# Map Making for INS

Discussion in 'The Projects Forum' started by saionide, Dec 26, 2010.

1. ### saionide Thread Starter New Member

Sep 13, 2009
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Hey all,

I saw that there was a post for an INS that was really helpful. I am working on a school project to create a robot that uses an INS. I was wondering if there are any ideas or suggestions to create a visual map on a monitor where one can see where the vehicle's current position is or to tell it where to go.

The robot is equipped with zigbee and is able to communicate with a laptop wirelessly.

2. ### thatoneguy AAC Fanatic!

Feb 19, 2009
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Do you already have the robot built?

INS only needs 2 things, position and time. It gets complicated when looking for 3 axis position, accelerometers will let you know the speed changed, and roughly by how much.

A simpler solution is quadrature encoders on all wheels and steering. If you know there isn't slippage, the map can be drawn as a sum of position measurements from the encoders.

Example would be hitting a wall, then backing up and measuring ticks from the encoders on the wheel until you hit the opposite wall. The math is geometry and wheel/tire diameter. This is how non-optical mice measured position/movement.

3. ### saionide Thread Starter New Member

Sep 13, 2009
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Yes, the robot has already been recently built.

But I want to program a built in map of an obstacle course/maze. The robot will be equipped with pathfinding so that it can try to make it from Point A to Point B. Will this project fail? Who knows, that's why we're doing it.

So back to the topic, I'm having trouble devising a way to actually store a map. I can either have to stored on the laptop or on the robot itself. The robot runs off of an x86 chip so you may think of it as a small computer. I am not too sure of the robot's capabilities because I was not the one who built it. I've found many reports on INS calibration and error checking, so I hope I do not run into any problems (but I will).ヽ（＃ﾟДﾟ）ﾉ

So any idea would be greatly appreciated, I am very abundant on time.

4. ### thatoneguy AAC Fanatic!

Feb 19, 2009
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718
Does the robot have any encoders on the wheels? Any accelerometers? GPS (if used outside)?

How is steering performed? Skid-steer or articulated front wheel?

How much of the processor time is idle? How much I/O do you have left to the processor/controller?

5. ### hgmjr Moderator

Jan 28, 2005
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Can we assume that INS stands for Inertial Navigation System?

hgmjr

6. ### saionide Thread Starter New Member

Sep 13, 2009
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Yes, INS I speak of stands for Inertial Navigation System.

The robot as of now is not equipped with GPS, it is an option but we are trying to avoid that. The vehicle uses front wheel steering and is controlled through a microprocessor. I/O's are not an issue as they are abundant. The processor on the robot is fairly good and I do not think it will be a problem, sorry for the vagueness but the hardware is still fairly new to me. The robot has really nothing programmed on it at the moment and we are still in the brainstorming phase. The main functions of the robot does not necessarily have to be done on the robot itself because of the wireless capability on the robot.. The robot will be equipped with accelerometers and gyroscopes, the number of rotation on wheels and degree of steering can also be taken from the robot and processed. There are endless possibilities on how to achieve this...

The problem as of right now that I am trying to solve is how to make the interface for the control station. I need to find a way so that I can visually show a map on a laptop that shows the position of the robot, similar to how a GPS for a commercial vehicle shows your position. The only difference is that instead of the map showing where you are relative to where you are facing, I want an overhead map showing where vehicle, also providing X-Y coordinates. As of right now I am not worried about the altitude of the vehicle... for now...

Importantly, which makes life easier, the laptop and robot communicate with each other either wirelessly (WiFi) or zigbee.

7. ### thatoneguy AAC Fanatic!

Feb 19, 2009
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718
Pick a direction, say, forward, call it the X axis.

When the robot is rolling in that direction (wheel encoders), put a pixel for each wheel rotation or similar. When one wheel spins faster than the other, the line will curve (or if you use steering), then you are traveling on the Y axis.

When it is done navigating through the maze, you will have a "map" of the path the robot took.

8. ### saionide Thread Starter New Member

Sep 13, 2009
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Ahh... I may have misworded my problem. （ll ﾟДﾟ）!!!

The problem I have is that I already have a map made, and I want to give my robot an initial position and tell it to go to another position on the map. The vehicle will never have the task of making it's own map... for now... later I will add a function that will show any obstacles or collisions on the map, but the layout of the area will already be given to the robot, its up to the robot which route to take (the fastest).

I will also be programming path finding function on the robot.

I want to simulate a robot that is finding its way through maybe an underground tunnel... that has mostly 90 degree turns.

9. ### thatoneguy AAC Fanatic!

Feb 19, 2009
6,357
718
Same solution, but in reverse. Draw the dots corresponding to wheel revolutions and steering, so the robot can reproduce them.

saionide likes this.
10. ### saionide Thread Starter New Member

Sep 13, 2009
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Hmm... I like the idea. I shall take this into consideration.

I'm sorry for the confusion but the question I am asking is a method for drawing a map for an INS to use. I am trying to preprogram a map into the robot.

So what I am trying to do is just create a map on a computer then I can say from this starting point, move 4 units right and then 3 units up. This does not necessarily have to be for an robot using INS, the detail about my project involving an INS should not affect how the map would be. I am trying to do this project one step at a time. -_-

But I do like the method said above of using INS robot creating the map.

So to reiterate, I am looking for a method for drawing a map with boundaries and trying to get an object to move around the map. Let's say I wanted to make a rendition of pacman, how would i create the stage and be able to control pacman?