Figure 1 - Gearbox with 3 cogwheels

Requirements

• Ozeki Gears: Gears build instructions
• Ozeki Sniffer: Sniffer build instructions
• Ozeki Speeder: Speeder build instructions
• Ozeki 10 installed: Installed Ozeki 10 Robot OS
• Lego connection installed: Installed Lego Bluetooth connection
• SNAP basics: Basic knowlege of the Snap programming language

Torque - it is a rotation force. In other words, the torque is a measure of how much a force acting on an object causes that object to rotate. The greater the torque of the engine, the greater the weight the robot can pull.

The heavier the weight you want to pull with your robot, the more torque required. In the previous lecture you have learned how you can make the Speeder faster using gears. The disadvantage of this is that the robot will be weaker. If you try to pull an object with it, the Sniffer is more likely to pull it then the Speeder. If you would like to make the Speeder more powerful, you just need to swap the cogweels with each other. So the smaller-diameter cogwheels must be driven by the motor, and the larger-diameter cogwheels must be connected to the wheels. Due to this, the Speeder will be slower than the Sniffer but it will be more torque. So in this case, the Speeder can take more weight than the Sniffer. By solving the following tasks you will be know the reasons.

Figure 2 - Gears make your motor stronger

You have solved similar tasks in the previous lectures, so it will not be hard for you to create this program. But to make it more useful, create two entry point for starting and stopping the robot. In the first part of the program you need to start the motors of the robots at 30% power, while in the other part you just need to stop them. Look at Figure 3 for help.

Figure 3 - This program code moves the Speeder for 3 seconds

You certainly noticed that the Sniffer pulled the same weight more confidently than the Speeder. The Sniffer is stronger because the large motors rotate the same angle as the wheels because they are connected to the large motors directly. But in case of the Speeder, the motors rotate less degrees than the wheels due to the gears. The lower the angle the motors have to turn to drive the wheels, the weaker the robot.

Figure 4 -

In this case, you can see that the robot become slower than the Sniffer. Do you know why it got slower? Due to the cogwheel swapping, the large motors rotate more degrees than the connected wheels. And this is why the robot become stronger. To make it even more understandable, there is an example on Figure 5 below. It is similar to the gearbox in the Speeder. So the smaller-diameter cogwheels are driven by the motor, and the larger-diameter cogwheels are connected to the wheels. Build your own Gearbox for trying it out.

Figure 5 - Use 2 gear wheels. The smaller gear should move the bigger one

There is a video below for demonstrating how the gearbox works with 2 cogwheels. If you rotates the smaller cogwheel, you should see that the larger one moves slowly. But if you rotates the larger cogwheel, the smaller one rotates faster.

Video 1 - Using 2 cogwheels

After you saw how the Gearbox works with 2 cogwheels, let's see how it works with 3 cogwheels. On Figure 6, you can see that one other cogwheel is connected to the previously seen Gearbox. If the small cogwheel were driven by the motor and the left-hand cogwheel was connected to the wheels, then the robot would be even stronger than if it was used the 2-cogwheels Gearbox. Upgrade your own Gearbox and rotate the two extreme cogwheels.

Figure 6 - Create stronger motion with 3 cogwheels

The video below demonstrates how the 3-cogwheels Gearbox works.

Video 2 - Using 3 cogwheels

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Program code

Figure 7 - Program code to move the robot slowly

Download the SNAP program The program code is capable of starting and stopping both robots at the same time. It is easier to follow the guide if you have the code in front of you: Download the SNAP program files

More information

• Plan the travel distance
• Move along a path
• Measure the time of the motion
• Calculate the speed of the robot
• Measure distance
• Build a speed camera
• Determine the collision point
• Predict the result of a robot race
• Make your robot faster or slower using gears
• Make the robot more powerful using gears