With an incredibly fast growth in automation and robotics being witnessed over the last few years, all industries, especially manufacturing, are starting to adopt the technology into their processes. Industrial robots now do repetitive tasks, with a high degree of accuracy and precision and the products coming off the line are of far better quality.
Without doubt, the main reason manufacturers are using robots is that their output is increased due to the robots not needing to take breaks as human workers do. Furthermore, these machines can work in environments that are dangerous or harmful to humans. Ultimately, that results in better health and safety in the workplace.
Major Types of Robot
Looking at the mechanical configuration of robots, we can classify them into six main types, namely cartesian, articulated, SCARA, polar, delta, and cylindrical.
This is the most common type of robot found in industrial scenarios. In configuration it looks much like a human arm, connected with a twisting joint to a base. There can be anything from two to ten rotary joints that connect the arm links, and each of those joints provides one more degree of freedom. They may be orthogonal or parallel joints. The most commonly used robots are articulated with six degrees of freedom.
- They work fast
- They take up little room on the factory floor
- They produce a much higher output
- Easy to align several robots
- They must have a dedicated controller
- The programming is quite complicated
- The kinematics are also complicated
Also known as a gantry or rectilinear robots, cartesian robots are rectangular in configuration. They have three prismatic joints used for the delivery of linear motion, sliding on the three X, Y, and perpendicular axes. Some also have a wrist attached, allowing for rotational movement. These types of robot are generally used in industrial application because the flexibility in the configuration makes then ideal for specific applications.
- Highly accurate in positional terms
- Simple to operate
- Can easily be programmed offline
- Handle heavy loads easily
- Don’t cost so much
- They require a large area for installation and operation
- The assembly is quite complex
- Limited movement, only one direction at any one time
- Requires large operational and installation area
SCARA stands for Selective Compliance Assembly Robot Arm. These robots have work envelope shaped like a donut. They have two parallel joints, each providing compliance in a specific plane. There are vertical rotary shafts with an end effector on the arm that has horizontal movement. SCARA robots are specialized in lateral movement, and tend to be used on assembly lines. Not only are they faster in movement, they also integrate better than cartesian or cylindrical robots.
- They work fast
- They are excellent at repetitive work
- They have a large workspace
- A dedicated controller is required
- They are limited to planar surfaces
- They are not easy to program offline
Also called parallel link robots, the delta robot has a series of parallel joint linkages, all connected with one common base. Because each joint has direct control of the end effector, the end effector positioning can be controlled with the robot arms easily, which leads to very fast operation. With a work envelope shaped like a dome, these robots tend to be used for product transfer or high-speed pick-and-place applications.
- Very fast
- High level of operational accuracy
- Operation is complicated
- A dedicated controller is required
Polar robots are configured with one twisting joint that connects the arm and the base, and two rotary and one linear joint combination that connects the links. Sometimes called spherical robots, they have a work envelope spherical in shape and a polar coordinate system formed by the axes. Polar robots have one central shaft that pivots and a rotating arm that can be extended. Formed much like a gun turret, polar robots can sweep through a large space but arm access is limited only to the workspace.
- Has 360° reach
- Can reach blow or above any obstacle
- Large work output volume
- Don’t need so much floor space
- Reach does not extend above itself
- Has only a short reach vertically
- In the rotary motion direction, they have low repeatability and accuracy
- Not so common in new designs anymore
Cylindrical robots have a minimum of one rotary joint, placed at the base, and a minimum of one prismatic joint, used to connect the links together. Their workspace is cylindrical and their configuration is of a pivoting shaft with an extending arm that slides to move vertically. As such, a cylindrical robot has horizontal and vertical linear movement. And on the vertical axis, it also has rotary movement. The end of the arm is compact in design, allowing the robot to reach into a tight work envelope without losing any repeatability or speed. Cylindrical robots tend to be used in the simpler applications, like picking up, rotating, and placing materials.
- Simple to install and operate
- Requires the minimum amount of assembly
- Has 360° reach all around itself
- Doesn’t need much floor space
- Capable of carrying large payloads
- Cannot get around obstacles
- Rotary motion direction is low in accuracy
- Not commonly used in new designs
When deciding to implement automation and robots into their working practices, any business must carefully consider what type of robot they need for specific applications. Manufacturers must take several factors into consideration like orientation, load, precision, speed, travel, duty cycle, and the environment, before they choose the types of robots that they require to provide effective and profitable results.
Leading companies in robotics are now providing specific robots and automation solutions to cater to individual needs. And as time goes by, we can expect to see more and more customized robots in the workplace, although almost all of them will be based on one of the above six types.