Intelligent Motion Unites Diverse Worlds
Intelligence means different things to different people. Intelligent motion control generally has incorporated motion and machine logic, plus power switching, in the same control package. Lately, other functions such as predictive maintenance, machine safety, and advanced communications, are increasingly part of the mix of "intelligent motion" architectures.
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Intelligence means different things to different people. Intelligent motion control generally has incorporated motion and machine logic, plus power switching, in the same control package. Lately, other functions such as predictive maintenance, machine safety, and advanced communications, are increasingly part of the mix of 'intelligent motion' architectures.
Motion intelligence equates with a new breed of drives that incorporate tasks once reserved for a separate motion controller or centralized controls, according to B&R Industrial Automation Corp.'Functions, which previously could not be performed, analyzed or monitored, are now done using drive-based functions executed synchronously to the drive's position control loop in a 400-microsecond cycle,' says Markus Sandhoefner, B&R's Industry Segment manager.
As a general trend, B&R notes that controls, visualization, and motion are uniting. 'Fast processors have become a commodity, so all these tasks can be executed on one processor, eliminating costs for communication infrastructure and hardware,' he says.
Predictive maintenance is one of the added functions. New drives can run diagnostics in real-time, allowing users to set tolerance bands for any of hundreds of drive parameters (torque, speed, position, temperature, etc.). Moreover, several parameters can be configured with drive-level algorithms into a composite parameter—for example, system friction—to derive more reliable and accurate operation, explains Sandhoefner. Machine controls can then generate a screen message or even notify users by e-mail about a developing condition for 'on demand maintenance.'
He points to intelligent drives' ability to act as a 'sensor' to optimize the machine process using drive-inherent parameters (see more in online version of this article). Also, a quality function can be integrated with the drive's ability to generate real-time product/process quality control data for tracking by the main control system. B&R's Acopos Servo Drive offers various intelligent features (photo).
Motion̠ not a subsystem
For Rockwell Automation, the term 'integrated motion' represents the characteristics of intelligent motion. Brian Lieser, marketing manager—Kinetix Motion Control, says, 'Integrated motion, or Kinetix, describes a machine control architecture that integrates sequential, motion, power, and mechanics into a single platform.' Motion-control requirements take on a machine architecture (or line) perspective, which is quite different than traditional treatment of motion as a machine subsystem, he explains.
A single software program, RSLogix 5000, is used for programming, commissioning, and diagnostics of an entire machine system—including motion. The result is simplified setup of drives, motors and actuators, plus easier implementation of integrated solutions. 'Engineering and maintenance of separate traditional non-integrated systems overburden both OEMs and end-users with non-value-added tasks that constrict their ability to innovate and be more productive,' adds Lieser.
Kinetix Integrated Motion focuses on the entire machine life cycle, from an OEM's motion system design and selection to machine productivity at the user's site. Substantial benefits accrue to OEMs and end-users from:
Shorter time to market with faster application development;
Faster machine speeds for greater productivity;
Seamless transfer of motion information throughout the machine/production line to reduce downtime and optimize processes; and
Lower system costs from less panel space and wiring needed.
Bosch Rexroth Electric Drives & Controls division uses its IndraDrive product line to define 'intelligent motion' through more processing power implemented at the drive level to expand overall machine capabilities. IndraDrive incorporates a digital signal processor (DSP) to handle motor feedback for closed-loop optimization. A logic controller in the drive adds intelligence, while optional Rexroth IndraLogic, with IEC 61131 programming and function blocks, streamlines single- and multi-axis motion logic. Target applications are servo, spindle, and variable-speed control.
Add safety, maintenance
'IndraDrive closes the position and velocity loops instead of the main control system and maintains the motor within its command,' states Rick Rey, product manager at Bosch Rexroth.
The company regards integrated safety technology and predictive maintenance as part of intelligent motion architecture. Distributed control places intelligence within each drive, allowing safety monitoring, maintenance, and other functions to run locally. 'Adding [another] drive adds more intelligence rather than sharing the fixed amount of a centralized system,' Rey continues.
