Want advise for a outdoor off-road robot

[rockclodbuster]

I everybody. I am new on this forum and I need advise.

I am thinking about building a autonomus outdoor off-road robot with two old clod buster axle, two motor, two steering servo, a novak ESC (from r/c world) and 7.2 volt batterie.

I have all this allready, plus an arduino duemilanove and an pololu serial micro servo controler. i want it whas able to navigate trough rough terrain by itselft with the possiblility to pass in manuel mode in casse of major troubble. i want to instal two axe (x,y) inclinometer to prevent rollover and a remode display for sensor, batterie voltage, mode (man or auto) and other thing.

in the robot:
Arduino Duemilanove
Pololu serisl micro servo controler
communication devise (maybe 2 set off onshine high sensitive transmiter/receiver)
range sensors (maybe sharp IR GP2)
voltage sensors (for the main batterie, 7.2 volt)
inclination sensors (3 axe acelerometer)
encoder (one per axle, don’t know what)

in the remote
Arduino pro mini
netmedia 20x4 bleu serial display
phiget mini joystick
some push bouton

I have highlight the thing I want your advise and your help.

thank for reading

[rockclodbuster]

thanks

yes, I think this is the best way to go

150-200 feets

after reading carffuly the spec of Shapr IR, I don’t think is good for my use, ther rage are to short for forward viewing. i am planing using two ultrasonic range sensor in front for stereo view (like human eyes) and Sharp IR for periférical view. the scaning laser are to expensive for me .

yes, i have see it. i will use the high precision one wen i build the remote.

no, I don’t have any picture a this time

[rockclodbuster]

I have check my axle and I don’t see were i can put the encoder. they have the place for the disc on a gear but not the encoder in front.

[rockclodbuster]

i am thinking about hacking a ball mouse for her encoder and putting it on the motor shaft. my only reserve is the max RPM this encoder can handle, the motor turn at around 10 000 RPM at max speed on 7.2 volt. with a 32 sector disc (the standard mouse encoder disc) and phototransitor mount in quadrature, this mean 1 280 000 pulse per minutes. maybe to much . hum, not a good idea.

I need to know the speed and the direction of my motor, a simple magnet don’t work. exept if i use two reed switch with a few milimeter between it, I will know witch is the first to be activated so a know the direction and the speed. thank for the magnet idea. two head are better then one.

[rockclodbuster]

I have start the initial programming of my robot. I have buy three Sharp GP2D12 IR range sensor and Summerour Sharp IR Turret mounted in the front of the chassie for indoor speed and brake test.

For now, I only use the center sensor for simplier programming. they run a about half speed (1.5m/sec) and they stop at 10cm of the wall then backward arount 20cm and go forward again for 10cm, almost evry time. I have try it outdoor but it dont see the concret as well as painted wall. so after a hard hit, I planning ordering utrasonic sensor for longuer range and less sunray perturbation.

Next step is making it follow wall, creating a smooter speed control and creating my magnetic encoder.

I continu the treat in the robot project showcase.

[jbrunet]

You seem to have a good idea of what is required.

We would suggest you start work on getting the sensors and actuators working with an Arduino and then make the robot autonomous by adding some basic logic or AI. Once this is complete, try to integrate remote control with a bypass.

Communication : You have many options for this, depending on what range you expect to obtain?

Range Sensors : The SHARP IR distance sensors can provide rudimentary obstacle avoidance. GPS is also useful for automonous robots, especially in outdoor navigation. Scanning Laser Rangefinders really excel.

Voltage sensors: Phidgets has a voltage sensor that could interest you. This will interface with an Arduino.

Encoders: What kind of wheels/axle do you have, a picture would help.

[jbrunet]

For the wheel encoders, the Wheel Watcher Optical Encoders should be good for many different projects. It is simply a matter of determining if you can place the encoder disks on your wheels. Worse case you can print out custom disks on a printer or hand fabricate something easily with white/black alternating slices or even black/metallic(reflective).
This will allow the encoder to produce the pulses.

[cbenson]

Hi rockclodbuster,

It is rare you will find an ideal place for an encoder when hacking a project. Some other options include:

• Place the encoder off axis (on a parallel axis) connected by either gears or a timing pulley. This complexifies the design a bit, but allows you to use almost any encoder.
• Make your own encoder: this would mean printing a disk and using two infrared detectors (we will have these on our website shortly).
• Use a magnetic sensor and place one or more magnets on the rim of the wheel. You would need to make custom code, but mechanically it would be by far the easiest to implement.

Hope this helps,