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1  Using Arduino / Sensors / Re: Autonomous Lawn Mower Navigation on: March 21, 2013, 09:06:41 am
johnwasser,

could you give a short explanation of the process you are describing.

Do we put the GPS units in the same location until they agree on a coordinate then start doing calculations? Or are we surveying for a set time until they have a good average location and then doing locations. Things are clearing up and we are doing a test today. Your advice is very helpful.
2  Using Arduino / Sensors / Re: Autonomous Lawn Mower Navigation on: March 20, 2013, 05:05:09 pm
Yes exactly the same. How long does a base station need to gather data before it has a known location?
3  Using Arduino / Sensors / Re: Autonomous Lawn Mower Navigation on: March 20, 2013, 01:21:44 pm
After being outside a while the readings went from about 9m to 0m when they were about 1m apart. I think it's safe to assume the two GPS receive different errors therefore making the an infeasible solution. You keep mentioning differential GPS but I don't know how that would work, is it significantly different than what I am trying to do?
4  Using Arduino / Sensors / Re: Autonomous Lawn Mower Navigation on: March 20, 2013, 10:13:29 am
So far it seems that the errors that each GPS gets are independent of each other. At about a foot apart our Due calculates the approximate distance between the two is anywhere between 9m and 90m which makes no sense. Worse case scenario is that they should read about 20m apart assuming each GPS has 10m accuracy and each is assumed to be right next to each other at first reading then eventually drifts to the farthest part away of its accuracy.
5  Using Arduino / Sensors / Autonomous Lawn Mower Navigation on: March 19, 2013, 04:30:30 pm
My group is trying to navigate a lawn mower in an open field using one of two methods.

Having two GPS units and using what we are referring to as relative GPS:
Essentially we have one stationary GPS that assumes the first point it reads is the point it is at and all other data it receives has error in it. It calculates this error and sends it over to the "rover" so that it may calculate what the error is and subtract it from its own coordinates. We are assuming since the units will be in a 30 m radius the errors received by both GPS will be similar. Is this a correct assumption. Is there a way to get <1m accuracy using 2 GPS units?

The second method is using an accelerometer, gyroscope, and single GPS combined with a Kalman filter.
While there is information on combining the accelerometer and gyroscope, I'm not sure how to begin filtering the the GPS into this system.

Any advice is appreciated on how to waypoint navigate our lawn mower with a minimum of 1m of accuracy.
6  Using Arduino / Networking, Protocols, and Devices / Re: How to measure XBee signal strength? on: March 03, 2013, 03:34:03 pm
My advisor was happy with the way I have got the RSS in transparent mode. Basically I got it done with some time to spare. I have another school project that will take all my time up, but after that I will tackle API mode. Your help has been greatly appreciated! Without some pointers I don't think I would have gotten as far as I did. No it isn't pretty or smooth, but it works which was all i needed for the grade. Also to whoever said I was trying to get some distance measurement out of this misread or I mistyped. I really just wanted the signal strength without any relation to distance.
7  Using Arduino / Networking, Protocols, and Devices / Re: How to measure XBee signal strength? on: March 01, 2013, 06:53:22 pm
Sorry if I haven't understood your advice not trying to talk to all three. I eventually just want 2 Arduinos and 2 XBees. I am using the computer mostly for debugging purposes. I will try the posted code. I really wasn't trying to be difficult or ignore your advice, but now I get what my problem is after the third time you've explained it haha. Now that I know the +++ is working and actually outputting readable commands I will slowly try and implement a signal strength indicator.
8  Using Arduino / Networking, Protocols, and Devices / Re: How to measure XBee signal strength? on: February 28, 2013, 04:32:22 pm
Played with the code some more and now I am getting consistent results with X-CTU

Code:
void loop()                   
{
  pressed = digitalRead (button);
    if (pressed == 1)
    {
      delay(1020);
      Serial.print("+++");
      delay(1020);
      Serial.println("ATDB");

      //Serial.println("You Pressed The Button!");
    }
/////////////////////////////////////////////////   
  if ( Serial.available() )
  {
    GotChar = Serial.read();
    Serial.print(GotChar);
   }

The Serial Monitor on the XBee now returns
+++ <delay> ATDB
OK(first hex character)<delay>(second hex character)

any reason for the second delay?and why OK shows up all at once with the first hex character?

