Mini robotic arm

After having some ice cream I got the idea for this robotic arm.



moving a little bolt from one side to the other side

  • Actuators / output devices: 4 micro servos
  • Control method: controlled by a PIC16F690 assembler firmware
  • CPU: PIC16f690 micro controller
  • Operating system: self made assembler code
  • Power source: 4.8V to 6V from 4 battery cells
  • Programming language: PIC Assembler
  • Sensors / input devices: teach in system with 4 potentiometers

This is a companion discussion topic for the original entry at

Is that first video shown at

Is that first video shown at real speed? That little guy is pretty damn fast!
Nice use of a simple gripper design.

No doubt others will want to know too - where did you get your servos from?

I love how small and simple

I love how small and simple it is :slight_smile:

Good implementation of that controlling mechanism (I forget the name).

maybe the proportional

maybe the proportional integral and differencial? PID control :P  yeah nice little one

I am one of those others who

I am one of those others who would really like to know where you got your servos from.


Cool ,i like its speed .

Where did you get those servos im interested in buying some.

Servo Type and details

The mini robot works with the following servo type :



dimension: 19.7 x 8.2 x 24 mm

weight: 4,4 g

torque: 5 Ncm

settling time for 60 degrees: 90ms

coming from a local dealer for electronic parts in Germany

** i found it**

i found it in conrad’s electronics e-shop.

Here it is:

Mini Robots speed

The video which shows the robot working is at real speed (see servo data)

The programm moves the servos at full speed to the next position and a short delay time after each command allows all of the servos to reach their final position.

That means that it is possible to increase the speed a little bit more by doing some fine tuning of the delay times after each command.

The second video shows the “Teach-In-Arm”  which allows the Controller to “copy” the movement of this arm to the robotic arm.

The final thing which is still not implemented is the routine which saves the “Teach In” data 5 or 10 times per second, so that the conroller is able to replay it in a loop with the original speed or with a lower or higher speed.


Nice arm. It looks great. I like the way you did the gripper. Very simple.

I don’t think it cost only $20 though. Those topline servos alone are $10 a piece.

servo price

you are right,

I exchanged the price for thr servos with another project.

But in this case one servo costs about 10 EUR.

I corrected the total costs to a better guess

Thanks  :slight_smile:


so simple and yet so cool

I like how u have used a

I like how u have used a control to be able to control the arm yourself. Remote control would  be pretty cool as well

**details **

can you post some details and pictures about your robot ? please.


Good Work…

I like it a lot… It’s small, simple, fast, and it looks easy to build…Oh gosh I need more time to work on my projects… :frowning:

some more photos of the mini robot

complete “teach in” system (mini robot, teach-in-arm with four potis, controller board with the PIC16F690)


total length of 140mm (5,5 inch)


the gripper:


the gripper servo:


That's all !

source code

hi! can you send to me the source code of this project and the list of materials? i would like to make this as our project. thanks so much! my email add is [email protected]… tnx

hi… this project is great…

hi… this project is great… could you please help me with this?

some more information ? especially for controlling RC-Servos

Hi Stephen,

sorry for the late answer. but I was not here for a longer time.

And there were also a lot of other “problems” which had to be solved using my PIC Controllers.

i.e. self made electronics for a RC-Excavator which works similar to the digital system used in slot cars. To replace a lot of wires between the rotating part of the excavator and the track unit, a small PIC 12F629 reads the pulses from up to 5 channels of a RC-Receiver and leads their information via a 2 wire connection to a second PIC12F629. At the second board the power is seperated from the data. The PIC is reading the data, and generates the PWM output for the 5 Servo output connctors. the 2 wire connection is made with a cheap 6,3mm mono microphone plug which is also used as the axle for the rotating part.

The arm of the excavator is also powered by standard servos and so it was necessary to change the control behavior from proportional to integral so that the servos move like real hydraulic cylinders which are controlled by valves.

I used the same 12F629 type for that job and added some features like adjustable limit positions and starting point programmable by one jumper, and automatic return to park position when missing the pulses for some seconds.

But back to the mini robot. I will try to contact you by mail for more help with that project.

Now the clock shows 1.05am at my location (Germany). Time to leave


Greetings Stoerpeak



I would like to make this soon.  It would be really nice if you could email me the list of materials to make the arm and the teach system.  Thanks, that would be great.  Email me at [email protected]  Thanks