ASTA Workshop – Basic Robotics Erik Von Burg, MacArthur Elementary School ( firstname.lastname@example.org ) Bill Johnson, Scottsdale Community College (SCC) ( email@example.com ). Goals:. Have FUN!!! Demo the power of robotics to: improve problem solving skills utilize math skills
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ASTA Workshop – Basic RoboticsErik Von Burg, MacArthur Elementary School(firstname.lastname@example.org)Bill Johnson, Scottsdale Community College (SCC)(email@example.com)
First Robot Across Finish Line WINS!!
Mission Mapping Example
1 F 16”
2 R 45°
3 F 8.5”
4 R 90°
5 F 30”
First Robot Across Finish Line WINS!!
The NXT uses 4 different ways to control movement:
- Tire rotations*
- Degrees turned by tire
(360° = one rotation)
- Unlimited (used with sensors)
*rotations is the easiest to use
Students use a concrete model of the robot wheel called a “wheelie” to determine the distance travelled for different numbers of rotations. By plotting the data, they can see the relationship between distance and rotations.
measurement reference points
Distance traveled, Dt is:
Dt = n × C
n = number of tire rotations
C = tire circumference
An alternate approach using speed over time (Dt = S × t) is NOT recommended because speed is not constant.
Start anywhere behind the starting line and park the bot between the finish lines. The bot must not be over either of the lines.
Extensions: 1) drive past two lines, reverse back and park
2) try a different speed
The bot must be completely within lines.
Start the bot any where behind the starting line. The bot should move forward and come within 0.5 jn without any piece of the bot touching the wall.
The bot should stop within 0.5 in of the wall.
Run challenges – 30 Min
Fill in score sheet
Dt = n × C
In the above equation, we can control the distance traveled and number of rotations. With a little algebra, we can find the circumference of the wheel.
C = Dt / n
This can be done a number of ways. Initially, concrete methods are the best because students will understand them more readily.
- did the robot run straight??
- measurement skills/reference points
- measuring distances
- making data tables
- plotting data
- fractions vs decimals
- wheel diameter/circumference
Experiments should be encouraged!!
Question: How many rotations does it take to complete a turns of various angles?
Using a concrete model will help students visualize the number of rotations it takes to complete various turns.
One wheel turns while the other is locked into position.
Tire rotations = path length/tire circumference
# rotations = (desired angle/360°)(2πr)/C
r => turning radius (distance between the tires)
C => tire circumference
The bot must move forward one rotation, complete a 360° pivot turn, and move forward again one rotation. The bot should finish the movement exactly in line with its original trajectory.
Oversteer (decrease turn)
Perfect Turn Parameter
Understeer (increase turn)
Why do this test?
This will help develop experiential knowledge, so students can reasonable estimate 90° turn parameters. The movement after the turn highlights turning parameter errors.
Program the bot to move forward and turn 90ᵒ. Repeat this a total of four times, and end the with one final movement forward. Test the turn duration and adjust as necessary.
All forward should be the same duration ( movements about 2-3 rotations).
When the bot completes its movements, check to see if it under or over turned and adjust the turn parameter appropriately.
Why this test?
This test helps determine the 90° turn parameter, and it illustrates compounded error.
Start the bot any where behind the starting line. The bot should move forward and turn to park within the parking space. No part of the bot can be touching or over the boundaries.
No part of the bot can be out of the parking space.
Start the bot any where behind the starting line. The bot should move forward, turn towards the wall, park between the lines, and stop within 0.5” of the wall. No part of the bot can be touching the wall.
Distance should be less than 0.5”.
Place one of the robot’s wheels on the tape line. Program the robot to complete the figure 8 without having that tire stray from the tape line.
Blue tape lines
- reference points (x-y)
- initial alignment “angle”
L ~ d (π/180) a
where L is the lateral placement error,
d is the distance traversed, a is the misalignment angle
Example: for d = 30”, a at 2° , L ~ 1.05”
(position errors cumulate as bot moves away from starting point)
keep doing whatever action that is being done BEFORE the WAIT block UNTIL the desired sensor is triggered – then continue actions along the sequence beam
(look for “coaches resources” link)
(in search field - type Lego robots+FLL)