 360 degrees.  No conversion is needed.

Below is an example program that demonstrates how to use Python to read the Tilt Angle data.

# On Spike Prime, the first 2 lines should be:
# from spike import PrimeHub
# myHub = PrimeHub()
from mindstorms import MSHub
myHub = MSHub()

# See https://lego.github.io/MINDSTORMS-Robot-Inventor-hub-API/class_device.html for documentation
import hub
from utime import sleep_ms
gyro = hub.port.A.device

# Initialize global variables
GyroTiltAngle = 0        # expected range 0 to 360

print("Starting Gyro calibration. A tone will be played once calibration is complete.")

# Force reset the gyro by turning on top left LED segment @ Mode 5
gyro.mode(5, bytes([1, 0, 0 , 0]))

# Wait till the sensor finish rebooting. Must keep Gyro stationary during this time.
for x in range(100):
    gyro.mode(0)
    # if gyro is not able to properly get data -> SLEEP and keep trying
    if gyro.get(0) == []:
        sleep_ms(500)

# The Gyro is now ready for use
myHub.speaker.beep(70, 1)

# Loop to retrieve Tilt Angle value from sensor
gyro.mode(4)
while (1):
    sleep_ms(300)
    # Get Tilt Angle data from gyro @ Mode 4
    GyroTiltAngle = gyro.get(0)[0]
    # Print to console
    print("Tilt Angle:", GyroTiltAngle)