One of the most exciting topics in manufacturing is industrial robotics. Robots had their origins in the 1960s, but it was not until several years later that their implementation in companies began widely, due to the reduction of their manufacturing cost and the technological progress of the time.

The first applications of industrial robotics were in the operations of pick and place or material handling, but over time their function has been diversifying to become essential collaborators in almost all modern manufacturing processes.

The ease of creating an increasingly compact industrial robot has led to the emergence of so-called cobots, which take up less physical space and, like their bigger brothers, are capable of performing highly specialized operations such as welding or painting, but with design more focused on interaction with the people with whom they collaborate.

Industrial robots and cobots bring many benefits to parts manufacturing, for example, they reduce cycle time and manufacturing costs. On the other hand, they standardize the quality of products and help workers perform complex tasks, such as moving large and heavy parts or assembling small components, as in electronic manufacturing.

The era of automation has brought with it a huge wave of opportunities for people involved in the industry, new jobs have been created, accidents and occupational risk have been reduced. Moreover, by being able to delegate repetitive tasks to robots, creative work has increased.

Finally, there is no doubt that the incorporation of robots in companies has brought great challenges, but at the same time it has increased their flexibility, thus transforming them into more profitable, competitive and efficient companies in their manufacturing processes.

12.1 Introduction and classification of robots

According to Guizzo (2020), a robot can be defined as “an autonomous machine, capable of detecting its environment, performing calculations to make decisions and performing actions in the real world”. Therefore, it can be deduced that robotics is the engineering discipline that deals with the design, construction, and operation of robots.

Erroneously, robotics tends to be restricted to the field of robots, but it is important to note that this concept is much broader, as it can be applied to many situations, for example, an automatic inspection system where a variable is acquired (perception) and a command is executed, such as the rejection or acceptance of the part (action). Another scenario where robotics is present is home automation, in which a variable such as the amount of light entering a room can be detected, to close the windows, or automatically measure the pH level of the garden and water it.

Robots are the perfect assistants in a manufacturing cell thanks to their ability to perceive the external environment. For example, distinguishing the arrival of a part at a workstation and moving its arm to take the part to a machining center. This action is carried out by means of sensors, which are specially designed depending on the variable to be acquired. There is pressure, contact, humidity, speed, inductive, magnetic, optical sensors, and many more.

The action performed by a robot is implemented by means of actuators, which usually always exert a physical operation. Currently, the actuators that are most commercialized for industrial robotics applications are classified in the following (figure 1):

Figure 1. Types of actuators most common in industrial robotics applications
FESTO. (n.d.). Actuadores. Retrieved from https://www.festo.com/mx/es/c/productos/automatizacion-industrial/actuadores-id_pim5/#
For educational purposes only.

 

Parts of an industrial robot

According to Groover (2018), an industrial robot consists of several subsystems, as shown below (figure 2).

Figure 2. Subsystems of an industrial robot

 

• Mechanical subsystem: it has the mechanical configuration of the joints and arms of the robot; it is responsible for giving it flexibility and range.
• Electrical subsystem: it is responsible for supplying the necessary power to the motors, this subsystem also contains the communication interfaces, such as the serial or USB ports that the robot needs to communicate with the outside.
• Control subsystem: here, lies the robot motion logic, mathematical models, control loops, direct and inverse kinematics. Thanks to this subsystem, the robot can follow the trajectories previously defined in the programming.
• Process subsystem: it has to do with the environment where the robot will be working, the type of activity it will develop, whether it will work with people or machines and the cycle times it must meet to achieve the production goals.
• Sensor subsystem: Robots have two types of sensors: internal and external, the former serves to support the control loops to determine the position of the robot, its speed, the weight it is carrying, among others. They are specifically designed to monitor the internal functions of the robot and are factory installed. On the other hand, external sensors have to do with the process that the robot does, their function is to tell it that something is happening in its environment, and it must perform some tasks. They will be required in quantity and performance depending on the design of the working area.
• Planning subsystem: here the trajectory and types of movements are defined, as well as the speed and sequence of operations that the robot must perform to carry out a task. It contains the step-by-step programming of what you need to execute.

