Visvesvaraya Technological University Belgaum, Karnataka-590018
PROJECT REPORT [10AU85] ON “APPLICATION OF COBOTS IN AUTOMOTIVE ASSEMBLY LINE” Submitted In partial fulfillment of the requirement for the award of the Degree of BACHELOR OF ENGINEERING IN AUTOMOBILE ENGINEERING By PRAFULLA V (1NH13AU046) BALU KRISHNAKUMAR MENON (1NH14AU007) Under The Guidance of Mrs. SMITHA B. S. Assistant Professor Department of Automobile Engineering, NHCE
2017-2018 NEW HORIZON COLLEGE OF ENGINEERING (Autonomous college Permanently Affiliated to VTU Approved by AICTE) Accredited by NAAC with ‘A’ Grade
DEPARTMENT OF AUTOMOBILE ENGINEERING
CERTIFICATE
This is to certify that the Project Report [10AU85]
on
APPLICATION OF COBOTS IN AUTOMOTIVE ASSEMBLY LINE
is bonafide work carried out by
PRAFULLA V (1NH13AU046) BALU KRISHNAKUMAR MENON (1NH14AU007)
In partial fulfillment for the award of degree of Bachelor of Engineering in Automobile Engineering of the Visvesvaraya Technological University, Belgaum during the year 2017-2018. It is certified that all corrections/suggestions indicated for Internal assessment have been incorporated in the report deposited in the departmental Library. The project report has been as it is satisfying the academic requirements in respect of project report prescribed for the Bachelor of Engineering Degree.
Signature of Internal Guide Signature of HOD Signature of Principal External Viva
Name of the Examiners Signature with Date
1
2
ACKNOWLEDGEMENT
The satisfaction that accompanies the successful completion of any work would be incomplete without the mention of people who made it possible and whose constant encouragement and guidance has been a source of inspiration through the course of completion of this project.
We wish to thank the Almighty for all the blessings we have received.
We express our heartfelt thanks to Dr. Mohan Manghnani, Chairman, New Horizon Educational Institutions for providing this endower.
We would also like to express our heartfelt thanks to Dr. Manjunath, Principal, New Horizon College of Engineering for providing a friendly atmosphere to work in.
Any amount of gratitude is incomplete without thanking Dr. Sridhar Kurse, Professor and HOD, Department of Automobile, New Horizon College of Engineering who has continuously supported and motivated us in completion of this project.
We sincerely thank Prof. Karthik A.V, Assistant Professor, Department of Automobile, New Horizon College of Engineering who has guided us throughout the completion of this project.
We thank the entire staff members of automobile Department, New Horizon College of Engineering and everyone who has directly or indirectly helped us in completion of the project.
Declaration
We, Akarsh, Aldwin Rajan, D Praveen, Ashwin Unnikrishnan students of 8th Semister, B.E Automobile Engineering, New Horizon College of Engineering declare that the project work titled “Influence Of Canola Oil On Performance And Emission Characteristics Of A Single Cylinder Diesel Engine” has been carried out by us and submitted in partial fulfilment of course requirement for the award of degree in Bachelor of Engineering in Automobile Engineering of Visvesvaraya Technological University, Belgaum, during academic year 2017-2018.
Date:
Place:
PRAFULLA V. (1NH13AU046)
BALU KRISHNAKUMAR MENON (1NH14AU007)
Application of cobots in automotive assembly line
Table of Contents
Chapter 1 - Introduction 1.1 – Abstract 1.2 – Project objective
Chapter 2 – Company Profile 2.1 About Continental AG 2.2 Key milestones 2.3 Company mission 2.4 Company values
Chapter 3 – Cobots 3.1 Introduction to cobots 3.2 Types of cobot operation 3.3 Cobot lifespan 3.4 Cobot applications
Chapter 4 – Selection 4.1 Of YSD line 4.1.1 Data 4.2 Of cobot
Chapter 5 – Components 5.1 Gripper design and validation
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5.1.1 Repeatability 5.2 PCBs 5.2.1 PCB defects
Chapter 6 – Change of Location 6.1 – Data 6.2 Gripper validation 6.3 Risk assessment 6.3.1 Risk analysis 6.3.2 Risk evaluation 6.3.3 Poka Yoke 6.4 Cobot operation
Chapter 7 – Result
Chapter 8 – References and literature review 8.1 – Technical papers 8.2 – Cobot safety and programming 8.3 – Case studies 8.4 – Related articles
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Chapter 1 - INTRODUCTION
1.1 Abstract
Founded in Hanover, Germany in 1871, Continental AG can look back at a history of success. As an automotive supplier and industry partner, the technologies, system and service solutions on offer make mobility and transport more sustainable, safer, more comfortable, more customised and affordable, that help protect the environment and that give individuals more opportunities to shape their own future. Collaborative robots, or cobots, are complex machines which are designed to work hand in hand with human beings. In a shared work environment, they support and relieve the human operator. This helps free up the human operator to be deployed elsewhere on different assignments as required. Consequently, this saves countless man- hours and increases production rates as well as production efficiency exponentially.
