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#Lego mindstorms gyro boy ev3 python software
#Lego mindstorms gyro boy ev3 python code
#Lego mindstorms gyro boy ev3 python trial

For example, if you tell you robot to drive straight, and it turns slightly to the left, gyro.angle() will return a negative value corresponding to the number of degrees your robot is off course. If the robot turns slightly off course, gyro.angle will return a positive or negative number depending on the direction and number of degrees your robot is off course. If your robot is driving straight, gyro.angle() should return zero degrees if there is no tracking error on the robot. However, because of brick processing lag (Lego EV3 bricks are slow to run programs and process data from sensors), we also need to compensate for this by multiplying that correction by the scaling factor (Kp). Then for the robot course correction, we want the robot to turn in the opposite direction of the error, by at least the amount of the error. In this particular case, to get our robot to drive straight, we are using the gyro sensor to measure (in degrees) the amount the robot is off course (the error).

#Lego mindstorms gyro boy ev3 python trial

The scaling factor Kp is first determined using a bit of educated guessing and then is fine tuned by trial and error. The correction in this case can applied as an increase/decrease in the power level of the motors, or as the angle parameter in the Pybricks robot.drive(speed, angle) function. The result is a correction for the system. Then we multiply that error by a scaling factor called Kp. Proportional Controller - correct current errors Introįor a P (proportional) controller, we use a sensor to measure something that you are trying to control and then convert that measurement to an error.

the derivative (D) term that tries to tries to correct errors that hasn’t even occurred yet ( future errors).

the integral (I) term that tries to correct past errors, and.

the proportional (P) term tries to correct the current error,.

At its core, each element of a PID controller deals with a specific type of tracking error: A complete mathematical description of a PID Controller is fairly complex, but the basics of the approach can be to control Lego EV3 robots. The term ‘PID’ is an acronym for Proportional Integral Derivative. PID OverviewĪ PID Controller is a common technique used to control a robot. This article will use the Lego Gyro because it might be a conceptually easier for new FLL participants to understand. Most articles on Lego EV3 PID algorithms use a line follower example (using the Lego Colour sensor) to describe it. The faster-turning wheel should rotate through two rotations (720°) so the wheel rotating half as fast will rotate 360° in the same time.Driving straight using a gyro and PID algorithm Speed 50% for the faster (left) wheel, so the right wheel will need a speed of 25%.

#Lego mindstorms gyro boy ev3 python software

A 'steering' setting of 25 in the Move Steering block of the standard Lego software means that the right wheel will turn half as fast as the left wheel.

Medium turn right (equivalent to a 'steering' setting of 50 in the Move Steering block of the standard Lego software, with only one wheel rotating) with a wheel rotation of 1380° (speed 40%, brake on).

Note that a hard turn on the spot like this corresponds to a 'steering' setting of +/-100 in the Move Steering block of the standard Lego software. The left wheel will turn forwards through that angle and the right wheel will turn backwards through the same angle so that the robot itself turns on the spot.

Make the robot do a hard turn right (on the spot) with 685° wheel rotation (speed 40%, brake on).

#Lego mindstorms gyro boy ev3 python code

This code was explained on the motors page. The script above includes lines (highlighted) which detect when both motors have completed their movements.