Ultrasonic ranger SRF08 underestimates the distance
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Posts: 46,084
In a message dated 6/21/2004 12:08:07 PM Eastern Daylight Time,
s.nelick@v... writes:
> I'm glad to see your note. I don't know the answer to your question, but
> I'm
> getting similar results from my SRF08. I thought my SRF08 was defective, but
> after seeing your note, maybe my SRF08 is OK.
>
How far above the surface do you have the sensors mounted? The higher the
better - they will sometimes pick up ground reflections since the outgoing
"beam" is conical in nature.
Sid
[noparse][[/noparse]Non-text portions of this message have been removed]
s.nelick@v... writes:
> I'm glad to see your note. I don't know the answer to your question, but
> I'm
> getting similar results from my SRF08. I thought my SRF08 was defective, but
> after seeing your note, maybe my SRF08 is OK.
>
How far above the surface do you have the sensors mounted? The higher the
better - they will sometimes pick up ground reflections since the outgoing
"beam" is conical in nature.
Sid
[noparse][[/noparse]Non-text portions of this message have been removed]
Comments
s.nelick@v... writes:
> I'm glad to see your note. I don't know the answer to your question, but
> I'm
> getting similar results from my SRF08. I thought my SRF08 was defective, but
> after seeing your note, maybe my SRF08 is OK.
>
Addon: The best way to test and calibrate the SR is to point it towards the
ceiling with nothing around it, then place objects in the beam pattern.
Sid
[noparse][[/noparse]Non-text portions of this message have been removed]
kender_a@y... writes:
> This is exacly what we did.
>
>
Then you've done your best. There is something about the SRF08 that is
markedly different than the 04 - can't remember exactly what it is, but if I recall
correctly it pointed me away from the 08. Right now I'm using the 04 with
ecellent results. You might contact Bruce at www.rentron.com. He is an expert
on the SRF devices.
Sid
[noparse][[/noparse]Non-text portions of this message have been removed]
The SRF08 was pointed verticaly to the ceeling, which was 150" away.
There was also an incondescent ligth 70" away from SRF08. I expected
to get the first bounce reading of 70", but it actually was 28".
Although at short distances (under 10") the readings were correct.
Does anybody know what went wrong?
Thank you,
Nick
I'm glad to see your note. I don't know the answer to your question, but I'm
getting similar results from my SRF08. I thought my SRF08 was defective, but
after seeing your note, maybe my SRF08 is OK.
In my case, I have been testing with an SRF08 and and an SRF04, both on
front of a BoeBot. The SRF04 seems to get a steady distance reading, and the
reading is what I get when I measure the distance. Sometimes the SRF08
reports the same reading as the SRF04, but sometimes the SRF08 jumps back
and forth between two readings, one reading is the same as the SRF04, and
one reading might be a lot lower.
Anway, I'm going to study the specs for the SRF08 and learn how to lower the
sensitivity, and also study all the readings from the SRF08. I've been using
just the first reading from the SRF08, and I haven't looked at the other 16
possible readings that are available.
Steve
_________
Original Message
From: "Nick Alexeev" <kender_a@y...>
To: <basicstamps@yahoogroups.com>
Sent: Monday, June 21, 2004 11:00 AM
Subject: [noparse][[/noparse]basicstamps] Ultrasonic ranger SRF08 underestimates the distance
> Colleagues,
>
> The SRF08 was pointed verticaly to the ceeling, which was 150" away.
> There was also an incondescent ligth 70" away from SRF08. I expected
> to get the first bounce reading of 70", but it actually was 28".
> Although at short distances (under 10") the readings were correct.
> Does anybody know what went wrong?
>
> Thank you,
> Nick
>
>
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed. Text in the Subject and
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>
> Yahoo! Groups Links
>
>
>
>
>
towards the
> ceiling with nothing around it, then place objects in the beam
pattern.
>
> Sid
This is exacly what we did.
Nick
one measuring mode. Make sure you're reading the correct register.
-- Jon Williams
-- Applications Engineer, Parallax
-- Dallas Office
Original Message
From: Nick Alexeev [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=yCIb-Vi3Wfts_LYYs4NJkfb5i6qCc9Zmmu2DqhphuieGq8hdXH7dgtZE2RLzxzD6v8hL83UN16c2JQq4]kender_a@y...[/url
Sent: Monday, June 21, 2004 10:01 AM
To: basicstamps@yahoogroups.com
Subject: [noparse][[/noparse]basicstamps] Ultrasonic ranger SRF08 underestimates the
distance
Colleagues,
The SRF08 was pointed verticaly to the ceeling, which was 150" away.