1.2 Project objective
The project deals with the implementation of cobots on the shop floor of a production plant, namely Continental Automotive India, to free up manpower and increase production as required in response to demand. One area where installation of the cobot would benefit production is the installation of speedometer needles or pointers, on Printed Circuit Boards (PCBs). The application of the cobot is such that it could carry out jobs on multiple workstations within its operable workspace. A deeper look is carried out in the following chapters.
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Chapter 2 – COMPANY PROFILE
2.1 About Continental AG
Continental AG is a leading automotive manufacturing company specialising in tyres, brake systems, interior electronics, automotive safety, powertrain and chassis components, tachographs, and other parts for the automotive and transportation industries. They are the world’s fourth largest tyre manufacturer, after Bridgestone, Michelin and Goodyear. Starting as a rubber manufacturer in 1871, Continental was ranked third in global OEM automotive parts sales in 2012 according to a study sponsored by PricewaterhouseCoopers, sfter the acquisition of Siemens AG's VDO automotive unit in 2007. In 2008, Continental appeared overextended with its integration of VDO and had since lost almost half of its market capitalisation when it found itself to be the takeover target of the family-owned Schaeffler AG. By 2009, Schaeffler successfully installed the head of its motor division at the helm of Continental. Schaeffler AG is the controlling shareholder and currently owns 46% of Continental shares.
Continental is structured in five divisions:
Chassis and Safety
Powertrain
Interior
Tyres
ContiTech
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One of Continental's main areas of expertise and technological leadership is fuel consumption reduction, achieved through more efficient fuel injection systems, reduced rolling-resistance tyres, and hybrid propulsion systems. Continental sells tyres for automobiles, motorcycles, and bicycles worldwide under the Continental brand. It also produces and commercialises other brands on a regional level, such as General (US/Canada), Gislaved (Canada, Spain, Nordic Markets), Semperit (industrial applications), Euzkadi (Mexico/Latin America) and Barum to serve EU & Russia. Continental's customers include all major automobile, truck and bus producers, such as Volkswagen, Daimler AG, Ford, Volvo, Iveco, Schmitz, Koegel, Freightliner Trucks, BMW, General Motors, Toyota, Honda, Renault, PSA and Porsche.
Continental tyres on a Mercedes-Benz SLS AMG
In 2001, Continental acquired a controlling interest in Temic, Daimler Chrysler's automotive-electronics business, which is now part of Continental Automotive Systems. The company also purchased German automotive rubber and plastics company Phoenix AG in 2004, and the automotive electronics unit of Motorola in 2006. Continental acquired Siemens VDO from Siemens AG in 2007. In Argentina, teamed up with FATE in 1999 for the production of tyres for cars, trucks, and buses and exports the production of the San
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Fernando plant to the rest of South America. In 2007, the company began to construct a plant in Costa Rica to produce powertrain components for North America. Continental also produces wheels for (mountain) bikes and continuously provided grippy rubber soles for Adidas running shoes like the Ultra Boost.
2.2 Key milestones
1871 - Continental-Caoutchouc- und Gutta-Percha Compagnie is founded in Hanover on October 8 as a joint stock company. Manufacturing at the main factory in Vahrenwalder Street includes soft rubber products, rubberized fabrics and solid tires for carriages and bicycles. 1882 – The rampant horse is adopted as the trademark. 1892 - Continental is the first German company to manufacture pneumatic tires for bicycles. 1898 - Begins production of automobile pneumatic tires without tread pattern in Hanover- Vahrenwald. 1901 - The first Daimler-produced car to be called Mercedes achieves a sensational victory on Continental pneumatics in the Nice-Salon- Nice car race. 1904 - Continental presents the world’s first automobile tire with a patterned tread. 1908 - Continental invents the detachable rim for sedans—a remarkable innovation to help save time and effort when changing a tire. 1921 - The company’s 50th anniversary sees Continental become the first German company to launch the cord tire on the market. The stiff
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Application of cobots in automotive assembly line linen square-woven fabric is thus replaced by the more pliable cord fiber fabric. 1936 - Synthetic rubber is introduced into the tire manufacturing process. 1955 - Continental is the first company to develop air springs for trucks and buses. Continental is the first German company to start manufacturing tubeless tires. 1967 - Opening of the Contidrom tire testing facility on the edge of the Lüneburg Heath. 1972 - Continental launches the studless Conti-Contact winter tire. 1995 - The Automotive Systems division is established to intensify the systems business with the automotive industry. 1997 - Continental presents ISAD (Integrated Starter Alternator Damper). ISAD combines the vehicle’s starter and generator in a single unit. 2003 - Unveiling of ContiSportContact 2 Vmax, the world’s first road tire approved for speeds of up to 360 km/h. 2008 - Production of lithium-ion batteries for use in vehicles with hybrid drives begins in the Nuremberg plant. 2011 - Acquisition of the tire operations of the Indian-based Modi Tyres Company Ltd. with production facilities in Modipuram and Partapur. Production of electric motors starts at the Gifhorn plant in Lower Saxony, Germany. 2012 - Comprehensive testing of automated driving starts in the U.S. state of Nevada. A highly automated Continental test vehicle has covered 15,000 miles of public roads so far—without any accidents. 2018 - Continental Appoints Alexander Klotz as new India R&D Center Head.
