Comments for Lucky Larry

Comment on Arduino: Modifying a Robot Arm by larry

larry — Fri, 19 Mar 2010 09:32:39 +0000

It can be pretty accurate and you can use the h-bridge chips with PWM to create speed control. But you can only measure the motors rotation using a rotary encoder otherwise you can’t accurately read the motor position – its a problem I’m facing with the arm currently as I have no real way to measure movement of the motor whereas with servos this is built in so they tend to be more accurate for robotics.

Comment on Arduino: Modifying a Robot Arm by calfred

calfred — Fri, 19 Mar 2010 05:39:29 +0000

wow. i didn’t know you can control DC motors like that!?
thanks for posting this. very valuable. it’s so accurate , more accurate than servos.

Comment on Arduino: (Very) Basic motion tracking with 2 PIR sensors by john

john — Thu, 18 Mar 2010 20:30:28 +0000

thanks a million!!! im ordering the parts soon and i will keep you posted.

Comment on Arduino: (Very) Basic motion tracking with 2 PIR sensors by larry

larry — Thu, 18 Mar 2010 09:30:18 +0000

Hey John, welcome to working with Arduino!

You can use any of these parts in the US it’ll all work the same so there’ll be no difference at least not at this level. In fact you’ll probably find it much easier to get parts in the US – checkout sparkfun.com they have a few bits.

You’ll be glad to know I’m a complete novice and if I can do these projects then anyone can – I’m mainly a programmer so I’m now beginning to find my limits when dealing with schematics and electronics.

Regarding the sketch you could easily add in another few PIR sensors and LEDs. Let me know how you get on and I’ll give you a hand if you get stuck.

Larry.

Comment on Arduino: (Very) Basic motion tracking with 2 PIR sensors by john

john — Wed, 17 Mar 2010 20:13:04 +0000

one more thing can you sketch up this same thing but have one more sensor and led? thanks!!!

Comment on Arduino: (Very) Basic motion tracking with 2 PIR sensors by john

john — Wed, 17 Mar 2010 20:08:38 +0000

i am all new to this and i’m doing it for fun can all theses things be done in the US and can a novice do this protect easily please reply!!!

Comment on Arduino: Controlling the Robot Arm by Ryan

Ryan — Tue, 16 Mar 2010 00:21:54 +0000

Yeah, a simple processing sketch requests the acc data via a serial com port (the USB receiver MCU). The watch then sends back 7 bytes of info, whihch includes button presses & XYZ values. Very straightforward.

At the moment I have coded it simply, so that a change in one axis above or below a threshold results in the corresponding motor activation (by passing an ASCII value to the arduino as per your sketch). What would be nice is to code it so that the last acc value is stored and then compared to the current value, so that the motors could respond immediately to movement (rather than having to move your arm all the way down or all the way up to activate the corresponding motor).

I am also playing with RoboRealm (image processing software) at the moment too, eventually Id’d like to bolt a webcam to the arm and have it identify tarkets and track movement. Definitely getting into servo’s there tho!

Comment on Arduino: Controlling the Robot Arm by larry

larry — Mon, 15 Mar 2010 11:40:33 +0000

sweet! look forward to seeing the video. So how does your acceloremeter move the arm – does it just do a different motor depending on the movement?

Comment on Arduino: Controlling the Robot Arm by Ryan

Ryan — Sun, 14 Mar 2010 19:37:49 +0000

Looking forward to seeing that Larry

I finished my arm, thanks for your guide. Interfaced it with the accelerometers in the Chronos watch too, works nicely! Will try and get a video up soon.

Ryan.

Comment on Arduino: Controlling the Robot Arm by larry

larry — Sun, 14 Mar 2010 12:20:50 +0000

Hi Rohan,

You will need some servos to do this which Arduino can control very easily. Depending on how many joints you want but start with 2.

To control them you’ll want to use something like Processing.org for which you can use the librarys to control the servo position.

For Inverse Kinematics to work you need to be able to accurately measure the degrees of movement in each joint – hence Servos, although you can can do stepper motors and the rotary encoder route but why bother.

I will write an IK tutorial up that shows how to calculate the angles very easily in Processing – its not a ‘true’ way to do IK but the end result is the same and the trigonmetry is easier to understand. I can also write up a brief traditional tutorial on IK too.

I was looking at getting 5 servos and an arm kit myself to do this so if you find any cheap enough let me know.

Larry.