'The safety function is implemented for personal protection in accordance with European standard EN 954, category 3—without the need for additional hardware or indirect control solutions,' he says. If an operator enters the machine work area, system sensors communicate with the drives to slow (or halt) the axis as appropriate, then let the machine resume normal operation without added downtime as the work area clears.
Predictive maintenance allows checking friction conditions, stiffness of an axis, and backlash or play in the mechanical system. An intelligent drive can issue warnings to the main controller (or operator interface) to indicate an impending fault 'before the problem escalates or damages the machine,' adds Rey.
Baldor Electric's view on intelligent motion centers on the ability to meet many motion application requirements through programming. 'By providing an open programming interface, designers have freedom to develop software to meet their exact requirements, deal with different input conditions, and act accordingly,' says John Mazurkiewicz, servo product manager at Baldor. 'Freedom to design software for machine requirements allows designers to overcome limitations placed on them by predefined sequences.' Intelligent motion also gives machine designers freedom to program machines for numerous products or conditions, for example, where frequent product size changes occur. Downtime associated with mechanical changeover is reduced as a result.
Various Baldor products cater to different application needs. Reportedly, preprogrammed sequenced positioning is easily set up by table values in Flex+Drive; product size variants are simply handled by MintDrive, programmed via HMI panel input; while Baldor standalone motion controllers serve either single or multi-axis machines.
Intelligent motion is implemented in Baldor products via Mint (Motion INTelligence)—a comprehensive, Basic-like programming language for motion, I/O set up, and HMI tasks.
Mint's flexibility allows programming different machinery scenarios. The software's array handling capabilities are said to ease recipe programming. 'Different move types supported by Mint, such as indexing, flying shears, software gearboxes, and cam profiles provide design engineers flexibility in defining their motion profiles to optimize machine throughput,' remarks Mazurkiewicz. 'Mint's modular programming allows building of applications in manageable blocks.'
Define in software
Intelligent motion is the 'ability to define every aspect of the motion controller in software and deploy it on hardware of the user's choice,' says Rahul Kulkarni, product manager-Industrial Control at National Instruments (NI). NI offers its LabView platform with SoftMotion and reconfigurable I/O technologies to aid users in creating a custom motion controller either on a real-time operating system (RTOS) or on a field-programmable gate array (FPGA) —depending on a particular application's price/performance needs.
Machine builders with high-speed applications may go the FPGA route, with its 200 kHz performance or about 10x faster than a standard motion controller, notes Kulkarni. FPGAs also add reliability to a design. They allow changes in the device control strategy when needed, for example, to add an emergency condition to the algorithm, he explains.
Besides defining supervisory control, trajectory generation, and spline interpolation, NI's SoftMotion Development Module for LabView allows users to incorporate advanced algorithms or model-free adaptive (MFA) control for position and velocity control. Kulkarni mentions one example. Cybosoft—an NI Alliance Partner—applies SoftMotion to coordinate multiple axes, but augments PID position and velocity control with its own MFA control algorithm for high-precision/speed applications in nanotech and semiconductor manufacturing.
Josef Hammer, product manager for Simotion at Siemens Energy & Automation Inc., notes that in the past, control products were optimized for a particular task—that is, PLCs for logic tasks, motion controllers for motion tasks, and so on. To arrive at a complete running machine, it was necessary, but far from simple, to unite different underlying control philosophies, interfaces, and engineering tools.
Machines emphasizing intelligent motion as an optimal solution must go beyond motion-control features and 'integrate all other control capabilities necessary to automate the entire machine in a uniform way,' Hammer explains. He further characterizes 'intelligent motion' as an offering open to more than one hardware platform, for user flexibility, and providing the latest access methods like OPC and TCP/IP communication for integration to business systems and Web services.
