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A Head to Head Comparison of On-Line Motor Tools
We looked at two with similar, yet different approaches
Randy Frank, Contributing Editor -- Design News, June 4, 2006
To address increasing system complexity, several suppliers have developed and continuously improved the capability of on-line motor/motion control tools. The ready access to these tools and insight they provide makes them a must-have for many engineers. However, choosing the proper tool requires exploring the various features and design attributes.
For this comparison, Design News selected two motion control tools that provide far more than an interactive selector guide. Alpha gear's Cymex 3.0 and Rockwell Automation's Motion Analyzer 4.0 allow the user to input system data and see the impact on the system's gear box, motor and other sub-systems. The well-established and frequently-updated Cymex 3.0 and Motion Analyzer 4.2 provide an interesting contrast in the system analysis for motion control systems. To make the best use of these tools, engineers should consider that the most important and unique analysis aspects of each tool are based on the tool suppliers' products.
alpha gear Cymex 3.0 Motion Plus Edition
Alpha gear's 7-year-old Cymex 3.0 approaches motor sizing from a gear box maker's perspective and includes gear reducers in the servo system calculations. Predefined application choices include rack and pinion, belt drive, ball screw, general load, turntable and chain drive, all in either approximation or detailed format. The tool provides data on the coefficient of friction, efficiency, helix angle, width of the pinion and density of the material. Cymex' database contains almost 800 alpha gear reducers' parameters. Instead of motors from just one manufacturer, users can chose from Allen Bradley, WMC, CT Indramat, KEB, Omron, Parker, Seidel, Siemens and Mitsubishi product lines. Among the three variable pieces (the application, gear reducer and motor), a transformation element of either a spur stage, pulley stage or coupling can be inserted with user-defined values.
System Requirements
Cymex system requirements include a PC with 500 MHz-processor or higher with a Microsoft Windows NT, XP or 2000 (not Windows 95/98/ME) operating system and a minimum of 50 MB / 12 MB free hard disk space for the program.
The Details
Motor manufacturers provide the data for Cymex. To ensure accuracy, alpha gear requires each motor manufacturer to enter and approve the data used in the spreadsheets. Cymex does not perform drive sizing, but it uses the theoretical characteristic curves of the servo manufacturer to verify if RMS calculations are within the continuous curve and the peaks are within the peak curve.
Cymex provides a real-time calculator tool with the ability to calculate the gravitational effects in the rotary table and bearing life, as well as shaft integrity/safety factor. Users can enter multiple motion profiles into one file, switch back and forth, monitor the results, and see how the curves and graphs change in realtime as the parameters change. The Power Profiler feature allows the selection of different linear motion profiles including 1/3-rule, 1/2-rule, sinusoidal, and polynomial and shows the resulting waveform for the distance, speed and acceleration.
In addition to the combined motor with gear reduction selection, Cymex has a couple of unique capabilities. If the rotary table is mounted vertically, the tool calculates the effects of gravity. The tool takes into account the weight of the table, which can cause bending on the output shaft. In addition, Cymex can map out 10 loads in various locations in polar coordinates and calculate the equivalent center of gravity and mass.
The other rather unique aspect of Cymex is that it calculates bearing life hours, as well as the safety factor on an output shaft. For gears that have an output shaft, the tool calculates the safety factor against bending and permanent deformation bending, as well as a failure point due to fatigue over time. The x and y distances entered by the user tell the program where the loads are located on the output shaft.
Cymex has the ability to import ASCII files, as well as actual scope traces with torque/speed information. Alpha gear engineers use this feature to determine if the gearbox is within its design capability. In addition, users can add different motors including stepper, dc, reluctance, or induction motors to the Cymex database.
To take full advantage of the power of Cymex and understand its capability and nuances, alpha gear offers Cymex training courses that include detailed briefings and exercises. For alpha gear customers, a booklet allows users to learn by working with examples, such as loading a turntable in the vertical plane with offset cubic masses to determine the resulting forces.
What's Next?
Based on internal testing currently being conducted, in the near future Cymex will be able to print out solid models after sizing the gearbox and selecting the motor and perform a geometry check to locate the correct adapter plate for the servo to the gearbox. In addition, this next generation will produce a CAD file with a solid model that includes the adapter plate. "It actually assembles the model with the right pieces," says Michael Anselmo, Application Engineering Manager at alpha gear. This more advance version could be available later this year.