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2.3 Company Mission
The company’s goal is to actively protect the resources available on our planet. That is why their actions are characterized by the constant pursuit of higher efficiency. As a responsible, leading company and the partner of choice, they invent, develop, produce and market indispensable and pioneering technological solutions. They are guided by social trends, such as the rapid growth of the world’s population and the resulting increase in urbanization, demographic changes and – in particular – globalization. Four megatrends can be derived from these global developments. They form the foundation of our strategy and our business activities:
Safety: zero accidents To protect life and conserve resources
Information: saving time, increasing comfort Intelligent mobility through constantly connected driving
Environment: clean air Resource-efficient and emission-free driving
Affordable mobility: individual mobility for all Enabling more freedom and opportunities
“For people and society, our solutions therefore mean the protection of life and health, a higher quality of life, faster progress, increased environmental protection, as well as more opportunities to personally shape the future. We thus assume social and corporate responsibility by advancing sustainable mobility. Continental today helps protect millions of road users around the world against accidents and their consequences. Continental
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Application of cobots in automotive assembly line contributes to cleaner air. Continental is paving the way for safe, efficient and intelligent mobility.” Dr. Elmar Degenhart, Chairman of the Executive Board of Continental
2.4 Company Values
Continental comprises more than 240,000 passionately committed people who realize the dream of mobility every day for customers and users in 61 countries. That is how they create sustainable value. At Continental, all employees share four fundamental corporate values. They form the roots of their corporate culture: • Trust • Passion To Win • Freedom To Act • For One Another Only in an environment shaped by those values can essential and pioneering services, solutions and input be created.
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Chapter 3 – Cobots
3.1 Introduction to Cobots
A cobot, or collaborative robot is a robot intended to physically interact with humans in a shared workspace. The definition of collaboration is the action of working with someone to produce something, and cobots are designed to work alongside an individual as a valued part of the team and not a replacement. If recent research is anything to go by, collaborative robots are the workforce of the future. Cobots were invented in 1996 by J. Edward Colgate and Michael Peshkin, professors at Northwestern University. A 1997 US patent filing describes cobots as "an apparatus and method for direct physical interaction between a person and a general purpose manipulator controlled by a computer." Cobots resulted from a 1994 General Motors initiative led by Prasad Akella of the GM Robotics Center and a 1995 General Motors Foundation research grant intended to find a way to make robots or robot-like equipment safe enough to team with people. The first cobots assured human safety by having no internal source of motive power. Instead, motive power was provided by the human worker. The cobot's function was to allow computer control of motion, by redirecting or steering a payload, in a cooperative way with the human worker. Later cobots provided limited amounts of motive power as well. German based industrial robot pioneer KUKA released the first cobot LBR 3, in 2004. This computer controlled lightweight robot was the result of a long collaboration with the German Aerospace Center institute since 1995. Universal Robots released its first cobot, the UR5, in 2008. In 2012 the UR10 cobot was released, and later a table top cobot, UR3, in 2015. Rethink Robotics released an industrial
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Application of cobots in automotive assembly line cobot, Baxter, in 2012 and smaller, faster collaborative robot Sawyer in 2015, designed for high precision tasks. FANUC - the world's largest producer of industrial robots - released its first collaborative robot in 2015 - the FANUC CR-35iA with a heavy 35kg payload. Since that time FANUC has released a smaller line of collaborative robots including the FANUC CR-4iA, CR-7iA and the CR-7/L long arm version. Cobots can have many roles — from autonomous robots capable of working together with humans in an office environment that can ask you for help, to industrial robots having their protective guards removed as they can react to a human presence under EN ISO 10218 or RSA BSR/T15.1.
Collaborative industrial robots are complex machines which work hand in hand with human beings. In a shared work process, they support and relieve the human operator. One example: a robot lifts and positions a heavy workpiece whilst a human worker welds light iron hooks to it. During this task, the operator and the various elements of the robot, such as the robot arm and tool, are in close proximity to each other. The robot and the worker may come into direct contact with each other as a result. A comparable situation can be found with mobile service robots, which are being used in increasing numbers in the proximity of human beings in occupational contexts and in public or private environments.
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To date, the use of robots has required guards in order to protect persons present in the robot's working space reliably against exposure to mechanical impact and therefore injury caused by parts of the robot moving at high speed. During revision and restructuring of the standards relevant to industrial robots, a further new area of application has been created, that of collaborative robots. The revised EN ISO 10218 standard Parts 1 and 2 and the ISO/TS 15066 specification, work on which was begun in 2010, define the safety requirements for the sphere of collaborative robots. Besides the robot itself, the collaborative robot in this context includes the end effector,
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Application of cobots in automotive assembly line i.e. the tool adapted on the robot arm with which the robot performs tasks, and the objects moved by it.
In 2017, collaborative robots (cobots) began to overtake the robotic market. According to BIS Research, by 2021, the collaborative-robot market is expected to grow to approximately $2 billion and 150,000 units. Several industries are looking towards cobots as a way of introducing the new automation future.
