Let's Make Robots!

Movable head without pulling wires

I'm working on a small form factor turret with a movable head.  The design has a camera (w/ raspberry pi) on a spherical mount that can rotate altitude and azimuth directions.  Unfortunately, since its a turret, it must be able to twist infinitely without getting its wires tangled.  Any ideas?  I've been thinking about a laser based system, but I seriously doubt that that is going to be able to transfer enough data to stream video.  Anyone have a simple suggestion that hopefully keeps everything hard-wired?  

T'Rex Controller Oops (Possibly Fixable)

Hello All,

I recently purchased a T'Rex Controller from Sparkfun that I think I probably blew a FET or two. I forgot to turn of the power while I was detaching the controller from my T'Rex Tank.  I'm looking to see if I just need to buy a new controller or if I can repair the one I have. So here's the symptoms:

How many sensor is needed for a line follower?

Line followers use 2-8 reflectance sesnsors for detecting the line.


This product has swift movement and turns, it uses 5 sensors 3 in middle and 2 on sides, but does the middle one is neccessary in any way? Or does it is just consuming one extra ADC pin?

I am looking for a perfect sensor array for line following robot.

LMR morès and web etiquette

tl:dr-If you violate our sense of order with (commercial) rudeness, you earn our rudeness in return.  Not saying it's right or wrong-just what to expect.

Fiberglass/Plywood panels

This might be in the wrong forum, if so, I apologize.

I'm doing a major re-design of RT, and trying to figure out a way of making more professional looking panels for the outside.

Mainly, the current method of laser-cut plywood shows off the grain after painting.  I want to get rid of that.  I've got a few options.

1 - Laser cut acrylic (expensive)

2 - CNC routed PVC sheet (moderately priced, will have to outsource to a friend)

Reverse commands

My problem is regarding the following link:

For movement, FRITSL use the following code:

low s.8
high s.9

high s.8
high s.9

low s.9

My results are:

How to connect the AERS-Sensor?

Hi guys! I am a new LMR-member and I will soon build my first robot. I have already ordered all parts. The problem is that "Sharp Analogue InfraRed Range Finding System (AERS-sensor)"  was delivered without cables. It is not described in the manual how I can do that or which cables I need. I am very greatful. if someone could describe to me how I can connect the cables to the sensor.

Help with 3D printers

Hello Guys,
I have to make a project for college and I am thinking to build a 3D printer in that project. I am absolutely new to this field and all I know about this field is how the printer works. I did some research and I found this printer. It will cost about Rs. 22,000 (or $350). As I said, I am absolutely new to this field so I need help.

Hall effect activity on a nema 17 stepper?

I am trying to figure out a way to trigger a switching signal using a bipolar nema 17 stepper motor,  without altering the wiring.  An example would be to turn on/off an LED when change in speed or direction of the nema 17.  Without attaching anything into the wiring or the core/shaft. 

GSM/GPRS module and arduino


I've just bought a gsm/gprs module named GTM900b and 

and arduino UNO and I was searching about I/O pins but

unfortunately I have a big problem with pin names ...

can anyone help me how to connect it to the arduino and get it to work ?

Stock Up Electronic Parts and Components

As the golden week of National Day is coming, both the suppliers and shipping agency are busy with preparing for the 7-day holiday now. To avoid the package delay and stockout status after the holiday, let's start to stock up with 18% discount now.

Check the deals here: http://www.icstation.com/newsletter/eMarketing/Stock_Up_0923.html

New Univeristy Project

Hi Guys,

I'm totally new here but wanted to ask some advice, we have been tasked to create a robot to carry a coffee cup over a certain distance without using power! Well electric or wind up? What can we do?



Questions on RF links and VirtualWire

Hi guys 

First of all I want to say this threat have nothing to do with robotics. Instead its about using some Arduinos to make a weather station. I've seen some of you are using RF links and VirtualWire in your projects so I hope you can help me anyway! :-) 

Sending serial data once during a rotation (routine) of the MPU6050 sensor.

Hello LMRians. How's everyone doing?

I have been fiddling around with an MPU-6050 and Arduino. Basically, a current idea is to flip in between Power-Point Slides based on the direction of rotation of the sensor. In short:

Complete Novice

Hello everyone. I am really interested in robots and I used lego mindstorms once but I want to upgrade to a new league. Im in high school and i need someone to help me. Any ideas on how I could start? Please reply soob thanks

Change of plans: from 2d mapping to biped.

A while ago I was happily planning to build a robot that was able to map it's environment, but quite soon I realised that 2d mapping is part of a bigger picture. A robot that is only aware of where it is not a goal in itself, especially if it's an autonomous robot. I tried to find a purpose for such a robot for quite a while, but I couldn't think of anything without getting way over my head into object recognition etc. Fortunately I like to plan things before building something so no harm was done.

Making a robotic arm which will collect vegetables

Now i got a stable base that can run on dirt and can bring a payload of 2kg, remote controlled and a good brain which can get where are the veggies.

The robot base is controlled with arduino, and i want it to control a robotic arm to collect things.

What is the cheapest way to get an arm that can lift at most 1kg, grab firmly but not squeeze?

Robot Class

I am in the process of submitting a course proposal for an adult evening education program that would introduce people to robotics. One of the entries that I must fill in deals with expected material costs. I would appreciate feedback on what would be appropiate expenses and whether the school should include the costs as part of the registration or if the student should buy the components as needed. I am in favor of having an option not to build.

On a similar note, would it be better to first offer a course in "C" programming geared to a possible robotics controller board?

Detecting someone is using a Desk. [Sensor Advice]

I want to do a system or robot that detects someone is using a desk. My question is which sensor or type of detection you would recommend me to use to allow to know someone is using a desk.


My choice are:

-Using an LED and LDR under the table if a person sits, it will detect. (If they wear a black cloth maybe it will not reflect back).

-Use an RFID tag, the person that uses the desk's touch with a tag.

-Distance sensor, in ebay this sensor is very cheap.


Not Automatic choice

Again ... Encoder Counts Problem

I am again… !

Encoders problem again…!

Odometery problem again…!