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1  Using Arduino / Sensors / Re: Suggest an ultrasonic sensor on: May 08, 2013, 04:33:45 pm
Hello, this is Tom Bonar from MaxBotix Inc.  I saw your forum post and thought I would lend some insight and assistance regarding the use of ultrasonics.

@Kushki
You state:  For ranging I need to be able to read the distance at least 20 times in a second although higher is better (>20 Hz, 30 Hz is awesome).  The minimum range is 4m or higher.
Like AWOL stated, the longer the range is the slower the refresh rate is going to be.  Also at longer ranges, if you have fast refresh rates, there is a high probability that the ultrasonic reflection you get back may have been from a previous transmit burst.  If this reflection comes back to the sensor shortly after the transmit burst the sensor will view it as a target and report the range as such.  Sensors such as our 10 meter HRXL-MaxSonar-WR sensors have the range that you are looking for, but because of the speed of sound they do not have the refresh rate you desire.  

Does this information help?

@AWOL

You state:  Operating ultrasonics in a street environment on a moving vehicle is going to limit range even more, I'd imagine - too many sources of noise.

The MaxBotix HRXL-MaxSonar-WR sensors have an advanced acoustic noise filter that can and have handled acoustic noise that comes from operating on a highway.  One of our customers mounts our sensors on semi-trucks for controlling the hydraulic on trailers to raise and lower them as needed when passing under bridges.  Information on this application can be read on our website at http://maxbotix.com/articles/069.htm.  This article was written by the customer that uses the particular sensor.

Does this information help?

If assistance is needed regarding choosing an ultrasonic sensor for an application or if a sensor will work in your application please feel free to email me directly at thomas@maxbotix.com.  I am here to make sure you are supported in your application.

Please let me know if you have any questions.

Best regards,

Tom Bonar
Technical Support
of MaxBotix Inc.
Phone: (218) 454-0766
Fax: (218) 454-0768
Email: thomas@maxbotix.com

Web: www.maxbotix.com

Follow us on Facebook at: http://www.facebook.com/pages/MaxBotix-Inc/125159384204938
2  Using Arduino / Sensors / Re: Maxbotix MB1030 R232 serial connection to arduino on: April 01, 2013, 12:48:30 pm
Hello!  This is Tom Bonar from MaxBotix Inc.

I saw your forum post, and would like to give some assistance regarding your technical questions.

You asked in your forum post what asynchronous serial with RS232 means.  Wikipedia, has a good definition on this term.  Please read the following exert from Wikipedia. Asynchronous serial communication describes a serial communication protocol in which a start signal is sent prior to each byte, character or code word and a stop signal is sent after each code word, so as to make the communication asynchronous. The start signal serves to prepare the receiving mechanism for the reception and registration of a symbol and the stop signal serves to bring the receiving mechanism to rest in preparation for the reception of the next symbol.

RS232 means that the signal sent from the sensor is held low (0) when no signal is being sent, and brought high (typically 12V, but in the case of our sensors Vcc) when signal is being sent.

In your forum post you also asked "it says to invert the signal, but I have no idea what I should do for that"?

A computers DB9 port by default will read RS232 signal using software such as HyperTerminal.  Some microcontrollers will require an inverter to read the signal, this is because they may only accept a TTL serial input.

To invert an RS232 signal to TTL, a component such as a Max232.  Using this device, will allow the sensor to be read by a component that is only able to have TTL input into the component.

Finally, you stated "I want a pure software approach to this and I am sure there is, but the non-standard voltages and the inverted signal are killing me."

After a quick search on google, I have found the following forum "Reading serial data from MaxSonar ultrasonic rangefinder".  This was written for Arduino, while using the RS232 output of our sensor.  Please be aware, we haven't tested this code, but none the less should be beneficial for you.

Please let me know if you have any questions.

Best regards,

Tom Bonar
Technical Support
of MaxBotix Inc.
Email: thomas@maxbotix.com
Web: www.maxbotix.com
3  Using Arduino / General Electronics / Re: Power Issues creating sensor read issues on: February 18, 2013, 01:53:18 pm
Hello!  This is Tom Bonar from MaxBotix Inc.

