Write a series of articles that show ways to measure velocity using NXT sensors. - velocity using rotation sensor
- degrees to rotations
- rotation to circumference
- rotations to distance
- use Investigator mode
- plot degrees vs time
- convert degrees to rotations
- convert rotations to distance
- plot distance vs time
- vary power to motors - any difference between plots? (will see steeper slopes for larger powers)
- use d2,t2 - d1,t1 to determine velocities for different motor powers - do they agree?
- what happens if you program the motors to go backwards?
- randomly select a distance and mark it with tape on the floor. Have students use their data only to go up to finish line.
- velocity using ultrasonic sensor
- use Investigator mode
- start close to wall and move away
- vary power to motors (run three times for each power, if feasible)
- plot velocity vs time (for different motor power)
- notice positive slopes
- start a distance from wall and move toward it
- vary power to motors
- plot velocity vs time (for different motor power)
- notice negative slopes
- use d2,t2 - d1,t1 to determine velocities for different motor powers - do they agree?
- Instructor selects a motor power and a distance (less than 2 m). Students use their data in a challenge to go up to but not over the finish line.
- velocity using light sensor
- similar to a photogate - show students how it works with a cart on a track and Loggerpro
- use a piece of white posterboard
- create varying strips of of black tape of different widths (three of each size)
- use Investigator mode
- test each strip size at different powers
- calculate velocity by dividing length of black by time in light sensor reads black
- three strips provide data to get an average
- Give the students a motor power and time, ask them to calculate how far the robot will go.
- Write a program using this data to go up to but not over the finish line.
- Do the picket fence activity with the NXT
- this is like the LoggerPro activity where you drop the picket fence through a photogate to measure gravitational acceleration
- create a picket fence (equally spaced white and black stripes) - measure them
- Make sure the robot is pretty close to the fence
- measure at least 10 points per second
- Have the robot go by the picket fence with the light sensor pointed toward the picket fence on the side of the road
- Determine speed (for a constant speed robot)
- Determine acceleration for an accelerating robot
- Angular velocity
|
|