Programs

This is a program for communicating with LEGO Mindstorms Bluetooth between two bricks. The goal of the program is to control one of the bricks with another brick. The controller has two touch sensors that control the direction and two buttons on the brick itself that control the power. 

The control brick has two motors attached that are controlled. 

The goal of this program is to be used as an example of how to use the EV3-G Bluetooth. Yes, it requires two bricks, but most of the schools have two bricks and could test the program. 

Part of the Perfect STEM course, you should have a Raspberry Pi and an LED connected on GPIO 18 for this example to work.

The block has the following parameters from left to right:

• Degrees – the degrees the front wheels of the car will turn;
• Power – the power of the car;
• Limited/Unlimited – if the value is marked by a tick, the car will move for an unlimited period of time; if the value is marked by an x, the car will move for the specified number of rotations;
• Rotations – the number of rotations the car will make. 

The block has the following parameters from left to right:

• Maximum angle – the maximum steering angle of the front wheels. It is measured from position of straight wheels, to maximum left or right position.
• Relaxation coefficient – the relaxation coefficient regulates how smoothly the robot follows the line. The default value is 1. In general the range for the coefficient is between 0.5 till 2. If the difference between the value measured by the sensor on black and on white is great i.e. on black is 10 and on white is 80, then the coefficient should be smaller. If those values are closer, then the coefficient should be larger.
• Value on black – the value detected by the light sensor in reflected light mode when it is on the line.
• Value on white – the value detected by the light sensor in reflected light mode when it is outside the line.

Proportional implementation for keeping the LEGO Mindstorms robot straight. The program will take the value of the Mindstorms Gyro sensor and will apply this value to the steering block. This will make the robot steer in a direction that would put the robot in a straight position again.

The experiment contains a plot of the Curren Power of Motors B and C and the values of the Gyro Sensor when the robot is moving with a power of 100%. What you could see is that it is not actually moving with a power of 100% because the current power is about 75-80%.

Using the On for degrees (rotations) option of the the Medium Motor Move Block you program the motor to rotate for the given number of degrees. However, sometimes is useful to program the motor to go to a given position, instead. To achieve that you can use this block. It takes the start position of the motor as 0 degrees. Then when you run the block with given number of degrees it just rotates the motor to that position. For exaple if your current position is -20 degrees and you run the block with 30 degrees, the motor will rotate for 50 degrees. But if your current position is 10 degrees the same program will rotate the motor for 20 degrees.