@PostHoles
The current draw of our sensors is not enough to damage a component such as the yellowjacket.  Our LV-MaxSonar-EZ have a max current draw of ~7.5mA and an average current draw of ~2.1 during operation.  The max current draw occurs during the transmit burst of the transducer.  Such low current draws are not capable of damaging the component being used to read or control the sensor.

Our MB1010 sensor referenced in your post will operate at 2.5V DC to 5.5VDC. 

Have you been able to correct the issue? Please let me know if you have any questions by emailing thomas@maxbotix.com and I will be glad to assist you. 

Best regards,

Tom Bonar
Technical Support
of MaxBotix Inc.
Phone: (218) 454-0766
Fax: (218) 454-0768
Email: thomas@maxbotix.com
Web: www.maxbotix.com
Follow us on Facebook at: http://www.facebook.com/pages/MaxBotix-Inc/125159384204938

Technical support and sales are subject to
the terms and conditions listed on our
website at http://www.maxbotix.com/ MaxBotix,
MaxSonar,EZ0, EZ1, EZ2, EZ3, EZ4, AE0, AE1,
AE2, AE3, AE4, WR1, WRA1, and WRLA1 are
trademarks of MaxBotix Inc.
4  Using Arduino / Sensors / Re: slight change in sketch means sensor won't let servo run with the +5v connected on: February 18, 2013, 01:43:19 pm
Hello!  This is Tom Bonar from MaxBotix Inc.

@PrinterBird

I see that you are using one of our LV-MaxSonar-EZ sensors in your application, and you are trying to use it to trip an Arduino at a set distance in your sketch.  The distance that you mentioned of 2 inches, is not able to be done with our sensors.  The LV-MaxSonar-EZ sensors have a minimum reported distance of 6 inches.  This means that anything closer than 6 inches is reported as 6 inches.  If you change your sketch to trip at 7 or 8 inches, your programming should work. The sensor will provide range data to the detected object from 6 inches to 255 inches.

Please let me know if you have any questions by emailing thomas@maxbotix.com and I will be glad to assist you.

Best regards,

Tom Bonar
Technical Support
of MaxBotix Inc.
Phone: (218) 454-0766
Fax: (218) 454-0768
Email: thomas@maxbotix.com
Web: www.maxbotix.com
Follow us on Facebook at: http://www.facebook.com/pages/MaxBotix-Inc/125159384204938

Technical support and sales are subject to
the terms and conditions listed on our
website at http://www.maxbotix.com/ MaxBotix,
MaxSonar,EZ0, EZ1, EZ2, EZ3, EZ4, AE0, AE1,
AE2, AE3, AE4, WR1, WRA1, and WRLA1 are
trademarks of MaxBotix Inc.
5  Using Arduino / Sensors / Re: MaxSonar Noise Problem? on: February 08, 2013, 12:50:59 pm
Hello! This is Tom Bonar from MaxBotix Inc.

Mark I saw your forum post and I would like to help you with your application.  Can you please email me at thomas@maxbotix.com with your wiring diagram, and any questions you have regarding our sensor?

Please let me know if you have any questions.

Best regards,

Tom Bonar
Technical Support
of MaxBotix Inc.
Phone: (218) 454-0766
Fax: (218) 454-0768
Email: thomas@maxbotix.com

Web: www.maxbotix.com

Follow us on Facebook at: http://www.facebook.com/pages/MaxBotix-Inc/125159384204938

Technical support and sales are subject to
the terms and conditions listed on our
website at http://www.maxbotix.com/ MaxBotix,
MaxSonar,EZ0, EZ1, EZ2, EZ3, EZ4, AE0, AE1,
AE2, AE3, AE4, WR1, WRA1, and WRLA1 are
trademarks of MaxBotix Inc.
6  Using Arduino / Sensors / Re: Extreme data variation with MaxBotix Ultrasonic Rangefinder on: January 10, 2013, 01:56:12 pm
Hello, this is Scott from MaxBotix Inc.

We have been communicating through email, and I wanted to publish the resolution to this problem on the forum.

