Productivity enhancing robot based applications are omnipresent in discrete manufacturing across the world. The advancement during the last 30 years has been significant. Initially single robots were used for relatively simple and monotonous tasks in hazardous environment. Today multi-robot synchronized configurations are dealing with sophisticated assignments in flexible production cells. ABB has been a prime driver in this rapid development process. The following article highlights the milestones achieved along this exciting journey.
The first industrial robot appeared in 1961 when a Unimate was supplied to General Motors for tending a die casting machine. The Unimate, the brain child of Joseph Engelberger, the ”Father of the Industrial Robot”, was hydraulically driven, a technology that dominated the fledgling industrial robot business for its first decade. Then in 1974, the Swedish company ASEA developed the IRB 6, the first all-electric industrial robot. This 6 kg capacity device was unique, not only in the drive system but also in its anthropomorphic configuration and its use of a microprocessor control system. It set new robot standards in the small footprint, the speed of movement and positioning accuracy and gave rise to a number of IRB 6 look-alikes.
Electric drive robots opened up new applications not possible with hydraulic machines, in particular arc welding. However, the first application outside of ASEA was polishing stainless steel pipe bends for the food industry at Swedish company, Magnusson. Its first IRB 6 was installed in 1974 1, with further units delivered in 1975. These robots ran virtually non-stop in a dirty environment for over 25 years. This factory became one of the first in the world to operate around the clock, seven days a week, completely unmanned.
1 In 1974 Magnusson AB became ASEA’s first external robot customer. Manager Leif Jönsson together with Lennart Benz of ASEA monitor the installation.
2 The SAAB Model 99 of 1975 was an early spot welding application.
|Spot welding continued to be the domain of the hydraulic robot until 1975 when ASEA launched the IRB 60, similar in design to the IRB 6 but with a 60 kg capacity. The first of these was supplied to Saab in Sweden for spot welding car bodies 2. Perhaps the ”final nail in the coffin” of the hydraulic robot spot welder was the IRB 90, launched in 1982, which ASEA designed specifically for spot welding. It was a full 6-axis device with integrated WAC (water, air, current) supplies built into the arm.|
Robots for painting
However, still in the era of the hydraulic robot, a significant event took place in Norway, which was later to impact on ASEA’s robot business. Trallfa, a small agricultural engineering company was having difficulty in recruiting labour to paint its wheelbarrows and sought a solution through automation, a challenge taken up by a young engineer, Ole Molaug. In 1966 he developed the world’s first painting robot driven by hydraulics, of which an early version is shown in 3. It differed from the Unimate in that it had continuous path control and programs were created by recording the spray patterns of a skilled painter onto magnetic tape.
drive paint robot, the TR-5000, in 1988 – the year ASEA merged with the Swiss company, Brown Boveri to form ABB. Prior to this development, hydraulic drives were exclusively used for painting robots due to their intrinsic safety.
3 Early version of the Trallfa paint robot from 1969.
|Initially, this automatic painter was used solely internally but such was its success that Trallfa decided to market it outside the company. Its first sale of the Trallfa TR-2000 was in 1969 to Swedish company, Gustavsberg for enamelling sanitary wear such as bath tubs and shower trays. |
In 1985 Trallfa was acquired by ASEA and soon afterwards development started on an electric drive painting robot, culminating in the release of ABB’s first electric
The TR-5000, however, saw intrinsic safety achieved with electric drives and their inherent benefits of speed, accuracy and electronic controls were brought to the painting process.
Evolution of robot mechanics
Such was the elegance of the IRB 6 design that its basic anthropomorphic kinematics with rotary joints movements are continued in today’s range of ABB robots. What has changed over the 30 years has been the speed, accuracy and space efficiency with larger working envelopes and more compact footprints.
ABB’s first major advance in robot mechanics after the IRB 6 was the 10 kg capacity IRB 2000 launched in 1986 4. In this second generation design, backlash-free gearboxes replaced ballscrew drives for the ”hip” and ”shoulder” axes, resulting in better spatial kinematics. But, the other significant change was the switch from DC to AC drive motors. AC motors deliver higher torques, are physically smaller than DC motors, are brushless and consequently easier to maintain and have a longer life.