Anatomy of an industrial robot

The manipulator arm consists of two main components which are the joints and the links.

1. Joints: are responsible for providing relative motion between two links, generally a robot will have as many degrees of freedom as it contains joints, there are five types called L, O, R, T, V (figure 3).
2. Links: are the rigid parts of the robot, which are held together by joints. There are two types: input link and output link.

Figure 3. Relationships between joints and links

Groover, M. (2018). Automation Production System and Computer Integrated Manufacturing (5th ed.). United States: Pearson.
For educational purposes only.

 

Industrial robots can be classified based on the following categories (figure 4).

Figure 4. Classification categories of industrial robots

Classification based on your working envelope

Starting from the definition of the five types of joints (L, O, R, T and V), you can have 125 combinations (5x5x5) for the design of the manipulator arms. On a regular basis, five configurations predominate in the market, depending on the type of joints used and their working envelope.

Click on each type of configuration for more information.

 

Workspace

The workspace is the spatial volume of work of the robot and is defined by all the points it can reach without considering the final actuator or end effector. It is limited by the configuration of mechanical devices, since each joint of the robot is restricted to a range of motion. In figure 5, you can see a set of workspaces generator by different configurations of joins.

Figure 5. Workspaces associated with various types of robots

Baizid, K., Ćuković, S., Iqbal, J., Yousnadj, A., Chellali, R., Meddahi, A. (2016). IRoSim: Industrial Robotics Simulation Design Planning and Optimization platform based on CAD and knowledgeware technologies. Robotics and Computer-Integrated Manufacturing, 42. Retrieved from https://doi.org/10.1016/j.rcim.2016.06.003
For educational purposes only.

 

Classification by type of control

• Servo-controlled: they are governed using information from sensors that continuously monitor the speed and position of the robot axes and their associated components. The feedback provided by this information is compared with that which the robot has been pre-trained with and is stored in its memory devices.

• Not servo-controlled: non-servo-controlled robots lack feedback, and their axes are controlled by a system of mechanical stops and limit switches.

Classification based on its energy source

Robots can be classified based on the type of energy that powers it.

Classification based on the trajectory

Industrial robots can be programmed for actions such as simply traveling a distance, to perform their pre-programmed operations with different types of trajectories generated through different control techniques. There are three types of trajectories.

Actuators

The actuators or end effects (figure 6) are located at the end of the robot arm, they can usually be interchanged for different tasks. Most actuators can be grouped into two categories.

• Grippers
• Tool

Figure 6. Various configurations of grippers type actuators
Universal Robots. (n.d.). Application Builder. Retrieved from https://www.universal-robots.com/es/builder/

The grippers are actuators used to hold and manipulate objects during a work cycle. There are different types.

• Mechanical grippers: formed by two or more fingers, which are controlled by the robot to open and close.
• Vacuum grippers (suction cups): the parts are held by means of air suction.
• Magnetic grippers: to hold ferrous parts.
• Adhesive grippers: they use an adhesive substance to hold the part.
• Simple mechanical grippers: as hooks, shovels, ladles, or other similar.

Tool

The tools are used where the robot must perform some type of process or operation on the workpiece. Therefore, the robot will move the tool relative to an object that may be fixed or moving.

In any case, the robot must not only control the position of the tool, but it must also manage its operation, transmitting the control signals to activate or deactivate it.

 

12.2 Economic evaluation of a robot

The purchase of a robot should always be evaluated in terms of profitability for a company; it is estimated that its direct cost barely reaches 30% of the total investment that will be required to put it to work at 100%. Meaning, other expenses such as painting or flooring booths, the adequacy of the facilities and the purchase of tooling, among others, must be considered. There are two points to consider when assessing the profitability of the robot, the first is the time in which the investment will be recovered and the second is to determine the ROI or internal rate of return, for this, there are the following formulas.

Return on investment

 

Where:

P = Number of years to recover the investment
C = Total cost of the system
W = Annual salary of replaced workers
I = Savings in productivity
D = Allowed depreciation
M = Maintenance cost
S = Cost of support staff

Annual return on investment

 

Where:

ROI = Annual percentage of return on investment
C = Total cost of the system
W = Annual salary of replaced workers
I = Savings in productivity
D = Allowed depreciation
M = Maintenance cost
S = Cost of support staff
N = Lifetime of the project

Example of payback and annual returns on investment

• Calculate the annual return on investment and ROI for the following financial year.

