|
|
|
![]() |
|
|||||||
|
||||||||
![]() |
| Thread Tools | Rate Thread | Display Modes |
|
#16
|
||||
|
||||
|
Re: Hall Effect Sensor.
Here are a few tips on the Hall Effect sensors:
These guys simply output a digital signal corresponding to whether or not a gear tooth is in front of them or not, and the polarity of the signal depends on the direction of gear rotation wrt the sensor itself (see the data sheet for more details: http://www.allegromicro.com/datafile/0660.pdf). Think of this device as a one-bit wheel encoder when you program for it. The air gap, according to the manufacturer, should be 0.5-2.5mm, though they assure us that their adaptive sensing technology can make it work for an even bigger gap, especially with larger gear teeth. The device has an open-drain output stage, but the digital inputs on the RC have pull-up resistors built-in, so you can directly connect the signal to the RC's inputs. Try to avoid grounding the signal wire, though, as this would technically be a short-circuit. Don't worry if you do -- the manufacturer says it has short-circuit protection on the output stage. |
|
#17
|
||||
|
||||
|
Re: Hall Effect Sensor.
We are given two Hall Effect Sensors. By using them to count teeth of sprockets on opposite sides of your robot you can calculate the difference in number of wheel rotations, and from that rotation of your robot.
If they are used this way, i believe, they work as a replacement for a gyro, although they would not account for being pushed or otherwise interfered with. - Toby |
|
#18
|
|||||
|
|||||
|
Re: Hall Effect Sensor.
Guys,
Read some of the posts above before making guesses. The Hall effect sensors are easy tachometers that can tell you how fast a gear is rotating and how many gear teeth have passed by the front of it. Using two on the same gear, about 90% apart, can also give you direction information with some simple electronics or software interpretation. The accelerometer can be used only to give an indication of turning. It will give a large output for a bump or fast turn and a small output for a slow turn. Combine the data from all three and you will know that you have traveled "X" inches in some direction relative to your starting direction. As a caveat, if your wheels are not firmly on the ground, counting gear teeth tell you nothing. |
|
#19
|
|||||
|
|||||
|
Re: Hall Effect Sensor.
Quote:
![]() |
|
#20
|
||||
|
||||
|
Re: Hall Effect Sensor.
http://www.allegromicro.com/datafile/0660.pdf
I can confirm that is the proper spec sheet for the hall effect gear tooth sensor that is included in the 2005 FRC KOP. It is labled Data sheet 27627.107 |
|
#21
|
|||
|
|||
|
Re: Hall Effect Sensor.
Quote:
|
|
#22
|
||||
|
||||
|
Re: Hall Effect Sensor.
Arghhh! I don't understand lol.
Ok the Hall Effect sensor counts teeth and has to be mounted very close to the gear. The accelerometer measures acceleration. How is that done and where does it have to be mounted. How do all these values come together in the RC and help me? What does the code that we get for both these sensors do? |
|
#23
|
|||||
|
|||||
|
Re: Hall Effect Sensor.
Quote:
|
|
#24
|
||||
|
||||
|
Re: Hall Effect Sensor.
So... They are sprocket-tooth encoders. Check.
How do we wire them? They have 4 pins, I haven't checked but it seems like they might fit on a PWM cable, but that only has 3 pins, so is it possible to wire it with only 3 pins or do we need to make new cables? --Jonathan |
|
#25
|
|||
|
|||
|
Re: Hall Effect Sensor.
Quote:
http://www2.usfirst.org/2005comp/Specs/gths1.pdf For a basic overview, looking from the top of the sensor, the pins from left to right are supply, output, int. connection, and ground. it can take 4.5 to 24 volts input voltage (you would probably use 12), and the output will provide a digital signal whenever a gear tooth passes by (whether or not the output is high or low when a tooth goes by depends on the direction of rotation). CHECK the spec sheet before you try it. It is helpful to see the diagram and check for yourself. Scott |
|
#26
|
|||
|
|||
|
Re: Hall Effect Sensor.
Quote:
|
|
#27
|
||||
|
||||
|
Re: Hall Effect Sensor.
Quote:
What kind of value does it give out? |
|
#28
|
|||||
|
|||||
|
Re: Hall Effect Sensor.
Has anyone had any luck with mounting the hall effect sensors?
i haven't found anything that fits them....... also, if you haven't read the manual it states that you must connect pin 4 to pin 3 externally. -Leav |
|
#29
|
||||
|
||||
|
Re: Hall Effect Sensor.
Quote:
|
|
#30
|
||||
|
||||
|
Re: Hall Effect Sensor.
Quote:
Please read http://www.chiefdelphi.com/forums/showthread.php?p=307123&highlight=encoders#post307 123. We were talking about encoders on that page but the theory of quadrature remains the same as what Mr. S is talking about. Last edited by Mike Betts : 13-01-2005 at 16:16. Reason: Fix URL Link |
![]() |
| Thread Tools | |
| Display Modes | Rate This Thread |
|
|
Similar Threads
|
||||
| Thread | Thread Starter | Forum | Replies | Last Post |
| Making a Sensor Board | SpaceOsc | Technical Discussion | 11 | 15-05-2004 12:46 |
| heres the code. y this not working | omega | Programming | 16 | 31-03-2004 15:18 |
| Banner Sensor Programming Problem | 2Crisis | Programming | 4 | 24-02-2004 13:40 |
| IR sensor trouble | D.Viddy | Electrical | 2 | 30-01-2004 09:49 |
| Quick Optical Sensor Question | zorro | Technical Discussion | 10 | 21-01-2003 06:39 |