motion \'mo-shen\ n 1 a: an act, process, or instance of changing place : MOVEMENT b : an active or functioning state or condition (Merriam Webster's Collegiate Dictionary)
Industry is stepping up its high protein diet, and motion control has to obey the new lean manufacturing rules. "Integration best describes the overarching trend in motion control today," according to expert Bob Hirschinger, general motion control product engineer at Rockwell Automation. "Motion control users now expect systems where multiple control functions integrate on single platforms for faster development, higher performance and lower overall automation system costs."
Sectors relying on motion control, including packaging and material handling, face increased system performance requirements to raise process speeds and throughput. "To meet this need, we see users migrating from mechanical control systems, such as line-shafts, to electronic servo control systems," Hirschinger adds. "We can integrate motion and sequential control functionality into a single multi-tasking controller platform... all system control elements not only reside on the same hardware chassis, but within the same multi-tasking, multi-processor control architecture, providing faster communication than is possible over a multinode network. These multi-processor architectures are not only scaleable as needs grow but are extremely powerful in eliminating hidden-task complexities that often plague process developers."
To achieve faster application development, today's more complex production processes are requiring tighter integration between motion and sequential control. According to Hirschinger, traditional control architectures offer only one function per device. "For example, three or more separate controllers are required for motion, sequential and other control functions. And these controllers must be linked together using hardwiring, serial interface, or some other communications interface. Naturally this can create challenges when synchronizing and programming the system." Because separate application programs must be written for each controller, "each with its own programming package and unique programming, the result is an application that is difficult to program and maintain, exhibits inadequate reliability, and may not meet performance requirements."
Hirschinger continues: "We can integrate motion and sequential control functionality into a single multi-tasking controller platform. This gives users higher system performance, faster application development, easier maintenance and lower system costs. Performance is enhanced because all system control elements not only reside on the same hardware chassis, but within the same multi-tasking, multi-processor control architecture, providing faster communication than is possible over a multinode network. This approach offers the flexibility to expand as needed and may be successfully applied in multiple control disciplines, eliminating multiple programs and redundancies for greater cost savings. These multi-processor architectures are not only scalable as needs grow but are extremely powerful in eliminating hidden-task complexities that often plague process developers."
Adds Dave Faulkner, executive vice president of marketing at software company Cimetrix Inc: "I like to look at the existing PC market and PC technologies. These technologies dwarf the motion and controls market in size and manufacturers are using them in new ways on the manufacturing floor-first as HMIs, now for actual machine control."
The integration of different system components poses several challenges to manufacturers, Faulkner points out. "As OEMs move to PC technology, they are not locked into one controls supplier-they can buy best of breed software and hardware components. This also brings integration headaches." Standards and customer support can ease these problems.
Meanwhile, programming methods vary by industry, constrained by support infrastructure. For example, the use of packaging machines in the food and beverage sector "dictates that PLC style programming be used," says Faulkner, which is "sometimes difficult in complex motion applications." Other industries, such as semiconductor and SMT, "can support software written in C++." Another challenge is scalability. "One packaging line may have many simple single axis motion controllers, combined with more complex pick and place systems requiring motion technology with kinematics, conveyor tracking and vision guided motion," explains Faulkner. "Users end up with completely different motion solutions on one line, which is difficult to maintain and train service people," he adds.
Other concerns include ease-of-use and ease-of-integration with other parts of the machine, according to National Instruments vision and motion product manager Jayson Wilkinson. "Motion can be difficult and time consuming," Wilkinson tells IEN. "For the engineers that want to get their systems up and running fast, they don't want to spend a lot of time programming or configuring a complicated system. Engineers need faster, more powerful machines with just as much control and flexibility without taking a long time to get it up and running."
Advances in Motion
Motion control fits into the trend toward integrating the enterprise. "With networks such as Ethernet-based LANs, information is now being shared from production machines up to the enterprise level," notes Bill Green, divisional product planning manager, at Parker Compumotor. "High-speed serial networks are also being implemented to connect the devices common to factory automation, including PLCs, motion controllers, I/O modules and vision systems," Green says. The packaging machinery, pharmaceutical, biomedical, semiconductor fabrication, disk drive and computer peripherals industries could benefit most from these advancements, he believes.
Green also sees automation and motion control benefiting companies implementing lean manufacturing. "As production shifts to JIT manufacturing and batch counts decrease, it is important to minimize machine downtime," he continues. "Programmable motion controllers with easy-to-use front-end software and human-machine interface (HMI) technology enable rapid changeover between batches. This minimizes downtime and increases profitability." The future will bring a "continuing influence of Internet and networks connectivity, increased emphasis on front-end software, and operating on open architecture hardware," as well as faster processors and smaller product size.