3.2 Types of cobot operation:
Cobots are lightweight with aluminium arms and joints powered by less robust harmonic drives. Following are the major types of cobot operation:
• Speed and separation monitoring - Sensors detect human presence and reduce the cobot’s operating speed as the human gets closer. • Power and force limiting - This defines today’s typical cobot. By limiting speed, payload and force, the cobot stops almost
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instantly when it encounters an obstacle and the energy of any collision is kept below ISO-defined maximum levels. • Safety-rated monitored stop - Proximity and other sensors stop the robot when a human enters its workspace. Either the robot or the human operator moves, but not both at the same time. The robot can swiftly resume its tasks when the human leaves but this operating model loses most collaborative advantages and still requires traditional safety guards. • Hand guiding - The human operator uses a hand-operated device to directly control the robot.
3.3 Cobot lifespan
Universal Robots has several robots that have been in service for more than 10 years. Where industrial robots are big heavy pieces of machinery with sealed drives that might work for decades, cobots are lightweight with aluminium arms and joints powered by less robust harmonic drives. In Universal Robots’ machines, those drives are designed for a minimum lifespan of 35,000 hours. That’s about four and a half years of continuous operation which equates to many more years of use in real world applications like machine tending. For high load applications, it quotes five to six years before a joint might need to be replaced.
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3.4 Cobot applications
The six most common applications of cobots are listed as follows:
Pick and Place
Manual pick and place is one of most repetitive tasks performed by human workers today. The mundane nature of the task can often lead to mistakes, while the repeated physical motions can lead to strain or injury. Pick and place applications are a good start for first-time cobot users. A pick and place task is any in which a workpiece is picked up and placed in a different location. This could mean a packaging function or a sort function from a tray or conveyor; the later often requires advanced vision systems. Pick and place functions typical require an end-effector that can grasp the object. It could either be a gripper or vacuum cup effector.
Machine Tending
Machine tending requires a person to stand for long hours in front of a CNC machine, injection-modeling machine, or another similar device and tend to its operational needs. This could be tool changes or replacement of raw materials. The process is long and tiresome for the human operator. Not only do cobots free up the human operator, but a single cobot can also tend to multiple machines, leading to increased productivity. These type of cobot applications may require the cobot to have input and output (I/O) interfacing hardware specific to the machine. The I/O hardware indicates to the robot the next cycle or when material needs to be replenished.
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Packaging and Palletizing
A subset of the pick and place is the packaging and palletizing of products. Products before leaving the factory floor need to be properly prepared for shipment. This may include shrink- wrapping; box assembly and loading; and box collating or placing onto a pallet for shipping. These tasks are repetitive and involve small payloads, making them ideal for cobots. Rapid product changeover is key for any business running a high to low mix of volume production. Conveyor tracking is required for this application to synchronize robotic movement with a conveyor. A vision system also may be needed for products with a non-uniform shape.
Process Tasks
A process task is any that requires a tool to interact with a workpiece. Common examples are a gluing processing, dispensing, or welding. Each of these process tasks requires a tool to go down a fixed path repeatedly. These process tasks take a significant time to train new employees to obtain the required finish. By using a cobot, the programming can be performed on one unit and copied to others. The cobot also solves the problem of having a worker performing precise and repetitive movements. Traditional welding robot systems, for example, require expertise in robot programming and welding techniques.
The benefit of many cobot systems are the ease of programming either through place and position record methods or traditional CAD/CAM programming, easing the robotic programming and allowing anyone with welding experience to program a cobot. A polyscope interface helps maintain a constant TCP speed. This guarantees the robot deposits material at a constant rate. The
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end-effectors in these cases are unique as they need to hold a welding torch, sealant, glue, or solder paste.
Finishing Tasks
Finishing tasks performed by human operators require a manual tool and large amount of force. The vibration from the tool can cause injury to the operator. A cobot can provide the necessary force, repetition, and accuracy required for finishing jobs. These finishing jobs can include polishing, grinding, and deburring. The robot can be taught manually or via computer programming methods. Cobots that have force control can help make the robot more robust. This allows the robot to deal with different dimensioned parts. This is achieved through force sensing, either via the end-effector or internally.
Quality Inspection
The last task that can be accomplished via a robot is quality inspection of parts. The process usually involves full inspection of finished parts, high resolution images for precision machined parts, and part verification against CAD models. Mounting multiple high-resolution cameras onto cobots can automate the process for faster results. The inspection can also be captured digitally and digitize the comparison to computer generated model process. Using cobots for inspection can result in higher- quality inspection, resulting in more accurate production batches. End-effectors with high-resolution cameras may be required for the inspection, as well as vision systems and software.
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3.5 Case Study
The multinational Continental is a good example of the transition taking place in the industry; as a leading company in the automotive sector, Continental is by far the most robotized Spanish manufacturer in the business and the first to pioneer the move towards industry 4.0. In 2016, the company decided to acquire several UR10 cobots to automate the manufacture and handling of Printed Circuit Boards, bringing down changeover times by 50%, from 40 to 20 minutes when compared to performing the task manually.
Challenge:
Continental is a constantly growing company which, during its 25 years of history in the automotive industry, has always focused on innovation and as a result, has won numerous major projects in the face of competition from other top level players. Cyril Hogard, plant manager at Continental Automotive Spain, emphasizes that one of the main challenges of the industry is to improve productivity given that the company operates within a very competitive sector. When he first heard about collaborative robots 2 years ago he was quickly convinced that the cobots would be a cornerstone for the growth of Continental Automotive within Industry 4.0, based among other things on fast and easy integration, minimal maintenance and improved productivity.
