Field+of+View

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Introduction to Mobile Robotics > Field of View Exploration i. Do your marks seem to follow any kind of pattern, trend or outline of a shape? If so, describe it.
 * Worksheet: Field of View **
 * Phase 1: Find Detection Boundary – Evaluate your Findings **
 * 1. **Mentally “connect the dots” for the pattern of marks you made.

ii. What does this “outline” represent in terms of what the sensor can detect?

i. What is the maximum distance that the ultrasonic sensor could detect for this object?
 * 2. **Locate the tracing that is farthest from the ultrasonic sensor. Place the object at this location again, and record the sensor’s reading from the NXT’s viewscreen.

ii. Where was the object located in relation to the sensor at this distance?

i. Is this “widest detection range” wider or narrower than the robot’s physical width?
 * 3. **Find the two points along the same horizontal line that are farthest apart. This is the farthest to the sides that your sensor can detect an object of this size.

ii. If the robot moves in a straight line, is the ultrasonic sensor’s detection “width” sufficient to ensure that it will detect an object of this size before the robot runs into it? Hitting the very edge of the tire still counts as a collision!


 * Phase 2: Scale Model – Measure and Plot **
 * Record your calculations: **
 * 4. **<span style="font-family: 'Arial','sans-serif'; font-size: 16px;">What is the actual distance between two horizontal lines on the Graph Sheet?


 * <span style="font-family: 'Arial','sans-serif'; font-size: 16px;">5. **<span style="font-family: 'Arial','sans-serif'; font-size: 16px;">What distance is represented by the gap between two lines on the Graph Sheet?

<span style="font-family: 'Arial','sans-serif'; font-size: 16px;">distance it represents? Express your answer as a ratio in the format 1:__
 * <span style="font-family: 'Arial','sans-serif'; font-size: 16px;">6. **<span style="font-family: 'Arial','sans-serif'; font-size: 16px;">What is the scale (size ratio) between the graph paper distance and the physical

<span style="font-family: 'Arial','sans-serif'; font-size: 16px;">i. In what important ways is the scale model the same as the full-size pattern?
 * <span style="font-family: 'Arial','sans-serif'; font-size: 16px;">Phase 2: Scale Down – Evaluate Your Findings **
 * <span style="font-family: 'Arial','sans-serif'; font-size: 16px;">7. **<span style="font-family: 'Arial','sans-serif'; font-size: 16px;">Look at your graph sheet.

<span style="font-family: 'Arial','sans-serif'; font-size: 16px;">ii. Are there any ways in which the scale model is not the same as the fullsize pattern?

<span style="font-family: 'Arial','sans-serif'; font-size: 16px;">iii. On the whole, do you feel that the scale model is an acceptable way to store the information from this experiment?

<span style="font-family: 'Arial','sans-serif'; font-size: 16px;">i. Explain what this scale factor means.
 * <span style="font-family: 'Arial','sans-serif'; font-size: 16px;">8. **<span style="font-family: 'Arial','sans-serif'; font-size: 16px;">Recall the scale factor (size ratio) that you calculated in question 6.

<span style="font-family: 'Arial','sans-serif'; font-size: 16px;">ii. If two points on the full-size pattern were 22 cm apart, how far apart should they be on the scale model?

<span style="font-family: 'Arial','sans-serif'; font-size: 16px;">iii. If two points measure 2.3 cm apart on your scale model, how far apart should they have been on the full-size pattern?


 * <span style="font-family: 'Arial','sans-serif'; font-size: 16px;">9. **<span style="font-family: 'Arial','sans-serif'; font-size: 16px;">Locate the tracing that is farthest from the 0 cm marking on the graph sheet.

<span style="font-family: 'Arial','sans-serif'; font-size: 16px;">i. Where was the object located in relation to the sensor at this distance?

<span style="font-family: 'Arial','sans-serif'; font-size: 16px;">ii. Measure the distance from the 0 cm marking to the farthest marking. How far is it on the graph sheet?

<span style="font-family: 'Arial','sans-serif'; font-size: 16px;">iii. Using your scale factor (size ratio), calculate how far the object should actually be. How far away should it be?

<span style="font-family: 'Arial','sans-serif'; font-size: 16px;">iv. What is the maximum distance the Ultrasonic Sensor can detect a cansized object, and in what direction must it be?

