5.8: Exercises
- Page ID
- 59299
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Take-home lessons
- Most of a robot’s sensors either address the problem of robot localization or localizing and recognizing objects in its vicinity.
- Each sensor has advantages and drawbacks that are quantified in its range, precision, accuracy, and bandwidth. Therefore, robust solutions to a problem can only be achieved by combining multiple sensors with differing operation principles.
- Solid-state sensors (i.e. without mechanical parts) can be miniaturized and cheaply manufactured in quantity. This has enabled a series of affordable IMUs and 3D depth sensors that will provide the data basis for localization and object recognition on mass-market robotic systems.
Exercises
- Given a laser scanner with an angular resolution of 0.01 rad and a maximum range of 5.6 meters, what is the minimum range d a robot needs to have from an object of 1cm width to definitely sense it, i.e., hit it with at least one of its rays? You can approximate the distance between two rays with the arc length.
- Why does the bandwidth of a Ultra-sound based distance sensor decrease significantly when increasing its dynamic range, but that of a laser range scanner does not for typical operation?
- You are designing an autonomous electric car to transport goods on campus. As you are worried about cost, you are thinking about whether to use a laser scanner or an ultra-sound sensor for detecting obstacles. As you drive rather slow, you are required to sense up to 15 meters. The laser scanner you are considering can sense up to this range and has a bandwidth of 10Hz. Assume 300m/s for the speed of sound in the following.
- Calculate the time it takes until you hear back from the US sensor when detecting an obstacle 15m away. Assume that the robot is not moving at this point.
- Calculate the time it takes until you hear back from the laser scanner. Hint: you don’t need the speed of light for this, the answer is in the specs above.
- Assume now that you are moving toward the obstacle. Which sensor will give you a measurement that is closer to your real distance at the time of reading and why?