4 IRB 2000 arc-welding, AC-powered robot was born out of an egg at a show in Brussels in 1986.
5 IRB 6000 with its modular design concept was introduced in 1991 and became ABB’s most successful spot-welding robot.
Flexibility and adaptability are features constantly called for by industrial robot users, and in 1991 ABB met these demands head-on with the heavy duty (150 kg capacity) IRB 6000 5. Aimed primarily at spot welding and large component handling, the IRB 6000 was built on a modular concept with a range of base, arm and wrist modules so that it could be optimised for every user’s needs. The IRB 6000 was also highly cost competitive through its ”lean design” with 60 % fewer parts than the IRB 90. It was ABB’s most successful spot welding robot with many large multi-robot orders from leading car manufacturers.
While the anthropomorphic arm has dominated the scene for the past 30 years there are some high-speed small part assembly and product picking applications where the design is limited and other configurations have emerged.
One of the most successful designs was the SCARA (Selective Compliance Assembly Robot ARM), developed by Professor Hiroshi Makino at Yamanashi University and launched commercially by several Japanese robot manufacturers in 1981. ABB introduced its own SCARA, the IRB 300 in 1987.
In 1984 ABB developed what was believed to be the world’s fastest assembly robot, the IRB 1000, which had a ”pendulum” configuration with the arm suspended from a pivot. The arm’s moving masses were concentrated at the pivot, minimising the moments of inertia and resulting in accelerations of 2g within a working envelope much larger than possible with a SCARA.
versatility when handling small items such as electronic components to chocolates 6.
|But even these robots were not fast enough for on-line picking operations in such as the electronics and food industries. To meet such demand ABB introduced the IRB 340 FlexPicker robot in 1998. Based on the Delta robot conceived by Professor Raymond Clavel at EPFL in Switzerland, the FlexPicker is capable of 10g acceleration and 2 picks per second, matching human operators in both speed and|
6 The FlexPicker in action.
Advances in control systems
While mainstream robot kinematics has continued on an evolutionary path, the control systems, operator (HMI) interfaces and software have changed beyond all recognition. The control system for the IRB 6 in 1974, later designated the S1 and very advanced for its time, had a single 8-bit Intel 8008 microprocessor, an HMI with a 4-digit LED readout and 12 punch buttons, and rudimentary software for axis interpolation and movement control. It needed specialist knowledge to program and operate.
The first ”breakthrough” in set-up and programming came with the S2 introduced in 1981. Based on two Motorola 68000 microprocessors, the S2’s HMI or ”teach pendant” incorporated a joystick for intuitive jogging and positioning of the robot axes. Also introduced were the concept of the TCP (Tool Centre Point) and a new programming language, ARLA (ASEA Programming Robot Language). These features made programming and set-up easier and quicker for both experienced and untrained robot users.
Other new software for S2 included, limited process software such as arc welding functions and ”built-in” weld timers for spot welding, and a kinematic model of the robot arm. The latter enabled the IRB 6000 to gain a level of performance not limited by the physical stiffness of the physical structure, and was ABB’s first step along the road to the complete dynamic and kinematic modelling available in today’s products.
The S3 control unit introduced during 1986 differed from the S2 mainly in its switch to AC drives such as for the IRB 2000 series. The next big change came with the S4, launched in 1992 and which many in ABB regarded as big an advance as the introduction of the IRB 6 and S1. Over 150 man-years went into developing the multi-microprocessor S4, which could control six external axes, all welding parameters as well as the robot’s own six axes.
The S4 controller was designed to improve two areas of critical importance to the user; the man-machine interface and the robot’s technical performance.
The S4 controller was designed to improve two areas of critical importance to the user; the man-machine interface and the robot’s technical performance. A vital key to the former was the ”Windows” style teach pendant. It was the same familiar environment as used in PCs with drop down menus and dialogue boxes, so that set-up and operation of the robot was made simpler. At the same time programming was made easier through a new open multi-level programming language, RAPID with the flexibility to develop or adapt functions to meet each user’s specific needs.
