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Where to put stronger servos on humanoid?

I have servos (17  of them ), making the Sainsmart 17 DOF robot, and I have 2 more very strong servos.
I am wondering which joints will need stronger servos, ankles, hips?

Get problem when control servo RC by potentiometer

Hey guys!
Im working a robot arm control by potentiometers
I write the code in arduino like that : myservo.write(map(value,0,1023,0,180)); When the potentiometer at 0 position( analog=0), the servo vibrates. After i rotate potentiometer until the value= 80, the servo is stop vibrating and moving 
Can you give me some suggestion to solve the problem  

Sincerely thanks!

Get confusion when making trainable robot

Hey guys!
Im really interested in this robot ( the link below)


I know that to rembember the the moves of robot . I need to store the value in the array of EEPROM

However, i get some problems. The moves does not smooth while I apply the available code in the link
Can any one guild me how to let the move between servo become smoothly 
Sincerely thanks!

News About LMR Start Here Robot

For those of you interested in the LMR Start Here Robot, we would like to inform you that it is now also available through RobotShop at approximately $20USD less than it was before.

Building this kit is a great way to start into Robotics and learn the basics so we wanted to make it available for LMR members. The tutorial and videos are easy to follow so you can build your first robot in a few hours.

LED lights

Hello world, 

any idea where to find candy looking LED lights like these for a lower price?


Need a good dc motor driver?

Hi all I have a quick question. I have a couple DC drill motors and gear boxes and I wont to make a robot. I am looking for a 20ish amp motor controller. I either need a dull one of two single ones. What do you all recommend? It needs to be able to plug into a regular receiver since I am going to be using a Dx7s and a simple dsmx receiver. I could be biger than 20 amps just I thought 20amps would be a good base line. I want to find something cheep like under $50.

Programming Language

I've written most of the mechanical aspects of my robot in C++ (native to Arduino DUE) and am moving on to the brains, which is a Raspberry Pi 2.

I'd like to write this in a higher level language than C or C++. I am annoyed at the hoops I have to jump through to deal with strings and for that matter arrays.

I see two main choices, Python, and there is a Python 2.7 and a Python 3.4, and Node.js. What I have at the moment is OpenCV with Python 3 bindings, pocketsphinx, and eSpeak.

LiPo battery monitor

I haven't used LiPo before but I see that it needs to be monitored to make sure the cell voltages do not drop too low. The same is true with  LiIon.

I see two ways of handling this.

Arduino Speech Code

Based on a talking-lift-buttons project published on instructables (credits to ICstation); I have modified the schematic to the following:

- Arduino Nano controls the audio storage chip APR9600 which includes 8 messages.

- Arduino generates random 8 numbers

- each number calls one of the 8 messages.

The result, it will look like as if the Arduino is talking out of its own mind.(more realistic if we extend this systems into say 50 phrases or more which may need a different audio storage module than APR9600)

Order cancelled?

I placed the order from marketplace and was charged from paypal but I chack back next day it shows "cancelled".

How does that work now? Maybe you want to shut it off and re-direct back to RobotShop instead of confusing people?

Wild Thumper 6W - Problem with motors or T-Rex controller (PWM signal)

Dear Sirs,

I need your help again because I don't know what is happening with the wild thumper motors or T'rex controller. I explain.

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.

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 ??

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;

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.