Industrial robots are the backbone of the manufacturing industry. It is impossible to imagine modern factories without robots. All this automation in manufacturing units of all scales is done using industrial robots. Industrial robots perform tasks that are repetitive, difficult, or dangerous for human workers. Even jobs that humans can perform are performed with greater productivity and efficiency when performed by robots. Robots enable programmable automation and can perform all types of tasks that do not require general human intelligence. They are better at doing whatever they were programmed to do.
Industrial robots come in different sizes and shapes. We have already discussed the basic structure of an industrial robot. The basic construction of all industrial robots remains the same. Despite this, different robots look so different and at the same time so similar. There are many different ways to assemble industrial robots. The fact is that each robot is unique, as it was designed to perform a unique task in a unique work environment. Despite different sizes, shapes, appearance and tasks, all industrial robot designs can be broadly categorized into the following classes.
- Cartesian robots
- Articulated robots
- Cylindrical robots
- Delta robots
- Polar robots
- SCARA Robots
- Cobots
Let's learn more about all these types of industrial robots.
Cartesian robots
Cartesian robots are the simplest of all types of robots. These robots perform linear movements in space along Cartesian axes – X, Y and Z axes. Movements along three different axes are orthogonal to each other. The robot has a kind of cubic workspace. These robots are commonly used as pick-and-place for packaging, inspection and loading of materials. All CNC machines and 3D printers are essentially Cartesian robots.
These robots are most popular among all types due to their simplicity, high accuracy, high precision, low cost and stroke length. Building and programming these robots is easier because all movements are linear along orthogonal axes. Due to the linear movements, the stroke can be easily adjusted to any length and size. Linear movements can be activated with extreme accuracy and precision. However, linear movements limit the robot's flexibility. The robot can only perform specific movements and it may be more difficult or impossible to perform certain tasks. Due to linear movements in orthogonal dimensions, the robot generally requires more space to operate. For operations that require fast movements at specific points, the Cartesian design may be too slow to work around.
Articulated robots
The movement and configuration of an articulated robot is similar to that of a human arm. Articulated robots have rotating joints driven by servomotors. The joints serve as the robot's axes. There can be anywhere from two to more than ten rotary joints, each providing additional freedom. These robots typically operate in four to six axes. The links rotate and twist to operate in the working environment.
These robots have great speed and flexibility. The robot can easily reach any point in the workspace. This is why these robots are used in various applications that involve complex movements and detailed tasks. These robots are commonly used for welding, machine tending, coating, painting, material handling, and packaging. The only disadvantages of the hinged design are complexity and cost. Due to the rotary movements, it is comparatively difficult to program these robots. Construction also requires more parts and careful assembly. Due to the use of servo motors and other mechanical parts that allow rotary movement, these robots are expensive to manufacture.
Cylindrical robots
Cylindrical robots are designed to operate in a cylindrical workspace. The robot has a rotating joint at the base that can rotate 360 degrees. A linear arm is connected to the rotary shaft which can move up, down and back and forth. Therefore, there are three axes of movement, one circular and two linear. These robots are powered by powerful motors designed to lift and carry heavy weights. Cylindrical robots take up a lot of floor space, often more than is needed for workspace. Unlike articulated or Cartesian robots, these robots do not offer any unique advantages except a high payload capacity. This is why cylindrical robots are less common. These robots are still used for arc welding, painting, coating and material handling in many places.
Delta robots
Delta robots are also called parallel robots. These robots have three arms connected to a common base mounted on the top of the robot. Each arm is shaped like a parallelogram and is placed at the apex of an equilateral triangle at the base. Delta robots have a semi-spherical workspace. The motors are placed in the base of the robot, which supports most of the robot's weight. The three arms of the parallelogram are lightweight and can be moved quickly around the workspace. These robots are designed to work with small loads. Mainly these robots are used for welding or packaging materials. Due to a triangular design with lightweight arms, the robot can move and operate quickly within the workspace, allowing for quick packaging or quick welding.
Polar robots
Polar robots are based on the polar coordinate system. The robot has two rotary joints and one linear joint. Rotary joints are used to move the robot arm around a sphere. The linear joint extends the arm to increase your workspace. These robots are good at lifting heavy loads. However, these have complex designs and programming. Due to the two-axis rotary motion, manufacturing this robot is expensive. Furthermore, polar robots take up a lot of floor space, more than the required work space. With these disadvantages, polar robots offer only a few advantages compared to Cartesian robots. This is why, in most applications, articulated robots have replaced polar robots. Articulated robots have similar complexity in design and high cost, but offer more flexibility and require less space.
SCARA Robots
SCARA stands for Selective Compliance Assembly Robot Arm or Selective Compliance Articulated Robot Arm. These are special articulated robots designed to have more flexibility around the X and Y axes while having rigid transitions around the Z axis. These robots can be designed to handle light to moderately heavy loads. The design is optimized for high position repeatability. Compared to other articulated robots, SCARA requires less floor space and can be easily assembled. SCARA robots are used for rapid picking and positioning and material handling tasks. These robots are generally seen as a fast alternative to Cartesian robots.
Cobots
Cobots are also called collaborative robots. These robots are designed to operate and share their workspace with human workers. They are employed in material handling, quality inspection, bolting, palletizing, sealing, machine servicing, polishing, etc. These large, complex robots are designed to have flexible, adaptive mobility to work in a shared space. As these robots have a shared workspace with humans, safety is the first thing considered most important in their design. Working together with humans requires the use of many sensors on the robot and the program's interpretation of human behavior. The manufacturing and commissioning of these robots often requires numerous licenses and safety guarantees. Due to co-working, design and operation have many restrictions. Typically, the robot is explicitly made to operate at lower speeds to ensure human safety.
Conclusion
Cartesian, Articulated, SCARA, Polar, Delta, Cylindrical and Collaborative are the broad categories of industrial robots. These are the most common types of robots. There may be differences in robot designs with various links and joints, joint type, size and shape of the robot. Despite these differences, most industrial robots certainly fall into one of these classes.
