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stefano.antonelli
08-06-2007, 11:17 AM
Hello,

I want to create my first robot using the bridgeware concept but I am not at all expert about electronic so my "design" can be completely wrong.
My robot will be a Ping-Pong robot and will be created using the following hardware:


2 DC motor to operate two wheels that will be used to actually throw the ping-pong balls. I will need to accurately set wheel speed and I will need to change or even reverse it as soon as possible (less than 1 second). Depending on the radius o of the wheel the motor should be able to reach up to 1000 rpm or even more. A possible candidate is the BaneBots MP-36016-385, maybe it is a too much but I cannot predict the real requirements.

3/4 servo for moving the robot head
1 servo for feeding balls in the robot head (maybe this one should be a stepper motor or another dc motor)
To the best of my understanding I can control all this motors and servo using a Robotics Connection Serializer or :

one Phidget 4-servo controller with 2 motor Controller for example the BaneBots Motor-Controller
one Phidget 4-servo controller to handle all the others servo. I want also to add a sensing mechanism that is able to detect the ball hitting the table. I think that that could be done using one or more microphone but I do not have any idea on how to integrate a microphone in this robot other than attaching the microphone to the PC audio card.

Based on this I have the following questions:
Is the configuration with the 4 servo-controller and motor controller correct to control the BaneBots gear motor ?
If I will use the Robotics Connection serializer can I avoid to use the motor controller?
Do you have any other way to add one or more microphone inputs on a "bridgeware" Robot?
Could it be possible to use a vibrational sensor to sense the ping pong ball hitting the table ? (not a lot of vibration indeed but it can be perceived touching with a finger the table). Any comment/correction/suggestion will be greatly appreciated.

Stefano

Alex
08-08-2007, 03:55 PM
Hey Stefano!

Seems like you have a pretty good grasp on research, but I have to ask, what sort of background do you have? The robot that you wish to build as your first robot is a pretty complex machine and will take a lot of knowledge from many different fields and may be too much for a beginner to take on. Or am I just totally misunderstanding you and this isn't your first robot, just your first "bridgeware" robot?

stefano.antonelli
08-09-2007, 04:07 AM
Hello Alex,
first of all thank you for your reply.
This will be my first Robot, I am an expert software engineer and when I was young I build some RC planes, moreover I am a physic so I should (hopefully) understand some of the problems and again I should be able to learn. Finally I know I will make mistakes :-(.

Going back to the ballbot (this is the name I decided to give to my robot) my first task is to have the two DC motor moving two wheels that will throw the ping-pong ball.
I need to easily control the speed of the wheels, for example I need to be able to set speed of a wheel to 500 RPM clockwise and the other to 500 RPM anticlockwise and to change both, in less than a second, to 300 anticlockwise and 350 clockwise (both wheel inverted the rotation).
Probably I can use a replacement motor directly attached to the wheel but using a gearbox I should obtain a greater control of the speed, in any case I need to experiment.
Considering that my first test will use a 2'' foam wheel or a 2'' Colson Wheel, my first questions regarding motors are:
In order to be able to obtain RPM in the range of 200-1000 RPM, is it better to have a 1023 RPM(16:1) or a 3272 RPM (5:1) gear-box?
Should I use only the replacement motor without gearbox?

I would like to use the Serializer but it seems that is out of stock and I would like to start the project as soon as possible. Because of that I will start with the Phidget 4-Servo Controller and the bane-bot motor controllers (18A).

Are they OK to control the 28 mm BaneBot RS 385 5:1 gearbox motors?

Thank you again for the help

Stefano

PS. sorry for posting also motor questions in this thread but I wanted to keep all questions in the same post. From now on I will try to keep things separate.

Dave
08-10-2007, 08:40 AM
I want also to add a sensing mechanism that is able to detect the ball hitting the table. I think that that could be done using one or more microphone but I do not have any idea on how to integrate a microphone in this robot other than attaching the microphone to the PC audio card.

For this, I recommend attaching some piezo-electric sensors to the table, then running them to the analog inputs on the Serializer or Phidgets 8/8/8.



Is the configuration with the 4 servo-controller and motor controller correct to control the BaneBots gear motor?


Yep, you got it.



If I will use the Robotics Connection serializer can I avoid to use the motor controller?


Yes, but you'd have to use smaller motors. The motor you mentioned might work, but some of those motors with high stall currents (I believe it's 17A for the motor you mentioned) draw a vicious current spike when they start, which could damage the Serializer. I'll contact Robotics Connection and find out what kind of momentary current the Serializer can handle, then we'll be sure.



Do you have any other way to add one or more microphone inputs on a "bridgeware" Robot?


Mic inputs for audio or impact sensing? For impact sensing, see my previous comment. If you're talking about audio capturing... Well that would involve sound cards, and I'm not much of a programmer so I'll let someone else answer this question.



Could it be possible to use a vibrational sensor to sense the ping pong ball hitting the table ? (not a lot of vibration indeed but it can be perceived touching with a finger the table).


I think piezo sensors would be worth a try, but if you set your threshold low enough to detect a ping pong ball hitting the table, you might run into problems. People walking around the table might cause the same amount of vibration. Pad the feet of the table, maybe?

Dave
08-10-2007, 08:54 AM
Finally I know I will make mistakes :-(

Well, I'm glad you got that realization out of the way early on in the game. This will make the whole experience easier and more fun for everyone involved.



Considering that my first test will use a 2'' foam wheel or a 2'' Colson Wheel, my first questions regarding motors are:
In order to be able to obtain RPM in the range of 200-1000 RPM, is it better to have a 1023 RPM(16:1) or a 3272 RPM (5:1) gear-box?
Should I use only the replacement motor without gearbox?


You could probably get away with using the motor without a gearbox. Still, I'd recommend a low reduction gearbox like the 5:1, simply because it has a long drive shaft that's easier to attach a wheel to.



I would like to use the Serializer but it seems that is out of stock and I would like to start the project as soon as possible. Because of that I will start with the Phidget 4-Servo Controller and the bane-bot motor controllers (18A).

Are they OK to control the 28 mm BaneBot RS 385 5:1 gearbox motors?


The controller can handle 18A peak and 5A continuous. Your motor will draw 17A peak and 1A with no load. So the answer is "yes."



Thank you again for the help

PS. sorry for posting also motor questions in this thread but I wanted to keep all questions in the same post. From now on I will try to keep things separate.

Don't worry about it. I'd rather see one thread, so we don't have to hunt through the forums and figure out who's doing what and what's going where. Thanks for posting!

Alex
08-10-2007, 09:04 AM
If you have some super human ability and build this robot or at the very least get to a point where you have some pretty decent functionality before the end of August, be sure to enter our "Submit Your Project and WIN!" contest. You could win up to $100 TR bucks:)

http://www.trossenrobotics.com/robotics-rfid-hci-home-automation-contest.aspx

stefano.antonelli
08-13-2007, 07:56 AM
Thank you very much for the valuable suggestions.
I will try to use the piezoelectric sensor for ball bouncing detection, it should be easier to handle than trying to extract the sound of the ball from an audio signal.

Does the Phidget vibration sensor will work with the Serializer? If I correctly understand the important spec is the voltage output range that should match the Serializer Analog Input.

I really would like to have something working before end of August but it will be a sort of miracle :-)

Thanks again

Alex
08-13-2007, 08:49 AM
The Phidget Vibration Sensor should work with the Serializer with no problems. As you stated, it's just a standard 0-5V analog sensor and that's what the specs call for with the Serializier:)