Types of industrial robots: what they are and how to choose them

ISO TR/8373-2.3 norm defines industrial robot as: "automatically controlled, reprogrammable, multipurpose manipulator, programmable in three or more axes, which can be either fixed in place or mobile for use in industrial automation applications".

Industrial robotics origins

The very first industrial robot originates in 1959 thanks to the minds of George Devol and Joseph Engelberger and has a weight of approximately two tons, which is definitely too heavy if compared to the ones that are installed on robotic cells today.

The first installation in an industrial line takes place in 1961 at GM Ternstedt in Trenton, NJ. At the end of the 1960’s industrial robots land in Europe as well and a concrete diffusion of this tool began. However, these are steel structures with slow and inaccurate hydraulic motors.

Degrees of freedom and load capacity of the first robots were limited. Their first industrial applications were in the automotive field. As a matter of fact, robots were equipped with welding grippers to weld and assemble car bodies. The first examples of their massive use were those of Nissan in Japan and Fiat (1972) in Italy, where several robots were used to weld the car components - an Italian invention which was later adopted by all automotive industries.

It is therefore clear that despite the obvious initial limitations, the great entrepreneurs of history were able to see the infinite potential of these tools and since then their evolution has never stopped.

Robots today

In recent years, the various types of industrial robots available in the industrial automation sector have evolved, becoming increasingly compact, efficient and versatile.

Nowadays, robots carry out accurate processes in the industrial field such as drilling, palletizing, storage, CNC tending, grinding, milling, painting, glazing and laser cutting, especially in critical workplaces, thus safeguarding the health of workers.

In the evolution of industrial robots, an important role was played by some of the brands that invested resources in research and development and that are normally integrated in our automatic lines and robotic islands: KUKA, ABB, Kawasaki, FANUC. Amongst these, shines an all-Italian reality: Comau, which is one of today’s biggest companies in the industrial robotics world.

Robot classification: 4…plus 1

• Cartesian Robots (portal robot, xyz robot or ICS = Integrated Combination System): they’re a combination of two or more linear or rotary electric axes. Therefore, they are the type of robot with the simplest and easiest kinematics to operate. Each axis has only one degree of freedom.

• Anthropomorphic (or articulated) 6-axis robots: they are the most flexible robots. With six degrees of freedom, they are able to mimic almost all the movements of a human arm, including those of the hand. For this reason, a single machine is often sufficient, even to carry out the most complex movements. They are suitable for handling and/or assembly operations at extremely varied x,y,z coordinate points. They are widely used in the automotive industry for the assembly and welding of car parts, but they are suitable for all industrial fields.

• SCARA Robots (acronym for Selective Compliant Assembly Robot Arm): this type of robot is designed for fast and precise operations. The first one was created in the early ‘70s after observing that the most frequent movement cycles can be performed with four axes (= four degrees of freedom). Its major strength over other robots is the fact that the lifting movement of a workpiece is performed on one axis only. This simplifies its structure and makes it more reliable. Two articulated arms move in a horizontal plane, hinged at one end with a fixed vertical axis, while at the other free end there is a Z axis. With respect to the latter axis, it is possible to move vertically and rotate.

• Delta Robots: this type of robot consists of 3 arms connected by universal joints at the base. The key feature of its design is in the arms, which maintain the orientation of the end device. It’s specifically conceived to optimize the speed and versatility of high-speed picking and handling of small components in a variety of industries including food, pharmaceuticals, and electronics. Delta robots are available with 3, or 6 axes. Their unique parallel kinematic structure and very large work perimeter make them ideal for more complex automation applications. They guarantee rapid acceleration and high speed and are characterized by extraordinary levels of performance that allow to keep the number of robots required on a line to a minimum and to limit the production layout.

Alongside these robots, there is another very special category which is that of collaborative robots or Cobots. Cobots are a type of robot designed to work in contact with humans. The best-known model is definitely the ABB Yumi. This kind of robots is often used in the medical/pharmacological field.

To build a Cobot, the manufacturer or robot integrator must comply with a series of specific rules. In fact, Cobots in general can only operate around people at certain speeds, they cannot overheat and must avoid human contact by stopping or changing direction.

Types of industrial robots and application complexity

In the field of industrial applications, robots can be classified according to 3 levels:

1. Level 1 robots: the first level is characterized by robots whose purpose is to outperform, in a consecutive and repetitive manner, a specific task programmed by using a specific software. The classic example of the use of this robot occurs in the product assembly phase, where automation replaces humans in repetitive, tiring operations and therefore subject to drops in product quality. Besides the type of job, it is also possible to set the speed of each individual operation, thus ensuring an increase in productivity within a company.
2. Level 2 robots: these robots are much more flexible. They can autonomously adapt to changing operating conditions. For instance, they are equipped with vision systems and Artificial Intelligence, which make them capable of identifying the objects to be manipulated and to perform simple changes in trajectory and/or management logic (always within the pre-set program).
3. Level 3 robots: such robots are able to make autonomous decisions (which are not foreseen by the manufacturer) using neural networks. These kinds of robots are currently still being studied because they are very complex.

How to choose the right type of industrial robot?

The choice of a certain type of robot so that it is a truly effective industrial automation for your company - is closely linked to many factors. Let's see them together.

1. The type of industrial application

Inside this parameter are contained many questions:

• What object should the robot manipulate?
• Which operations should be carried out by the robot?
• How big and heavy is the object?
• What performance must the robot guarantee?

That's because each application requires a specific model of robot. Let's take welding, for example: it cannot be done with all types of robots. Usually, you need anthropomorphic robots with certain characteristics.

2. Available spaces

In many cases, some companies are looking for small-scale automations. Some robots are more suitable for compact applications – such as those that Tera Automation has integrated into its T-Flexicell robotic cells.

3. Budget

Budget is a very important parameter for a company. Each automation can be tailored to the type of application you want to realize respecting the budget constraint. Robots usually have similar prices for the same type of application. Then the different brands can – under certain circumstances – show price fluctuations by providing additional accessories and functionalities.

4. Shipping time

Some models may be available sooner than others, so you are encouraged to purchase one out of necessity. It all depends on the urgency of the project.

5. Design

Some models of industrial robots may meet your tastes more than others because, for example, they match by design or colour with the rest of your machines.

A fundamental detail: the system integrator

The choice of the right robot certainly plays a central role in the success of the project.Yet the system integrator may have an even greater importance. And it is important to distinguish between a system integrator and a reseller right away.

System integrators are able to guarantee a complete package including supply of properly configured and equipped machinery, installation, training, maintenance and all-round assistance. They can transfer all their know-how to their customers at any time and guide them in integrating the robot within their company. In addition, they can carry out demo sessions to show first-hand the potential of a robot in a specific application.

Conversely, resellers only supply the device and, in some cases, only the contact of the machine manufacturer and optional accessories. They are not always able to provide direct assistance and make modifications or customizations. Therefore, resellers often only act as intermediaries. Obviously, a valid system integrator offers an enormous added value to the robot, because it allows it to fully exploit its potential in any field of operation.