As good managers know, it's bad policy to keep employees in the dark. This principle was literally true at Eastman Kodak. Consequently, the Rochester-based manufacturer of photographic film became an early advocate of automated processes.
"High-volume production and a light-sensitive product," says Allen Presher, VP of marketing, Ormec Systems Inc., "made Kodak engineers pioneers in the field of advanced motion control." One of those engineers--Presher's brother, Gordon--capitalized on that expertise, founding Ormec in 1982. The company's mission: multi-axis control solutions for high-speed, line-oriented automation.
The PC takes control
A visit to Ormec unveils what the company calls a new era in industrial controls. By this, they mean the use of IBM-PC compatible architecture to coordinate multiple control tasks. Ormec's OrionTM family of motion controllers, good for applications involving as many as 14 axes, fulfills that strategy.
"The problem with using a PC as a platform for motion control," explains Technical Marketing Specialist Chris Englert, "has been the lack of essential industrial features." Orion, he says, not only capitalizes on the power and value of an off-the-shelf motherboard, it provides many features of industrial hardened PCs. These include watchdog timers, an emergency stop input, and non-volatile memory for machine configuration parameters.
Controller components include the motherboard, system module, discrete I/O board, and DSP axis modules. The motherboard features an Intel microprocessor from the 80486 family, a 16-bit ISA bus, 4 Mbytes of DRAM, and a 256K cache.
Orion's system module plugs into the 16-bit ISA backplane. It comprises two standard, front-loading PC Card slots: One accepts Ormec's Motion-Basic(R) system card, which includes a DOS operating system extended for real-time multi-tasking, and dedicated motion-control software. The second PC Card slot supports an additional memory card, as well as a PC Card hard drive for storing application programs.
Closed-loop motion control comes via the DSP axis modules. Each unit controls one or two servomotors and features a Texas Instrument digital signal processor. Pluggable terminal blocks interface to high-speed sensors, optional analog inputs, and integral programmable limit switches.
"With Orion," says Allen Presher, "we utilize torque control to minimize the role of the servo drives as an intelligent component in the system, and centralize software control in the motherboard." Ormec achieves this by interfacing the controller's main processor with the digital processors on the DSP axis modules. A dual-port RAM shared-memory interface speeds this interprocessor communication.
"There's a lot of incentive to integrate control tasks into a cohesive architecture," adds Englert, "rather than talking controller to controller, where each unit might use a different language." The DSP modules contribute to this philosophy by servicing all real-time requirements of the servo system. This, says Englert, frees up the main processor for other tasks.
Programming involves what Ormec calls its MotionBASIC(R). With this strategy, all the software required for most motion-control applications can be plugged into the PC Card memory slot on the front of the controller. System Cards are available with 2 to 40 megabytes of non-volatile Flash RAM; applications requiring added memory are supported with a second memory card or hard drive with up to 260 Mbytes.
Since the Orion motion controller supports an industry-standard Flash File system, updating software on the card is as simple as copying/deleting files using any DOS or Windows file manager. If the user doesn't have access to a computer with a PC Card slot, he or she can accomplish file management using the controller's RS-232 development port in conjunction with Ormec's MotionDeskTM development software.
"One of the drawbacks with software-based machines in the past," Englert claims, "was maintenance. If there was a problem, the operator would have to take the machine off line to replace the ROM and correct it. With Orion, the user simply removes the PC card and puts a new one in to update all software."
Where is Orion headed? "There's a group within General Motors, Ford, and Chrysler," says Presher, "that has written a white paper calling for an open modular Architecture Controller: Our goal with Orion is to leverage PC hardware and software into solutions for the automation control marketplace."
Compact drives: More from less
Ed Steiner used to work for the other pillar of Rochester's economy: Xerox Corp. As a Xerox project engineer, he designed the electronic control systems for the company's first two high-speed duplicators. Steiner left Xerox in 1977 to found Industrial Indexing Systems, Inc. (IIS)--one of the first companies to develop and manufacture microprocessor-based servo systems for industrial use.
The company's latest offering? Delta SeriesTM motors and drives. Here, the focus is on high performance, a small footprint, and low cost. "If you have a single-axis machine," says Frank Pecenco, IIS applications engineer, "driver size is not so critical. But, if you have a multi-axis machine, size can become a major issue."
ASIC chips and an embedded 32-bit RISC processor give the Delta Series drive its compact size. Supplied by Hitachi, the microprocessor updates feedback loops at very high speed, while saving space and minimizing cost. The chips decrease the number of physical components, and, at the same time, increase driver capabilities.
All driver parameters are digitally controlled for consistent performance; they are also accessible via built-in keypad and display. This allows users to program servo parameters without an external programming device. The built-in display gives real-time readouts of key servo parameters and diagnostic conditions.
Pacenco points out that an RS232 port is available for programming the driver via a personal computer. PC software, he adds, is available for complete drive set up, diagnostics, and PC screen oscilloscope functions.
High-resolution resolver or optional encoder feedback ensure precise speed control and accurate electronic gear ratios. Built-in acceleration and deceleration control, as well as S-curve profiling, make the driver very flexible for stand-alone applications. In all, the units support six modes of operation:
Pulse position control. The Delta Series driver functions as a position loop that accepts pulse train commands from a stepper controller, PLC, or encoder.
Speed control. The driver accepts commands from a pot, follower tachometer, dancer loop, or positioning controller.
Analog torque control. Input comes from a dancer loop, tension controller, or positioning controller.
