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EV3 Phi. Acceleration. Simple explanation and examples Pro Preview

We will demonstrate with a robot what the acceleration is and the effects of high and low acceleration.

  • #411
  • 16 Apr 2017
  • 4:34

Definition of acceleration

Acceleration is the change of speed over time. The faster you try to increase the speed of an object, the bigger the acceleration.
If you speed up slowly, the acceleration is low.
 

Explanation of acceleration

A race-car usually starts a race with great acceleration.
A full cargo truck has low acceleration.

The greater the acceleration, the more obvious are the effects of the inertia.
Today we programmed our robots to have low acceleration so that the cup stays on the brick.


Examples of high and low accelerations

Changing the motors in an instant, from 0% to 50% or from 50% to 100% leads to the cup falling.
It falls because of the inertia of the cup. And the large change of speed leads to high acceleration.


If we change the speed slowly from 0 to 100, over the span of a few seconds, the acceleration will be lower and the inertia effects are not visible.
Such program is attached below this video.

 

English

First, the cup is falling because of intertia and second because of the acceleration. Let's discuss the acceleration of the robot and what is generally acceleration.

Acceleration is the change of speed over time. The faster you try to increase the speed of an object the bigger the acceleration of this object. If you speed up slowly like this, the acceleration is low. If you speed up very fast, the acceleration is large. A race car usually starts race with a great acceleration. That's for example. A full cargo truck on the other hand has very low acceleration. The greater the acceleration the more obvious are the effects of the inertia. So, it's not like we can separate acceleration from inertia but the largest the acceleration the more obvious the inertia is. Today we programmed our robots for different accelerations. For low and for high. And you saw how the cup was falling from the display of the brick. If we have a program where we just change the power of the motors on different steps, the whole robot will behave in the following way.

So, we have three different blocks changing the speed of the robot. But the robot can accelerate in a different way. Without the cup falling. Previously you saw a program where we reach a speed of 100 where the robot accelerates very fast because we just set the block to 100 but now let's accelerate to 100 slowly. Place the robot like this here. Place the cup and start the program.

It's again a robot that accelerates from 0% to 100% and then back from 100 to 0 but this time the cup does not fall. Why? Because the acceleration is not that big. Again.

This program, I'll attach it below in the video, is kind of complex. And we haven't discussed loops and variables and mathematical operations with the software so it might be difficult for you to implement but you can at least take a look and in some of the next sections of the course we'll reach such programs. What you need to remember is the following. If we have a robot that's not moving so the power is 0 of the motors. And we set the power to 100 it will almost instantaneously move with a speed of 100% of the speed of the motor. So, the acceleration is very large. The speed will change in a number of milliseconds from 0 to 100. And this means that speed is changing very fast. If you have a robot where the speed is not changing very fast, then the acceleration is small. We have a program that works like this. The robot is again reaching 100 but it takes the robot like 2-3 seconds. And this makes the acceleration very small. If you have small acceleration, you have small inertia. If you have large acceleration, you have large inertia.

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