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angle/direction sensing (was Memsic sensor and rotation) — Parallax Forums

angle/direction sensing (was Memsic sensor and rotation)

ArchiverArchiver Posts: 46,084
edited 2003-09-17 15:39 in General Discussion
Hi,
I'm looking for a way to sense the direction that my robot is facing (Yaw).
I've been looking at a couple of gyroscopes online, but the cost and wait
time (2 months) are prohibitive. These are Murata's Gyrostar, and Analog
Device's ADXRS150-EB (the evaluation board). Both seem pretty interesting
giving a reading of acceleration as your bot turns, which you should be able
to integrate to get velocity and angle.
This area is new to me so perhaps I'm overlooking an economical method for
figuring out the angle. I have other accelerometers in the circuit from
which linear velocity and distance is gathered in both x and y directions,
as well tilt in x and y (using the memsic ic). Perhaps there's some trig
function that derive's Yaw from these other properties?
Alternatively does anyone know of any other more affordable gyros. There's a
nuts and volts article on Austria Microsystem's AS5020 but if I understand
it correctly you need to have a fixed magnet or metal object close by as a
reference point?
Cheers,
nick

Comments

  • ArchiverArchiver Posts: 46,084
    edited 2003-09-16 18:08
    If you just need a general direction without precision positioning, modify a
    compass with some sensors and read out the position from it.

    jim
    http://www.geocities.com/jimforkin2003/


    Original Message
    From: nick stedman [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=As4kACs1t7qYzoZi9G2j47cT8ylld31gpCgchdtXeoPVaPNJqMxTEgN1E5oik27_QW8KcDMC-6uPeqP8axWyHpZF]nickstedman@s...[/url
    Sent: Tuesday, September 16, 2003 12:03 PM
    To: basicstamps@yahoogroups.com
    Subject: [noparse][[/noparse]basicstamps] angle/direction sensing (was Memsic sensor and
    rotation)


    Hi,
    I'm looking for a way to sense the direction that my robot is facing (Yaw).
    I've been looking at a couple of gyroscopes online, but the cost and wait
    time (2 months) are prohibitive. These are Murata's Gyrostar, and Analog
    Device's ADXRS150-EB (the evaluation board). Both seem pretty interesting
    giving a reading of acceleration as your bot turns, which you should be able
    to integrate to get velocity and angle.
    This area is new to me so perhaps I'm overlooking an economical method for
    figuring out the angle. I have other accelerometers in the circuit from
    which linear velocity and distance is gathered in both x and y directions,
    as well tilt in x and y (using the memsic ic). Perhaps there's some trig
    function that derive's Yaw from these other properties?
    Alternatively does anyone know of any other more affordable gyros. There's a
    nuts and volts article on Austria Microsystem's AS5020 but if I understand
    it correctly you need to have a fixed magnet or metal object close by as a
    reference point?
    Cheers,
    nick


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  • ArchiverArchiver Posts: 46,084
    edited 2003-09-16 18:11
    You might consider the Devantech CMPS01 compass that is available from
    Acroname. I've used it with BASIC Stamps and the Javelin Stamp.

    -- Jon Williams
    -- Applications Engineer, Parallax
    -- Dallas Office


    Original Message
    From: nick stedman [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=pGYGLOuiM6b_upwImlReRaYVt-ZEZiu9ZMN8Llv5tpH1wCiNL1atjcuMzE3Z4uTJOQ5NWIsjExGpd-Ubl78]nickstedman@s...[/url
    Sent: Tuesday, September 16, 2003 11:03 AM
    To: basicstamps@yahoogroups.com
    Subject: [noparse][[/noparse]basicstamps] angle/direction sensing (was Memsic sensor and
    rotation)


    Hi,
    I'm looking for a way to sense the direction that my robot is facing
    (Yaw). I've been looking at a couple of gyroscopes online, but the cost
    and wait time (2 months) are prohibitive. These are Murata's Gyrostar,
    and Analog Device's ADXRS150-EB (the evaluation board). Both seem pretty
    interesting giving a reading of acceleration as your bot turns, which
    you should be able to integrate to get velocity and angle. This area is
    new to me so perhaps I'm overlooking an economical method for figuring
    out the angle. I have other accelerometers in the circuit from which
    linear velocity and distance is gathered in both x and y directions, as
    well tilt in x and y (using the memsic ic). Perhaps there's some trig
    function that derive's Yaw from these other properties? Alternatively
    does anyone know of any other more affordable gyros. There's a nuts and
    volts article on Austria Microsystem's AS5020 but if I understand it
    correctly you need to have a fixed magnet or metal object close by as a
    reference point? Cheers, nick


    To UNSUBSCRIBE, just send mail to:
    basicstamps-unsubscribe@yahoogroups.com
    from the same email address that you subscribed. Text in the Subject
    and Body of the message will be ignored.


