Case Studies Of Industrial Robots


Yaskawa, Germany - IFR Robot Supplier

Yaskawa Nordic develops a revolutionary co-worker

One of the hottests topics in today's robot environment is the development of co-worker robots. Having a robot working closely together with an operator to perform some, but not all of his tasks will improve the operator's productivity. The challenge is that the operator and the robot will be so close together that the robot might harm the operator without strict robotic safety measures, so the present development focus is more aimed at the robot safety topics than the specific robotic applications. Aiding, but not substituting the operator makes the co-worker applications simpler, cheaper and more flexible, which opens up for robot sales in bigger volumes into the SME (Small & Midsized Entreprises) segment, which until now has been rather untouchable for the robot manufacturers.

At Yaskawa Nordic we also believe in co-worker robots, but we think that one should take a broader approach and also include robot-cells in the concept. A co-worker robot-cell is more challenging and expensive than a co-worker robot, but it also makes the operator many times more productive, and, on top of this, an intelligently designed robot-cell can remove, or at least dramatically reduce, the safety challenges related to having robots and operators close to eachother. One could say that the co-worker robot-cells aim at preventing safety problems where the co-worker robots aim at curing them.

So, where to find an industry with a need for co-worker robot cells? Yaskawa Nordic did that in printing, which is a huge industry, roughly 35% bigger than the automotive industry, with a skilled and expensive labour force - and with labour intensive finishing processes. The finishing processes are already highly automated, but ever changing and require a constant human supervision, so the operators cannot be eliminated by robots, but robots can eliminate heavy, repetitive manual works (a typical operator lifts 1.0-1.5 tons of paper or board per hour!). Thus, in principle, an ideal industry for co-worker robot-cells.

But the printing industry handles flexible substrates, which basically are untouchable for conventional robots, so this is where Yaskawa's dual-arm Motoman SDA robots come into the picture. The dual-arm Motoman SDA robots can grip the flexible substrates from more sides and can be programmed to copy the movements of an operator's two arms and hands down to the tiniest detail. This makes the Motoman SDA dual-arm robots unique for handling flexible substrates.

The first production line we decided to robotize is the sheet cutter line. The process as such is simple: A pile of big sheets with many images comes from the printing machine and shall be cut into smaller segments with only one image. The pile of sheets from the printing machine is normally 100 cm high, but the sheet cutter can only accept stacks of up to 15 cm, so the stack has to be split into smaller segments, where it is imperative that all sheets are registrered exactly on top of each other prior to cutting. The operator does this by manually lifting and airing small segments of sheets (1-2 cm, which corresponds to 7-14 kilos) from the pile and position them on a vibration table for proper registration. When the stack of sheets on the vibration table reaches 12-15 cm in perfect register the operator transports this stack on an air-cushion table to the sheet cutter and cuts the sheets. The Motoman SDA robot-cell robotizes this process.

A lot of complex process variables require a sophisticated, interactive HMI, and the robot-cell will not function without dynamic human interference. The airing process can only be performed properly with a specific diagonal twisting of both ends of the the stack of sheets at the same time. The topography or status of the surface of the pile will change from job to job due to the sheet quality, the printed images and the settings of the printing press. With thousands of sheet qualities and different images the robot can be exposed to millions of different jobs, so it is impossible to pre-program the robot for all these jobs. The only way to solve this challenge is with an interactive HMI where the basic robot movements are pre-programmed by skilled robot programmers, but where scanners dynamically register the sheet size and pile topography and adjusts the basic programs accordingly. Besides, the HMI takes active use of the skilled operators' experiences by letting them key in specific parameters such as stack heights, airing intensity, twisting angle etc all based on their personal preferences. This is what makes this cell a unique, real co-worker robot-cell, because some of its programming is performed by the sheet-cutter operators dynamically during the daily operation - and not as pre-programming by skilled robot programmers.

There is often a fundamental difference between the configuration of human and robotic working cells. In our situation we immediately discovered that the Motoman SDA robot should be in the same place as the operator, in front of the vibration table, to operate it properly. This was of course impossible, so we moved the robot to a position behind the vibration table, which allowed for both a human and a robotic operation - and at the same time we moved the robot out of the operator's main working area, dramatically reducing the safety challenges. Having the robot behind the vibration table opened up for an integrated pile-turning. Several printing jobs have to be turned upside down between printing and finishing. This is done at a pile-turner and takes roughly 2 minutes. We also established that a pallet change at the normal pallet lifting table (used to bring the top of the pile in an operator correct position) generates roughly 2 minutes downtime, which can be reduced to nearly zero with a new pallet lifting table with conveyor feeding. So instead of adding a co-worker robot to the 30-40 minutes manual workflow we developed a 12-15 minutes co-worker robot-cell workflow.

 The result is a Motoman SDA co-worker robot-cell for the printing industry, which to a large extent have eliminated the safety challenges while it removes the heavy lifts from the operator and improves the production capacity of a one-man operated sheet cutter line from 1½-2 pallets per hour to 4-5 pallets per hour. This reduces dramatically the production costs of sheet cutting, expecially in 3 shift operations, which makes it profitable to maintain printing in high-salary areas, where the majority of printing is consumed. And on top of maintaining the working positions locally and bringing the printing jobs faster to market using robots, energy consumption and pollution from transportation is minimized.

If we consider that the printing industry has more than 300,000 sheet-cutter lines installed, we are quite convinced that we are facing a rather significant market potential for co-worker robot-cells for the printing industry. But flexible substrates exist in many other industries than printing, so having cracked the code for handling flexible substrates, we are convinced that we have just seen the top of the iceberg of a range of totally new robotic applications requiring dual-arm robots. Honestly, we do not know where all these potential applications are, but moving from firm to flexible substrates gives a totally new approach to potential applications. We hope that our experience with this dual-arm Motoman SDA co-worker robot-cell can generate ideas for new applications among the creative system integrators.