Robotics Lab 1: Sensors
Overview: In this lab you will get a better feel for the kinds of sensors available for use in the class and the properties of those sensors. You will take sensor readings of several types of material with different colors at different distances using different sensors. You will record your results and write a lab report describing your data collection, your conclusions that you draw from the data, and any sources of error in the collection of your data. You will collect and record the data as a group, but each student must write his or her own lab report by themselves.
Collect one set of materials from storage at the back of the lab. The set should contain:
a handy board controller (with serial interface board and a telephone cable between them if necessary)
three analog sensors:
One light sensor
One IR proximity sensor (ET stye)
One IR emmitance sensor (top hat style)
Two Lego constructions
one larger one with a green base for the IR proximity sensor
one smaller one for the top hat style IR sensor.
posterboard sensor items.
one large posterboard with distances on it
several smaller ones with colored materials glued to them.
Black binder to serve as the “dark” sensed item.
Swing arm wall lamp with no shade (note that unlike other materials there is only one of these. If two groups are in the lab at the same time they will have to work on the part of the lab that uses the lamp at separate times.
one incandescent bulb
one Fluorescent bulb
In this lab you are going to take many sensor readings to get an idea of the sorts of sensor readings that you will get for a varity of stimuli. The program in the handyboard is setup to read from the sensors one at a time again and again till asked to move on. See the section on the program below to review further details.
Attach the ET IR sensor to the back of the larger lego construct. Put the sensor on the black line of the posterboard. One member of the group should hold the appropriate material at the correct distance from the black line. Start the program and take sensor readings using the ET IR sensor for the materials and distances listed below. Then take the entire set of readings again. (Do the second set of readings after the first rather than taking two readings of blue foam at 4 inches and then moving on to 6 inches.)
Material |
4 inches |
6 inches |
10 inches |
14 inches |
Fluorescent paper |
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blue foam |
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plain white board |
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Dark |
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Fluorescent paper 45 degrees |
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blue foam 45 degrees |
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white board 45 degrees |
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Dark 45 degrees |
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Fluorescent paper |
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blue foam |
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plain white board |
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Dark |
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Fluorescent paper 45 degrees |
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blue foam 45 degrees |
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white board 45 degrees |
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Dark 45 degrees |
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Now move on to the light sensor. The light sensor should be wrapped in an opaque material to give some directionality to the light. Take the readings required to fill in the table below. Use the light provided, changing the bulbs when needed. To obtain proper readings turn the main lab lights off when taking the readings, using the light of the incandescent, or Fluorescent bulb to work by.
Condition |
6 inches |
14 inches |
22 inches |
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Fluorescent bulb – sensor pointed at light |
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Incandescent bulb – sensor pointed at light |
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Fluorescent bulb – sensor 90 degrees from light |
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Incandescent bulb – sensor sensor 90 degrees from light |
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Fluorescent bulb – sensor pointed at light |
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Incandescent bulb – sensor pointed at light |
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Fluorescent bulb – sensor 90 degrees from light |
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Incandescent bulb – sensor sensor 90 degrees from light |
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Turn the regular lights back on.
Now take readings using the IR tophat sensor. Take the sensor and place it in the small lego construct so that the top of the hat is facing down. (this put it at a pretty good distance from the material that the lego is sitting on to give different readings based on colors. Now drag the entire contraption, legos, sensor and all over the items to be sensed in the table below and fill out the table.
Material |
Reading 1 |
Reading 2 |
Reading 3 |
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White board |
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Blue foam |
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Yellow foam |
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Black |
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Fluorescent |
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Finally, you are all bright young minds and must have interesting ideas about what can be sensed and what will make a difference. Come up with a few sensing conditions and record your observations. Be professional and don't cause trouble , but try the sensors something different. Come up with something interesting and record it. What will you use? The carpet? The computer? The walls? Something different?
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When you have taken your readings and recorded them, then you are done the in-lab group part of the lab. Each group member should take his or her copy of the data and write up their own lab report.
Your lab report will be a typed report in complete sentences which should include the sections recommended by
W. Dolphin in his Guide to writing lab reports. You do not need to add additional literature cited if you only cite documents from the class in writing your report.
The program running on the microcontrollers is written in IC (interactive C), a simple C-like language that we will use when programming these robots later in the projects.
The program uses the following user interface: When the robot controller is turned on, the program is run (default for handyboard robots). To begin the program for your purposes, push the stop button (you should hear a low beep, if so you know the program is running). This is move the robot into a mode that will read from an ET IR sensor in port 16 each time the start button is pushed. Just push the start button when you want to get a new reading. You will see the numeric value printed to the lcd panel.
When moving from one type of sensor to another, first push the stop button, then while holding the stop button, push down the start button as well.
You then push the start button to take readings from the current sensor and have those readings displayed on the LCD panel.
If the robot's program has become lost, you may have to download it again. This shouldn't happen, but if it does, see your instructor.