'Simotion from Siemens focuses on this intelligent motion,' says Hammer. 'It's an optimized system solution where motion control, logic control, and further technology functions are integrated and merged in a very efficient and useful way.' Simotion comes in three hardware versions (PC-, controller-, or drive-based platforms) to suit users' particular applications. And, he says, change of platform can be done almost without affecting previously developed application software.
Hammer relates all benefits of intelligent motion to cost reduction, whether due to reduced development cycles, more compact systems, or better access for support worldwide (see more online).
Brains and muscles
Danaher Motion's product manager, Lou Lambruschi, describes intelligent motion from a drive manufacturer's perspective as, 'combining the brains of a programmable controller with the muscle of solid-state power devices to create a packaged drive suitable for a wide variety of applications.' He explains that precise speed and position control are obtained by coupling a DSP-based logic section with a high-performance flux vector drive power section (and a suitable motor). 'With the user's input of a sequence of operation—similar to a PLC program—the drive will perform a complex sequence of movements, conditional on inputs, and provide useful outputs to monitor the process,' says Lambruschi. Danaher's new FX4000 Fusion series drives implement these features, along with flexibility to run ac induction, ac synchronous, and brushless dc motors.
Lambruschi attributes four user benefits to an integrated motion control/drive. Installation ease comes from only one unit to mount, wire, and program. Separate components would require numerous interconnections, more panel space, and possibly multiple software packages. One unit also means single source responsibility for technical support, avoiding multiple vendor compatibility issues. A packaged intelligent drive wiring offers more reliability with fewer interconnections than a separate drive and controller. It results in fewer loose or incorrect connections and less potential electrical noise (EMI/RFI). Lambruschi also mentions lower initial cost and less installation time versus a traditional drive with separate controller.
Paul Derstine, motion manager at GE Fanuc Automation, believes that 'intelligent motion' for general motion-control applications typically involves consolidation of several elements—motion control (path planning and loop control), logic control, I/O functions, and motor power amplifier—into a single product. He cites GE Fanuc's S2K servo/stepper motion controller as one product example.
He further mentions 'some moves to include the motor into this mix,' but concludes that harsh industrial environments and high motor operating temperatures limit the types of applications where this can yield long-term user benefits. Actually, the number of such products available indicates that other non-technical and market issues so far have limited motor-to-controller integration (see Control Engineering , Dec. 2001, 'Integrated Intelligent Motors and Control,' for example).
Benefits of intelligent motion for simple machines with limited axis-to-axis coordination include reduced wiring and fewer multi-vendor product integration issues. And if enough logic capability and I/O points are available, one controller could handle the entire machine, explains Derstine. 'Often the goal of intelligent motion is to achieve distributed control to reduce motor and motion-centric I/O wiring on long production lines or machines,' he says. 'In this case, a centralized motion and logic controller and 'dumb' amplifiers distributed over a high-speed fiber-optic link may offer the most effective solution.' Hybrid architectures of this type provide centralized programming with the benefits of distributed motion.
More intelligence to come
Rockwell Automation's Lieser believes that the trend to adopt integrated motion on a common platform will accelerate as more OEMs and end-users realize the benefits. 'They will drive additional innovations in networks and information to further mainstream the motion system with the rest of the machine and product line,' he says.
Similarly, Mark Crocker at Baldor UK Ltd. says, 'The next five years will see a convergence of technologies such as PLCs and motion controllers. Decentralized control will become more commonplace, with Ethernet becoming the dominant fieldbus.'
Programming wizards, aids for writing applications, and graphical programming methods will become more commonplace. Motion control languages and environments will start to catch up with PC-based programming environments, explains Crocker. Soft motion also will become more common, fueled by more powerful, cost-effective computers—and the onset of Ethernet. 'We are then likely to see more traditional PC-based programming languages, such as Visual Basic, C++, and C#, become popular for motion programming. Interfaces to motion control and I/O devices will be through ActiveX controls (or its future derivative),' adds Crocker.
