Let's Make Robots!


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Launching the Internet of Toys (IoT)

Erle Robotics and Canonical combine forces once again to launch the "Internet of Toys" (IoT).  Collaborating with the Hybrid Group, they will build the next generation of toys bringing together makers, hackers, DIY robot enthusiasts and developers.  


What are you building for Halloween?

So, is anyone building anything fun for Halloween? Cool decorations, costumes or animatronics?

I'm working on a candy jar skull to great trick-or-treaters at the door. The lid will open and reveal a "Take One" sign written in fake blood. The jaw is also animated and I plan to add sound and animated LED eyes.

Inverse kinematics for a cable robot?

Does anyone have a source that can teach me how to do the inverse kinematics for a wire or cable driven type of bot?  I wanna make a skycam that uses 3 steppers instead of the usual 4. 

Motor control or servo control


I came across this circuit on google. It controls motor speed by simple flip-flop that gives a PWM signal.

The question is can this be used as a servo control ?

first use 5 volts supply instead of 12 volts ...then by replacing the 3RD NPN transistor with a servo. the + goes up, the - goes down and the signal feeds from the flip flop...can we do that ??

Phoenix code my hexapod

Ive built a small hexapod using MG90 servos and i would like to use a lynxmotion SSC-32 and botboarduino to control it using the phoenix code. Im actually looking for the proper code and some kind of step by step guide to configuring the firmware and stuff. Ive been looking at the arbotix code and can see that i need to change some numbers like the coxa length, femur length and ETC. But im sure theres a few more things that need to be changed. I also want to use my PS2 controller to operate it during off-line play.

Avrdude error @ Dagu Mini Driver

I am not able to upload a sketch to Dagu Mini Driver and get the error message avrdude:
verification error, first mismatch at byte 0x0000 0x3f = 0x41.

Problem with arduino code

how to i make this two diferent codes work a¡in the same skecth but with afecting the other. When i tried combining them together, it started working slow, as if one is working after the other. Here is the two code combined

#define trigPin 6 

#define echoPin 7



int speakerPin = 8; 

Servo gripperPin; 

Servo wristPin; 

Servo armPin; 

Servo shoulderPin; 

Servo basePin; 



int potpin = 0; 

int potpin1 =1;

int potpin2 =2;

Solar charger for multiple batteries

Hi everyone,

I couldn't decide which forum topic to use for my post so I'll post right here in the "Absolute beginners" because I'm actually a programmer and I'm quite new to electronics so I don't want to put expectations too high. I may do or say something that looks pretty stupid for an experienced robot builder so forgive me and don't hesitate to mention it if it happen, I'm here to learn.

Now that I'm done with the presentation part, here is my multipart question.

I managed to build some kind of Solar Li-Po charger using a tutorial and stuff I bought at Adafruit.

Restless PID controller


I am building @ mecanum bot and am in the process of tuning the PID-controller for the wheels. The PID-algorithm I implemented works pretty well (I think), but still I am not satisfied. I could do with some advice.

I define motor speed in terms of the number of state changes per second (SC/sec). Max number of SC/s is 5000. If I set the desired speed at 3000 the results are as depicted in the graph. 

Forum Ideas

Hello all,

I was thinking that it would be nice to give positive feedback to people who help with questions or post a cool project other than just responding to the post. Something like a "give cred" button or a thumbs up button. When the person post topics a small counter would indicate current credibility next to their avatar. The "collect" button is nice but I use it for projects or post I want to keep returning to and sometimes I just want to let the person know their project is awesome or they were super helpful. 

Few questions about Spider Controller (DAGU)

Hello all!

I'm newbie and I have few questions about Spider Controller (from DAGU).

1) When USB is plugged and the battery is plugged too - which source of power controller will be use for servos?

2) As i understand, If i use analog servos I should plug it to PWM-outputs. And digitall servo can be plugged to any output. Am i right?

3) Can't understand what is the role of ON/OFF switcher. It is for battery only?


Many thanks in advance.

How do you do precision positioning

for a school project i'm making a robot that is connected via bluetooth to my pc and I need to have it's exact position and it has to be able to drive in a straight line.

Does anyone know what kind of sensor would be best to use and in what way it should be programmed??

Creative Commons License Idea

The idea of implementing the Creative Commons License (used on several other sites with user-generated content) was suggested to us and we're eager to get your feedback. Thank you for the suggestion AndyGadget.

If you're not sure what Creative Commons is or why it exists, take a look at the Creative Commons Website here:


They also have a cute video about why they exist:


Terms and Conditions - V2

Dear LMR Friends and Family:

Yesterday we sent our new (first!) terms and conditions (T&Cs) for the LMR website (outside of the Marketplace, which was already governed by T&Cs) to all LMR members.

We’ve received mixed feedback. While most of you recognize the need to put T&Cs in place (when RobotShop recently purchased the site these were not in place), some feel that some of the conditions are a little heavy. Others have misinterpreted the scope of the T&Cs and RobotShop’s intent. 

Our version of the story

Hi everyone, I am Sandra Fradet, co-founder and co-owner of RobotShop.

We have read lots of different versions of the recent events on the web. Now this is the time that you have our version.

Threads and postings vanishing?

I had started e.g. this thread: http://letsmakerobots.com/5800mah-2s-25c-lipo-dagu-rover-5-power-distribution and there were a few answers to this and now they are all gone. What happened here? I can see it in the subsciptions but not in the forum anymore.


I know that there were more threads where I posted and more answers because the answers triggered emails. Many of these are missing now.

Wild Thumper woes with VNH2SP30 controller

I bought a 4WD Wild Thumper after building three different robots successfully with a mix of Raspberry PI and Arduino and the L298N motor controller which is obviously not up to the current draw of the thumper motors.

This lead me to the VNH2SP30 dual controllers. I have bought 2 both of which give a different amount of current in forward and reverse - whether used with a small salvaged DC motor (500mA typical draw) or with the wild thumper motors. I am using a 2 cell LiPo 20-30C.

Wild Thumper, progress but help/advice requested

Hi all,

I had a lot of trouble with motor driver boards and my Wild Thumper 4WD chassis - in the end I bought a more expensive motor controller said to handle 60A. I am controlling the paired (left/right side) motors by PWM signal and  it now drives forward/backwards/left/right etc.

Question about Dagu 4 Channel motor controller

As pointed out in
the frequency of the PWM for the motor controller might be an issue.

I am using this motor controller:
Dagu 4 Channel 5-12V, 2A Brushed DC Motor Controller
actually it looks a bit different:

but I assume that both are the same.