The Motion in MotionBASIC®

ORION® is particularly well suited to control line-oriented applications common to packaging, web processing, assembly and textile machines. These types of machines have traditionally relied on mechanical lineshafts, gearboxes & complex mechanical devices such as differentials, geneva mechanisms, cams, linkages and crank mechanisms. The combination of state-of-the-art control, concurrent MotionBASIC® and advanced electronic gearing in ORION® offers an alternative with unparalleled flexibility, speed, accuracy and reliability ... as well as simplicity.

A Superior Electronic Lineshaft
Not all electronic lineshafts are created equal ... especially when it comes to building one that consistently provides higher accuracy than sophisticated mechanical systems. This is accomplished in ORION® using a direct DSP-to-DSP broadcast communications network we call MotionDATA. MotionDATA employs synchronous error correcting broadcast communications to transmit real-time position information. These data packets are processed by a virtually unlimited number of servo axes within a few millionths of a second of each other during each position loop update. This highly precise coordination occurs 1,000 to 4,000 times per second and is integral to electronic gearing precision.

In addition to providing unparalleled precision, MotionDATA guarantees integrity and prevents occasional spurious electrical interference from compromising the accuracy of your automation and the quality of the products it produces. These capabilities simply can’t be provided by products which utilize quadrature signals as the basis for their electronic lineshaft.

ORION® allows you to configure your machine drive system in software, allowing all the servo axes to be linked to the same source of information, or alternatively establishing sub-lineshafts as appropriate. In addition, each electronic lineshaft (or sub-lineshaft) can be driven by commanded or actual position from its "pacer" axis to meet the needs of your application.

GEAR statement
The GEAR statement provides an elegant way to coordinate the motion of one or more servo axes to the motion of an electronic lineshaft pacer encoder or master axis. User unit conversion factors allow a GEAR AT 1 TO 1 statement to maintain perfect synchronization of the output shafts of servo-driven gearboxes even if the servos have different position transducer resolutions and/or gear ratios.

The GEAR statement also allows the follower servo to engage an intermittent motion to the pacer as a function of travel of either the pacer or the follower axis. For user-units of degrees, the statement GEAR FOR 180 IN 360 causes the follower to rotate for 180o during 360o of pacer rotation.

Motion Contouring
For motion control applications which require contouring, ORION® provides the combination of processing muscle, elegant system architecture and flexible MotionBASIC® software to get the job done.

MotionBASIC® supports both position-based (CAM statement) and time-based (PROFILE statement) contouring.

ORION® Architecture Ideal for Contouring
Both the CAM and PROFILE statements utilize motion tables (up to 32,000 entries) to define a series of sequential motion segments. These MotionBASIC® arrays can be loaded from CAD systems, spreadsheet programs or generated by a MotionBASIC® program.  The motion tables are prepared and downloaded into the Motion Memory on the Axis Module ready for execution. The DSP processes these arrays in real-time at rates up to 5,000 per second to create complex motion contours.

Multiple arrays stored in motion memory, the ability to switch between motion tables in real-time and motion table queuing and repeating allows maximum versatility for tough applications---but are also simple to implement in software.  Error codes and diagnostic information are also provided to help debug motion execution, table placement, and linking.

Position-based Contouring
The MotionBASIC® CAM statement generates motion profiles on a FOLLOWER axis based on the position of a PACER axis (another servomotor or a remote encoder). The relative speed and distance covered by the FOLLOWER axis depends on PACER motion.

CAM commands execute motion that is linked to the cycle of the machine. As the machine speed increases or decreases, the PACER speed increases or decreases as well, causing the CAM motion profile to stay synchronized with the machine cycle.  Generating position-based motion tables electronically simulates complicated mechanical cam action. Data segments in the cam table can be interpolated for smoother segment transition during execution.

Time-based Contouring
The MotionBASIC® PROFILE statement generates motion profiles that are defined by an array of position and time parameters.  PROFILE statements are used when one or more servo axes must follow a specified contour in a fixed amount of time. PROFILE statements can be used to execute motion that is time-independent of machine speed, but can also be triggered to start at a pre-determined point in the machine cycle. As the machine speed increases or decreases, the execution time of the motion profile stays constant.

Executing Contoured Motions Defined in Arrays
When the application calls for implementing motion with special move requirements, contouring provides a method to place a customized array of motion segments in the DSP motion memory, and execute it.  Special move requirements include speed and/or distance contours that cannot be performed using simple trapezoidal motion profiles. This information is loaded by MotionBASIC® into the on-board motion memory of the appropriate Axis Module(s).

When a CAM or PROFILE statements is executed, the Axis Module(s) begins processing the data in the motion memory, executing the defined motion.  Versatile ways to initiate table execution are available with MotionBASIC® contouring. The point to start and stop motion is specified as a command variable with automatic wraparound or one-shot execution capability.

Contouring Development Environment
Motion segments contained in a motion table are incremental distances to be moved during the execution of that segment. Different motion table formats are provided to handle regularly spaced segments, and also irregularly spaced segments. Diagnostic variables are provided containing status about loading, conversion and execution of contouring commands.

The CAM statement provides the ability to execute a position-based motion curve replicating the operation of a mechanical CAM-follower mechanism.  Programmable CAMs generated in software are faster to develop, easily modified and can be adapted to the specific needs of the application.

The PROFILE statement provides the ability to generate customized velocity profiles that are always completed in a specific cycle time.  Motion segments (defined by an array of distance and time parameters) allow you to create highly customized velocity contours.

Click here to view/print/download an Adobe PDF of this document (499k).