B&R Industrial Automation sees intelligent motion trends ongoing in distributed drive functions, standardized communication, automatic update of firmware, and integrated programming environments—claiming strong participation in all of them. 'These trends will prevail and be intensified with the use of additional IT technology standards in machine control,' says Sandhoefner.
B&R has implemented Ethernet based real-time communication to the drive via its development of Ethernet Powerlink. 'In the future, drives will be able to publish information as decentralized Web servers accessible by the Internet. This opens up a new range of functions that can be executed at the drive level,' he adds.
Full transparency from the drive up to the line host will follow, easing access to machine process data and cutting system cost. For example, specific machine part maintenance alert could come directly from the drive via e-mail.
Bosch Rexroth's Rey points out that packaging and printing industries have already benefited from drive-based intelligence. In the next few years, he sees other industries expanding use of intelligent motion in multi-axis servo applications. 'Going forward, machine builders will continue to implement intelligent motion into their machines for systems that will be more flexible to application changes,' he says.
Among near-future developments, Siemens' Hammer notes more modular machines incorporating distributed logic and motion control. One of many in the system intelligent motion controllers, would handle a specific machine module, each sharing/exchanging data via a high-speed, real-time network. These intelligent modules would likely be mobile, so they could serve various production lines as needed, he explains.
Hammer also sees newer machine safety systems coming. These would implement in intelligent controls and sensors all features, including redundant checks, needed to move a machine toward a safe state in case of intrusion. Intelligent safety control has the potential to save costs by eliminating existing costly electrical solutions.
National Instruments expects intelligent motion increasingly to incorporate high performance motion control with non-PID control loops on flexible technologies like FPGA and RTOS in various form factors. Also part of this trend will be 'seamless integration with other disciplines, such as vision, analog and digital I/O modules, and communications,' concludes Kulkarni.
E pluribus unum (one, out of many) may not be a bad metaphor for this intelligence trend.
More about intelligent motion
Added machine and system functions are becoming integrated into new control architectures, where more cost-effective output in the form of “intelligent motion” is the uniting influence.
B&R Industrial Automation Corp. ’s Industry Segment manager, Markus Sandhoefner, mentions that an intelligent drive can act as a “sensor” to optimize the machine process, using drive-inherent parameters like acceleration, speed, and position. An example concerns the adaptive control system for a robot arm that changes tuning parameters in real-time based on changing load conditions. Process torque and speed variation due to robot axis position changes are calculated and evaluated online in the drive, he explains. “This ensures optimized settings of PID control loops to achieve maximum precision and throughput in any load condition without the use and evaluation of additional sensors.”
Process/product quality is another expansion of intelligent motion’s control functions. Sandhoefner cites the jam detection mechanism of an envelope-printing machine that produces 90,000 parts per minute. It relies on accurate reading of a photo eye set in a narrow position window (&4°) within a full rotation of the motor. Precise process evaluation was achieved by monitoring the sensor directly inside the drive in real-time. “The result is then transferred to the main controller once per cycle and fed into a shift register, so several process steps in a row can be tracked for successful print production,” he adds.
Siemens Energy & Automation ’s product manager for Simotion, Josef Hammer, elaborates on the cost reduction benefits of intelligent motion in three areas:
Reduction of engineering time —A uniform, easy to use tool for all engineering tasks (sizing, parameterization, programming, and test) and for all system elements (drive control, motion control, logic control) dramatically reduces the time for application development, education, and commissioning. “Object orientation and library concepts accelerate the development of multiple machines by reusable software,” he says.
Reduction of size and cabinet space —Cabinet space does not support machine functions and costs money. Compact solutions are gaining importance, supported by drive-based solutions where motion and logic control are directly integrated in drive hardware.
Accessibility worldwide —A machine working at an end-user location probably still needs support, explains Hammer. Ability to diagnose and troubleshoot the unit online, even download software from anywhere worldwide can virtually eliminate cost-intensive service trips. These features also allow helpful maintenance functions like automatic generation of e-mails, fax, or cell-phone alerts to service personnel about special machine conditions.
