Click the images to select the respective gears. Start with the first pair and add more pairs as needed: [ remove pair ] Select your drive motor to see the theoretical output speed in RPM (Rotations Per Minute): Assuming that the red gear is the input, the gray beam is the output and that the yellow gear is not rotating (e.g. fixed to a motor): specify numbers of teeth for red and yellow gear below, then click calculate. The red dot marks the position of your driver gear's axle. Select the position of your follower gear's axle to see the available gear combinations:We're sorry, but we could not fulfill your request for /sumobot-challenge/ on this server. An invalid request was received from your browser. This may be caused by a malfunctioning proxy server or browser privacy software. Your technical support key is: 36fb-035a-1756-6707 You can use this key to fix this problem yourself. and be sure to provide the technical support key shown above.
Students learn about electric motors and rotational sensors. They learn that motors convert electrical energy to mechanical energy and typically include rotational sensors to enable distance measuring. They also learn the basics about gear trains and gear ratios. Students create a basic program using the LEGO® MINDSTORMS® NXT interface to control a motor to move a small robot. Then, through a 10-minute mini-activity, they make measurements and observations to test a LEGO rotation sensor's ability to measure distance in rotations. This prepares them for the associated activity during which they calculate how many wheel rotations are needed to travel a distance. A PowerPoint® presentation, worksheet and pre/post quizzes are provided. Electrical and mechanical engineers use motors to perform many tasks. Motors are used in a wide variety of machines, everything from pencil sharpeners to school buses. Knowing how motors work, including their internal components, such as rotational sensors and gears, helps students understand this fundamental, everyday device.
After this activity, students should be able to: Explain how a LEGO robot uses a motor and gears to move. Explain how motors rotate and enable motion by converting electrical energy to mechanical energy. (Be ready to show students the 18-slide Motors and Rotational Sensors Presentation, a Microsoft® PowerPoint® file, to teach the lesson. In advance, make copies of the Electric Motors Pre-Quiz, How Does a Rotation Sensor Work? Mini-Activity Worksheet and Electric Motors Post-Quiz, provided as attachments and slides, including answers. For a mini-activity, student groups use LEGO robots.) Have you ever wondered how your car windows move up and down when you press the window button? (Listen to student ideas.) They are controlled by electric motors that draw on energy from the car battery and move the glass of the window up or down. Electric motors are all around us—in CD and cassette players, in electric cars, and in subway trains! Today we will learn about how electric motors work.
In addition, the LEGO MINDSTORMS NXT motor comes with a rotation sensor inside its casing (you cannot see it from the outside). This sensor provides us with information about how much the motor moves, as you will see in today's lesson. (Continue by showing the presentation and delivering the content in the Lesson Background section.) Lesson Background and Concepts for Teachers This second lesson of the unit reviews motors—the fundamental device that causes motion in LEGO robots, and a device that might be considered equivalent to "muscles" in the human body, as presented in Humans Are Like Robots (unit 1). In the associated activity, students calculate how many wheel rotations are needed to travel a distance, an illustration of the use of rotational sensors and mathematics in engineering. Present the lesson using the content provided in the slide presentation, as described below. For this lesson and its associated activity, student teams each require a LEGO taskbot, which is used throughout this unit.
//five_minute_bot/steps.html or with the base set. What is an Electric Motor? How Does a Rotation Sensor Work? Presentation Outline (Slides 1-18) Administer the pre-quiz by handing out paper copies; the quiz is also on slide 2. The answers are provided for the teacher on slide 3 for discussion after students have completed the quiz.Discuss how an electric motor works, making sure to mention that electricity is converted to motion.Explain that a LEGO MINDSTORMS NXT motor has gears and a rotation sensor inside its casing.Discuss some real-world applications of electric motors, such as electric pencil sharpeners, car windows, electric can openers, fans, refrigerators, washing machines, vacuum cleaners, etc.Explain how the motors help the NXT taskbot to move. Make the robot/human comparison by going through the movement process for each: computer brick > electrical signals through cables > motor > movement, compared to: the human brain > electrical signals through the nervous system > muscles > movement.
Divide the class into teams and challenge each to develop a program to make the NXT taskbot move forward and then turn right. Have students implement the program on the robot to show that it works. If they are familiar with programming NXT robots, this serves as a refresher task. If they are not familiar with programming NXT robots, give them time to brainstorm and experiment to figure it out. The answer for this program is provided on slide 17. (Note that the What Is a Computer Program? unit has considerable additional information about NXT programming basics.) Use slide 9 to explain the functionality options for how to program the motor to move.Explain to students that the NXT motor casing also includes a rotation sensor that senses the rotations of the hub where the wheel is attached. Then give students a few minutes to write down the components of the stimulus-sensor-coordinator-effector-response framework for this activity; the stimulus-to-response framework answer is provided on slide 18.
Introduce students to a mini-activity (10 minutes long) to develop their understanding of how rotation sensors work. The activity objective is to test the rotation sensor's ability to measure distance in rotations.Begin by briefly explaining how gears transform rotations. Emphasize that gears do not mesh perfectly, which results in errors in readings of the number of rotations. Hand out the worksheet paper copies. Proceed to the mini-activity instructions (slide 13). Have students collect data and make observations about sensor accuracy on the worksheet (also on slide 14). Lead a class discussion so students can share their mini-activity experiences, results and conclusions. Expect students to report that their mathematical calculations do not always match up to actual measurements. This may be the result of calculation mistakes, imperfect meshing of gears, variation in wheel positioning, etc. Next, conduct the associated activity. After the associated activity is completed, administer the post-quiz by handing out paper copies;
the quiz is also on slide 15. The answers are provided on slide 16. Slides 17-18 contain answers. electric motor: A motor is an electrical machine used to create motion. The device converts electricity (electrical energy) into motion (mechanical energy). Typically performed by rotating an object. rotational sensor: A sensor that measures the turning movement of a wheel for purposes of calculating distance traveled. Pre-Quiz: Administer the three-question Electric Motors Pre-Quiz, by handing out paper copies (also on slide 2). Students' answers reveal their base understanding of electric motors. Answers are provided on the Electric Motors Pre-Quiz Answer Key (and slide 3). Mini-Activity: Have students use the How Does the Rotation Sensor Work? Mini-Activity Worksheet as they conduct a 10-minute activity to explore how the LEGO rotation sensor works (slides 11-14). They collect data and record their observations on the worksheet. Circulate through the room, observing students and checking their work.