October 18, 2019

Why a robotic workcell make sense

The forefront in industrial automation is given by robotic workcells. It's a cage, in which a robot is doing tasks. Combining many cells together results into an assembly line which can do more complex work. Right now, robot workcells are used seldom in the reality. The reason is, that it's unclear if the concept is the right one. To investigate the pros and cons of a cell we have to look at the robot itself. It doesn't look like a real robot, but it's movement are very mechanical. In contrast to a real robot, the machine is not able to interact with humans, and everything what the robot is doing looks unnatural.

This is the most dominent reason, why robotic workcells are rejected by engineers. Their goal is to program more advanced systems which are looking human like and can interact with humans. The open question is, if this kind of behavior make sense and perhaps it slows down the technology. In general, there are two different sorts of robots available. The first one is hidden in a cage, which means, that humans can't interact direct with the machine, while the second category of robots is able to interact with humans.

The interesting fact is, that only non-interactive robots can be used for factory automation. If the costs of the assembly line should be reduced and if the aim is to replace human workers with machine the only way in achieving that goal are robots in a cage. These systems are designed with autonomy in mind. The idea is that the human operator press the start button, and then the machinery is doing all the work.

The other group of robots, which are working outside the cage next to humans are not designed for maximizing the productivity, but they are useful for story telling. A typical example are social robots which are used in a screenplay as an actor near to a human actor. This kind of machine needs to be interactively. That means, it is working in the same space like a human and it make no sense to start this machine if no humans are in the environment. On the first look, intteractive robots are more advanced, but they have a poor performance in producing goods.

Let us suppose, the goal for a robot is fixed and it's equal to produce something in an assembly line. The workcell which is a robot in a cage is the only sense making design for this purpose. The main advantage is, that the robot is working in a simplified environment. Every object is on the right position. This allows to create software which is doing the same task over and over again. The result is a typical robot movement which is boring to observe. Most cage centric robots are hidden in a box. That means, the human is not monitoring the movements anymore, but for the human only the output is relevant. The system is working similar to a 3d printer. He gets some input and produces some output. And what the robot is doing in detail is not important. Such kind of automation pipeline is a here to stay. That means, robotic workcells are the best practice method for factory automation. There is no need to program the robot in a human like way or allows the program to become more flexible.

There is no need, that humans and robots will become friends, this allows the robot to do what robot can do best, which is executing the same task with high precision. Nobody would ask, if an office printer, a cooler or an elevator can become more human like. Because there is no need to communicate with these machines. They can be hidden behind a wall and the only interesting question is, if the output of the machine has a high quality. That means, the inner working of a printer is less important, but only the produced sheet of paper is under investigation.

In the case of interactive robots which are working outside of a cage the situation is the other way around. For a human like robot it is very important who the arms are looking and if the movement is natural. In most cases, highly interactive robots are equal to social robots. They are designed as an cute animal which has eyes, emotions and the ability to understand natural language. This improves the human machine interaction. Or let me explain it from another perspective. A social robot without eyes, without a coat and without emotions doesn't make much sense. The social robot is byitself the interface to a human. That means, the human approaches the robot and the robot should smile and come closer to him.

It's important to know, that social robots are not useful for factory automation. A negative example would be an office printer which has emotions. He can decide by it's own which kind of quality is required. This kind of skills are not needed for an office printer. It would lower it's performance. In most cases, a robot design has to given in advance. An robot can become a cage robot or a social robot but not both at the same time. This design decision has to do with the requirements. For example if the requirement is, that the machine should print 100 papers in a minute in high quality, the resulting machine can only be realized with a certain design. To reach this high output, the machine will work mainly in the repetitive mode which very robotic. The problem is, that this will prevent, that the machine can interact with humans or has the ability to express emotions.

industrial automation

Industrial automation is not about robots itself, but a robot gripper is only a tool for the assembly line. An industrial workcell which is operating on the assembly line looks different from a robot. The main difference is, that all the tasks are repetitive. There is no need to make decisions in a complex environment because the factory provides a simpler task. All the objects have a certain position and the program is always the same. The term robotics doesn't fit to such tasks, but it's an automation problem. There are different machines connected with an assembly line and the task to program these machine for a maximum throughput.