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    http://docs.yahoo.com/info/terms/




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    abuse@p....
  • ArchiverArchiver Posts: 46,084
    edited 2003-09-16 18:15
    Nick,
    Both gyro chips that you mention produce angular velocity directly, not
    angular acceleration. Integrating velocity to produce position has the
    problem that any DC offsets also get integrated, producing a ramp in
    position, which acts as a drift error. Have you considered a digital
    compass circuit instead, which would give an absolute reference for
    direction?
    Dennis

    Original Message
    From: nick stedman [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=uDXtW5F26L3ThhbqDEXp9R4H5xJdzPSTB0Rp16zYdMqWh5ZovQQPIX3HDds63mb22ssC9qdZ9Pe1dyTuWLLHUaHwIw]nickstedman@s...[/url
    Sent: Tuesday, September 16, 2003 9:03 AM
    To: basicstamps@yahoogroups.com
    Subject: [noparse][[/noparse]basicstamps] angle/direction sensing (was Memsic sensor and
    rotation)


    Hi,
    I'm looking for a way to sense the direction that my robot is facing
    (Yaw). I've been looking at a couple of gyroscopes online, but the cost
    and wait time (2 months) are prohibitive. These are Murata's Gyrostar,
    and Analog Device's ADXRS150-EB (the evaluation board). Both seem pretty
    interesting giving a reading of acceleration as your bot turns, which
    you should be able to integrate to get velocity and angle. This area is
    new to me so perhaps I'm overlooking an economical method for figuring
    out the angle. I have other accelerometers in the circuit from which
    linear velocity and distance is gathered in both x and y directions, as
    well tilt in x and y (using the memsic ic). Perhaps there's some trig
    function that derive's Yaw from these other properties? Alternatively
    does anyone know of any other more affordable gyros. There's a nuts and
    volts article on Austria Microsystem's AS5020 but if I understand it
    correctly you need to have a fixed magnet or metal object close by as a
    reference point? Cheers, nick


    To UNSUBSCRIBE, just send mail to:
    basicstamps-unsubscribe@yahoogroups.com
    from the same email address that you subscribed. Text in the Subject
    and Body of the message will be ignored.


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    http://docs.yahoo.com/info/terms/
  • ArchiverArchiver Posts: 46,084
    edited 2003-09-17 15:39
    Thanks for the responses.
    It's amazing, I had been searching for digital compasses at Digikey and only
    found ones that cost a minimum of $500. But I overlooked the simple google
    search. These look interesting...<http://www.dinsmoresensors.com/>. Anyway,
    I decided to go with the devantech compass, because I've been happy with
    their other sensors. Also, the retailer is in my city, so I won't need to
    wait very long to get it.
    Cheers,
    Nick


    on 09/16/03 1:11 PM, Jon Williams at jwilliams@p... wrote:

    > You might consider the Devantech CMPS01 compass that is available from
    > Acroname. I've used it with BASIC Stamps and the Javelin Stamp.
    >
    > -- Jon Williams
    > -- Applications Engineer, Parallax
    > -- Dallas Office
    >
    >
    >
    Original Message
    > From: nick stedman [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=qJAS5P7aTaAZaRTFGSgrjneye4lKoT7LjLyEUq-ofQjISw1958gUzKeD1UMMGWDgPqU6g1Lkcp4mppaeDI1QR3l9Wg]nickstedman@s...[/url
    > Sent: Tuesday, September 16, 2003 11:03 AM
    > To: basicstamps@yahoogroups.com
    > Subject: [noparse][[/noparse]basicstamps] angle/direction sensing (was Memsic sensor and
    > rotation)
    >
    >
    > Hi,
    > I'm looking for a way to sense the direction that my robot is facing
    > (Yaw). I've been looking at a couple of gyroscopes online, but the cost
    > and wait time (2 months) are prohibitive. These are Murata's Gyrostar,
    > and Analog Device's ADXRS150-EB (the evaluation board). Both seem pretty
    > interesting giving a reading of acceleration as your bot turns, which
    > you should be able to integrate to get velocity and angle. This area is
    > new to me so perhaps I'm overlooking an economical method for figuring
    > out the angle. I have other accelerometers in the circuit from which
    > linear velocity and distance is gathered in both x and y directions, as
    > well tilt in x and y (using the memsic ic). Perhaps there's some trig
    > function that derive's Yaw from these other properties? Alternatively
    > does anyone know of any other more affordable gyros. There's a nuts and
    > volts article on Austria Microsystem's AS5020 but if I understand it
    > correctly you need to have a fixed magnet or metal object close by as a
    > reference point? Cheers, nick
    >
    >
    > To UNSUBSCRIBE, just send mail to:
    > basicstamps-unsubscribe@yahoogroups.com
    > from the same email address that you subscribed. Text in the Subject
    > and Body of the message will be ignored.
    >
    >
    > Your use of Yahoo! Groups is subject to
    > http://docs.yahoo.com/info/terms/
    >
    >
    >
    >
    > This message has been scanned by WebShield. Please report SPAM to
    > abuse@p....
    >
    >
    > To UNSUBSCRIBE, just send mail to:
    > basicstamps-unsubscribe@yahoogroups.com
    > from the same email address that you subscribed. Text in the Subject and Body
    > of the message will be ignored.
    >
    >
    > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
    >
    >
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