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11
Software / Re: Axon II button not being recognized?
« Last post by Hero I on October 17, 2014, 02:18:51 PM »
The above solution worked.

12
Mechanics and Construction / Parallel Gripper Kit - $14.99
« Last post by ServoCity on October 17, 2014, 07:15:04 AM »

Get a grip! The first in our line of standard size gripper kits is here. The Parallel Gripper Kit A is a simple, durable, and versatile kit that is great for all kinds of robotic applications. The grippers move towards one another in a parallel motion, hence the name, and have a maximum width of 2.80. By incorporating the Actobotics 0.770 hub pattern into the back plate, and 1.0607 hole spacing on the grippers, you can easily attach nearly any Actobotics component to the assembled kit. Designed for use with any standard size Hitec or Futaba servo (sold separately). The kit is easy to assemble and requires only a Phillips Head Screwdriver. Watch our step by step assembly video for detailed instructions.

Actobotics Parallel Gripper Kit A (for standard size Hitec or Futaba Servos) - $14.99
http://www.servocity.com/html/parallel_gripper_kit_a__637092.html



Assembly video:
Standard Parallel Griper Kit Assembly (Full Instructions)


More gripper kits coming soon: http://www.servocity.com/html/robots___accessories.html
13
Mechanics and Construction / Questions about robot actuators
« Last post by ganvarel on October 16, 2014, 10:26:14 AM »
Hi to all, I'm new to this forum ( but not to robotics ). I'm no pro but just a hobbyst, however ( being a programmer ) I have a basic knowledge of physics and other stuff necessary to build robots.

I have built some simple robots ( some crawlers and a bioloid, plus some wheeled robots ) and I have always used dc motors and servomotors. But I'm trying to build something more interesting, a two legged humanoid the size of a child to experiment with AI and machine learning in robots.

I have made my homeworks and researched a bit the topic of actuators. What I have seen is that hobbysts use servos ( obviously ), but pros use custom built motors, linear actuators with dc motors, linear motors ( the ones that work like the maglev ), pneumatics, hydraulics, and so on.

For various reasons I don't think that hydraulic or pneumatic actuators are a good practical choice, so the only remaining realistic actuator type is the electric motor.

I have seen that the universities and labs around the world use frameless dc brushless motors ( torque motors ) + harmonic gears or custom built linear actuator with springs and other mechanisms to implement compliant joints.

But there is another type of electrical actuator, the so called linear motor ( also called direct drive linear motor ). I'm talking about this thing https://www.youtube.com/watch?v=SHTvv47Cs-E

This type of motor is fast, has great peak force, no bearings, pulleys, gears, etc... It seems a really good choice, but no humanoid or legged robot in existence uses them. Why? Is there a catch?
14
Misc / Fall Wire Sale - 50% OFF!
« Last post by ServoCity on October 16, 2014, 07:44:17 AM »
Don't miss our 50% off Wire Sale going on now thru October 19th!

Save big on select servo extensions!


http://www.servocity.com/html/servo_extensions___leads.html
15
Electronics / Protection circuits for GPIO pins of a Raspberry Pi bot
« Last post by RpiHacker on October 15, 2014, 07:39:23 PM »

Greetings,

I am making plans to build a GPIO breakout board for the Pi B+ and intend to use two (2) SN7407 ICs to make available 12 buffer circuits (3.3V to 5V level shifter) for connection with motor controllers, servo controllers, sensors, and other bells / whistles I will be cobbling in the future as the Pi bot gets built-out.

In addition to the level shifter for GPIO outputs, I intend to include a number of voltage dividers on the breakout board to protect the Pi GPIO inputs.

In looking at the value of R1 in the attached circuit I interpret the value of R1 as shown 4k7 to be 4.7 K ohms, on the other hand, I suppose it it could mean R1 can vary between 4k and 7k as the applied voltage varies between 5V and 30V.

I would appreciate it if someone would clarify the nomenclature 4k7 and any comments or advice you care to share on building the GPIO breakout board.

The above circuits, along with other Pi GPIO protection circuits, can be found at:
 < http://elinux.org/RPi_GPIO_Interface_Circuits >

Thank you for any thoughts and comments you may share.
16
Electronics / Controls Braking vs Dynamic Braking for Motors
« Last post by Tranq97 on October 15, 2014, 03:55:48 PM »
Okay, so for a very large brushless DC motor, I need to be able to stop and slow the motor at chosen rates. I've looked up a lot of different options:
Mechanical Braking wear would cause too much hassle.
'Crossing the Poles' wouldn't be powerful enough and I wouldn't be able to chose the deceleration rates.
Controls braking, where the H-Bridge is toggled to run back on the motor, giving an opposing force against the momentum for the motor.
And dynamic braking, mostly used for locomotives and gives the 'generator effect' a hard time by giving the motor a load of resistance.
These motors would go on the arms of the robot, not wheels.
I simply need to explanation as to which braking method I should use and why.
I found a lot of the information here: http://www.societyofrobots.com/schematics_dcmotorbraking.shtml.
Thank you in advance.
17
Software / Re: Axon II button not being recognized?
« Last post by Webbot on October 15, 2014, 11:41:20 AM »
All input devices, sensors etc need to be read before you start checking their values.
So to fix your code then just add  a single 'button.read();' near the top of your function - before any 'button.isXXXX()'  calls. All of the isXXXX calls then compare the last read with the previous one.

Also your 'now = clockGetus();' could just be 'now=loopStart;'

[edited] to fix typos!

[edited again to add the following] Assuming you've generated the help files.... then in Studio go to Help|Documentation/AVR8 and in the browser page type 'switch' into the search box and selected 'Switch webbot'
You'll then see help on all the commands
18
Software / Axon II button not being recognized?
« Last post by Hero I on October 14, 2014, 10:43:47 PM »
I'm using WLS 1-14 and Axon II and I can't get the push button to work on the Axon II.

Below is the my code and you can see that every second I'm outputting "Hello World!" to the standard out which does exactly that.

However, when I press the button on the Axon II, it's not recognizing any action because I'm not getting any of the output that is programmed in any of the "if" statements.

Does anybody know what my problem might be?

Code: [Select]
TICK_COUNT appControl(LOOP_COUNT loopCount, TICK_COUNT loopStart)
{
TICK_COUNT delta, now;
static TICK_COUNT last = 0;

now = clockGetus();
delta = now - last;
if (delta > 1000000) // 1.0 second
{
cout << "Hello World!\n";
last = now;
}

if (button.isPressed())
{
cout << "Pressed\n";
}

if (button.isReleased())
{
cout << "Released\n";
}

if (button.isDepressed())
{
cout << "Depressed\n";
}

if (button.isWorking())
{
cout << "Working\n";
}

if (button.isChanged())
{
cout << "Changed\n";
}

return 0;
}
19
Software / Re: Webbotlib Studio FBoot only works the first time!
« Last post by Hero I on October 14, 2014, 10:24:08 PM »
I tried dropping the baud rate down to its lowest level and still no luck.

I then installed WLS 1-14 and tried the "AVR Dragon (Atmel AVR Studio)" option and it works every time I tried it. I'm happy with this setup and will continue to develop using this method.
20
Software / Re: WebbotLib Studio new release
« Last post by Webbot on October 14, 2014, 12:23:42 PM »
Version 1-14 is released. Check out the News page http://webbot.org.uk/iPoint/35.page
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