Peak Performance

ACTIVITY HEADER

 

 

 

Name of Activity Peak Performance
Author Jay Clark
Keywords NXT, car, course, fastest, flat, inclined, gear, gear ratios, torque, speed, optimization, building, drive gear, driven gear, 1 Hour Total
Subject NXTs
Grade Level K, 1, 2, 3, 4, 5, 6, 7, 8, 9+
Time 1 Hour Total
Brief Description Students must gear their NXT car to complete the course the fastest. The course consists of a flat section and an inclined section.
Lesson Objectives: To learn about gear ratios, gearing for torque vs gearing for speed, optimization, and building.
Materials Needed: NXT kit
Ramp
Computers running MINDSTORMS
Preparation and Set Up: Prepare one or more courses – With a flat beginning and an incline ending. The length of both sections will determine the optimum gear ratio. To allow for extensions, set up other courses with varying distances of the course components.
Necessary Background Using gear ratios students can gear their cars for more torque or more speed. If the drive gear is bigger than the driven gear, the car will be geared for speed. If the other way around, it will be geared for torque.

A car geared for torque will be slower, but will climb better. A car geared for speed will be quick, but might not be able to climb the ramp.

Vocabulary:

Gear Ratio – The ratio of the speed of rotation of the drive gear of a gear train to that of the driven gear.

Drive Gear- The gear attached to the source of torque. (Usually the motor).

Driven Gear – The gear that receives motion from the drive gear.

Optimization – Finding a balance between design concerns that yields the best solution.

Procedure Introduction – 10 Minutes Ask students if they’ve ever used gears before. More than likely, they’ve driven a 10 speed bike before, and never knew how the gears worked. Introduce students to gears and gear ratios. Using a pre-made gear train, show them the size of the drive gear and the driven gear, and ask if the driven gear will spin faster or slower than the drive. If they are having trouble seeing it, ask them for every one rotation of the drive gear, how many times does the driven gear rotate? Explain torque vs. speed. ie. tugboats – high torque, low speed. Handheld fans- high speed, low torque. Introduce the concept of optimization. Introduce the activity Activity – 40 minutes Clean up/ Wrap up – 10 minutes

  • What was easiest? What was hardest?
  •  What would you have done differently?
  •  What were some good ideas you saw that other groups came up with?
Extensions: Have the students try a different course with different dimensions and slopes.
Reference 1 http://sites.tufts.edu/stompactivitydatabase/files/formidable/e.jpg
Reference 2 http://sites.tufts.edu/stompactivitydatabase/files/formidable/f.jpg

Speed Fans

ACTIVITY HEADER

 

 

 

Name of Activity Speed Fans
Author STOMP
Keywords fan, LEGO, speed, touch sensor, programming, 1 Hour Total, 4-6
Subject NXTs
Grade Level 4, 5, 6
Time 1 Hour Total
Brief Description The activity involves building a fan out of LEGOs and creating a MINDSTORMS program that will change the speed of the fan every time the touch sensor is pressed.
Lesson Objectives: Gain basic understanding of programming with MINDSTORMS.
Materials Needed: NXT Kits/ RCX Kits.

Computers with MINDSTORMS or ROBOLAB installed.

Necessary Background Knowledge of programming with MINDSTORMS.

Vocabulary:

Touch sensor

Power Levels

Procedure 1) Explain the basics of programming. 2) Distribute the kits and explain the task ( i.e. to build a fan that changes speed when the touch sensor is pressed) 3) Have the students build a fan out of LEGOs in their kits. 4) Let the students try to figure out how to program the fan on their own. If they need help explain to them how the power level of the motor can be changed every time the touch sensor is pressed thus changing the speed of the fan.
Extensions: Program the fan using loops.
Use the activity to talk about air flow.

Relay Race

ACTIVITY HEADER

 

 

 

Name of Activity Relay Race
Author STOMP
Keywords vehicles, steep ramp, relay, team, course, cars, gears, weight, weight distribution, friction, power, accuracy, wheel, axle, speed
Subject NXTs
Grade Level 4, 5, 6, 7, 8, 9+
Time 2 Hours Total
Brief Description Students will build two types of vehicles, one that is good for going fast on a flat surface and one that is good for climbing a steep ramp. Students will work together to create a relay team of 2 cars that must complete a course with a flat area and a steep ramp.
Lesson Objectives: To learn about gearing and how it can help with climbing ramps.
To learn complex programming that includes Bluetooth for communication between NXTs.
Materials Needed: Poster board, cardboard, wood or foam core for a ramp sloped about approx. 30 degrees from the horizontal.
NXTs or RCXs
Gears
Assorted building materials.
Computer running ROBOLAB or MINDSTORMS
Preparation and Set Up: Setup the relay course.
Set up a flat track that is five feet long with a start and finish and set up the ramp.
Collect necessary materials.
Arrange students into groups of 4.
Distribute the necessary materials.
Necessary Background One of the important things about robots is their ability to communicate to each other. Robots are often limited in their capabilities because it is too difficult to construct multi-tasking robots. For this reason, many different specialized robots are constructed, and then these robots are programmed to communicate to each other. For example, a certain Mars rover may specialize in searching for rock, while another may specialize in drilling rock. These two rovers can work together by sending signals to each other, in the same way we communicate, yet simpler. The following activity incorporates specialized robots that can communicate to each other to complete different sections of a single task: a relay race with different terrain.

CONCEPTS:
Building

Mechanical advantage of gears
- Small gear on motor, larger gear on wheel and axle for more torque to drive up the ramp
- Large gear on motor, small gear on wheel and axle for more speed to drive across the floor

Weight distribution of vehicle
- More weight on the front of the ramp vehicle
- Less weight for the entire floor vehicle

Friction
- Wide wheels for more contact surface area on the ramp vehicle
- Narrow wheels for less contact surface area on the floor vehicle
- Spacing between wheels and sides of vehicle so that the wheels rotate without rubbing

Power
- Large diameter wheels in the front of the ramp vehicle
- Ramp vehicle should be short in length

Accuracy
- Long floor vehicles with four wheels to ensure that the vehicle travels as straight as possible towards the stationary ramp vehicle

Procedure
  1. Introduce the activity and tell students that two people in their group will build and program a car to travel as fast as possible on a flat surface, and the other two people will be building a programming a car to drive up a ramp.
  2. Allow students to build their cars. Remind students that gears might help them build a car that can climb a ramp.
  3. Have students program their vehicles.
    1. The first vehicle must travel 5 feet to the base of a ramp and then stop. The students should use time to stop their robot, or use a light sensor if the course is marked with tape.
    2. When the first vehicle stops, it must send a message to the second vehicle (a number). This will trigger the second vehicle to start climbing the ramp.
    3. The second vehicle should start climbing the ramp when it receives the message from the first vehicle.
    4. Communication between RCXs/NXTs may be tricky.
      1. Use the ‘send mail’ and ‘wait for mail’ icons on the floor and ramp vehicle, respectively.
      2. Each group should send a different number so as to avoid confusion between RCXs and NXTs.
      3. Zero the receiving mailbox at the beginning of the program.
      4. Press run on both robots before starting the relay.
  4. Allow students to test their cars and rebuild/reprogram accordingly.
  5. At the end of class gather the students together. Have each team run their cars and time how long the relay takes from start to finish.
  6. Talk about what designs and programs worked the best and how you could improve upon each teams work.
Reference 1 http://sites.tufts.edu/stompactivitydatabase/files/formidable/Team-up-for-a-Relay.doc

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