Extending constructions without instructions. Basic Principles. Straight Beams
Tips and common mistakes when connecting two beams together.
- #433
- 03 May 2017
Tips and common mistakes when connecting two beams together.
Experiment with changing the orientation and direction of gear wheels. Here are part of the tasks that you should complete before moving forward with the course.
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.
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.
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.
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 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.
What is allowed and what is not when building without instructions.
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.
Our next robot is called CastorBot, because of the castor ball.
Let us do a quick recap of the whole lifting mission and its solution
Let's move with the VEX EDR robot using its motors, the wheels and some RobotC programming. We devide the program in three parts - Connect the motors, program the controller and turning.
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?
In this tutorial we go through the VEX IQ Challenge. Most of the challenges are related with manipulating objects. The most common object used in competitions are balls. That is why we take a look at a simple mechanism that can be used for throwing a ball.
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.
In this video we discuss the durability of the construction of LEGO robots and how do we make them more durable.
In the first part we built our first 3D LEGO model. Today we will smooth the model we have created and go through the process of creating PDF instructions for building it.
What should you do as a teacher when the students are calculating the gear ratios and number of needed rotations?
One of the very common tasks on different FIRST Technical Challenge competitions is to collect objects. In this case, these are colourful specifically shaped plastic object or in simple terms - balls.
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