One of the issues that is happening is by using the LV-MaxSonar-EZ sensor on a Quad-Copter, the sensor is not able to adjust for the large amount noise of the copter which means the sensor is unable to range reliably. The Quad-Copter in flight acts as a constant noise source. In addition,  many quads have been found to supply unstable power to the sensors.  After testing a quad-copter at our facility, we have found that the MB1240 and MB1242 operated the best on multi-copters.

Our engineers have found that it is best not to mount the sensor in the prop-wash.  Prop-wash can act as an acoustic noise that can cause interference with the sensor.

Additional engineering recommendations are to use our MB7954 cable and MB7961 Power Supply Filter kit with the sensors.  The reason for this recommendation of the MB7961 is the control device for the multi-copter may not output stable power to the sensor.  The MB7961 can help stabilize the power that is supplied to the sensor so the best performance is achieved. Additionally, the shielded wire ensures no noise is injected into your sensors connection wires which can cause performance issues.

Please let me know if you have any questions by emailing scott@maxbotix.com

Best regards,

Scott Wielenberg
Technical Support & Sales
of MaxBotix Inc.
Phone: (218) 454-0766
Fax: (218) 454-0768
Email: scott@maxbotix.com
Web: www.maxbotix.com
Follow us on Facebook at: http://www.facebook.com/pages/MaxBotix-Inc/125159384204938

Technical support and sales are subject to
the terms and conditions listed on our
website at http://www.maxbotix.com/ MaxBotix,
MaxSonar,EZ0, EZ1, EZ2, EZ3, EZ4, AE0, AE1,
AE2, AE3, AE4, WR1, WRA1, and WRLA1 are
trademarks of MaxBotix Inc.
7  Using Arduino / Project Guidance / Re: Reliable movement detection for a year on: November 15, 2012, 12:54:49 pm
Hello this is Scott from MaxBotix Inc.
 
I saw that you stated: “I have thought about using the MaxSonar sensor (http://www.adafruit.com/blog/2009/06/23/getting-started-with-the-maxbotix-sonar-sensor-quick-start-guide/), but I don't know if it will be precise enough. The sensors will be placed at 3 different locations at a spiral staircase, and should be activated when people are present in it's area."
 
You may want to consider using one of our ProxSonar sensors. We have them available in either a USB or Pin Out interface depending on the interface you want to use. Both sensors have a pin that can be monitored that gives a digital high/low signal if a person is in the detection zone of the sensor. The interface with the pin out configure is able to operate within 2.5V to 5.5V and the USB only operates from the voltage supplied by the USB port. Our HRLV-MaxSonar-EZ may be a good rangefinding sensor for your application also.  There is some multi-sensor operation built into the sensor.  We are currently testing these parameters yet at our last trade show, we had 4 sensors (3 ProxSonars and 1 HRLV-MaxSonar) operating at our booth independently without interference in the reported range.   
 
The LV-ProxSonar-EZ ultrasonic proximity sensor can be seen here http://maxbotix.com/Ultrasonic_Sensors/Ultrasonic_Proximity_Sensor.htm.
The USB-ProxSonar-EZ ultrasonic USB proximity sensor can be seen here http://maxbotix.com/Ultrasonic_Sensors/USB_Proximity_Sensor.htm.
 
If you are looking for the range to the person in the stair well you may want to test the HRLV-MaxSonar-EZ. The sensor can be connected to Arduino or other control device that is programmed to ignore distances after a certain amount. The HRLV-MaxSonar-EZ can be seen here http://maxbotix.com/Ultrasonic_Sensors/High_Resolution_Sensors.htm.

Please let me know if you have any questions by emailing me at scott@maxbotix.com. I hope this information help. 

Best regards,

Scott Wielenberg
Technical Support & Sales
of MaxBotix Inc.
Phone: (218) 454-0766
Fax: (218) 454-0768
Email: scott@maxbotix.com
Web: www.maxbotix.com
Follow us on Facebook at: http://www.facebook.com/pages/MaxBotix-Inc/125159384204938
8  Using Arduino / Sensors / Re: recommedation for ultrasonic water level sensor? on: September 21, 2012, 11:30:09 am
@gardner
Hello this is Scott from MaxBotix Inc. 

