+ Post New Thread
Results 1 to 15 of 15
  1. #1
    Junior Member level 1
    Points: 152, Level: 2

    Join Date
    May 2019
    Posts
    15
    Helped
    0 / 0
    Points
    152
    Level
    2

    Choose a proper magnetic field sensor

    Hi, i'm designing a smart parking and want to use magnetic field sensor on the ground (under the car) to detect the parking free/busy status.
    I prefer magnetic field sensor because ultrasonic need straight line of sight and cannot work within the box. And infrared sensor have problem in sun light. Other sensors cannot work on the 20-100 Cm distance (If this consideration have fault, please tell me)
    So i need help to choose a proper "chip" for my PCB that have a cheap price.
    Thanks

  2. #2
    Super Moderator
    Points: 265,324, Level: 100
    Awards:
    1st Helpful Member

    Join Date
    Jan 2008
    Location
    Bochum, Germany
    Posts
    46,357
    Helped
    14108 / 14108
    Points
    265,324
    Level
    100

    Re: Choose a proper magnetic field sensor

    How do you detect car presence with a magnetic field sensor?

    I would suggest a sensor loop as used for traffic light control.



    •   AltAdvertisement

        
       

  3. #3
    Banned
    Points: 6,361, Level: 19
    Achievements:
    7 years registered

    Join Date
    Dec 2012
    Location
    New Delhi
    Posts
    1,209
    Helped
    182 / 182
    Points
    6,361
    Level
    19

    Re: Choose a proper magnetic field sensor

    Try using SPAD LiDaR device, like VL53L0X for your purpose. Depending on what you are envisioning this might work better. Be aware that this too gets limited in bright outdoor direct sunlight.



  4. #4
    Full Member level 6
    Points: 4,791, Level: 16

    Join Date
    Feb 2002
    Posts
    321
    Helped
    30 / 30
    Points
    4,791
    Level
    16

    Re: Choose a proper magnetic field sensor

    You could try the TI mm wave sensors.



    •   AltAdvertisement

        
       

  5. #5
    Super Moderator
    Points: 81,905, Level: 69
    Achievements:
    7 years registered
    Awards:
    Most Frequent Poster 3rd Helpful Member

    Join Date
    Apr 2014
    Posts
    16,627
    Helped
    3764 / 3764
    Points
    81,905
    Level
    69

    Re: Choose a proper magnetic field sensor

    Hi,

    In my eyes the simplest, with low effort should be an ultrasonic sensor.
    But it's not clear to me why you think it will not work in your case.
    --> please make a draft about your application.

    There are already car detectors in parking houses... how do they work? Can't you use them as proven technique?

    Klaus
    Please don´t contact me via PM, because there is no time to respond to them. No friend requests. Thank you.



  6. #6
    Junior Member level 1
    Points: 152, Level: 2

    Join Date
    May 2019
    Posts
    15
    Helped
    0 / 0
    Points
    152
    Level
    2

    Re: Choose a proper magnetic field sensor

    Ultra Sonic cannot work behind a plastic box. So, i need a sensor that be able to detect material: detect metal of car's body and not deceiving with my plastic box.
    and about direct sunlight problem => that is crucial. because my application is on-street



  7. #7
    Super Moderator
    Points: 81,905, Level: 69
    Achievements:
    7 years registered
    Awards:
    Most Frequent Poster 3rd Helpful Member

    Join Date
    Apr 2014
    Posts
    16,627
    Helped
    3764 / 3764
    Points
    81,905
    Level
    69

    Re: Choose a proper magnetic field sensor

    Hi,

    You don't give much information. You will have your reasons, but it makes it almost impossible to help.

    Regarding IR and sunlight: usually sunlight is cancelled out by modulating the IR source and detecting the modulation signal...

    Klaus
    Please don´t contact me via PM, because there is no time to respond to them. No friend requests. Thank you.



    •   AltAdvertisement

        
       

  8. #8
    Super Moderator
    Points: 54,121, Level: 56

    Join Date
    Apr 2011
    Location
    Minneapolis, Minnesota, USA
    Posts
    13,191
    Helped
    2628 / 2628
    Points
    54,121
    Level
    56

    Re: Choose a proper magnetic field sensor

    I was just about to recommend something like an electronic compass made from hall sensors (example, digital compass in automobiles). But hall sensors respond to a magnetic field, and steel cars lack magnetism to influence a hall sensor.

