Expert Witness Forensic Engineer Industrial Controls Automation New Orleans
Arthur Zatarain
Project Profile
Patent infringement: Motion Control Software

Patent infringement: several patents for workstation software to facilitate the creation of device-independent motion control software. The software system was disclosed as a Windows programming environment having a three layer WOSA-like structure: an application layer, a "motion component" middleware layer, and a driver "service" layer. This application-to-driver linkage can be considered similar to how workstation applications "drive" peripheral devices via an application program interface that in turn links to driver interface functions that generate device-specific control commands.

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Rather than drive a printer or plotter, the disclosed three layer motion control software system generates hardware-dependent command codes for "motion control devices." The system allows the creation of hardware-independent motion control software consisting of abstract "motion control operations." The system can interface with any motion control device having a suitable driver.

The accused distributed control systems (DCS) used the OPC (OLE for Process Control) open architecture data exchange protocol to link Human Machine Interfaces (HMI) to industrial process controllers. That combination of workstation software and OPC servers was alleged to infringe the disclosed three-layer WOSA-like software system.


The disclosed target device is termed a motion control device consisting of a controller and mechanical system. A hypothetical example of the overall system includes a computer workstation connected to a motion controller that powers an X-Y table. The workstation generates control commands in a device-dependent language based on abstract motion operations, such as "move relative." The control commands in hardware language are transmitted to a motion controller that then performs closed loop motion control of mechanical hardware.


A more complex example of related technology is a multi-axis robot having direct closed loop control by a motion controller. Although the motion controller manages the position and speed of each robot motion axis, the overall coordinated robot movements are managed by a higher level robot controller. The high level robot controller is not an aspect of the invention; the patented system relates only to workstation software that generates control commands for the motion control device itself.


The accused DCS systems did not connect with motion control devices such as robots and X-Y tables. A typical accused motion control device consisted of an industrial control valve that was driven by an analog output from a process controller. The control valve usually had no position feedback to the process controller because the controller's loop regulated a process variable, such as water temperature, rather than the valve's physical position.


In some cases the accused devices were fitted with a locally-mounted valve positioner. In this situation, the closed loop control of valve position is performed by the local positioner rather than the industrial controller. Any position feedback to the controller was for information purposes rather than to accomplish closed loop position control.



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