There was also an incondescent ligth 70" away from SRF08. I expected
to get the first bounce reading of 70", but it actually was 28".
Although at short distances (under 10") the readings were correct.
Does anybody know what went wrong?
Thank you,
Nick
SRF08 communicates with the host via I2C. This is very convenient for
robotics, as many robots require more than one sonar sensor.
-- Jon Williams
-- Applications Engineer, Parallax
-- Dallas Office
Original Message
From: Newzed@a... [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=PxHAzk3XnV06Mmo1PWz-HSUde_GPuJPWvW5PmVWW8X_wtDxbIzU_bz9cZ30WKl_D2w4nBh8]Newzed@a...[/url
Sent: Monday, June 21, 2004 12:36 PM
To: basicstamps@yahoogroups.com
Subject: Re: [noparse][[/noparse]basicstamps] Re: Ultrasonic ranger SRF08 underestimates
the distance
In a message dated 6/21/2004 1:32:18 PM Eastern Daylight Time,
kender_a@y... writes:
> This is exacly what we did.
>
>
Then you've done your best. There is something about the SRF08 that is
markedly different than the 04 - can't remember exactly what it is, but
if I recall
correctly it pointed me away from the 08. Right now I'm using the 04
with
ecellent results. You might contact Bruce at www.rentron.com. He is an
expert
on the SRF devices.
Sid
I made this troubleshooting step. Both centimeter and inch readings
are off, but consistent between each-other. However, I haven't
checked the time of flight (in ms) yet.
Nick
--- In basicstamps@yahoogroups.com, "Jon Williams" <jwilliams@p...>
wrote:
> Are you reading back inches or centimeters -- the SRF08 has more
than
> one measuring mode. Make sure you're reading the correct register.
>
> -- Jon Williams
> -- Applications Engineer, Parallax
> -- Dallas Office
>
>
>
Original Message
> From: Nick Alexeev [noparse][[/noparse]mailto:kender_a@y...]
> Sent: Monday, June 21, 2004 10:01 AM
> To: basicstamps@yahoogroups.com
> Subject: [noparse][[/noparse]basicstamps] Ultrasonic ranger SRF08 underestimates the
> distance
>
>
> Colleagues,
>
> The SRF08 was pointed verticaly to the ceeling, which was 150"
away.
> There was also an incondescent ligth 70" away from SRF08. I
expected
> to get the first bounce reading of 70", but it actually was 28".
> Although at short distances (under 10") the readings were correct.
> Does anybody know what went wrong?
>
> Thank you,
> Nick
calibrate the device.
Jon
Original Message
From: Nick Alexeev [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=-WoUqXXSmbRs0NJWmlJvSiyVRufQTYwXTQ1W6GpWPD2H2EdaMtOuyyU9qnVwWd2Q_G1NqLoPv6uqiG47hw]kender_a@y...[/url
Sent: Monday, June 21, 2004 2:35 PM
To: basicstamps@yahoogroups.com
Subject: [noparse][[/noparse]basicstamps] Re: Ultrasonic ranger SRF08 underestimates the
distance
Jon,
I made this troubleshooting step. Both centimeter and inch readings
are off, but consistent between each-other. However, I haven't
checked the time of flight (in ms) yet.
Nick
--- In basicstamps@yahoogroups.com, "Jon Williams" <jwilliams@p...>
wrote:
> Are you reading back inches or centimeters -- the SRF08 has more
than
> one measuring mode. Make sure you're reading the correct register.
>
> -- Jon Williams
> -- Applications Engineer, Parallax
> -- Dallas Office
>
>
>
Original Message
> From: Nick Alexeev [noparse][[/noparse]mailto:kender_a@y...]
> Sent: Monday, June 21, 2004 10:01 AM
> To: basicstamps@yahoogroups.com
> Subject: [noparse][[/noparse]basicstamps] Ultrasonic ranger SRF08 underestimates the
> distance
>
>
> Colleagues,
>
> The SRF08 was pointed verticaly to the ceeling, which was 150"
away.
> There was also an incondescent ligth 70" away from SRF08. I
expected
> to get the first bounce reading of 70", but it actually was 28".
> Although at short distances (under 10") the readings were correct.
> Does anybody know what went wrong?
>
> Thank you,
> Nick
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s.nelick@v... writes:
> Well, this robotic navigation is complicated .....