Solution:
The company Continental Automotive Spain chose Universal Robots to perform the tasks of handling and validating PCBs and components
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Application of cobots in automotive assembly line during their manufacturing process, a monotonous and repetitive task which at the same time requires precision and delicacy. Initially they installed two UR10 robots for loading and unloading PCB boards and for assembly of components. Currently six UR10 cobots are installed with three additional UR10 projects underway. The first project was initiated with special enthusiasm as the use of collaborative robots meant working with a groundbreaking technology with processes based on a more modern robotic philosophy, in accordance with the new Industry 4.0, heralding the emergence of the Smart Factory where automation and the Industrial Internet of Things (IIOT) are key. The UR robot application was accomplished by the engineer Víctor Cantón, who accepted the challenge despite having no experience in robotics up until then. However, within a few weeks he understood the basics of the UR cobots and was able to start the programming. Having a UR available at a very early stage of the project allowed him to carry out tests and calculations of the cycle and movements in a laboratory in order to streamline and accelerate the implementation. “I immediately saw the advantages of collaborative robots. Easy integration, zero maintenance and higher productivity.” Cyril Hogard Plant manager
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The Continental team is very pleased with the results of the implementation of the UR cobots on their production line: Control and flexibility: The company managed to keep control over the decisions made by the robot thanks to very simple programming; all the electronics and robot controllers are combined within a central point, allowing them to make programming changes without the help of outside experts. Less burden for the team: The cobot arrival meant a change in the role of operators who no longer have to perform menial tasks such as moving components from one station to the next. They can now concentrate on skilled tasks that contribute to improving production. Cost reduction: Automating the work of moving parts and components around the plant has allowed Continental to reduce operating costs by bringing down changeover times by 50%, from 40 to 20 minutes when compared to performing the task manually. Security: the team at Continental is very satisfied with the security measures associated with collaborative robots. For example, the operator can enter the cell at any time and the robot stops instantly due to additional sensors that stop when the operator get close to the robot.
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Chapter 4 - SELECTION
4.1 Of YSD line
The Bangalore plant of Continental Automotive India consists of many automotive assembly lines. Each line caries out different processes and with it comes its own constraints. The following constraints were considered when choosing the location or assembly line for the implementation of the cobot:
• Optimal location for productivity and human collaboration. • Manpower to be relieved. • Processes or tasks to be completed. • Arm length, cobot reach and flexibility. • Overall reduction in cost.
Based on the above mentioned constraints, the YSD line at the plant was selected for cobot implementation.
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Above shown is the YSD line before cobot implementation. This line has 8 workers carrying out multiple tasks on multiple machines. The line is operational throughout the day, comprising 3 shifts each day, for 5 days a week. Therefore, the line was a prime candidate for cobot implementation, which would reduce the number of workers and free them up to work elsewhere.
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Considering all the processes involved, this is the layout that was designed and proposed for the implementation of the cobot. The cobot would replace one human operator for every shift, drastically reducing errors and downtime, as well as increasing accuracy and quality. This results in increased productivity for the plant and therefore a better value for money proposition as compared to the previous situation.
To successfully implement the cobot in the line usefully, first the different processes carried out in the line must be considered. This involves observation of the human operators for an extended duration and noting down data for further consideration.
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4.1.1 Data
The step-by-step procedure of the operations carried out on the YSD line that were taken into consideration for cobot implementation are as follows:
• Bringing or refilling trays with PCBs (Printed Circuit Boards). • Opening the machine lid. • Picking up the PCB from a tray and placing it on the machine. • Closing the machine lid and waiting for the machine to process. • Opening the machine lid after process completion and picking up the PCB from the machine. • Placing the PCB on a separate tray for completed boards. • Clearing the tray with completed boards when the tray is filled.
The following data was recorded after extended observation of the above mentioned operations on various machines by human operators in the YSD line:
Machine Machine Machine Machine Machine 1 2 3 4 5 Trial 1 70 125 58 64 75 Trial 2 77 170 57 59 70 Trial 3 90 87 56 64 75 Trial 4 75 85 54 59 71 Trial 5 94 82 56 60 96 Trial 6 76 84 56 61 70 Trial 7 75 85 57 61 71 Trial 8 74 84 57 63 70 Trial 9 74 86 56 62 70
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The table shows the time taken by the different machines (in seconds) to carry out the operation for 9 individual trials. After extrapolating the data, the following conclusion was arrived at:
Process Average Time Taken (in seconds) Loading time 4 Machine processing time 78 Idle time 6 Unloading time 4 Total cycle time 92
The table shows the average cycle time for one machine being 92 seconds (here, Machine 1). Each machine will have its own average cycle time, which can be compared to the cycle times after cobot implementation.
4.2 Of cobot
As seen in the case study previously, Continental AG has already implemented cobots in their assembly lines in other countries. The cobot chosen for this application was manufactured by Universal Robots.
Universal Robots has sold more than 24,000 collaborative robots which are used in several thousand production environments every day around the world
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They have three different collaborative robots, which are easily integrated into existing production environments. With six articulation points and a wide scope of flexibility, these collaborative robot arms are designed to mimic the range of motion of a human arm.
The following constraints were considered while choosing the cobot:
• Space available for cobot without intrusion. • Manpower to be relieved. • Weight of the cobot. • Payload to be handled. • Arm length, cobot reach and flexibility. • Cost.
