F.I.R.S.T.® Support Notes
We will post answer to questions from teams so that everyone has access to the latest information.
1. "I was wondering if you for see any potential problems with other robots using the same sensor at the same time during competition?"
Great question. It is possible the MB1010 sensor may detect other sensors in the same vicinity. but it becomes very improbable as targets are closer to the sensor. For example, if looking at a wall that is 3 feet away, the time of flight for the sonar travel will be 5.3mS (calculated using 148uS * 36in), and another sensor operating close by might get picked up about 11% of the time. (calculated using (148uS * 36in)/49000uS ) And as distances get longer, this can occur with a higher probability.
2. "How can we be sure that the signal we get back is from our sensor and not from another sensor on another robot on the field during competition."
Another great question. If you use the RX pin to command the sensor to range at something other than it's default read rate, or even at a random time (you would use a pin from your controller to do this), and then one checks that two readings in a row agree, it then becomes almost impossible for the two readings to agree unless it is from a valid target.
3. "With the LV-MaxSonar-E21 being in the parts kit this year, How much would it take to break one of these sensors and how could teams get the very best results while using these?"
The most common way to break the sensor would be reverse the polarity and moisture. We have provided the the teams a quick start guide for the LV-MaxSonar-EZ1 so they can be set up to work. You can check out the quick start guide at http://www.maxbotix.com/articles/016.htm . Last year some teams used the sensor to measure the distance from the wall to position for placing the tubes. This worked very good and allowed the opperators to know the robot was positioned at the right distance. However we have left it open for the teams to be creative.
4. "How tolerant is the LV-MaxSonar-EZ1 to ambient noise?"
The LV-MaxSonar-EZ's noice tolerance can be viewed at http://maxbotix.com/articles/012.htm along with our other sensors.
5. "What do the beam patterns mean and how do I change them?"
The beam patterns show how far out you can detect different sized objects. If you look at http://maxbotix.com/pictures/sensor_beam/Beam%20Pattern%20MB1010.gif you can see that the larger the object is the further away a sensor can see that object. The beam pattern is calibrated at our facility so the user doesn't need to calibrate them to their need.
6. "How can we make sure we are sensing the back board and not another object, like another robot?"
First, the sensor will have to be perpendicular to the backboard and on the same plain as the backboard in order for the sensor to detect the backboard. If the sensor is off axis to the board, it will cause the ultrasonic sound to be reflected away from the sensor. A good example of this is to think of it as if you were to shine a flashlight in a mirror, does the light reflect back to you and cause you to illuminate? Or does it illuminate an area off to the side of you? This is the same concept for the ultrasonic sensor. If you put the sensor on an arm, this would likely help to align the sensor with the backboard. Without an arm the sensor will not see the higher backboards as the sound will reflect above the sensor.
You may want to review the playing field to locate any areas where you may have trouble detecting the target your trying to detect.
You may want to program the sensor so you can override the ranging manually if you feel the sensor is reporting the incorrect range, or if you feel like the sensor is receiving ultrasonic sound from other robots on the field.
7.) How do i connect the sensor up to a cRio?
If you are only using one EZ1 sensor you can connect the sensor +5v to a source of 5 volts. GND goes to a ground pin on the Analog Breakout that is in slot 1 of the cRio. AN should go to an analog signal input that can take 0 to about 3 volts, such as on the Analog Breakout. Please note that you should, if possible, get the 5 volts from the Analog Breakout, and use that ground as well, otherwise that AN voltage will be somewhat inaccurate. The cRio breakout will allow direct connection. Make sure that the ground for the Sensor, the power supply, and the cRio is on the same circuit to help with any electrical noise.
8.) How can we program the sensor on labview?
There is an example built into LabVIEW. From the front screen of LabVIEW, select Support then FRC example finder. From there choose sensors and then EZ1 MB1010 Sonar - Analog.
9.) I'm not sure which sensor has the analog envelope, the MB7060 or the MB7070?
The MB7060 does not report the analog envelope on pin 2. The MB7060 sensor outputs a pulse width on pin 2.
The MB7070 reports the analog envelope on pin 2.
