Video tutorials

Building a rack is a very important skill during competitions. You should try to build one, learn how to use it and have it as a tool for you next robots. But for this particular BoxRobot, we will not continue with a rack.

Using the rack depends on the experience of the team. Based on this a different number of gear wheels and racks would be used.

Build a rack and try to lift the robot with this rack. 

The next step of lifting a robot to a mission model is to try to use a rack.

Think of an attachment that leaves the Gecko on the mission model. Don't use the robot attachment that we already have. Just the box robot and the gecko. Nothing should support the Gecko when it is hanged on the mission model. 

In this tutorial, we add another mission to our current program. This mission is - hanging the Gecko from the FIRST LEGO League Animal Allies. 

What should you as a teacher know when the students are trying to achieve a program and robot attachment that could reproduce their behaviour 9 out of 10 times. 

The task in this tutorial is to execute the program 10 times and to do it yourself. If you have your attachment then use it. If you have our attachment then use it. But execute the program 10 times and make sure that it works. 

How great is the great attachment for lifting that we built in this course? How many times can it lift the robot without making an error? How great are your attachments and how could you test them? - the answer is simple. Just try 10 times and they should work at least 9 of them as our attachment is.

If you've done the calculation following the previous tutorials you would arrive at a result of 18.75 rotations. But this is not the correct answer. The calculation is wrong, because the math model that we've built, although kind of obvious, is not correct. When experimenting the correct number of rotations would be 37.5. This is a large difference. Two times larger. Exactly two times large. Something should be happening here - and this thing is "planetary mechanism"

This is a teacher's note about the math behind calculating gear ratios with for our lifting attachment. It math model we build in previous tutorials is not exactly correct and here is the explanation why.

Connect the attachment to the box robot and find the correct number of rotations of the middle motor that would bring the robot up and forward and would attach it to the mission model.

Sometimes the answer that you get by calculating seems not to be right. Is it the calculation that is wrong. Probably it is not the calculation, but something is happening with the robot. 

In the previous video, we found the correct answer for our task and it is 18.75, or is it?

What should you do as a teacher when the students are calculating the gear ratios and number of needed rotations?

Calculate the number of rotations you have to do with the motor to rotate the final small 8 teeth driving gear wheel to 1.25 rotations?

We calculate the number of rotatios when a gear system is involved. The driving wheel will have to do a number of rotations for the driven wheel to rotate to a desired number of degrees. In our specific case when the driven gear wheel is rotate to about 90 degrees the legs will lift the robot.

Let us do a quick recap of the whole lifting mission and its solution

Note for the teacher on making the construction more stable, more durable and using beams for this.

Following the principles from the previous video, try to make the attachment that you've built, more stable and durable. 

In this video we discuss the durability of the construction of LEGO robots and how do we make them more durable. 

Here is our solution for preventing torsion and bending of the LEGO Mindstorms EV3 axles.

The important task before the solution. If you haven't done it already, then attach a new axle at the front of the robot and extend the construction with gear wheels and axles to reach the two legs at the two sides of the robot. 

Construct two legs for both sides of the robot. The task for this video is to attach this two legs on both sides and to build a system of gears and axles that power those legs.

The most stressed wheel in our system is the driven wheel. We've already fixed the problem with the driving wheel of the scissor mechanism and now it is time to look at the drive LEGO Mindstorms wheel.