These potential cost reductions can be a competitive weapon for OEMs that adopt true intelligent motion systems.
Rahul Kulkarni, product Manager-Industrial Data Acquisition and Control at National Instruments (NI), provides some details on capabilities that new NI Motion Assistant 1.2 offers for “smart contouring,” a control method useful in metal working and CNC-type applications.
“With the new NI Motion Assistant 1.2, machine builders and OEMs can now design a motion application in an interactive environment and deploy that application by converting the project into C code for any C compiler, or into NI LabView virtual instruments,” says Kulkarni. The software’s patent-pending smart contouring functionality can be tapped via an application-programming interface (API) callable from C, Visual Basic, or LabView. (Engineers can download a fully functional evaluation version of Motion Assistant 1.2 by clicking here .)
Smart contouring defined
A contoured move is expressed as a series of points that the motion controller uses to extrapolate a smooth curve, explains Kulkarni. Curve points are generated by a CAD/CAM or graphics program. “Smart contouring is defined as the ability to take a specified set of contour points and apply user-specified velocity, acceleration, and jerk parameters to it such that the motion controller follows a trapezoidal or S-curve profile when extrapolating a smooth curve,” he states. This helps users define complex geometry and yet achieve trapezoidal or S-curve profiles for motion. It helps minimize the detrimental effects of jerk—the rate of change of acceleration or the third derivative of position with respect to time—on mechanical components, hence increases machine life.
NI Motion Assistant achieves smart contouring by remapping contour points based on desired velocity, acceleration, and jerk profiles—while maintaining the curve’s geometry. This patent-pending function in NI Motion Assistant 1.2 can be called up via programming languages like LabView, C, and Visual Basic at run-time for deployment on machines.
Baldor Electric application: Intelligent motion for fluid-filling machine
An advanced motion control system from Baldor Electric is at the heart of an innovative continuous fluid packaging machine developed by Fluid Packaging Solutions (Alpharetta, GA) to eliminate production delays caused by clean- or wash-in-place procedures. The new inline filling machine—Universal Flow Positive Displacement Filler—uses detachable pump carts and programmable motion to achieve batch changeovers, reportedly, of just a few minutes.
A precision servo motor system engineered with the aid of Baldor, and its distributor Control Corporation of America (Richmond, VA), is the basis of the Filler design. Four servo motor axes drive a flighted conveyor, load bottle/container “pucks” on the conveyor using a phasing conveyor driven by a feedscrew, and control the x- and y-motion of the filling head. The filling head synchronizes with the containers, then inserts and withdraws nozzles that fill from the bottom up, before returning to the starting position.
Fluid containers are filled four at a time, from pump carts that attach to the conveyor. Four nozzles on each cart are controlled by an additional servo axis to ensure precise fluid dispensing. The pump carts contain all the wetted parts of the system. A typical machine comes with two carts, allowing one to be moved for pressure-cleaning and priming for the next application, to not disrupt the filling process.
This technique provides a major productivity gain compared with typical existing fluid packaging lines, allowing Fluid Packaging Solutions’ machine achieve filling speeds of about 100 containers per minute. Changeovers reportedly take a new standard-setting time of under five minutes. It allows users to process much smaller batches, reducing inventory levels and business costs.
Cut development time
Baldor supplied all motion, I/O device, and human-machine interface (HMI) system components for the Filler machine, and wrote the application software using MintMT [multitasking] motion language. “Development time was greatly reduced, and machine functionality/flexibility was greatly enhanced by means of MintMT’s built-in multi-tasking operating system,” says Mike Mitchell, Baldor application specialist.
