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61
Mechanics and Construction / Re: Omni Wheel/Ball Transfer/Caster?
« Last post by Fr0stAngel on November 08, 2014, 01:54:32 PM »
Hi, I would recommend that you read the tutorials on Chassis and Robot Dynamics first.

http://www.societyofrobots.com/mechanics_dynamics.shtml#wheel

http://www.societyofrobots.com/mechanics_chassisconstruction.shtml

You will find some good information on wheel selection, types and torque calculation.

62
Mechanics and Construction / Re: Newbie needs help
« Last post by Fr0stAngel on November 08, 2014, 01:47:50 PM »
hello, and welcome :)

Your idea seems interesting... I believe it'd be best for you to gain some knowledge on simple sensors and actuators that you can used. A good starting place is the tutorials here .

http://www.societyofrobots.com/sensors.shtml
and
http://www.societyofrobots.com/sensors.shtml

Oh, and for working with fabrics, many people like to work with Arduino Lilypad
http://arduino.cc/en/Main/arduinoBoardLilyPad

You may find these projects interesting (although none of them use servos :( )
http://www.wired.com/2013/01/wearable-arduinos/#slideid-351551

Good Luck and Have fun learning
63
Electronics / Re: Filtering power supplies
« Last post by Fr0stAngel on November 08, 2014, 01:26:03 PM »
There are two main reasons for using filter caps with the power supplies (especially when using an inductive load with a high transient current demand i.e a high torque DC motor).
1- A reservoir capacitor (usually a large value 1000uF or more) is put between the power and ground. It acts as a voltage /charge reservoir for small periods of time when the motor draws a high current (i.e when you abruptly change the motor direction).
2- A filter capacitor (usually a couple of capacitors, 1uF and/or lower). Then tend to provide a low resistance path towards ground for high frequency noise signals generated when then motor is operated. The motor tends to generate high-freq noise because it is operated at high PWM freq (sometime 20kHz and more to lower the audible 'humm' produced during motor operation).

The actual value of capacitor used is dependent on the the motor's transfer function / response to operation at high frequency, but normally it's just easier to go for a value of capacitor that would provide a low resistance/reactance to high freq signal. 0.01 uF between motor terminals is used for just the same purpose.
A word of advise though, if your motor draws close to 1A current or more current during operation, the best solution is to either optically isolate the logic circuits (Microcontrollers, sensors etc) from the motor power circuit or another good solution is to use a separate power supply for both circuits (don't forget to put them to a common reference in case of dual power supply).

EDIT:
Quote
Just don't let anyone tell you they know THE best way to deal with noise. The most effective way will vary by situation.
Well ok, I take back my verdict on the optical isolation solution being the best   ;) it's just that normally what people describe the best is what works for them or whatever works for most of the people
64
Misc / Re: Robot Path Finding Project Home
« Last post by Fr0stAngel on November 08, 2014, 01:08:21 PM »
hmm... that's good to know. Do share the results when you are done :)
65
Electronics / Re: DIY 3D printer Project
« Last post by Billy on November 08, 2014, 01:56:52 AM »
If i wanted to increase the size of the heating bed could I put together some smaller heating beds to makes a larger surface?

I don't see why not. Maybe a little thermal insulation under the beds to help keep the edges of the individual heat beds closer to the temp of the active parts of the beds would help avoid cold spots.
66
Misc / Re: What is the best system to work with Axon
« Last post by heli on November 08, 2014, 01:01:09 AM »
Yes, McUber freezes up my whole system when bootloading with Windows 8.
Can windows 7 run on a 32 bit option from the start up disk?

Heli
67
Electronics / Re: DIY 3D printer Project
« Last post by vipulan12 on November 07, 2014, 03:50:22 PM »
If i wanted to increase the size of the heating bed could I put together some smaller heating beds to makes a larger surface?
68
Electronics / Re: Filtering power supplies
« Last post by Billy on November 07, 2014, 02:26:56 AM »
Hm...interesting.  I guess the question is: what happens if the cap is too large or small?  Is there a universal behaviour you'll see or is it just up to the circuit itself?

To filter noise from an encoder line, too large a cap and you will lose your signal at higher frequency. The impedance of the line driver in the encoder and the cap form a low pass filter. It may work great at low speed and then start malfunctioning at higher speeds.

On those 3 pin analog voltage regulators, too much cap and the spec sheet warns about oscillation.

Too small and you don't get much filtering.
69
Electronics / Re: DIY 3D printer Project
« Last post by Billy on November 07, 2014, 02:21:50 AM »
google "reprap" and start reading.

Here's one I made using an ARM7 to drive DC brushed motors with encoder feedback.
https://www.youtube.com/watch?v=SAGvzeQw2Oc
It's all custom except I bought the heated bed and the "hot end" which is the heated nozzle that plastic comes out of.
70
Misc / Re: What is the best system to work with Axon
« Last post by mallster on November 07, 2014, 01:35:44 AM »
I've found windows 7 64-bit and webbot studio to work well. However have not been able to workaround compile errors with webbot studio and windows 8.

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