Speed preset control. The Delta Series driver acts as a precision speed regulator that can use an analog speed command from an external source or internally set speed presets.
Speed/torque/position control. Users can operate the driver in any of these modes.
Electronic gearing. Here, the driver serves as a positioning follower that takes its commands from an external encoder. The electronic ratio between the master encoder and the servo adjusts via I/O or program parameters.
Industrial Indexing is presently developing a controller series to match the new driver line. According to Pecenco, "The new IIS DeltaMaxTM Controller will be compatible with DeviceNet, and will be one of the most compact controller/driver packages on the market."
From servos to steppers
The route from Rochester to Buffalo follows the Erie Canal, the 19th century's "western gateway." As a result, commerce and industry flourished in the Buffalo area. American Precision Industries, founded in 1947, is one of many companies that built its foundation on the region's early industrial might. Today, API's Motion Technologies Group encompasses five divisions: Deltran, Gettys, Harowe Servo Controls, Rapidsyn, and Controls. The Controls Div., established in 1989, has put new life into the company's stepper motor product line.
While stepper motion is a mature technology, it has gained intelligent electronic control only recently. This addition, however, broadens the appeal of steppers through smoother operating characteristics and greater control capability. Coupled with the traditional benefits of stepper usage, such as inexpensive motors and no feedback transducers, these features allow stepper penetration into many applications normally reserved for servos.
"When addressing single-axis applications requiring high-speed, high-torque capability," says Blaine Witt, API sales manager, Controls Div., "most customers think of a servo first, not realizing the stepper is as sophisticated as it is." As an example, Witt points out that API has developed optimized non-linear ramping techniques that maximize motor performance throughout the motor's speed range. This capability, unique to the company, gives the system designer several advantages previously unavailable with steppers:
A base speed that bypasses low speed ranges where resonance problems occur.
An acceleration rate that changes continuously as a function of speed for better utilization (more than 80%) of the motor's available torque.
As much as 60% faster acceleration to final velocity.
High speed for increased throughput.
Five parameters, programmed in via PC or dumb terminal, define the motion profile: acceleration time, base velocity, deceleration time, highest velocity limit, and maximum velocity. The result, says Russ Fulle, API application manager, is neither a sine wave nor a linear curve, but the best of both worlds.
"Most users enter an acceleration rate and a final velocity, and get a trapezoidal motion profile," Witt explains. "They have to precalculate what they think ramp steepness has to be. Optimized non-linear ramping accepts different parameters, and then calculates how long it takes to accelerate, decelerate, and what the final motion speed will be."
Though not applicable where a customer must change velocity on the fly, Fulle claims API's stepper software is ideal for "80%-90%" of those single-axis applications where the customer "needs to get from here to there as fast as possible."
Stepper solutions are not only penetrating single-axis applications, they are proving good for multiple-axis systems as well. Consider API's DM-225i "Intelligent Drive." Able to control as many as 15 axes from a single PC communication port, the microcontroller-based design incorporates the functionality of an indexer and drive in one unit.
Connecting the PC and Intelligent Drive via a serial link, Witt explains, eliminates the need for indexers and a multiple-axis indexer card. Instead, the drive interprets commands and performs the desired functions directly. Motion commands, for example, are converted to motor currents. Unlike conventional step-motor systems, the user does not need to generate step signals to perform the desired move.
"We use the power of the PC to perform all the calculations, and the drive processor to perform trajectory generation," says Fulle. "The computer's 486 or Pentium is a lot faster than the conventional indexer processor."
To control the DM-225i, the user can develop an application program using C-code. This program turns the PC into a machine controller. Another method lets the DM-225i "learn" and store specified application programs. In this configuration, PC communication control is removed and hardware inputs trigger the start of the stored application program.
What lies ahead for the companies along New York's Motion Control Corridor? More intelligence and networking to be sure. As an industry, motion control is still relatively young. Its growth has, and continues to, parallel that of computers and microprocessors. That fact, combined with the ever present need to automate and upgrade industrial processes, points to a good future for these western New York State companies.
|Servovalves keep pace
Not all motion control is electromechanical. Many problems involving position, force, acceleration, velocity, or flow control call for electrohydraulic or electropneumatic solutions. Moog Control, a division of International Motion Control Inc., is a world leader in these types of servo systems.
Established in 1957 with the invention of the original servovalve, the company continues to lead the industry with the introduction of its next-generation proportional valves. The new line will consist of both servo and directional proportional valves in NFPA D03, D05, D07, and D08 sizes. The valves will be offered for flow and pressure control applications, and come with either on- or off-board electronics.
"Applications that were once on/off are beginning to rely on proportional control," says Moog President Ed Krasnicki. Good for open- and closed-loop operation, the new valves feature a solenoid at either end of the spool, allowing a partial open.
Each valve size will be offered in multiple configurations. Selection parameters include flow rate, flow profile, no power positions, spool lap, electronics type, and electronics level. The D03 and D05 size valves will be direct-drive valves, while the D07 and D08 valves will be two-stage valves with a direct drive pilot stage. Each valve will include an integral LVDT for electric feedback on the main stage spool.
"These valves are being designed with the end user in mind," says Marketing Manager Sean Insalaco. In addition to greater performance and better flow capacity, they will feature fewer components for easy field repair, and on-board diagnostics for communicating with a supervisory computer or PLC.
Applications for the new valve line will include injection molding machines, steel-making equiment, machine tools, and sawmill machinery.