Mint language contains application-level software that takes the form of “keywords,” which also contributed to rapid software creation. For example, the FLY command synchronizes movement of two axes while controlling the position of one, providing a neat solution to match the filling head movement with the containers. Also used in the control program is OFFSET command, which allows adding a position move atop a base velocity to provide a solution for the “phasing conveyor” feed mechanism. “As this machine requires a large number of motion profiles—from simple velocity control, through point-to-point positioning, to reciprocating indexed movement—the language’s keywords saved many days of programming effort and allowed us to focus effort on adding features,” adds Mitchell.
All major axes on the main conveyor and pump carts are controlled by Baldor intelligent drives from its MintDrive or Flex+Drive families, which combine a single-axis drive with built-in positioning capability. They are linked by CAN communication running CANopen protocol. The main conveyor is the network’s master node; all the other drives are slaved to this axis. As a result, network traffic is minimal and CAN offers the speed necessary to coordinate system operation in real-time, with the master axis controlling the speed of dispensing.
Distributed and multi-tasking hardware/software architecture added system flexibility, including ability to take one or more pump nozzles offline, as required for maintenance or repair. The system will automatically recalculate filling speeds and adjust all axes to a new speed, says Baldor.
Further flexibility supported by Mint software is found on the pump carts, each of which has a human-machine-interface (HMI) panel. When disconnected from the conveyor, and wheeled away for cleaning, one of the intelligent drives switches to a secondary control program, becoming the master of a subsidiary control network that automatically rinses, cleans, and runs specific cleaning agents through the tank and pumps.
B&R Industrial Automation application: Intelligent motion enhances cut-to-length machine
Acopos intelligent servo drive technology from B&R Industrial Automation is applied by Eagle Manufacturing Corp. (Sterling Heights, MI) to enhance precision and throughput speed of its Eagle Cut-To-Length machine, while dramatically reducing waste. The machine combines six tools into one operating setup that automatically moves the required tool into place as directed by the controller. All tool changes occur “in-line and on-the-fly”—without interrupting upstream extruded material flow—using 22 servo drives. Fast setup and tool changes under five seconds are key features of the machine.
Eagle Manufacturing required the machine to cut parts with 1-mm (0.039 in.) precision at a line rate of 50 ft/min, obtained by an encoder signal fed into the master-axis drive. The master position signal is broadcast to the other 21 drives over B&R’s Ethernet Powerlink network, with each drive calculating its slave position in real-time following a cam function locally on the drive. Drive position control loop and Ethernet Powerlink cycle are fully synchronized for jitter-free operation. The 800-microsecond cycle time results in a position update for every 0.005 in. of fed material at the throughput speed of 50 ft/min. Acopos intelligent servo drive enabled this previously unavailable process quality, even with an increased number of motion axes, according to B&R.
Transporting extruded material through the cut-to-length machine presents a challenge because the material is not rigid or even. To prevent material tearing, the feeder-axis roll can’t exceed a certain force limit, but once the extruder finishes production, the feeder roll still needs to move the remaining material through the machine to prevent waste.
B&R solved the challenge through internal drive functions executed in real-time. Output torque limit of the feeder roll is adjustable at any time. The feeder roll follows the master encoder in speed control mode to prevent build-up of lag error. Speed set point is calculated by differentiating the master encoder position in the drive then feeding that value into an additional PID control loop. To keep the material under desired tension, set speed is multiplied by an adjustment factor entered into the system from any of five operator panels. When the master encoder stops, the drive automatically switches into position control mode, based on a “virtual master” that replaces the master encoder signals.
In addition, function blocks internal to Acopos drive handle inertia feedforward that allows fast, precise motion in case of low machine rigidity and high load-to-inertia mismatch. This overcomes gain-setting problems of the conventional PID-loop method. “Acopos generates the path profile online. When inertia is given—or can be determined by an algorithm—the servo drive calculates torque directly by multiplying acceleration and inertia in real-time,” says B&R Industrial Automation. “As a result, the current needed is determined precisely, whereas with conventional PID control loops, the current depends directly on the size of the lag error.”