Part three of the Catapult series is about loading the catapult automatically. We use a gear system with a medium complexity along with a very interesting "clutch" developed with parts entirely from the LEGO Mindstorms NXT kits. As a result, at the end of the video, the Catapult automatically loads and fires.
Time to lift the robot. The first approach is by using the 40 teeth gear wheels that come with the LEGO Mindstorms EV3 and NXT robotics sets.
Build a similar mechanism to this one. Similar, but for your robot. This is the task for you. Try, give yourself half and hour or even an hour.
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.
Vision is still one of the very few fields where a human being could outsmart a computer. Still. Colour/Light sensors are the cornerstones of implementing a smart LEGO Mindstorms robot that could at least partially do "vision". In this video tutorial, we are using the robotics sensor to detect loading and unloading of the catapult.
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.
Here is our solution for preventing torsion and bending of the LEGO Mindstorms EV3 axles.
How to align the wheels and how much should you push for this solution?
There were a few problems with the 40 teeth gears that we were using. Let's list some of them
The M08. AEROBIC EXERCISE is one of the very common types of mission in FIRST LEGO League robotics competitions. I think this pattern of missions was first introduced with the growing abilities of the participating students that were constantly reaching the maximum number of points. So the competition introduced mission that require a lot of time - 20-30 seconds, are time consuming and are complex. They requires a lot of moves. This here is a video tutorial on how it could be accomplished
In this tutorial, we add another mission to our current program. This mission is - hanging the Gecko from the FIRST LEGO League Animal Allies.
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.
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.
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.
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.
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.
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"
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?
What should you do as a teacher when the students are calculating the gear ratios and number of needed rotations?
In the previous video, we found the correct answer for our task and it is 18.75, or is it?
In this video tutorial we accomplish the basketball mission from the FIRST LEGO League 2020 reply competition. We use the LEGO Education SPIKE Prime competition robot called Gazon. You will learn the principles of accomplishing a mission of two parts - put the ball in the basket and lift the basket.
In this video tutorial we accomplish the Basketball mission 10 out of 10 times. We use one of the more complex attachments for the FIRST LEGO League 2020 RePlay competition. You will see an learn how to successfully and consistently complete a mission that requires the robot to put a ball into a basket and lift the basket, or lift the basket and put the ball into it.
This FIRST LEGO League robotics video tutorial is about the Treadmill mission and how it could be accomplished. The mission is from FLL 2020 RePlay competition. Almost every year there is a mission of this type where the robot must spend a lot of time with the mission model in order to turn or lift something. These are quite interesting and challenging missions.
In this video tutorial we look at an active attachment that uses gear wheel and the attachment is general enough to be suitable for reuse. This means that a lot of different missions could be accomplished with the same attachment. The goal of the attachment is to transfer power to a lever through a system of axles and gear wheels. It is interesting that we change the orientation of the gear wheels.
In this video tutorial we use an active attachment with a gears, built only form LEGO Mindstorms Robot Inventor parts, to accomplish the FIRST LEGO League 2020 Treadmill mission. The goal of the mission is to rotate the mission model for a couple of seconds so that a pointer makes a half circle rotation. What you will learn is a good principle to approach such missions.
This video tutorial demonstrated the use of an active gear attachment for catching a wheel and pulling it. This is how we accomplish the Rowing Mission from the FIRST LEGO League 2021 competition. What you will learn is how such an attachment works. How you transfer power from the top of the robot where the motors are to the bottom of the robot where the catching mechanism is. Check out the building instructions for the attachment.
This is a 10 out of 10 tutorial demonstrating the accuracy of an active gear attachment that accomplishes the Treadmill mission from the FIRST LEGO League 2020 RePlay competition. When the robot is well aligned to the line before that it is easy for the robot to accomplish the mission. You will see how we make use of the friction of the wheel to rotate the mission model.