>
> Steve
>
True - I wound up putting my SRF04 on a pedestal and it worked better, but it
still bounced off the wall if it got too close. The only thing I can suggest
for you is to build a "hood" out of balsa wood or something similar and put
it around your sensors. The idea is to keep the sonar beam as narrow as
possible to avoid picking up echoes from walls and floors. I would try it on the 08
first to see if it made any difference. I think if the "hood" extended out
about 2 inches that should be a bodacious plenty.
The alternative would be to see if you can find a piece of thin-walled PVC
pipe that would fit over the transmitter.
Sid
[noparse][[/noparse]Non-text portions of this message have been removed]
kender_a@y... writes:
> Wouldn't the beam bounce off the hood and always give a very short
> first reading?
>
Not if you put the hood on just the transmitter.
Sid
[noparse][[/noparse]Non-text portions of this message have been removed]
I tried pointing the BoeBot to the ceiling, and the SRF04 and SRF08 reported
the same readings for the distance to the nearest object. But, if the BoeBot
is roaming on the floor, I get diiferences like 100 inches from the SRF04
and 20 inches from the SRF08. If I go to the BoeBot and measure out 100
inches, and 20 inches, I see that the SRF08 apparently has a much wider beam
pattern than the SRF04. In the case of 100 inches and 20 inches, the BoeBot
was heading down a hall, and 100 inches in front of the BoeBot was a door at
the end of the hall. To get a 20 inch distance reading from the BoeBot, you
have to measure out at maybe a 45 degree angle from the BoeBot, and then you
hit point on a wall, that was on the left side of the BoeBot.
Well, this robotic navigation is complicated .....
Steve
_______
Original Message
From: <Newzed@a...>
To: <basicstamps@yahoogroups.com>
Sent: Monday, June 21, 2004 1:19 PM
Subject: Re: [noparse][[/noparse]basicstamps] Ultrasonic ranger SRF08 underestimates the
distance
> In a message dated 6/21/2004 12:08:07 PM Eastern Daylight Time,
> s.nelick@v... writes:
>
>
> > I'm glad to see your note. I don't know the answer to your question, but
> > I'm
> > getting similar results from my SRF08. I thought my SRF08 was defective,
but
> > after seeing your note, maybe my SRF08 is OK.
> >
>
> Addon: The best way to test and calibrate the SR is to point it towards
the
> ceiling with nothing around it, then place objects in the beam pattern.
>
> Sid
>
>
> [noparse][[/noparse]Non-text portions of this message have been removed]
>
>
>
> 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.
>
> Yahoo! Groups Links
>
>
>
>
>
>Hello Sid,
>
>I tried pointing the BoeBot to the ceiling, and the SRF04 and SRF08 reported
>the same readings for the distance to the nearest object. But, if the BoeBot
>is roaming on the floor, I get diiferences like 100 inches from the SRF04
>and 20 inches from the SRF08. If I go to the BoeBot and measure out 100
>inches, and 20 inches, I see that the SRF08 apparently has a much wider beam
>pattern than the SRF04. In the case of 100 inches and 20 inches, the BoeBot
>was heading down a hall, and 100 inches in front of the BoeBot was a door at
>the end of the hall. To get a 20 inch distance reading from the BoeBot, you
>have to measure out at maybe a 45 degree angle from the BoeBot, and then you
>hit point on a wall, that was on the left side of the BoeBot.
>
>Well, this robotic navigation is complicated .....
>
>Steve
Steve -
You may find this technical documentation useful if you haven't found it already.
Here is the technical documentation on the SFR08 including the beam pattern:
http://www.robot-electronics.co.uk/htm/srf08tech.shtml
Here is the technical documentation on the SFR04 also including the beam pattern:
http://www.robot-electronics.co.uk/htm/srf04tech.htm
I hope that turns out to be helpful.
Regards,
Bruce Bates
> for you is to build a "hood" out of balsa wood or something similar
and put
> it around your sensors. The idea is to keep the sonar beam as
narrow as
> possible to avoid picking up echoes from walls and floors. I would
try it on the 08
> first to see if it made any difference. I think if the "hood"
extended out
> about 2 inches that should be a bodacious plenty.
>
> The alternative would be to see if you can find a piece of thin-
walled PVC
> pipe that would fit over the transmitter.
>
> Sid
Wouldn't the beam bounce off the hood and always give a very short
first reading?
Nick
Yesterday night I have done some more testing. It turns out that
SRF08 measures the distances between 0 and 0.8m correctly, but if the
distance to the obstacle is longer then 0.8m, the unit reports 0.8m.
I need to srutinize the user manual some more.
By the way, does anyone know who provides the technical support for
SRF08?
