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.
- 18 Jan 2015
A motor for loading the catapult is added to the construction shown in this and in the following video lessons of the Catapult series. Firing is achieved by using gravity force again while loading is achieved with a motor. The power from the motor is transferred to the lever by a system of gears located on different axles. In this way the orientation of the gears is changed twice and transmitted four times.
The touch sensors used in the robot are very important. We should have a way to find out if the Catapult is already loaded and when we should stop loading. Configuring the motor to use rotations or degrees is a very bad practice and we should try to avoid it. Always try to use sensors.
Additional video lessons
You could find more explanations about changing gear orientation in the following video lessons:
All episodes from the series:
The current video lesson shows the robot built from LEGO Mindstorms NXT parts while the next one would use LEGO Mindstorms EV3 motors and sensors.
Building instructions for NXT Mindstorms Catapult Robot are given below. (The next lesson in the series would use EV3)
This is the initial construction of a catapult. The base on which we will place the rest of the robot. The goal of this construction is to give the catapult the ability to rotate.
Building instructions for a LEGO Mindstorms Catapult Motor and Touch Sensor that are used for triggers for firing objects
This frame holds the motor and ev3 brick used in the catapult. The frame is placed on top of the rotating base and thus could be easily rotated. The brick could be both NXT and EV3
Courses with this episode
The episode is used in the following courses where you can find additional tasks for it to use in class
Explore speed, distance and construction innovation for the catapult. Use the task in your classroom, for your team or at home to engage students in learning.
There are 3 tasks with 3 complexities giving 1,2 or 3 points.
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