A company is evaluating if it is profitable to buy and install a robot to take aluminum lift blocks to a CNC machining center. It is estimated that the increase in productivity due to the elimination of downtime by installing the robot will be $500 per month and the reduction in waste of defective products will be $250 per month.

The cost of the robot is 75,000 dollars, import taxes are 18% of the cost of the robot, plus 2000 dollars for the transportation of the robot from the U.S. to Mexico and 800 dollars insurance in case of damage while the robot is being transported. Other costs will include 6,000 dollars from the design and manufacture of the gripper, another 65,000 dollars will be spent on buying conveyor belts that feed material to the robot, sensors, PLC’s, and microcontrollers. The training in the use of the technology is valued at 1,500 dollars per engineer and 750 dollars per operator. The company plans to prepare a technical staff consisting of two engineers and three operators.

Currently, the plant operates with two shifts, has four workers per shift with an integrated daily salary of 15 dollars and work 288 days a year. With the implementation of the robot, there would be one worker per work shift (both shifts will continue to work) with an integrated daily salary of US $25 per day and maintaining the same number of working days.

The total depreciation of the system is estimated to be 25% per annum, a maintenance service for the robot has also been purchased from the company ABB at a semi-annual cost of 2000 dollars. On the other hand, there will be two support engineers for the operations of the robot, the time that each engineer will invest is estimated to be 35% of their working day to attend the robot, and each engineer will be paid $1200 per month. Finally, it has been estimated that the cost savings for the purchase of personal protective equipment for workers will be $450 per month. If the lifetime of the project has been estimated at 4.5 years, calculate the time in which the investment is recovered, as well as the annual return on investment.

Solution

Total cost of the system (C)

$75,000 Robot
$13,500 Tax
$2000 Transportation
$800 Insurance
$6000 Gripper
$65,000 Facilities
$5250 Training of engineers and operators
Operator training:
Total system cost (C): $167,550
Annual salary of workers (W)
Without the robot: (2 shifts) (4 workers) (15 dollars salary) (288 days) = $34,560
With the robot (2 shifts) (1 worker) ($25 salary) (288 days) = $14,400
Annual savings in workers' wages (W)= $34,560 - $14,400 = $20,160

Productivity savings (I)
Savings for downtime = ($500 monthly x 12 months) = $6000
Savings from waste reduction = $250 monthly x 12 months = $3000
Savings on personal protective equipment = $450 monthly x 12 months = $5400
Total productivity savings (I) = $14,400

Calculation of depreciation (D)
D = 25% of $75,000 (robot) + $6000 (gripper) + $65,000 (Installations)
Total depreciation (D) = $36,500

Annualized maintenance cost (M)
M = $2000 semester x 2 = $4000

Cost of support staff(S)
S= (2 engineers) (35% of their working day) ($1200 Monthly salary) (12 months)
S= $10,080
Estimated project lifetime (N) = 4.5 years

Return on investment

 

Interpretation of the results

The result shows that the 2.94 years (three years) from the start of the robot operation, the initial investment of $167,550 USD will be recovered. It must be considered that from this time onwards is when profits from the implementation of the robot will start to be made.

How much will be earned annually? This answer will be given by the Annual Return on Investment or ROI.

Annual Return on Investment (ROI)

 

Interpretation of the results

The ROI yielded 11.78% per annum, which means that a profit of $19737.39 USD per annum will be obtained, this amount came out of multiplying the cost of the investment which was $167,550 by the ROI of 0.1178. It should be considered that these annual profits will be earned after three years of operation, which is the time in which the investment will be recovered.

12.3 Robot programming

To program a robot, there are two techniques: online programming and offline programming.

1. Online programming
   Online programming consists of programming the robot directly at its place of operation. There are two main methods to perform it.
   • Learning by guided driving through the task (programming by demonstration).

• Learning by teaching box (programming with learning terminal).
  