    What kind of compass is in my steel car? By an internet search it appears that a different strategy is used in such compasses. A large ferrous mass alters the response of a hall sensor (or parallel hall sensors, or anti-parallel hall sensors) to the earth's magnetic field. This needs to be subtracted, but for your project it may work as a vehicle detector.

    The article below might have a method you can use to detect a steel vehicle.

    http://www.safety-devices.com/how-do...work-a-12.html



  9. #9
    Advanced Member level 5
    Points: 18,511, Level: 32
    Achievements:
    7 years registered

    Join Date
    Nov 2012
    Posts
    3,276
    Helped
    818 / 818
    Points
    18,511
    Level
    32

    Re: Choose a proper magnetic field sensor

    How about a large area coil using the principles of metal detector? They can have rather longer range and not affected by light etc etc.



  10. #10
    Advanced Member level 5
    Points: 18,511, Level: 32
    Achievements:
    7 years registered

    Join Date
    Nov 2012
    Posts
    3,276
    Helped
    818 / 818
    Points
    18,511
    Level
    32

    Re: Choose a proper magnetic field sensor

    because ultrasonic need straight line of sight and cannot work within the box. And infrared sensor have problem in sun light.
    The transducer can be mounted outside the box; it is quite robust. IR sensors are modulated; just like a remote control they can work in outdoor light. Will the magnetic field sensor will work at 100cm?

    Others have already pointed out some of these...



  11. #11
    Banned
    Points: 112, Level: 1

    Join Date
    Nov 2019
    Location
    London
    Posts
    16
    Helped
    0 / 0
    Points
    112
    Level
    1

    Re: Choose a proper magnetic field sensor

    The Magnetic Field Sensor can be used to study the field around permanent magnets, coils, and electrical devices. You can buy MC910 magnetic field sensor for your parking project.



    •   AltAdvertisement

        
       

  12. #12
    Super Moderator
    Points: 265,324, Level: 100
    Awards:
    1st Helpful Member

    Join Date
    Jan 2008
    Location
    Bochum, Germany
    Posts
    46,357
    Helped
    14108 / 14108
    Points
    265,324
    Level
    100

    Re: Choose a proper magnetic field sensor

    MC910 is a low frequency AC magnetic field sensor. Useless for car presence detection.



  13. #13
    Newbie level 1
    Points: 48, Level: 1

    Join Date
    Feb 2020
    Posts
    6
    Helped
    0 / 0
    Points
    48
    Level
    1

    Re: Choose a proper magnetic field sensor

    Quote Originally Posted by matriX_1500 View Post
    Hi, i'm designing a smart parking and want to use magnetic field sensor on the ground (under the car) to detect the parking free/busy status.
    I prefer magnetic field sensor because ultrasonic need straight line of sight and cannot work within the box. And infrared sensor have problem in sun light. Other sensors cannot work on the 20-100 Cm distance (If this consideration have fault, please tell me)
    So i need help to choose a proper "chip" for my PCB that have a cheap price.
    Thanks
    At present, on-street parking and outdoor parking lots generally use geomagnetic sensors. The magnetic field changes caused by the entry of ferrous vehicles are used to determine whether there is a car. The geomagnetic detector has a geomagnetic sensor inside.
    I have to say there are not many manufacturers doing this piece, most of them do indoor guidance. If you want to make related systems, you can ask some leading manufacturers like Aiko to ask.



  14. #14
    Super Moderator
    Points: 265,324, Level: 100
    Awards:
    1st Helpful Member

    Join Date
    Jan 2008
    Location
    Bochum, Germany
    Posts
    46,357
    Helped
    14108 / 14108
    Points
    265,324
    Level
    100

    Re: Choose a proper magnetic field sensor

    on-street parking and outdoor parking lots generally use geomagnetic sensors
    Any reference for this statement (product data sheet, literature quote)? I would expect inductive sensor loop as mentioned in post #2 and #9.



  15. #15
    Advanced Member level 5
    Points: 18,511, Level: 32
    Achievements:
    7 years registered

    Join Date
    Nov 2012
    Posts
    3,276
    Helped
    818 / 818
    Points
    18,511
    Level
    32

    Re: Choose a proper magnetic field sensor

    At present, on-street parking and outdoor parking lots generally use geomagnetic sensors.
    You can call them geomagnetic sensors but they are mostly a variant of metal detectors. They are well proven and tested designs.



--[[ ]]--