Home Explorer

Let's Make Robots Robots
1

Just bought the Tamiya Track & Wheel Set 70100 and Double Gearbox 70168 yesterday for HKD $80 (~ USD10). The tank base will be about 7" x 3".

I've built a simple radar station as shown on the video. It is an ultrasonic sensor mounted on a servo. The output of the sensor is fed to PC thru wireless module. The PC side software reconstruct a radar like screen for human to read. http://hk.myblog.yahoo.com/jw!afd6dGGRHBRkp2laqwk198fg/article?mid=320

I plan to improve the ultrasonic radar station with GD2D12, so that the radar station will have full range distance measuring capability. The radar station will be put on top of the tank. It collects data and transmits back to the PC thru the wireless module.

The tank will be equipped with rotation counter which mounted near the shaft of the gearbox, so that I know how many turns it make for each wheel. This information will be sent to the PC also. From this data, I will know how long the tank has been travelled, in which direction.

The PC side program will construct the map of my home accordingly from the data sent from the tank. Finally it will have a rough map of my home for navigation.

Most modules are ready, except the cheap wireless modules are not very stable.

The PC side map building program will be a challenge. Also, I am not sure if I can well estimate the location of the tank by counting the turns of the wheels only, without digital compass or other measurement. Anyway it is fun to build a tank and let it explore.

Tank Base

The tank base is ready. It ends up it can run on either sides. http://hk.myblog.yahoo.com/jw!afd6dGGRHBRkp2laqwk198fg

 

Radar Station Software

The radar station software is written in python. It need python 2.5, pyserial (for serial port communication), wxPython (for GUI).

The ultrasonic ranger keeps generating the data and feed to the radar station thru RS232. The data contains the servo position, and a list of time measurement of the echos. It is a DIY ranger, at each pulse, it records multiple echos due to multiple objects in front of the ranger. I am not sure if other rangers record multiple echo, or just give you one echo measurement.

The application has 2 threads. One is receiving the data (Radar object), and the other display the result nicely on screen (radarWin).

 

Exploring my home via infrared and ultrasound

  • Control method: self-control
  • Sensors / input devices: Ultrasonic ranger and infrared ranger
This is a companion discussion topic for the original entry at https://community.robotshop.com/robots/show/home-explorer
2

converge

Looks like CL is on his way to build himself a complete robot. Just put all these projects together: legs, arms and now a head with eyes.

Good Job CL! And welcome to the club.

Rik

3

that radar thing is so cool

that radar thing is so cool !!! nice project
The man who smiles when things go wrong has thought of someone to blame it on. - Robert Bloch
4

Again great work! - what RF

Again great work! - what RF modules are you using, and why would it interfere with the ultrasonic transducer? You said it was pretty accurate up to 3 meters, what is the resolution?

Are you using python for your PC code? I am pretty ignorant of Python (my background is C++ & Java) but I have seen more and more nice robotic programs done in Python. I assume not having to be compiled is advantageous in developing?

Do you have a skematic?

Keep up the great work!

GroG
my robots
my garden

5

Hi GroGI use the cheapest AM

Hi GroG

I use the cheapest AM RF modules, they are running 315MHz or 433MHz, AM modulation ($2 for transmitter + receiver). It means that it suffers from noises, short distance, and low level. I have developed the module to do encoding, error checking and etc., you may check here: http://hk.myblog.yahoo.com/jw!afd6dGGRHBRkp2laqwk198fg/article?mid=283

These modules are very primitive but very affordable. I was planning to put it everywhere, every robot. Right now I still have not figured out how to avoid interference from the motor in the receiver module. If I use a separated battery, it is working perfectly fine. Here is a simple remote control car that use this module: http://hk.youtube.com/watch?v=frihINmtjGk

I think there are similar products sold in US, but at a higher price.

About the resolution, I remember it measures up to centimeter and still quite accurate. The DIY ultrasonic ranger can go further, as long as the power to the transducer is strong enough. But I never test it, my home is not that big.

My background is C++, java also. I use also VB, perl, Python. I would say a script language is a definite advantage over C++, C#, java in the robotic R&D. Python’s OO features, runtime auto-compilation, availability of so many free modules/packages (neural network, numerical processing, opencv, GUI, 3D, pyODE, database etc…), makes it a perfect language to use. I use mainly python in my PC side robotic development. I’ve built the PC side bootloader, TWI gateway, robot arm controller, bipedal simulator, pattern recognizer, radar screen, CRO, … many other modules in python. It would be a thousand time slower if I do it in C++ or VB.

Skematic ? Which projects/modules are you refering to ?

 

6

your bots are very very

your bots are very very nice! Where did you learn all that?

I agree with rik, you could actually combine the various projects you’ve mad so far and make a really awesome robot out of them

7

hm…I learnt it mainly from

hm…I learnt it mainly from books and blogs. As I prefer to build from scratch, may be it looks a bit different.

Yes, combining the various projects may create new stuffs…so I try document more, create building blocks and have it ready for future use.

8

Wow, radar, smooth!!
Wow, radar, smooth!!

9

Hay can you poast the radar
Hay can you poast the radar software? I have always wanted to do something like that.

10

What is poast ? Do you mean
What is poast ? Do you mean to post the software ? The software is written in python. I may need some time to clean it up and share it here. But you may want to install python 2.5 if you are new to it.

11

Hi clcheunghk,Can you put a

Hi clcheunghk,

Can you put a link to the am rf modules? Fritsl has worked with an interesting rf module take a look here. Its certainly more expensive than $2 (very good price) - I think its @ 900 Mhz and probably FM or PWM of some sort, I have not read the specs.

For the skematics, I was curious about the transducer reciever pair, i thought that someone might be able to help diagnose or isolate the problem you were having. But, it sounds like you know what it is - (not enough isolation from electrically noisey motor )

Keep up the great work.

GroG.

12

I use this one, I don’t

I use this one, I don’t think you can get it in US/UK. But it seems quite similar to this one at sparkfun. I still have problem on the receiver (need separate power line for stability). Today I just re-read the specification. May be I can try raising the voltage of the transmitter to 9-12V and test the receiver side again. These ASK modules, I would pay no more than $3 to buy a pair.

The easy radio one, I believe it is FSK, but not sure if it is GFSK or not.

 

13

Data Transfer

Hey there CL.

First of all, this is a brilliant little project! I myself am attempting to do the same thing, but a static servo/sensor rather than on a tank.

Okay time for the question. I am using a PICAXE 18-M2 chip and a PICAXE AXE027 cable to connect to the PC. I have used your code and changed all of the ‘ser.read’ numbers to ‘2’ as I am using COM3. I have got my sensor and circuit working, and a radar screen pops up when I run the program, but it does not display any data like in your videos. What am i doing wrong?

Kind regards,
Olli