I noticed that you were looking for recommendations on tank level sensors.  We have a great sensor that is proven to work great in the application you have described.  You can see our tank test by clicking this link.  I would recommend testing MB7360 ultrasonic sensor.  This sensor features 1-mm resolution that is temperature, target size, and voltage compensation that ensures you receive the best results.  The MB7360 has the same form factor as the LV-MaxSonar-WR1 that you linked earlier.

I am glad to assist you with any other questions you may have.  If you have any, please email me at scott@maxbotix.com. Good luck on your project. 

Best regards,

Scott Wielenberg
Technical Support & Sales
of MaxBotix Inc.
Phone: (218) 454-0766
Fax: (218) 454-0768
Email: scott@maxbotix.com
Web: www.maxbotix.com
Follow us on Facebook at: http://www.facebook.com/pages/MaxBotix-Inc/125159384204938
9  Forum 2005-2010 (read only) / Interfacing / Re: Maxbotix LV-MaxSonar-EZ - random value drops on: November 03, 2010, 08:05:00 am
Hello,

I saw your forum post and have review your issue.

Causes of Incorrect range readings (with a properly installed and properly powered sensor)

Multiple Sensor Applications (Cross Talk)
Ultrasonic Sensors output and receive sound information when taking a range reading.  If multiple sensors are operational in the same environment this may cause one sensor to receive information sent by another sensor.  To eliminate interference, we recommend running sensors in sequence.  Refer to the examples of the three recommended ways to chain the sensors together.
http://www.maxbotix.com/uploads/Chaining_Application_Notes__AN_Output_Commanded_Loop_.pdf
http://www.maxbotix.com/uploads/Chaining_Application_Notes__AN_Output_Constantly_Looping_.pdf
http://www.maxbotix.com/uploads/Chaining_Application_Notes__AN_Output_Simultaneous_Operation_.pdf

External acoustic noise
External acoustic noise sources may cause false range readings, that make phantom objects appear (i.e. readings are too close).  

Soft or angled targets
Also soft targets or angled targets can be missed occasionally.  That is, there must be a return of sufficient amplitude for detection and if enough energy is not returned then the target is missed.  This missed target issue can be exacerbated up close, where the returning energy must be detected in the presence of very high energy ring-down, so soft targets, or off axis targets, may not be detected easily.  (We will set the sensor to optimize for this... but the rules of physics will still apply.)

Filtering in General
For filtering, do not average.  Do not average.  Do not average.  (Did I say, do not average?)  We have a lot of internal filtering in our products and if you receive readings that you feel must be filtered, do not use averaging.  Instead, throwing out the incorrect range values will produce the best results.  Averaging valid and invalid readings together will provide incorrect data.  

Filtering
The filtering that works best, is either a Mode filter or a Median filter.  (Did I forget to say, "Do not average the readings"?)
  
The Median Filter
The median filter would take the last group of readings and first sort them and then pull out the center reading.  Here one might take three or more readings (up to say about 11 for people sensing) and after sorting the readings in order of range, pull out and use only the middle (median) reading.  Fairly good filtering.

The Mode Filter
The mode filter would take the largest group of the same readings out of a set of even larger readings.  Very robust filtering.
Filtering for most applications, the Very Simple Mode Filter

The simplest mode filter, is simple as this question, "Do the last two readings agree?" (with in a certain distance, and the certain distance depends upon how much variation one expects in the actual use.  Even so most use the logic of "are these readings exactly the same")?  If so, use the readings, otherwise throw away to oldest reading, and compare the next reading with the most current reading and do this again.  Obviously with very noisy data, one might have to sample a larger group of readings, and pull out the most common reading, but for most applications, this simple two reading filter works very well.


Even so, for specific cases, one has to try and find out what works best.

Please let us know if you have any further questions. I request that you email me any questions at scott@maxbotix.com.


Best regards,

Scott Wielenberg
Technical Support & Sales
of MaxBotix Inc.
Phone: (218) 454-0766 Ext. 2
Fax: (218) 454-0768
Email: scott@maxbotix.com
Web: http://www.maxbotix.com
10  Forum 2005-2010 (read only) / Interfacing / Re: Maxbotix LV-MaxSonar-EZ - random value drops on: November 03, 2010, 08:03:56 am
first post  smiley
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