The Values I am getting are +- 2 hex digits so if I get 2D in XCTU i might get 2F in the Arduino Monitor
9  Using Arduino / Networking, Protocols, and Devices / Re: How to measure XBee signal strength? on: February 28, 2013, 04:15:44 pm
Okay so here is my setup the XBee is connected 5V to 5V, GND to GND, Tx of XBee to Rx of Arduino, and Rx of XBee to Tx of Arduino. Here is the portion of my code I am using to try and poll for the ATDB:

Code:
void loop()                    
{
  pressed = digitalRead (button);
    if (pressed == 1)
    {
      delay(1200);
      Serial.print("+++");
      delay(1200);
      Serial.println("ATDB");
      DB = Serial.read();
      Serial.print(DB,HEX);
      Serial.println("You Pressed The Button!");
    }

The Serial Monitor Returns
+++<delay>ATDB
4FYou Pressed The Button!
K2B

It seem the number after the K is the actual value I want. Not sure.
10  Using Arduino / Networking, Protocols, and Devices / Re: How to measure XBee signal strength? on: February 28, 2013, 03:50:14 pm
When +++ runs in my code will the XBee respond with OK in the serial monitor?
11  Using Arduino / Networking, Protocols, and Devices / Re: How to measure XBee signal strength? on: February 27, 2013, 05:32:58 pm
Thanks so much. Any simple example code for how to properly do the delays and what not for "+++" and "ATDB" in the loop? I think the issue is the SoftwareSerial after this discussion. Everything is on a breadboard so no worries about plugging and unplugging.
12  Using Arduino / Networking, Protocols, and Devices / Re: How to measure XBee signal strength? on: February 27, 2013, 05:09:01 pm
I am using the adafruit adapter kits https://www.adafruit.com/products/126. Like I said I have Tx and Rx connected to the Arduino pins 2 and 3 using the software serial library and 5V to 5V and GND to GND. Should I be using the Tx and Rx pins to pins 0 and 1 of the arduino and forgetting the software serial library all together? Can i still program and troubleshoot with the xbee plugged into these two pins. I remember vaguely a friend having trouble programming while those pins were occupied. Oric what you are saying is what I want to do. I'm not too concerned about the time lost checking this, but what you have responded is mostly what I have found on the internet. Very vague and I can't figure out why it isn't applying to my solution.

Thanks for all your responses. I really feel helped =)
13  Using Arduino / Networking, Protocols, and Devices / Re: How to measure XBee signal strength? on: February 27, 2013, 02:27:22 pm
I have a working program and hardware for my XBee Pro S2Bs using one connected through USB explorer operating the X-CTU terminal and one connected to an Arduino UNO running a loop. I can send and receive data fine from both the laptop and the Arduino. Basically the last goal I have is to get some sort of RSS. It is literally the last thing I need to do. I don't disagree API is better and much more elegant, but it seems much more difficult and I am in a little bit of a time constraint. I really wish I had series 1 seeing as all I wanted to do was point to point. Setting up point to point with the supplies available was hard enough and I'm just trying to put the last piece of the puzzle in. It doesn't have to be elegant and it doesn't need to be flawless this is just a proof of concept that I will have time later to  refine where I will learn API mode and change all the code to that.

Jack do you remember how you did the pusleIn to get the pulse from the RSSI pin? It seems like its only on or off for me and it only returns 0's in the serial monitor. There is one line of code on log.linmena something like that that has zero details. I need to know which pin to hook into what variables to declare. Seriously tried everything I know and I don't get anything other than zeroes. Maybe I could be implementing my code wrong?

14  Using Arduino / Networking, Protocols, and Devices / Re: How to measure XBee signal strength? on: February 27, 2013, 12:13:55 pm
I appreciate the thoughtful response, but I am not in API mode currently. This is something I will look into eventually but AT has been the easiest for me to set up and get a functioning program. The way I see it, is getting API to a working state is at least another 20 hours of work on my end to get to the same point I am at now. Really all I want to do is press a button, notice the button is pressed, send the XBee into command mode, send ATDB through the Arduino and then get that hex number. I will look into your API comments when I have more time. Is there anyone who has experience reading the RSSI value as a PWM?

Edit: Jack if you have some or know of easy to follow API mode tutorials for XBee Pro S2B I would gladly take a look at them. It seems that the information is just really hard to find and took me about 20 hours to get the two connected basically by tinkering and finding bits and pieces around the internet.
15  Using Arduino / Networking, Protocols, and Devices / Re: How to measure XBee signal strength? on: February 27, 2013, 11:58:35 am
That made a lot of sense what you pointed out. Basically at some button press I want to be able to send a packet, get a ping back, and then display the signal strength of that ping. I have the XBee connected to pins 2 and 3 of the Arduino through software serial. What you're saying is that when I type +++ into the serial monitor of the arduino that goes into my char variable straight to the Tx pin and the Rx pin is the on that needs to see it?
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