Cable Based Parallel Robot for Outfitting of Drilling Modules
Introduction
Concept Generation
Possible solutions are generated using a structured process involving problem decomposition, functional description, classification trees, and brainstorming. A functional description of the problem is shown in Figure 1.
Figure 1. Functional description
The functional description is used as a basis for research and systematic exploration of possible solutions.
Concept classification trees are made for each sub-function to explore the design space. For instance, the classification tree in Figure 2 is used to explore different ways to grasp the payload. 
Figure 2: A classification tree that explores different ways to grasp a payload
The process results in a multitude of concepts. These are evaluated and reduced to seven main concepts for further investigation. Some of these are shown in Figure 3.
Concept Selection
Each concept is given ratings on how they perform according to a set of selection criteria. A cable based parallel robot as shown in Figure 4 is regarded as the most suitable concept.
Figure 4: Cable based parallel robot
System Design
The system is simulated in order to determine the load cycle of the actuators as shown in Figure 5.
Figure 5: Torque and speed requirements of the actuators
Kinematic equations of the system are also derived. This allow the user to control translational and rotational speed of the payload without having to think about the movement of each individual winch.
3D-models, electrical schematics, finite element analysis, and hand calculations are carried out to further develop the system. Emphasis is put on modularity and light weight components so that the system can be assembled and disassembled as needed.
Results
The resulting concept has a load capacity of at least 490 kg, and maximum movement speed of 3 cm/s.
Final design
Illustration of the final product in use (with different actuator placement).
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