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The cobot selected for the application in the proposed layout after consideration is the UR10, manufactured by Universal Robotics.
The UR10 is a robot that has all the right specifications:
• It’s inexpensive. • It has the range that not many other cobots have. • It’s quite flexible in its programming.
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The lightweight, highly flexible, and collaborative UR10 industrial robot arm lets you automate repetitive and dangerous tasks with payloads of up to 10 kg. With a working radius of up to 1300mm, the UR10 collaborative robot puts everything within reach, freeing up your employees’ time to add value to other stages of production.
Following are a few technical details of the UR10 cobot:
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Chapter 5 – Components
5.1 Gripper design and validation
Regardless of how and why a collaborative robot is used, the unit must have some type of end effector to perform a work function. These end effectors come in many forms including vacuum cups, grippers, and other specialty tooling. Mechanical grippers provide a positive precise part pick up and have placement when used as end effectors on the collaborative robot. These grippers are typically driven electrically or pneumatically. Small motors are normally used to keep the weight of the gripper as low as possible. These small motors limit the jaw force produced by gripper. Higher forces may be achieved through gear reduction, which then limits the speed at which the jaws open and close. This will influence the overall cycle time of the cobot. Pneumatic grippers provide a simple open and close jaw position verses the programmability of the electric grippers. The pneumatic grippers for cobots are ideal in applications where the part size and shape stay relatively consistent. In most cases the pneumatic grippers are lighter since they do not incorporate an onboard motor. Pneumatic grippers can also provide higher grip forces depending on the input air pressure provided. Most of these grippers are provided without the extended jaw tooling. This allows the user to create tooling, to conform or encapsulate the shape of the part being handled. This jaw tooling is easy to create and can even be made using today’s modern 3D printers. By encapsulating the part with the jaw tooling the gripper can be operated at lower air pressures, which is ideal if the cobot is being used in a human collaborative environment. The lower air pressures mean less force and less chance of injury. As stated earlier, many of the collaborative robots are applied because of their ease of use verses being used in a human collaborative environment. In these
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Application of cobots in automotive assembly line cases, the pneumatic gripper can be run at high pressures producing higher grip force and potentially allowing a smaller, lighter gripper to be used. This has a positive effect on the total payload of the cobot.
Some technical specifications and other considerations for choosing a gripper are:
● Gripping strategy ● Tasks performed ● Grip types ● Fingers & fingertips ● Robot cell flexibility ● Power supply: electrical, pneumatic or hydraulic ● Ease of integration ● Payload and gripping force ● Gripper feedback and cost
Considering the mentioned constraints, a gripper was designed for use in the YSD line. Initial testing showed positive results:
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5.1.1 Repeatability
Often people will be mixed-up between accuracy and repeatability. In most cobot applications, repeatability is way more important than accuracy. In fact, you probably want to pick a part at the very same, exact spot you picked the previous one. Even if the absolute position of the cobot has a 0.5 mm offset in each axis, if you can repeat this position, your object will be grasped the way it is meant to be. This statement is especially true for collaborative robots. In fact, since you are not asking for a cartesian position, but a point in space (that has been determined manually), when you don’t take accuracy into consideration, but you want is for the cobot to repeat this position again and again, to do the exact same routine each and every time. The other aspect to discuss is: what is the repeatability threshold that is acceptable for a given application? Take for example a Universal Robot which touts a repeatability of +/- 0.1 mm, if you make a comparison, the average human hair is 100 μm (0.1 mm) thick, which means that the typical Universal Robots can repeat its position to the
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Application of cobots in automotive assembly line accuracy of the size of a strand of hair. If we think about it, no human can place an object which this kind of accuracy, inside 0.1 mm, every time. So, if the job was done manually, there is no way to be comparably accurate or repeatable for a human. Yes, humans have other advantages, particularly brains and touch sensitivity, which can compensate for the lack of repeatability. But since cobot can also have sensors and programs to accomplish these same things, nothing seems to be impossible for collaborative robots with the right setup.
• Axis New England have created a video which demonstrates that Universal Robots are even more precise than 0.1 mm. • In fact, with their experimentation, they have recorded a 0.01 mm repeatability. • If the job was done manually, there is no way to be comparably accurate or repeatable for a human.
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Application of cobots in automotive assembly line
5.2 PCBs
Printed circuit boards (PCB) are essential components of many electrical devices today, connecting different components to one another through a complex array of circuits. These boards consist of several layers of copper traces to make the connections, as well as plastics and other materials to protect those connections from the environment. The design and quality these PCBs directly affect how well the boards work in the final product, or whether they will work at all. The complexity of the PCB designing and manufacturing processes means there are numerous opportunities for PCB failure issues to arise. Some of these failures are a result of design oversights, such as insufficient clearances or incorrect measurements, which can negatively affect the functionality of the finished product. Others may result from problems in the manufacturing process, such as drilling errors or over-etching, which can be equally catastrophic. Fortunately, most of these errors can be avoided with knowledge and consideration for the manufacturing process, as well as awareness of the more common PCB manufacturing issues.