  

2. Offline programming
   
   Offline programming means creating a program for a robotic task without the need to be physically connected to the robot, or close to it.
   Robots understand instructions by means of a programming language (it can be a general-purpose language or designed exclusively by the brand that produces it). Figure 7 shows a small summary with the evolution of the most popular programming languages have been used in robotics applications to date.

Figure 7. Evolution of the programming languages used in industrial robotics

 

Most robots work with assembly languages, as they are ideal for sequencing activities and are easy to learn compared to high-level ones that, although more powerful, take more time to master.

A recommended methodology for the general programming of an industrial robot is constituted by:

1. Understanding the process. Collect as much information as possible about the task, as well as the components that will intervene in the process.
2. Performing the dot diagram. Technique used to describe in graphic form the sequence of operations of the process, as well as the points in space. The dot diagram can have the input signals indicated, as well as the output signals.
3. Performing the programming algorithm. Describe all the activities that the robot will have to carry out. The start for the programming algorithm is the dot diagram, then, the sequence of activities is enriched with programming details.
4. Recording points on the robot. Position and record by means of the teach pendant, teaching box, central computer, or any other method that the robot has the physical position of the manipulator according to the dot plot.
5. Performing the execution program. According to the language of the robot to carry out the programming of the activities according to the programming algorithm.
6. Simulating the run. If any software is available, it is recommended to carry out the simulation of the process before running it on the robot.
7. Downloading and running the program. Enter the program in the robot controller and run it step by step.
8. Saving the points and program. The point information, as well as the program, can be stored on USB memory sticks or on the robot's computer, if available.

12.4. Robots in the industry

The third industrial revolution began a process of computerization and automation that has not stopped to this day. With the arrival of intelligent systems, Big Data, the Internet of Things (IoT) and hyperconnectivity, we have witnessed the arrival of the so-called Industry 4.0 (figure 8).

Figure 6. Various configurations of grippers type actuators
Melanson, T. (2022). What Industry 4.0 Means for Manufacturers. Retrieved from https://aethon.com/mobile-robots-and-industry4-0/
For educational purposes only.

 

According to Melanson (2018), the fourth industrial revolution makes all elements in your supply chain smart entities, including everything from manufacturing, warehousing, and logistics processes to enterprise resource planning.

Robots have not been left behind, constituting one of the main pillars on which the autonomous manufacturing industry and intelligent manufacturing processes are based.

To learn more about the impact of robotics on new industrial processes, check out the following video:

The history of robots in the 4.0 industry is just beginning to be written, so it's up to you as an engineer to contribute to its development, bringing new ideas to improve the quality of human life in the industry.

Industrial robotics has changed the way companies do things; on the one hand, it has improved the quality of manufacturing processes, production has become more flexible and agile in the face of market demands, it has lowered manufacturing costs by eliminating downtime and reducing material waste, and it has also increased safety in the workplace. Despite all these advantages, some companies still doubt the implementation of these technologies for various reasons, one of them being their cost.

Understanding how a robot works and is programmed may not be so simple. It is necessary to know the process, the cycle times to be achieved and the physical limitations of the robot (workload or load capacity). In addition, you must know about programming logic, the input and output signals it handles, its specific programming language, among other things. This course of integrated manufacturing systems gives you the first step to know all these points and reinforce them with others that you will take later that will make you an expert in industrial robotics.

Do not forget that there is no robot intelligent enough to make decisions in a company, it will do what you teach it, so you must be prepared to program it efficiently and effectively and thus, increase the profitability of the company.

Make sure that you:

• Understand what a robot is and the subsystems that make it up.
• Comprehend the difference between a joint and a link.
• Identify which are the configurations of the joints.
• Classify a robot based on its main characteristics.
• Determine the time in which the investment of a robot is recovered, as well as calculate the ROI.