Regards,
Nick
--- In basicstamps@yahoogroups.com, "Jon Williams" <jwilliams@p...>
wrote:
> Check the docs, I believe that there is a register that lets you
> calibrate the device.
>
> Jon
>
>
>
Original Message
> From: Nick Alexeev [noparse][[/noparse]mailto:kender_a@y...]
> Sent: Monday, June 21, 2004 2:35 PM
> To: basicstamps@yahoogroups.com
> Subject: [noparse][[/noparse]basicstamps] Re: Ultrasonic ranger SRF08 underestimates
the
> distance
>
>
> Jon,
>
> I made this troubleshooting step. Both centimeter and inch readings
> are off, but consistent between each-other. However, I haven't
> checked the time of flight (in ms) yet.
>
> Nick
>
>
> --- In basicstamps@yahoogroups.com, "Jon Williams" <jwilliams@p...>
> wrote:
> > Are you reading back inches or centimeters -- the SRF08 has more
> than
> > one measuring mode. Make sure you're reading the correct
register.
> >
> > -- Jon Williams
> > -- Applications Engineer, Parallax
> > -- Dallas Office
> >
> >
> >
Original Message
> > From: Nick Alexeev [noparse][[/noparse]mailto:kender_a@y...]
> > Sent: Monday, June 21, 2004 10:01 AM
> > To: basicstamps@yahoogroups.com
> > Subject: [noparse][[/noparse]basicstamps] Ultrasonic ranger SRF08 underestimates the
> > distance
> >
> >
> > Colleagues,
> >
> > The SRF08 was pointed verticaly to the ceeling, which was 150"
> away.
> > There was also an incondescent ligth 70" away from SRF08. I
> expected
> > to get the first bounce reading of 70", but it actually was 28".
> > Although at short distances (under 10") the readings were
correct.
> > Does anybody know what went wrong?
> >
> > Thank you,
> > Nick
should absorb a lot of ultrasonics.
Has anyone tried this?
Mike Sokol
Original Message
From: "Nick Alexeev" <kender_a@y...>
To: <basicstamps@yahoogroups.com>
Sent: Tuesday, June 22, 2004 12:11 PM
Subject: [noparse][[/noparse]basicstamps] Re: Ultrasonic ranger SRF08 underestimates the
distance
> > The only thing I can suggest
> > for you is to build a "hood" out of balsa wood or something similar
> and put
> > it around your sensors. The idea is to keep the sonar beam as
> narrow as
> > possible to avoid picking up echoes from walls and floors. I would
> try it on the 08
> > first to see if it made any difference. I think if the "hood"
> extended out
> > about 2 inches that should be a bodacious plenty.
> >
> > The alternative would be to see if you can find a piece of thin-
> walled PVC
> > pipe that would fit over the transmitter.
> >
> > Sid
>
> Wouldn't the beam bounce off the hood and always give a very short
> first reading?
>
> 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.
>
> Yahoo! Groups Links
>
>
>
>
>
>
products. You might try them.
-- Jon Williams
-- Applications Engineer, Parallax
-- Dallas Office
Original Message
From: Nick Alexeev [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=0LFS8PTqyXfaFA-Fp3lJGozd_0fyq20_COTEYG2xlSXpkHysLvZHo0DaJYEMiLcxmpAhpZiNn5ohHxHy]kender_a@y...[/url
Sent: Tuesday, June 22, 2004 11:18 AM
To: basicstamps@yahoogroups.com
Subject: [noparse][[/noparse]basicstamps] Re: Ultrasonic ranger SRF08 underestimates the
distance
Hello!
Yesterday night I have done some more testing. It turns out that
SRF08 measures the distances between 0 and 0.8m correctly, but if the
distance to the obstacle is longer then 0.8m, the unit reports 0.8m.
I need to srutinize the user manual some more.
By the way, does anyone know who provides the technical support for
SRF08?
Regards,
Nick
--- In basicstamps@yahoogroups.com, "Jon Williams" <jwilliams@p...>
wrote:
> Check the docs, I believe that there is a register that lets you
> calibrate the device.
>
> Jon
>
>
>
Original Message
> From: Nick Alexeev [noparse][[/noparse]mailto:kender_a@y...]
> Sent: Monday, June 21, 2004 2:35 PM
> To: basicstamps@yahoogroups.com
> Subject: [noparse][[/noparse]basicstamps] Re: Ultrasonic ranger SRF08 underestimates
the
> distance
>
>
> Jon,
>
> I made this troubleshooting step. Both centimeter and inch readings
> are off, but consistent between each-other. However, I haven't
> checked the time of flight (in ms) yet.
