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46  Using Arduino / Project Guidance / Project advise.. Choosing a motor driver on: December 25, 2012, 04:58:27 pm
So I'm creating a project, First time i use an Arduino.

I'm using these 7.2, 4.7 Amp peak motors.
http://www.parallax.com/Store/Accessories/MotorServoControllers/tabid/160/List/0/SortField/4/ProductID/587/Default.aspx?txtSearch=ball+caster

Does anyone have a suggestion which motor driver or motor controller will go well with these motors and Arduino?
47  Using Arduino / Project Guidance / Following Robot Guidance on: November 30, 2012, 11:45:46 pm
So long story short, I will give a brief description of my project(I know there's similar, I would like guidance), and the parts that I'm ordering, guide me I'f theres an easier path or wrong procedures or wrong parts, most importantly motors and motor driver.

My project is an ultrasonic following robot.The robot will send out a pulse request(xbee), then begin timing. The receiver you wear gets the request(xbee) and sends out a pulse(Ping))).
The robot has 2 sonar sensors. It times which sensor gets the signal first, difference between, and uses this to calculate the direction and drive.

So using Ping)) ultrasonic waves (3 of them).. Turning 2 into receiver and 1 transmitter by ripping them out.
http://www.parallax.com/tabid/768/ProductID/92/Default.aspx

Xbee wireless, for pulsing the transmitter from robot to transmitter. works good with Arduino?
http://www.robotshop.com/sfe-maxstream-xbee-transceiver-wire-antennae.html?utm_source=google&utm_medium=base&utm_campaign=jos

Motor kit 7.2 VDC motors., Can I use this with the SN754410 motor driver? (most important)
http://www.parallax.com/Store/Accessories/MotorServoControllers/tabid/160/List/0/SortField/4/ProductID/587/Default.aspx?txtSearch=ball+caster

Good battery for the project? 7.2V / 2800 mAH Ni-MH Rechargeable Battery
http://www.robotshop.com/productinfo.aspx?pc=RB-Hpr-04&lang=en-US

48  Using Arduino / Motors, Mechanics, and Power / Choosing the right motor controller for my motors.. guidance on: November 30, 2012, 11:27:49 pm
Hello,

So I have an Arduino Uno r3 and deciding on purchasing these motor kits http://www.parallax.com/Store/Accessories/MotorServoControllers/tabid/160/List/0/SortField/4/ProductID/587/Default.aspx?txtSearch=ball+caster

Would they work with the SN754410 motor driver ?

and will these batteries work with the motor?
http://www.robotshop.com/productinfo.aspx?pc=RB-Hpr-04&lang=en-US

Thank you
49  Using Arduino / Project Guidance / Re: Ultra-Sonic Waves, Human Following Robot on: November 29, 2012, 08:27:56 pm
I'd go poking around on the ultrasonic transmitter to see if it provides a TTL (5V) version of the 40 transmit signal.  If so, I'd hook that up to a cheap OOK (On/Off Keying) transmitter to send a 40 kHz burst of RF pulses.  Then the RF receiver and a driver can drive the one ultrasonic transmitter.

Thank you for your response, I'm new to a big project like this, I have done very small projects, So hopefully you can bare with my rookie questions. There's a beggining to everything.

I'm not exactly sure what you ment. Researched what a OOK transmitter is and understand it, but in what portion will I include it in? so your suggesting the xbee wireless would send to the xbee wireless on the transmitter and that voltage will trigger the OOK transmitter to send a 40KHz burst becuase its "1"'s?

I don't think you need anything as expensive as an XBee, do you?
A cheap 418MHz (or similar) Tx/Rx should do the trick (watch out for false triggers from door bells!)

Some of the Devantech serial/I2C ultrasonic devices allow a "listen-only" mode, so don't require any surgery.

A problem I think you may encounter is the relatively narrow acceptance angle of some ultrasound receivers - off-axis reception may not be very sensitive.

Thank you for your response.
Now what do you mean I don't need something like an xbee, i researched and seen its a preferred way and easy to use? a cheaper 418MHz would be just cheaper cost wise right? nthn with making the project better or easier?

But If I remove the transmitter portion of the Ping)) it would just act as a receiver(or would I have to modify more?) or is the Devantech ultrasonic better to use because they use I2C ?
Again all I'm using the ultrasonic waves is to know the pulses so I can trigger the time.


Thank you Both very much!

50  Using Arduino / Project Guidance / Re: Ultra-Sonic Waves, Human Following Robot on: November 29, 2012, 12:36:27 am
Yes I heard about it! Nice find! Just finished watching it, very similar to what I was thinking!

Do you know how the xbee is being used, I have never used xbee or wireless before, is it simple serial communication? sending a carrier with eight 1, is he sad? how exactly is that done?
51  Using Arduino / Project Guidance / Re: Ultra-Sonic Waves, Human Following Robot on: November 28, 2012, 09:22:58 pm
Thanks for all the help.
I'm deciding to use PING)) sensors for the ultrasonic waves and distance measurements. And xbee for the wireless (To tell the transmitter to send a pulse. Do you think this is a good approach? I have never used them, but im guessing ping is straight forward, i think? and xbee still no clue.

Since the PING)) comes as a transicevier distance measure.. How do I adjust them to turn them into just a receiver and or just a transmitter? Do I physically remove them from the board?
52  Using Arduino / Project Guidance / Re: Ultra-Sonic Waves, Human Following Robot on: November 28, 2012, 06:47:55 pm
Great Idea, can you elaborate more?

So i was thinking.

I understand It's not phase so much as timing. So lets say the Robot sends out a pulse request, then begins timing(how?). The receiver you wear gets the request and sends out a pulse.

The robot will have 2 sonar sensors. (It times which sensor gets the signal first, difference between, and uses this to calculate direction.) How?

My main question is how to do the timing portion and what exactly is the calculation how do you configure that to the robots driving?
53  Using Arduino / Project Guidance / Ultra-Sonic Waves, Human Following Robot on: November 22, 2012, 12:59:10 am
Hello,

I'm using a transmitter to transmit 40k square sound waves to 2 receivers on a robot. I want the robot to know which direction the transmitter is and adjust to it (to later drive to it) .

So I'm in the first stages of figuring this out but confused and need help.(correct me if I'm wrong on anything)

To calculate the direction of the transmitter, I will have to know the phase difference between the waves of receiver 1 and 2, so I will be able to calculate which arrives first(but is it based on direction of which came first or strength?). But how do I calculate this phase difference? through hardware or software and how?

Moreover, how do I output the calculations of the phase difference (through micro-controller hardware or software)?

Please advise me if I'm in the right direction and if you have an idea or different approach.

Thank you

I'm using this kit for transmitter and receiver.
http://www.engineeringshock.com/40khz-ultrasonic-transducer-receiver-kit.html
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