5.2.1 PCB defects
Plating Voids - Plated thru-holes are copper-coated holes in a printed circuit board. These holes allow electricity to be carried from one side of the circuit board to the other. To create these holes, the PCB fabricator drills holes through the circuit board, puncturing the material all the way through. A layer of copper is then added to the surface of the material and along the walls of these holes through an electroplating process. This process deposits a thin layer of electroless copper onto the circuit board in a process called deposition. After this step, extra layers of copper are added and etched to create the circuit image. While effective, the deposition process is not perfect, and
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Application of cobots in automotive assembly line under certain circumstances can result in voids in the plating. Plating voids are effectively gaps or holes in the plating of the circuit board, and are usually the result of problems during the deposition process. These plating voids are particularly problematic because imperfections in the plating of a thru-hole prevent an electrical current from passing through the hole, resulting in a defective product. These plating voids happen because, for one reason or another, the material does not coat evenly during the deposition process. The reasons for this include contamination of the material, air bubbles caught in the material, insufficient cleaning of the holes, insufficient catalyzation of the copper in the deposition process or rough hole drilling. Any of these problems can result in plating voids along the walls of the circuit holes. Defects as a result of contamination, air bubbles or insufficient cleaning can be avoided by cleaning the material properly after drilling. Additionally, defects from faulty drilling can be avoided by closely following the manufacturer’s directions during use, such as recommended number of drill hits, drill in-feeds and drill speeds. Both problems can be avoided by hiring a well-qualified and experienced PCB manufacturing company. Insufficient Copper-to- Edge Clearance Copper is an incredibly conductive metal, which is used as an active component of PCBs. However, copper is also relatively soft and vulnerable to corrosion. To prevent corrosion and protect the copper from interacting with its environment, this copper is covered with other materials. Slivers - Slivers are narrow wedges of copper or solder mask produced during the PCB manufacturing process, and can cause serious problems during the fabrication of circuit boards. These slivers are often produced during the etching process, and can occur in one of two ways. First, slivers can be produced when an extremely long, thin feature of the copper or solder mask is etched away. In some cases, this sliver detaches before it fully dissolves. These detached slivers can float around in the chemical bath, and can potentially land on another
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Application of cobots in automotive assembly line board, adding an unintended connection. Another way to produce slivers is to cut a section of the PCB design too narrowly or too deeply. Even if they are intended to stay attached to the board, if an etched section is narrow enough or the etching is deep enough, a sliver of material can completely or partially detach, either producing a floating sliver or a peeled-back sliver. Both of these options can have serious negative consequences for the circuit board’s function. These slivers can either connect to other pieces of copper or expose copper plating that would normally be covered by the solder mask. The former problem can cause a short, therefore producing a defective circuit board, while the latter option can result in corrosion of the copper over time. Both of these problems reduce the lifespan of the circuit board. Slivers can be avoided by designing sections with minimum widths, reducing the chances of producing slivers. A manufacturer will usually spot potential slivers with a DFM check.
Chapter 6 - CHANGE OF LOCATION
Due to a decision taken by upper management, the location of the cobot implementation was changed from the proposed YSD line to the FCT (Functional Testing) line. Consequently, observations on the operations in the FCT line had to be observed and recorded.
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Application of cobots in automotive assembly line
6.1 Data
Machine Machine Machine 1 2 3 Trial 1 70 50 61 Trial 2 61 60 57 Trial 3 50 57 66 Trial 4 57 60 59 Trial 5 59 70 65 Trial 6 63 63 70 Trial 7 65 66 63 Trial 8 64 64 50 Trial 9 66 65 64
The table shows the time taken by the different machines (in seconds) to carry out the operation for 9 individual trials. After extrapolating the data, the following conclusion was arrived at:
Process Average Time Taken (in seconds) Loading time 4 Machine processing time 62 Idle time 7 Unloading time 4 Total cycle time 77
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Application of cobots in automotive assembly line
The table shows the average cycle time for one machine (here, Machine 1). Each machine will have its own average cycle time, which can be compared to the cycle times after cobot implementation.
The FCT line has 4 human operators compared to the 7 operators in the YSD line. Here, the objective remains the same, i.e., to reduce 1 human operator per shift for maximum efficiency. The FCT line layout being similar to the YSD line, no major changes in approach had to be taken.
6.2 Gripper validation
As before, the gripper validation tests showed positive results.
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Application of cobots in automotive assembly line
6.3 Risk Assessment
In accordance with ISO 12100, the risk assessment is implemented in a series of logical steps to enable a systematic examination of the hazards associated with machinery. Risk assessment is followed, wherever necessary by risk reduction as described in clause 6 of ISO 12100:2010. When this process is repeated, it gives an iterative process for eleiminating hazards as far as possible and for implementing safety measures. The risk assessment methodology includes but is not limited to:
6.3.1 Risk analysis
• Determination of limits • Hazard identification • Risk estimation
6.3.2 Risk evaluation
The risk assessment provides the information required for the risk evaluation, which in turn allows judgments to be made on the safety of the machinery. The diagram shows the step-by-step process of risk analysis:
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Application of cobots in automotive assembly line
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Application of cobots in automotive assembly line
6.3.3 Poka Yoke
Poka Yoke or mistake proofing is a simple technique that developed out of the Toyota Production system. It is normally a simple and often inexpensive device that prevents defects from being made or highlights a defect so that it is not passed to the next operation.