>
> Nick
>
>
> --- In basicstamps@yahoogroups.com, "Jon Williams" <jwilliams@p...>
> wrote:
> > Are you reading back inches or centimeters -- the SRF08 has more
> than
> > one measuring mode. Make sure you're reading the correct
register.
> >
> > -- Jon Williams
> > -- Applications Engineer, Parallax
> > -- Dallas Office
> >
> >
> >
Original Message
> > From: Nick Alexeev [noparse][[/noparse]mailto:kender_a@y...]
> > Sent: Monday, June 21, 2004 10:01 AM
> > To: basicstamps@yahoogroups.com
> > Subject: [noparse][[/noparse]basicstamps] Ultrasonic ranger SRF08 underestimates the
> > distance
> >
> >
> > Colleagues,
> >
> > The SRF08 was pointed verticaly to the ceeling, which was 150"
> away.
> > There was also an incondescent ligth 70" away from SRF08. I
> expected
> > to get the first bounce reading of 70", but it actually was 28".
> > Although at short distances (under 10") the readings were
correct.
> > Does anybody know what went wrong?
> >
> > Thank you,
> > Nick
>Hello!
>
>Yesterday night I have done some more testing. It turns out that
>SRF08 measures the distances between 0 and 0.8m correctly, but if the
>distance to the obstacle is longer then 0.8m, the unit reports 0.8m.
>
>I need to srutinize the user manual some more.
>By the way, does anyone know who provides the technical support for
>SRF08?
>
>Regards,
>Nick
Nick -
These are the folks who designed it:
http://www.robot-electronics.co.uk/
Regards,
Bruce Bates
front, where returns that are 'too close' are
ignored. This allows it not to false trigger on
the ringing of the output signal.
Thus, any returns from any 'shroud' you put around
it "should" be ignored. That's the theory, anyway.
Your mileage may vary.
--- In basicstamps@yahoogroups.com, "Nick Alexeev" <kender_a@y...>
wrote:
> > The only thing I can suggest
> > for you is to build a "hood" out of balsa wood or something
similar
> and put
> > it around your sensors. The idea is to keep the sonar beam as
> narrow as
> > possible to avoid picking up echoes from walls and floors. I
would
> try it on the 08
> > first to see if it made any difference. I think if the "hood"
> extended out
> > about 2 inches that should be a bodacious plenty.
> >
> > The alternative would be to see if you can find a piece of thin-
> walled PVC
> > pipe that would fit over the transmitter.
> >
> > Sid
>
> Wouldn't the beam bounce off the hood and always give a very short
> first reading?
>
> Nick
and my circuit supplied only 150mA. As soon as I added a 1A linear
regulator the SRF08 started to give adequate readings.
Many thanks to you all!
Nick
--- In basicstamps@yahoogroups.com, "Nick Alexeev" <kender_a@y...>
wrote:
> Colleagues,
>
> The SRF08 was pointed verticaly to the ceeling, which was 150"
away.
> There was also an incondescent ligth 70" away from SRF08. I
expected
> to get the first bounce reading of 70", but it actually was 28".
> Although at short distances (under 10") the readings were correct.
> Does anybody know what went wrong?
>
> Thank you,
> Nick
the power supply. The capacitor will provide additional power for short
duration peak current draws.
Woof
Original Message
From: Nick Alexeev [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=uagSSiwuI4USQw8Vm8DFrJ9wTRghAHnOAv4mmeI6kYt3HKuwZSh26SjZv1tSOf4LvaeDfFtelbA]kender_a@y...[/url
Sent: Thursday, June 24, 2004 12:12 AM
To: basicstamps@yahoogroups.com
Subject: [noparse][[/noparse]basicstamps] Re: Ultrasonic ranger SRF08 underestimates the
distance
Power supply was a problem. The SRF08 draws 225mA during the ping,
and my circuit supplied only 150mA. As soon as I added a 1A linear
regulator the SRF08 started to give adequate readings.
Many thanks to you all!
Nick
--- In basicstamps@yahoogroups.com, "Nick Alexeev" <kender_a@y...>
wrote:
> Colleagues,
>
> The SRF08 was pointed verticaly to the ceeling, which was 150"
away.
> There was also an incondescent ligth 70" away from SRF08. I
expected
> to get the first bounce reading of 70", but it actually was 28".
> Although at short distances (under 10") the readings were correct.
> Does anybody know what went wrong?
>
> Thank you,
> Nick
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