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Articulate Arm Robots
The first electrical robots was developed in the beginning of 1970 as a technology that should replace human workers in fields of hard monotone and hazardous work like spot welding, arc welding and handling etc. The target was to build a robot with a large work envelope and a great flexibility without any requirement of high accuracy and stability which wasn’t required for the applications in question. To achieve these goals the technology used is a so called serial linkage technology meaning that every additional axis is mounted on the previous one, see picture to the right. This technology has the advantage of being able to move the mechanics in all directions giving the required flexibility and envelope however without accuracy and stiffness.
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Traditional Machine Tools
It’s well known in the industry that all CNC Machine Tools have very high requirement of accuracy and stiffness to be able to manufacture parts for an industry that requires microns of accuracy in combination with a high chip removal capacity. However, what people normally doesn’t realize is that all traditionally Machine Tools on the market are also based on a serial linkage technology, like the robots, with all the disadvantages in the areas of accuracy and stiffness that comes with it. So, to compensate for this “bad” technology the Machine Tool manufacturers have to design the machines with massive structures and wide beds to make sure that the serial linkage system maintain the accuracy and stiffness also in the end of the last linkage. However, these massive structures and wide beds totally eliminates the flexibility that is significant for robots.
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Parallel Kinematics Machines
The dream of all developer within Machine Tools has always been to combine the flexibility and envelope of the robots with the accuracy and stiffness of traditional Machine Tools. In the last 20 years the focus of this development has been Parallel Kinematics Machines so called PKM. This technology means that the motions in X, Y and Z are performed by three or more parallel axis that give an outstanding stiffness and accuracy with a maintained flexibility and envelope, see picture to the right. The first machine that actually proved this technology was the Tricept that already 1994 performed real work in the industry and since then the Tricept has been able to keep the top position and has today 70% of the world market of PKM machines according to the International Parallel Kinematics Seminar in Chemnitz 2004.
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