Let's Make Robots!

DAGU robot arm with object Tracking

Tracks moving objects

Robot Arm with Object tracking Sensor. The IR eye is used as an Object detection and tracking sensor. For more details about the eye see: http://letsmakerobots.com/node/11293. The robot arm will try to keep the distance between the sensor and the object fixed. Based on the data received from the four IR sensors the controller will decide the suitable position of the servo motors to keep the distance between the sensor and the object fixed. The controller used for this project is the Wild thumper controller board. for more details about the controller see: http://letsmakerobots.com/node/24368.

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if it is required to set accurate position of the robot arm then the Grip length must be calculated in term of grip width. The Grip used in this arm is from DAGU.The grip mechanism uses a scissor action to open and close the gripper, so the grip length changes depending on the grip width. The relationship of length to width was determined to be a third order polynomial( see http://letsmakerobots.com/node/24441):

y = -0.0181x3 + 0.0557x2 - 0.2001x + 10.64  

where, y; is the Grip length and x is the grip width

The Dagu robot arm has 6 DOF ( 6 servos). they are:

  1. Base Servo
  2. Shoulder Servo
  3. Elbow Servo
  4. Wrist Servo
  5. Hand Servo
  6. Grip Servo


Range of Motion

 Servo motors are controlled by pulse-width modulated signals that control the position of the servo actuator. Servo pulse widths vary from 500 to 2500 microseconds, which corresponds to a servo rotation angle of approximately 0° to 180°. A pulse width of 1500 microseconds will set the servo at the neutral position, or 90°. The range of motion and direction of travel for the servos used in the DAGU arm are summarized below:

Grip Servo



The Robot is now finished and tested. Any comments and/ or suggessions are welcomed.


seems like a scared little animal lol

Hi friend, I like your robot I need some imformation about it please. What do you think about your robot? Is it a good robot? have any problem? I need buy one, but im not sure. I know is a DAGU robot, but in robotshop.comm someone said they have a very high rate of failure and the gripper and wrist are especially susceptible. Please help me I need to know If you recommend me this robot, I want to teleoperate the robot with a sensorised glove (acelerometers and gyroscopes).

Sorry about my english, im from ecuador.

well, if you are asking about the Robot Arm platform, it is cheap one (low price compared with others) also it sufferes from many design problems. i do not recomend it for researches or education. it maybe ok for hobbies and demos.

i could not understand your requirements exactly, but it may not be the correct choice for you. the following are some of the problems:

the platform body is heavy.

the joints is not exactly fitted.

no ballbearings used.

the length of the grip is long compared with the length of the forarm (this could be the worst thing)

the rotating base is not correctly designed.

my platfrom is currently broken and is not working anymore!!

thanks you, it is all i need to know, well you have cleared my doubts. I must find another robot for my applicacion because I need precision. I want to control a robot arm with the movements of my arm using a glove with acelerometers and gyroscipes. What do you think will be the best robot arm for my application? Its only for research proyect I need a small one like yours. Thank you again my friend.

you are welcom :)

The AL5D Robotic Arm from Lynxmotion could be a good choice for you. ( http://www.lynxmotion.com/p-816-al5d-robotic-arm-combo-kit-free-software.aspx) or order the version without the controller.

you may need to change the controller board in order to add the accelerometers and gyros. you can select one of the arduino based boards.