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[Project] Control a Crane System with Linkbot


Each Linkbot is a building block. Multiple Linkbots and accessories can be easily snapped together, without special tools, to create various Linkbot systems for different tasks and projects. In this project,3 Linkbot-I, 5 Linkbot-L, Cube Connectors, and other accessories are used to create a crane system. The project also demonstrates the application of the following advanced concepts: control Linkbot-L, control a group of Linkbots, write a C function, arcLength=radius*angle.

(Project Description and Program in PDF File)


  • Grades: 7 – 12

  • Duration: 6-20 Hours

  • Level: Advanced (control Linkbot-L, control a group of Linkbots, write a C function, arcLength=radius*angle)

Parts Used in the Project:

  • 3 Linkbot-I (used for the spool, gripper, and driver)

  • 5 Linkbot-L (used for four wheels and for swivel on the top).

  • 1 Linkbot Dongle (or another Linkbot as a Dongle)

  • 1 4” Wheels

  • 7 3.75” Wheels

  • 5 Ball Casters

  • 45 Cube Connectors (If you do not have 45 Cube Connectors, lower the height of the crane with less Cube Connectors and adjust the program accordingly).

  • 1 Gripper Pair

  • 94 Snap Connectors

  • 1 Hacky Sack

  • 1 string


Three Linkbot-I are used for the spool, gripper, and driver. Five Linkbot-L are used for four wheels and for swivel on the top. Make sure the following setup are taken into consideration:

  • All Bots start zeroed

  • Wheel Bots start with wheel on the outside

  • Spool Bot starts spooled so Gripper Bot is at max height

  • Gripper Bot starts hanging over frontLeft Wheel Bot

  • Order for IDs in Linkbot Labs (top to bottom): frontLeft, frontRight, backRight, backLeft, swivel, spool, gripper, driver.

  • Check your number of rotations to drop the Gripper fully and modify the program accordingly, especially if less Cube Connectors are used to reduce the height of the crane.

The Linkbots used in the Crane Systemm are labeled in Figure 1. Figure 2 shows the Crane System in a different view of angle to demonstrate how parts are snap connected.

Figure 1: The configuration with Linkbot-I and Linkbot-L for the Crane System.

Figure 2: Another view of the Crane System showing how parts are Snap Connected.

Programming the dog in Ch:

A Ch program can be used to control this Crane System. Details for each robot member function for CLinkbotI and ClinkbotL can be found in the textbook “Learning Robot Programming with Linkbot for the Absolute Beginner”. How to write a C function can be found in the textbook “Learning Computer Programming with Ch for the Absolute Beginner”. The entire PDF files for these two textbooks are available in C-STEM Studio.

/* File:

* Crane configuration has:

* Four Wheels: frontLeft, frontRight, backLeft, backRight (Linkbot L)

* Spool (Linkbot I with spool on joint 3)

* Swivel (Linkbot L)