Firewire type communication is growing in popularity in the motion sector. "It's excellent for high-speed, low cost communication with few axes using only a single cable," observes Jake Henry, motion product marketing specialist at Omron Electronics. Firewire also allows the "crucial high speed link between the controller and servo. SERCOS has proven itself to be a great interface for larger applications, but Firewire based communications easily and effectively addresses less complex applications," says Henry. Omron's servos have a port on the side that will allow users to add modules.
Today's servo "now integrates the capability of several different servos," Henry adds, and "sending motion controls wirelessly is an upcoming breakthrough. Motion data is critical, and wireless motion will allow users to quickly transfer large amounts of important data." With advanced technology PLCs more sophisticated motion control will be possible. "There's a push from PLC manufacturers to make PLC motion control more advanced," Henry notes. "A lot of motion applications need a PLC anyway. With a PLC, you can do all your control out of one box."
According to Alan Feinstein, vice president of marketing at Bayside Motion Group, "it has been quite some time since the motion control industry has seen an emerging market demand new motion technology...the emergence of fiber optics has not only created a need for re-packaged products, but more importantly, a need for new operating characteristics of drives." Component manufacturing requirements "preclude the use of rotary step and servo motor as couplings drive screws make it virtually impossible to transmit very small moves," Feinstein tells IEN. "A newer and more appropriate drive mechanism, based on piezo elements, provide excellent performance characteristics and can be easily applied to linear and rotary motion stages."
Meanwhile, the "overall motion system must have the ability to move in extremely small increments. Actuating a stage in 50nm to 100nm increments is no trivial task and there are few bearing structures that provide the stiffness and smoothness to achieve this," according to Feinstein. While current air bearing technology could "support the motion requirements," the bearings "depend on a large puck size to provide bearing stiffness, making them too large and bulky for the majority of applications." Traditional mechanical bearing stages "face issues related to the bearing roundness and compliance," he adds, but Bayside's "closely matched hollow rollers and patented Autoflex preload provides the bearing smoothness necessary to make such small moves." (Click here for more details on Bayside.)
National Instruments' Wilkinson points to "smart motors and smart drives" as two innovations coming in the near future to the motion sector. Software is another: "Easier and more powerful software is one of the key innovations users will see in the next few years. In the past, software has not been as significant, but is starting to become one of the key differentiators in motion control products," Wilkinson states. In the next few years, "users can expect to see programming environments that can be mastered in a fraction of the time it takes to master some of the current environments."
Rockwell Automation product engineer Jeff Faris says that the "integration of motion control systems and the information that they control within the factory automation control system will make this technology more useful, less complex, more powerful, and physically smaller." As a result, a "further refinement of the physical machinery will be possible." As machines use fewer and smaller components, "new form factors for actuators and transmissions will be adopted," Faris continues. "Machinery will seem to absorb the actuator. An example of this might be as simple as the use of a linear motor, or as complex as an electronic cam. In general, the changes in motion control, whether physical or electronic, will allow the user to more quickly fit the technology to the machine and spend a greater percentage of his/her time on process improvement." Companies supplying these advanced motion solutions must "possess the ability to communicate globally (real time), manage complex logistical issues, deliver value-focused added expert engineering services locally when needed," Faris contends.
Increased SERCOS speeds "will lead to this standard being more widely adopted," predicts Rod Dorschner, senior product engineer at Rockwell Automation. "Technology advancements now enable distributed control benefits of the digital connection between the control and drive while allowing the two to be physically separated," he says. "In the past, users had to run an analog line from controller encoders to motors. Users can now mount the drive closer to the motor. This ability to distribute drive systems on a production line, remote from the controller, has advantages in certain applications, such as modular packaging involving two lines running on the same controller. In this scenario, one line could be shut down while the other runs, or both lines could be running two distinct packaging operations from the same controller. This gives users flexibility."
For example, Norfield Industries, a 40-year-old OEM of pre-hung door machines and systems worked with Saber Engineering, Rexel Norcal Valley Electrical Supplies, and Rockwell Automation to apply a new type of control system that integrates servo motion control, a programmable logic controller (PLC), and a touch-screen interface with an intuitive graphical interface. Their collaboration resulted in the Norfield Horizon Type 1 Machining Center. Says Chuck Knighten, director of technical development, Norfield Industries: "The ultimate goal was threefold: make machines easier to use for operators, more flexible for various door designs and decrease the cost of ownership." (Click here for more details on Norfield.)
Jan Bosteels, product manager at Advanced Motion Controls (AMC) offers a word of caution about the integrated enterprise, meanwhile. "The industrial networking industry is going through another round of declaring a winner, without providing a true solution to the use," Bosteels contends. "This time Ethernet is touted as the next solution to all problems, however Ethernet is just a mere physical layer connector. There is no industrial open standard defined as of yet." However, he believes that the availability of CANopen-based servo drives "further completes and complements the choice of devices users can connect to a network.