Examples of Poka Yoke:
• One of the simplest examples is the 3 pin plug, whereby it is impossible to insert the plug incorrectly into the socket. • Lane assist is a form of mistake proofing that prevents accidents. • Seat belt pre-tensioners prevent occupant from sliding under during accidents, a form of Poka Yoke. Types of Poka Yoke design: • Control - Eliminates the possibility of a mistake to occur (automatic machine shutdown). • Warning - Signals that a mistake can occur (blinking light, alarm, etc.).
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Application of cobots in automotive assembly line
Illustrated above is an example of Poka Yoke, that correlates human errors with various factors such as misoperation, error in adjustment etc.
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Application of cobots in automotive assembly line
6.4 Cobot Operation
The pictures above show the pick and place operation of the cobot being carried out in a test area. The gripper selected has two surfaces that are at right angles to each other. The arm holding the gripper can be rotated as and when required.
After successful integration of the gripper with the cobot, it was time to implement the cobot in the FCT line.
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Application of cobots in automotive assembly line
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Application of cobots in automotive assembly line
Chapter 7 - RESULT
The following data was observed in the FCT line after the cobot implementation:
PROCESS (Machine 1) TIME TAKEN (in seconds) Loading 4 Machine processing 62 Idle time 2 Unloading 4 Total cycle time 72
This can be compared to the data recorded in the FCT line before the cobot was installed. It is observed that the overall cycle time has reduced marginally (by 5 seconds) for each machine. The processes carried out by the cobot are done with greater accuracy as compared to the human operator.
Along with the reduction in time of the complete operation, the number of operators working on the Functional Testing Line is reduced by 1, bringing the count down to 3. As mentioned earlier, this is desirable as the collaborative robot is designed to work with humans, not replace them entirely.
The cobot can also run for longer periods than the human operators without having to take breaks in between. A detailed flowchart describing the operations of the cobot is as follows:
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Application of cobots in automotive assembly line
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Application of cobots in automotive assembly line
Chapter 8 – REFERENCES AND LITERATURE REVIEW
8.1 Technical papers
• Prasad Akella, Michael Peshkin, Ed Colgate et Al., ‘Cobots for the automotive assembly line’, 1999 International Conference on Robotics and Automation, Detroit, MI.
• Bicchi A., Peshkin M., Colgate E., Safety for physical Human - Robot Interaction, Springer Handbook of Robotics , Springer, Berlin, Heidelberg; 2008. p.1335-1346.
• Krüger J., Lien T.K., Verl A., Cooperation of humans and machines in assembly lines. CIRP Annals – Manufacturing Technology 58 (2009), 628-646.
• Robotics Business Review, Universal Robots’ UR5 Goes to Work for Volkswagen, Sept. 1 2013, article:
• Rainer Müller, Matthias Vette, Matthias Scholer, ‘Inspector Robot - a new collaborative testing system designed for the automotive final assembly line’, Conference on assembly technologies and systems.
• Dvorak, Paul. "Poka-Yoke Designs Make Assemblies Mistake- proof." Machine Design, 10 March 1998, 181–184.
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Application of cobots in automotive assembly line
• Stewart, Douglas M. and Steven A. Melnyk. "Effective Process Improvement: Developing Poka-Yoke Processes." Production and Inventory Management Journal 41, no. 4 (2000): 48–55.
• https://www.festo.com/rep/en- us_us/assets/pdf/Festo_LWRobotics_White_Paper.pdf
• https://www.a3automate.org/docs/A3WhitePaper.pdf
• http://journals.sagepub.com/doi/pdf/10.5772/5664
• https://www.hindawi.com/journals/jr/2012/959013/
• http://www.robotics.org/userassets/riauploads/file/RIA_Collabor ative_Robots_White_Paper_October_2014.pdf
• https://www.automationworld.com/article/industry- type/discrete-manufacturing/cobot-end-arm-tooling-advances
8.2 Cobot safety and programming
• Universal Robotics https://www.universal-robots.com/media/1801971/ur-g3-safety- functions-20180418.pdf https://www.universal- robots.com/media/1801274/eng_americas_199933_ur_main- product-brochure_web.pdf
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Application of cobots in automotive assembly line
8.3 Case studies
• Universal Robotics https://www.universal-robots.com/case-stories/
8.4 Related articles
• https://www.sciencedirect.com/science/article/pii/S2212827114 011500/pdf?md5=915f3120d735181bfe474875e68a72fc&pid=1 -s2.0-S2212827114011500-main.pdf&_valck=1 • https://www.controleng.com/single-article/safety-and-control- in-collaborative-robotics • Deloitte, Made-to-order: The rise of mass personalisation, The Deloitte Consumer Review, July 2015 https://www2.deloitte.com/content/dam/Deloitte/ch/Documents/ consumer-business/ch-en-consumer-business-made-to-order- consumer-review.pdf • https://www.roboticstomorrow.com/story/2017/06/‘make-in- india’-initiative-could-be-a-bigger-success-with-help-of- cobots/10155/ • https://www.i-scoop.eu/industry-4-0/cobot-collaborative-robot/ • https://www.manufacturingtomorrow.com/article/2016/02/colla borative-robots-working-in-manufacturing/7672/
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