The concept employed by ABB to improve robot performance with S4 was ”Motion Control” using smart software functions rather than purely increasing mechanical performance. The foundation of this motion control is a complete dynamic model of the robot held in S4 and is the basis of QuickMove, a function in which the maximum acceleration in any move is determined and used on at least one axis so that the end position is reached in the shortest time. As a result, cycle time is minimised and not dependent purely on axis speeds.
Another feature emanating from dynamic modelling is minimal deviation from the programmed path, which is applied in TrueMove. This function ensures the motion path followed is the same whatever the speed and obviates the need for ”path tuning” when speed parameters are adjusted on-line.
With the dawn of the new millennium, robot productivity and communication needs were becoming ever more vital to lean production. ABB’s answer to these demands was the S4Cplus controller, first seen in 2000, which featured new computing hardware to deliver superior robot performance and enhanced communications capabilities. For the first time ABB adopted a standard PC format with a PCI bus and a Pentium MMX processor at the heart of the main control computer. It proved capable of controlling the fastest robots on the market including the FlexPicker.
Coordinated multi-robot control
A further dramatic advance in robot control was made by ABB in 2004 when it launched the fifth generation IRC5 control system. An outstanding feature of IRC5 is its ability to simultaneously control up to four ABB robots plus work positioners or other servo devices – a total of 36 axes – in fully coordinated operation through a new function: MultiMove.
Controlling up to four robots from a single controller minimizes installation costs and brings quality and productivity benefits.
Controlling up to four robots from a single controller minimizes installation costs and brings quality and productivity benefits. It also opens up completely new application possibilities, such as two arc welding robots working in tandem on the same workpiece deliver even heat input and eliminate distortion due to shrinkage on cooling; several robots in concert handling a single flimsy workpiece to prevent bending; and two or more robots lifting a load larger than the capacity of the one robot.
needs, while still readily expandable to meet future demands.
|In seeking a lean solution for robot control, ABB developed a modular concept for IRC5 7, in which functions are logically split into control, robot axis drives and process modules, each housed in identical standard ”footprint” cabinets. IRC5 controllers may be stacked, placed alongside each other or distributed up to 75 m apart. Installation is made even simpler by the two-cable link between modules, one carrying safety and the other Ethernet communications. The modular arrangement also means the system may be cost-effectively specified to match the customer’s immediate exact || .|
7 The modular controller IRC5 has the capability to control multi-robot applications.
Intelligent operator interface
Although complex, setting up and operating a multi-robot cell with fully coordinated motions was made easier for a user by FlexPendant, the world’s first open robot operator interface unit, developed for IRC5. The joystick is retained, not just for jogging each robot but also to manipulate all four robots as a single entity in synchronism, a feature unique to ABB.
FlexPendant has its own computing power with an open system PC architecture. It set new standards in ease-of-use and flexibility of operation with a full colour ”touch” screen, on which Windows-style menu-driven pages are displayed. Pages with familiar icons and graphics are available for different user levels, and new ones may be created to suit a user’s needs and applications. FlexPendant simplifies all aspects of robot cell operation from set-up and program loading through process development and cell operation to reporting and servicing.
Virtual robot technology
In 1994 when ABB brought out the S4 controller, it also introduced ”Virtual Robot Technology”, a unique concept in which simulation of a robot system on a PC utilizes exactly the same code to that which drives the real physical robot. In 2004, the second generation Virtual Robot Technology was launched alongside the IRC5. In this, even more behaviour patterns are simulated including all aspects of the production process and connected PLCs. This way total transparency between the virtual controller and the real IRC5 controller is achieved. Consequently, programs developed off-line are very accurate and run ”first time every time” helping to reduce lead times and set-up costs.
Over the past 30 years industrial robotics has advanced beyond all recognition. Having created the first all-electric microprocessor controlled robot in 1974, ABB has continued its pioneering developments, culminating in the IRC5 multi-robot modular control system in 2004. In the intervening 30 years, positioning accuracies have improved from 1mm to 10 microns, user interfaces from a 4-digit LED read-out to a full Windows touch screen display and computing power from 8 kB to 20 GB or more. At the same time reliability has increased to 80,000 hours MTBF (Mean Time Between Failures) in some applications and costs have plummeted so that today, the robot price is less in actual terms than it was 30 years ago. The world of the industrial robot is well past its early dawn.
For more information see www.abb.com/robotics