A Cable Array Robot Designed for Overhead Retrieval

Open Access
Author:
Miner, Daniel J
Graduate Program:
Industrial Engineering
Degree:
Master of Science
Document Type:
Master Thesis
Date of Defense:
None
Committee Members:
  • Dr Dave Cannon, Thesis Advisor
  • David J Cannon, Thesis Advisor
Keywords:
  • Material Handling
  • Cable Array Robot
  • End Effector
Abstract:
The Cable Array Robot Technology (CART), first patented by Holland and Cannon in 2004, represents a new class of robots which have demonstrated the ability to precisely manipulate heavy loads, such as shipping containers, over large workspaces. These characteristics make the robots suitable for many tasks traditionally completed by cranes or other material handling equipment, while providing improved efficiency. While the issue of load stabilization has been largely solved by using a cable array instead of a single vertical cable to suspend a load, a remaining issue with current cable array robot design, for some applications, is unintended collisions between the cables and obstacles in the workspace. This could damage the cables or the objects, poses a safety risk for anyone in the area, and reduces the size of the work envelope. Solving this issue, for cases such as lowing containers into the hold of a ship, could facilitate quicker acceptance of this robot class for widespread deployment. For this Penn State Masters Degree effort, new prototypes of end effectors which allow for overhead retrieval, similar to the function of a typical crane, have been developed. Two of the prototypes used one set of winches and cables to drive the end effector while the other set drives the crane function. Of these prototypes, one locates the second set of winches on the end effector while the other locates the winches at the masts. Another prototype implemented a cable reeving structure that used one cable from each mast in a continuous loop from the winches, located at the mast, to the end effectors. Finally, a prototype was developed which uses a set of pulleys, fixed to the same shaft, which uses a clotheslines approach to wind a second set of cables for crane functionality. The continuous loop and clothesline prototypes were tested using a cable array robot. While the continuous loop prototype failed to perform well, the clotheslines prototype was successful in providing crane functionality. Recommendations for improving the efficiency of the robot through nested arrays are suggested for future work.