<span style="font-family: 'Arial','sans-serif'; font-size: 16px;">short-range mode and a long-range mode. <span style="font-family: 'Arial','sans-serif'; font-size: 16px;">i. Is there any evidence of this switch happening in the pattern of the detection <span style="font-family: 'Arial','sans-serif'; font-size: 16px;">area? If so, what do you see that suggests there is some kind of mode <span style="font-family: 'Arial','sans-serif'; font-size: 16px;">switching happening?
 * <span style="font-family: 'Arial','sans-serif'; font-size: 16px;">10. **<span style="font-family: 'Arial','sans-serif'; font-size: 16px;">The NXT Ultrasonic Sensor has 2 modes that it switches between automatically: a

<span style="font-family: 'Arial','sans-serif'; font-size: 16px;">ii. At what distance does the transition from short-range mode to long-range <span style="font-family: 'Arial','sans-serif'; font-size: 16px;">mode appear to occur?

<span style="font-family: 'Arial','sans-serif'; font-size: 16px;">iii. Why might a sensor need multiple modes of operation?


 * <span style="font-family: 'Arial','sans-serif'; font-size: 16px;">Analysis and Conclusions: Conclusions & Exercises **

<span style="font-family: 'Arial','sans-serif'; font-size: 16px;">Explain the shape of the detectable area in terms of where and how far sound must travel in order to be sent out and received back. //<span style="font-family: 'Arial','sans-serif'; font-size: 16px;">Hint: Areas where the sensor could not detect an object mean that the ////<span style="font-family: 'Arial','sans-serif'; font-size: 16px;">sound waves did not reach those areas, did not return to the sensor from ////<span style="font-family: 'Arial','sans-serif'; font-size: 16px;">those areas, or were too weak to be detected by the time they returned. //
 * <span style="font-family: 'Arial','sans-serif'; font-size: 16px;">Conclusions **
 * <span style="font-family: 'Arial','sans-serif'; font-size: 16px;">11. **<span style="font-family: 'Arial','sans-serif'; font-size: 16px;">The ultrasonic sensor works by sending out high-frequency sound waves and measuring the amount of time it takes for the sound to reflect off an object and come back.

<span style="font-family: 'Arial','sans-serif'; font-size: 16px;">from for future use.
 * <span style="font-family: 'Arial','sans-serif'; font-size: 16px;">12. **<span style="font-family: 'Arial','sans-serif'; font-size: 16px;">Write a paragraph or two describing how you conducted your experiment, including step by step instructions so that someone could recreate your experiment in the future. Make sure to include instructions on how to store this data in a manageable

<span style="font-family: 'Arial','sans-serif'; font-size: 16px;">i. What was the maximum range of her sensor, and in which direction did it occur?
 * <span style="font-family: 'Arial','sans-serif'; font-size: 16px;">13. A **<span style="font-family: 'Arial','sans-serif'; font-size: 16px;">bove is the data taken from a scientist’s test of a similar ultrasonic sensor. She ran the experiment with the same method that you used, by sliding an object along until the sensor was able to detect it, and then marking that point.

<span style="font-family: 'Arial','sans-serif'; font-size: 16px;">ii. What was the widest part of the detection area, and how far from the sensor is it? <span style="color: #000000; font-family: 'Arial','sans-serif'; font-size: 16px;">i. What was the maximum range of her sensor, and in which direction did it occur?
 * <span style="color: #000000; font-family: 'Arial','sans-serif'; font-size: 16px;">14. **<span style="color: #000000; font-family: 'Arial','sans-serif'; font-size: 16px;">Another, much larger, sensor was tested here, but the detection range was so big that the scale of the graph had to be changed.

<span style="color: #000000; font-family: 'Arial','sans-serif'; font-size: 16px;">ii. What was the widest part of the detection area, and how far from the sensor is it?

<span style="color: #000000; font-family: 'Arial','sans-serif'; font-size: 16px;">i. Identify the longest distance you detected an object in this exploration.
 * <span style="color: #000000; font-family: 'Arial','sans-serif'; font-size: 16px;">15. **<span style="color: #000000; font-family: 'Arial','sans-serif'; font-size: 16px;">Sound travels approximately 340 m/s at sea level.

<span style="color: #000000; font-family: 'Arial','sans-serif'; font-size: 16px;">ii. How long did the ultrasonic wave take to reach the object? Remember that your readings are in cm.

<span style="color: #000000; font-family: 'Arial','sans-serif'; font-size: 16px;">iii. How long did it take for the wave to return to the sensor from the object?

<span style="color: #000000; font-family: 'Arial','sans-serif'; font-size: 16px;">iv. How long did the wave take to travel through the air, in total?

<span style="color: #000000; font-family: 'Arial','sans-serif'; font-size: 16px;">v. If the object had been 1 cm farther (the smallest increment the Ultrasonic rangefinder will detect), what would its sound wave travel time have been?

<span style="color: #000000; font-family: 'Arial','sans-serif'; font-size: 16px;">vi. What does this comparison tell you about the sensitivity of the timing circuitry in the NXT and the ultrasonic sensor?