• Groover, M. (2018). Automation Production System and Computer Integrated Manufacturing (5th ed.). United States: Pearson.
• Guizzo, E. (2022). What Is a Robot? Retrieved from https://robots.ieee.org/learn/what-is-a-robot/
• Melanson, T. (2018). What Industry 4.0 Means for Manufacturers. Retrieved from https://aethon.com/mobile-robots-and-industry4-0/

Videos

To learn more about Tesla, Amazon, and Audi, watch the following video:

• CNET Highlights. (2021, September 01). Factory Robots! See inside Tesla, Amazon and Audi's operations (supercut). [Video file]. Retrieved from https://www.youtube.com/watch?v=Zs5EMov15RA

To learn more about industrial robots, watch the following video:

• Top10 Files. (2019, November 28). Top 10 Industrial Robots [Video file]. Retrieved from https://www.youtube.com/watch?v=6L-V4xzUcmM

Readings

To learn more about industrial robots, we recommend reading:

• A3. (2021). 10 Industrial Robot Companies That Lead the Industry. Retrieved from https://www.automate.org/news/10-industrial-robot-companies-that-lead-the-industry

To learn more about cobots, we recommend reading :

• UNIVERSAL ROBOTS. (2022). USING COBOTS TO CONQUER THE NEW WORLD OF WORK. Retrieved from https://www.universal-robots.com/blog/using-cobots-to-conquer-the-new-world-of-work/

Description

Through the search and analysis of information, the student will review the concepts seen in class on the subject of industrial robotics and practice programming these using the robot, placing in the manufacturing cell of the campus.

Objective

To understand the concepts and characteristics of industrial robots.

Requirements

Robot installed in the manufacturing cell of your campus.

Instructions

Individually

1. First, visit the manufacturing cell of your campus and investigate the characteristics of the robot that is installed in it.
   
   Make a short summary where you include the following data:
   1. Brand
   2. Year of manufacture
   3. Model
   4. The configuration of the robot based on its working envelope (spherical, articulated, Cartesian, or other)
   5. The number and types of joints the robot has
   6. The type of end effector which it uses (gripper or tool)
   7. The max payload
   8. Type of programming it supports (online or offline)
   Include in your summary a photo of the teach pendant that it uses.
2. Then, look into the procedure to be followed to program the robot with your campus manufacturing cell manager. Carefully study its operation manual and design a pick and place routine that suits the characteristics of the working environment of the manufacturing cell and that can serve as an example to demonstrate the operation of the robot to your classmates.
3. Next, request the support of the manufacturing cell manager to carry out the programming of the robot and check the correct execution of the routine. Document the result of your work on video.
4. Finally, prepare a document in which you present your results, including the evidence of the activities carried out. Add at the end of the document a small conclusion about what you learned.

Deliverable(s)

Document with the development of the activity and video with the evidence of the programming of the robot.

Evaluation criteria

1. Make the summary with the data of the robot that is in the manufacturing cell of your campus
2. Design the pick and place routine based on the characteristics of the work environment of the manufacturing cell.
3. Perform the robot programming and generate the requested video.
4. Prepare the final document with the summary of the results obtained.

Description

Solve the exercises on the physical structure of industrial robots and answer a quiz with review questions.

Instructions

Individually

1. First, answer the 16 questions of the review question from chapter 8. Industrial Robotics from the textbook, click here.
2. Then, answer the problems from 8.1 to 8.5 in the section Robot Anatomy, from chapter 8 of the textbook, click here.
3. Next, conduct some research on offline programming systems and draw up a summary with the main open-source tools that are currently available to realize this purpose.
4. In addition, solve the following problem.
   
   

   A company is considering installing an industrial robot in an electronic component recycling plant. Currently, the company has two work shifts, with six workers each (the salary that the workers receive is 12 dollars a day and the plant works 240 days a year). With the implementation of the robot, there would be only two workers, who would receive a salary of 20 dollars, working the same number of days).
   
   The cost of the specialized robot is 40,000 dollars (the price includes the grippers and tools necessary for the task), in addition, another 80,000 dollars are considered for the conditioning of the premises and the training of the workers.
   
   The total depreciation of the system is estimated to be 20% per year due to operating conditions; it is also considered that monthly maintenance costs will reach 350 dollars. The average savings after installing the robot is estimated at $1,500 per month in terms of increasing working capacity and decreasing the costs associated with human personnel.

• Calculate the following:
  1. The time in years to recover the investment of the robot
  2. The annual return on investment

Deliverable(s)

A written report of the four activities, the problem must include the procedure and solution.