Let's Make Robots!

Inverse kinematics

Been trying to understand inverse kinematics for programming my quadruped Crap-Crab. I started out by reading Wikipedia's version, which lost me completely (WTF?). But then I found the explanation by this guy and it turns out, as I thought to begin with, that it's simply a matter of applied trigonometry.

Here is exactly what I need in a nutshell:

Arduino / ultra sonic sensor

I have not posted for a while good 2-3 years now as feel of ladder broke back,ribssss,concussion,blood clot spinal cord long time recovering but up and about now.Night mare few years

Trying to get back  robot building again,

having problems with Arduino Uno an my ultra sonic sensor HC-SRO4 

The program i used before does not seem to run them any more.

I have updated my libary with Newping...

Hexapod queries

Hi everyone,

I have been thinking of building a remote controlled hexapod from scratch including the code. However having never built anything like it and having basically no experience with arduino, I have a number of querys I would like your opinions on.

A robot shop in a van?

I'm curious. If I were to choose to be living in a van, how much of a robot shop could I take with me in a usable form?

I'm talking general tools including basic woodworking and metalworking. A 3d printer goes without saying.

And yes, I'd need enough space left over to live and perhaps even entertain in.

The budget for this thought experiment is $50,000 US and includes the large van or small Winnebago. At most two people would have to live and work in this. Any help in figuring out if this is possible and how to do it would be appreciated.

How to change the robot direction in Picaxe

Hello everyone ,

                I am new to picaxe , i am making a two and a three whell robot , i am stuck in a problem of rotating the robot body to other directions using picaxe commands . I need some help .

Hair dryer components not dangerous?

I've recycled the nichrome wire/element from a couple hair dryers and hot hair curler station for use in a 3d printer project.  All of the houshd items have an unusual heat proof material supporting the heater wire.  It is very thin,  almost feels like a stiff cardboard, but doesn't have any layers and light can be seen through it. Has a silver, mother-of-pearl type finish.

  It doesn't seem to burn since it holds red hot nichrome wire. I just want to make sure it is not asbestos or something.  Does anyone know what it is?



Stuff to get rid of

Hey guys I have some stuff that either I have no clue what it is, I dont know how to use it, or just simply dont want to use it. Ill post some pictures and things as I find stuff.


Here is the first thing, It is a bluetooth module I bought off ebay and didnt know it wasnt broken out. If you want it, PM me an offer. :D

A new cheap 2D Robotic Obstacle Detector

It allows your robot to determine the distance to obstacles and walls and to avoid them.

Here are some parameters:

* detectable range: 20 cm to 150 cm (6 to 60 inches )

* 7.5 degrees angular resolution

* 2 scans per second

* 180 degrees view

* easy interface with other boards it comes pre calibrated

* USB interface power and data  Rs232  and SPI

It is intended more for terrestrial robots (is a bit slower than the laser rangefinders) 

Here is the link :

Servo problems!

I'm having a lot of problems with the servos I'm using to build a quadruped robot. I should start by mentioning that I bought the servos from Dagu like 4 years ago, BUT most of them had never even been unpacked until recently.

The problems are the following:

Which voltage regulator to use?

Hello all,

For my project, I intend to use a 3.7V LiPo, 4400mAh for my datalogger. 

With my Arduino Pro Mini comes the MIC5205 LDO regulator which I'm using now but I intend to build my own PCB and am looking into other regulators / buck-boost converters.

Which ones would you recommend? I'm very new into this so any help is appreciated.

Voting is now over for the Village to Raise a Child Campaign - 2552 votes

Hello guys,

Some of you might know that I had submitted my entry as part of the Village to Raise a Child Campaign. It's about changing the way Nepal learns through building robots.

The campaign has reached the voting phase and I am in need of your support.

Please support this project by voting at : http://tinyurl.com/lyv86lz

Linux: no /dev/ttyUSB0 device created when plugging picaxe28 board with picaxe27 cable


I'm playing with the "start here" robot kit and having trouble. I'm expecting the device /dev/ttyUSB0 to appear when I plug the picaxe 27 cable on the picaxe 28 board. Nothing appears. I have tried the 2 first solutions in the picaxe manual and I am not going to recompile the kernel, as suggested in solution 3. (using my working computer here).

I'm currently running Linux Mint 17 64 bit, based on Ubuntu 14.04 LTS. I have admin rights.

I am using linAxepad 1.5.0.

Flash Memory of Arduino Uno


Sketch uses 13,308 bytes (41%) of program storage space. Maximum is 32,256 bytes.

Global variables use 2,082 bytes (101%) of dynamic memory, leaving -34 bytes for local variables. Maximum is 2,048 bytes.

processing.app.debug.RunnerException: Not enough memory; see http://www.arduino.cc/en/Guide/Troubleshooting#size for tips on reducing your footprint.

adopted a h bridge here and facing issues

Hi all,

ages ago I found oddbots cool h-bridge on this page which works quite well. I started with 100x160mm boards and made two boards for two bridges in order to controll 2x2 motors.

A few weeks ago I got into contact with the pcb-tool Eagle and gave it a try to place two h bridges on one board 100x80mm (freeware edition).

As far as I can see I just copied the bridges. The only think that differs from the two-board version is, that I used the same power/gnd traces for both bridges.

Help with an uncommon controler board

Since the last kid code workshop I participate, I have one kid that send me email questions on programming.

He is 11yo, a little specific as he's highly gifted (don't know the proper english word) and questions are always interesting ;)

Nothing for LMR at that point.  But this week end, I was invited by the parents and discovered that he wanted also start some robotics.

WANTED: Arduino Mega Or Clone

Does anyone have an arduino mega or a mega clone that I could buy or trade parts for, or do you know where I can find one for cheap.





Simple servo bracket

Birdmun an Hi jinx got me looking into open scad, he is code a bracket for a servo you can adjust just by playing with a few numbers, the software is free and there's some tutoreals on line and youtube, you can export STL's as well. I did not think I would like it but after playing with it, my mind is more open, for simple shapes it is very fast.


Servo Bracket p, li { white-space: pre-wrap; }