Intelligent Manufacturing € July € 1996 € Vol. 2 € No. 7

Ford Installs Intelligent Cell Controller

Automotive manufacturer Ford Powertrain Operations (Dearborn, Mich.) has developed a flexible manufacturing system (FMS) that is being controlled by a intelligent cell controller. The system controls the movement of parts through the cell, issues supervisory control commands to the machine tools, and permits process engineers to create flexible routes for pallets of raw material.

The FMS is based on G2, a real-time intelligent software application from Gensym Corp.
(Cambridge, Mass.). The intelligent cell controller performs fully automatic closed-loop control in a multi-platform, multi-system, discrete-parts manufacturing environment.

Ford's previous cell controller was based on a proprietary OEM architecture that lacked the flexibility to handle changes and updates needed to handle new revisions of software, hardware, and parts to be produced. Using G2, Ford implemented a cell control system based on an open architecture, commonly available tools, and industry standard hardware, software, and protocols. G2 runs on a UNIX workstation, communicating via TCP/IP to an Oracle database on a VAX. The automated guided vehicle (AGV) system control computer is directly connected to G2. FANUC and GE2000 controllers and Allen-Bradley machine controllers are all integrated with G2 via the Manufacturing Messaging Specification (MMS), an industry standard.

The application itself is a very flexible and powerful control system. Process engineers use a process plan editor to define and maintain process plans for different parts and revisions. The process plan editor is a graphic-based front end to an Oracle database. Objects and icons represent steps of a plan which can be graphically manipulated, with changes reflected in Oracle.

During operation, as raw castings are loaded onto a pallet and introduced into the cell, the intelligent cell controller queries Oracle for the process plans for all of the different part types on the pallet. The controller then determines an efficient route for the pallet and issues commands to the AGV system, directing it to move pallets from machine to machine for processing. When a pallet arrives at a machine, G2 downloads an NC program to the machine's controller, and activates processing.

During processing, the intelligent cell controller monitors the machine tools for status and alarm conditions. It warns operators of problems, and may stop the machine. The intelligent controller provides a full man-machine interface to control cell operations. Operators can place the machines at various levels of manual control, and temporarily remove stations from G2 control. The pallet router tracks the state of each machine, and dynamically determines which pallet moves to make. Tool management and added cell-level functionality will be added in the future, using the object-oriented design and open systems approach as a foundation.

The cell controller's open architecture permitted Ford to mix and match machine tools from different vendors, allowing the best machine tools for the job to be selected. Ford also dramatically reduced the number of man-years required to implement the application, compared to building it in a conventional programming language. The budget for the cell controller is less than one-tenth that for a system built in a conventional language. The shop-floor operators were able to begin using the system with no formal training.
Click here to return to Table of Contents for the Intelligent Manufacturing July issue.