AMC continues to develop digital servo drive solutions that "will support both centralized and decentralized applications with various industrial networking capability," states Bosteel. "The industry is trying to define open standard networking solutions with limited success,' he notes, but "open standards pose somewhat of a dilemma for manufacturers in that they can 'replace' but also 'be replaced' by a competitor. That is why the larger manufacturers try to steer 'open standards' in favor of their own preferences." Bosteels does not believe that this approach benefits the user. "CANopen is governed by an independent, non-for-profit organization and does not suffer" from such drawbacks, he opines. (Click here for more details on Advanced Motion Controls.)
Motoring Up New Drives
"New harmonic drives and RV drives have been introduced with integrated brushless servo motors," comments Jeff Stoehr, marketing and sales manager of Harmonic Drive Technologies' Factory Automation Group. "These are the ultimate in compact and powerful servo actuators designed for precise positioning," and provide "lower control complexity, higher torque throughout the speed range, lower cost and, in some cases, smaller size." And a new linear actuator using the RV cycloidal gearing laid out in a track developed by Teijin Seiki, Harmonic Drive's parent company, is now being tested. This low-wear device will be able to precisely move robots along a track as it interacts with several machine tools, according to Stoehr.
"Manufacturers of large robots have found the RV drive to offer the right combination of precision and durability," Stoehr notes. "For similar reasons, RV drives are ideal for manufacturers of tool changer carousels and turret drives in machine tools, welding positioners, and index table drives. All require high torsional rigidity and overload capacity." Harmonic drives are well-suited for applications where "weight is a factor or space is very tight," says Stoehr. (Click here for more details on Harmonic Drive Technologies.)
Baldor Electric's John Mazurkiewicz tells IEN that "digital control systems provide an alternative to analog motion control, and make it easier to set up and adjust. Since current control loops require very fast response, the small delays caused by digitization had limited digital controls from high bandwidth systems. Recent advances in fast digital control processing solved the delay problem. Control loop algorithms compensate for the delays and complexity of the model. This helps achieve a high dynamic bandwidth and smooth response with no overshoot." These controls are set up with a menu driven, PC- based software program. A keypad, as pictured, replaces laptop setup for Baldor's Series 23H digital controls, easing operator interface.
"The software sets up parameters automatically, and downloads these into EEPROM, a procedure that minimizes on-board memory," says Mazurkiewicz. "Serial bus configurations can connect as many as 16 digital units in a 'leader-follower' relationship for full system synchronization, while a host computer or multi-axis controller provides system control." Digital controls may also include "anti-windup protection and non-linear algorithms to allow the user to set physical limits to acceleration, velocity, and current commands," he adds.
Linda Warner, marketing manager at Performance Motion Devices (PMD) sees the use of chip-based motion control "expanding across industries as diverse as semiconductor handling to glass making," as design engineers focus on cost reduction and speed. "We even have one product that can control up to 4 axes where motor types are not the same," she notes.
Eaton Corp chose a chip driven solution when it needed a small, general-purpose motion controller for use in its 300mm medium current ion implanters. The company's engineers needed to control three axes of motion with low-current DC brush-type motors. Eaton turned to Performance Motion Devices' MC1401A servo control chipset. "PMD's chipset was selected primarily for its S-curve motion profile capability....By using S-curve profiles, the cycle time of certain moves was reduced by as much as 20% in Eaton's application," explains Mike Harris, Line Product Manager at Eaton. (Click here for more details on Eaton.)
Entering the Internet
Motion control is also migrating to the Web. Z-World's expandable SmartStar embedded computer delivers a modular infrastructure with low-cost I/O points, says Z-World marketing communications specialist Chantel Beck.. When used in conjunction with partner Rabbit Semiconductor's RabbitLink interface card, "both remote programming and debugging are possible via the Internet," Beck adds.
RabbitLink can also be used to "provide a portal to the Internet, enabling the system to send email or generate web pages via a simplified protocol with the software resident on card," Beck notes. "Users can access and program Rabbit-based systems via a high-bandwidth Ethernet-based connection, locally or at remote locations."
Logosol Inc president and CEO Dr. Lubo Kostov believes that "there is a clear migration from centralized to distributed motion control." For example, Logosol's Rabbit-powered LS-980 network master controller and LS-173 multiple AC/DC intelligent servo drives eliminate excess wiring, provide improved scalability, and can work with network communication.
Distributed programmable architecture allows a modular approach. A programmable network master controller is interactive, and allows both logic functions and human interface via hand-held units. "The most important piece is the RabbitCore Module with Dynamic C software (manufactured by Rabbit Semiconductor). It allows multiple servo, stepper and digital I/O modules to be controlled by a single master with a variety of interface options such as serial, parallel, TCP/IP etc." says Kostov.