To access the Motion Plus version of alpha gear's Cymex 3.0 go to http://rbi.ims.ca/4924-566 (registration required). For more information about Cymex 3.0 contact Mike Anselmo, manselmo@ALPHAGEAR.com.
Rockwell Automation Motion Analyzer
As a motor and drive manufacturer, Rockwell Automation designed a system tool to choose both the motor and amplifier, but still offers users the ability to select the gearbox from four options. Motion Analyzer 4.0 provides the choice of seven different motor product families. The motor, amplifier and gearbox can be chosen either manually or automatically. The optimization tools in Motion Analyzer allow users to maximize ratios, inertia and mechanical alternatives for motion control applications, determine system performance, and perform tolerance analysis. The tool provides a multi-segment cycle profile with unlimited profile steps. Text or graphical views in the tool provide information regarding motor plus amplifier cost, winding temperature, peak velocity, peak torque, inertia ratio, average current, peak current, bus utilization and line voltage. The tolerance analysis provides a graph of the peak velocity and velocity and torque profiles indicate overshoot. Users can import/export profiles, as well as export the application selections and details to Microsoft Word.
System Requirements
Motion Analyzer requires a Pentium III processor or greater (recommended), 128 MB RAM minimum (256 MB RAM recommended), minimum Free Space of 65 MB in the installation directory, minimum screen resolution of 800 x 600. The tool requires an operating system of Windows 98 release 2, Windows NT 4.0 Service Pack 6A (or greater), Windows XP Service Pack 1 (or greater), or Windows 2000 Service Pack 3 (or greater). Installation on WIN 95 will cause the system to become unusable.
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The Details
Originally, Rockwell Automation's Motion Analyzer was developed to quantify the motion profile and help the user size it. With Kinetic servo drives migrating to multi-axis, shared power supply design methodology, Motion Analyzer has become more of an indispensable tool for design engineers. Because of the interrelation of all the axes, operation at different times, and requirement for power at different times, it is virtually impossible to size the more cost-effective and space-effective multi-axis systems without using software.
Users commonly approach Motion Analyzer by entering the mechanical characteristics of their application including the desired cycle time and then selecting the smallest motor and drive combination to do the job. The motor, amplifier and gearbox of the eight axex can be specified separately as well as the cycle profile, load, actuator, and transmission. The performance on each axis shows the percentage rating to the maximum of parameters in the motor, amplifier and gearbox, as well as the torque-speed curves and the values of the key parameters for the three hardware components.
An important differentiating feature of Motion Analyzer is its ability to characterize motion based on an electronic cam profile. With the increasing popularity of the electronic cam for electronic gear ratio and other applications, determining the motion profile frequently requires 200 or 300 position points versus time.
Many of the questions Rockwell receives about the Motion Analyzer are used to define new features. The feature could be a new template or machine configuration. Rockwell recently added a module to support electromechanical actuators integrated into the servo motor.
What's Next?
Rockwell has already started to build more accurate models of the motors and drives into the software. In the coming years, Mike Woelfel, product marketing manager for Linear Motion & Presale Software, Rockwell Automation Kinetix Motion Business, expects to see people using Motion Analyzer the way they use MATLAB for simulation. "Engineers can really start to simulate their machines with this better and actually do their design on the computer without having to bolt everything together and verify it," says Woelfel. "I think we are going to see integration with CAD packages in the future."
To access Rockwell Automation Motion Analyzer 4.0 go to http://rbi.ims.ca/4924-559.
For more information about Motion Analyzer 4.0 contact Mike Woelfel, mgwoelfel@ra.rockwell.com.
| Useful Links | ||
| Check out these other on-line motor tools | ||
| Aerotech's motor sizing worksheet (version 2.8): http://rbi.ims.ca/4924-561 | Galil's MotionCode toolkit, a step-by-step design tool, registration required: http://rbi.ims.ca/4924-562 | Lin Engineering's Conversion Calculator: http://rbi.ims.ca/4924-563 |
| Schneider Electric's (Square-D) DigestPlus™ Selector — advanced product selection tool: http://rbi.ims.ca/4924-564 | ||
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A Head to Head Comparison of On-Line Motor Tools
We looked at two with similar, yet different approaches
