Video tutorials

DIfferent wheels and tires will result in different behaviour of the robot. That is actually pretty common sense. The real question is what is the influence. Would the robot make smaller deviations if it has smaller wheels or it will make larger deviations? The tires could also be quite dirty or brand new. Or the wheels could be attached in different ways. 

Should the robot be with a Front Wheel Drive or a Rear Wheel Drive to make it more precise? The answer is - front wheel will probably give you better results, but the wheel drive is not the most important thing. In this video tutorial on the LEGO Mindstorms Robots, we will do a few experiments to discuss the influence of the wheel drive on the precision of the movement.  

The LEGO Mindstorms EV3 set comes with two LARGE motors. But even though these motors look almost the same they are not quite the same. There are always some differences in their behaviour. If you have more than two motors, because you bought them or you won them somewhere at a competition, it is worth doing an experiment to find which pair of motors works best. 

You could use the LEGO Steel Balls as a third wheel on the robot. It is a caster wheel. But this is steel and as we know from basic existence on this planet, where there is steel there is also rust. The steel ball could get quite rusty and this could have an influence on the behaviour of the robot

The balance of the construction of the robot has a great influence on how it will move. This is especially true if you would like to move in a straight line. If the robot is slightly heavier on the right it will move to the right. Here we have two robots - a Five Minute robot and a Box Robot and we will discuss the differences in the constructions and why the box robot is much better than the Five Minute even though it is using the same parts. 

The robot can move with different speed by applying different power to the motors. It will most of the time make smaller deviations when it moves slower. But you can't just move with a power of 10 all the time. This is a way too slow especially for competitions like FIRST LEGO League or World Robot Olympiad. In this video tutorial I would like to discuss the balance between motor power and robot movement error, how does the battery influence the power of the robot and to conduct an EV3-G experiment that will record the values of the Gyro Sensor along with the current power. 

This is where the confusion really comes. We are keeping the robot orientation straight while the robot moves, but at the end the, robot is not at the fiinal location that we would like it to be. The robot is still about 2-3 centimeters away after moving for about a meter.

As the name indicates, ultrasonic sensors measure distance by using ultrasonic waves. One of the “eyes” on the sensor head is the transmitter and emits an ultrasonic wave and the other “eye” is the receiver which receives the wave reflected back from the target. 

The first part of making the robot move straight is to keep it oriented straight. While it moves it could make an error and turn slightly to the right and then the program should turn in back to the left to make its orientation straight. In this video tutorial, we would discuss how to implement a program to keep the robot orientation straight even when we are pushing or pulling it to either side and in the same time it has different wheels.

The integral part "remembers" the errors that the robot has made in the past and we can compensate for those errors. This will make the robot return back to the line that we would like to keep it aligned. 

We should multiply the error by a certain number and then add it to the steering of the LEGO Mindstorms Steering block. In this way, by changing the coefficient we change how much/fast should the proportional part influence the steering of the robot. 

In this video tutorial, we would do a few experiments with the coefficients for the Integral compensation. There are actually two coefficients - "c" and "b"

We keep the robot orientation straight while moving, but when we stop the robot could be in a different orientation. This applies for both using the Mindstorms Gyro Sensor when moving straight or the Mindstorms Color sensor when following a line. In this video tutorial, we will do a few examples of when an how this could happen.

Let's record the values of the Gyro Sensor while the robot is moving and is trying to keep its orientation straight. This is an interesting experiment and we will have to use file access to write the values to a file. 

How can you accumulate some energy in an LEGO Mindstorms EV3 construction an use this energy at a later moment? How does a Flywheel work, why is it important and what is the purpose? What is energy, inertial moment and angular velocity. These are just some of the questions we would answer in this series on Physics and LEGO Mindstorms.

This video tutorial is about understanding the "magic". In this video tutorial, we would conduct an experiment and will look at how exactly does the integral part of the PID algorithm compensate for the error that the LEGO Mindstorms EV3 robot makes. 

Introducing three main concepts - Energy, Inertia Moment and Angular Velocity. We describe what is the moment of Inertia, how do we calculate it and how do we measure it?

In the video we reach a conclusion. We have energy accumulated and to keep the system turning we need about 1J of energy each second to keep it turning.

The energy accumulated in the construction is about 2-3 Joules. In this first video we ask the question "How can we keep the energy in the system". How many Joules of energy should we input from the motor in order to keep the energy in the system.

We got the speed of rotations of the motor in Radians per second. Let's calculate the value for the speed of the whole system. We calculate that the wheels are rotating with 375 radians per second. Which is impressive and quite fast for this system. From this speed, knowing the inertia mass we can calculate how much energy is the system accumulating. 

We dispay the speed of rotation of the wheels on the brick screen. We use the math blocks to do a proper calculations from rotation to radians per second. Knowing the speed, the radiuses and the mass of the wheels we find energy in Joules accumulated in the construction.

One of the interesting things in this sequence of videos is the program. The program detects when the system has reached the maximum speed and then stops the motor from rotating. We detect this with the EV3-G software

There are two types of inertia to familiarize yourself with. One you know intuitively, while the other is more obscure. Both must be considered when building your own robots, especially in future competitions.