3D cable-based Cartesian metrology system

A novel cable-based metrology system is presented wherein six cables are connected in parallel from ground-mounted string pots to the moving object or tool of interest. Cartesian pose can be determined for feedback control and other purposes by reading the lengths of the six cables via the string pots and using closed-form forward pose kinematics. This article focuses on a sculpting metrology tool, assisting a human artist in generating a piece from a computer model, but applications exist in manufacturing, rapid prototyping, robotics, and automated construction. We present experimental data to demonstrate the operation of our system, we study the absolute accuracy and also measurement resolution, and we discuss various error sources. The proposed real-time cable-based metrology system is less complex and more economical than existing commercial Cartesian metrology technologies. (C) 2004 Wiley Periodicals, Inc .