Feature Machine Control with “Soft Motion” and Servo Systems with SERCOS interface Ann Hamil Tommy Thompson 1. Introduction Sanyo Denki’s product family includes the soft- ware-based controller called “AML®” that is provided by Automation Intelligence (AI), a subsidiary of Sanyo Denki. “AML” software is available with two hardware platforms: the “SMS-10/15” stand-alone controller and the “SMS-PCI” open controller. The “SMS-10/15” only runs “AML” software while the “SMS-PCI” allows “AML” to operate on any Windows-based PC along with other Windows applications such as web browsers or HMI ap- plications. The capabilities of “AML” are identical for either hardware platform. Also, AML-based controllers use the fiber-optic SERCOS interface to connect with servo systems and input/output (I/O) stations which in- cludes the Sanyo Denki “PV” and “PE” servo systems with the SERCOS interface. All the hardware for these various products is developed and provided by Sanyo Denki. In addition to “AML” development, AI serves as a sales channel for Sanyo Denki in North America and Europe. AI’s Partners in Motion network of distributors sells Sanyo Denki servo and control system products. AI also has a control system integration service that provides custom control solutions for both OEMs and end users, Fig.1 Overview of the Mechanical Design and serves as an important sales and support channel for Sanyo Denki products. This article discusses a machine that was recently Trays are placed one-by-one into a servo-driven Lug developed by an OEM in Texas, USA. The success of this Chain Conveyor from a stack of trays at the de-nesting new machine is a good example of the marriage between station. Fig.2 shows the entry of trays on the Lug Chain AI & Sanyo Denki technology along with the combined Conveyor. capabilities of the customer (Waldrop), AI’s local Partner in Motion (GEA of Texas), and AI’s system integration service. 2. Machine Description The MW Waldrop Company of Houston, Texas has been making machines for the meat packing industry since 1960. Until recently, these machines have been primarily mechanical with no electronic motion control. The redesign of the Pad Placing & Labeling Machine to replace mechanical components with servo technology had two primary purposes: increased speed and greater flexibility. In preparation for the addition of meat in downstream operations, the Pad Placing & Labeling Machine inserts Fig.2 Lug Chain Conveyor an absorbent pad into a meat packing tray and applies a label on the bottom of the tray. Fig.1 shows an overview As the individual trays advance with the Lug Chain of the mechanical design, as well as the major control Conveyor, software-programmable limit switches (PLS) components. in AML fire outputs to turn glue guns on and off at pre- cise positions in the cycle, depositing glue in the bottom of the trays. A servo-driven roller pulls a fixed length of laminate encased padding from an overhead web. By using a servo drive that electronically gears the drive roll to the lug chain, the length of padding can be adjusted simply by altering a recipe value from the HMI. Regis- SANYO DENKI Technical Report No.14 Nov. 2002|12 tration corrections are used to position the webbing 3. Control System Description relative to the knife, ensuring that the cut occurs be- tween the pads. The knife and pad depositing mechanism At the heart of the machine control system is the are mechanically linked to the main drive that controls “SMS-10” with “AML” (Fig.1). The “SMS-10” serves as a the Lug Chain Conveyor. Fig.3 shows Pad Placer Labeler. complete machine controller, communicating with in- dustry-standard SERCOS interface (IEC-61141) to four Sanyo Denki “PV” servo drives and an I/O station. An operator interface with color touch-screen is connected to the “SMS-10” using a serial port. The serial data is transferred using the DF-1 protocol, originally developed by Allen-Bradley, but now available as a standard on many industrial control devices. The Lug Chain axis serves as the drive-train master. It runs at a recipe-configurable speed that is set through the HMI. All other axes are electronically geared to the Lug Chain using the drive-train capability of “AML”. This ensures precise synchronization between all axes, and allows for electronic ratio changes for easy product changeover. Registration control, another key feature built into “AML”, makes accurate positioning of the la- bels and pads straightforward. Fig.3 Pad Placer Labeler Programmable limit switches are used to trigger I/O at precise positions within the machine cycle, based on axis On the underside of the machine, two servo axes are position, ensuring that glue application remains consis- used to apply a label to the bottom of the tray. The tent throughout the entire range of speeds. In addition, pre-printed labels (safe handling instructions or recipe “AML” uses the PLS function to check for the presence of suggestions) may range from 25-100 mm (1-4 inches), a tray at a specific position in each cycle. Empty lugs are and have only a small gap of approximately 6 mm (1/8"). tracked though the machine so that gluing, labeling, and The labels must be applied to the trays that are running pad placement operations are not performed on any at speeds of up to 350 trays per minute. The Label Feed missing trays. axis ensures that one label is delivered per tray, while “AML” also provides recipe support for easy change- the Label Applicator applies the label to the tray. Both over to different size products, allowing up to 128 recipes servo axes use photo-eye sensors tied to their built-in to be stored on the controller and reloaded from the HMI. high-speed probe inputs to capture the axis position In addition, a “teach mode” was developed to allow new when the label edge is detected. “AML” uses that infor- recipes to be set up very quickly. The operator simply mation to apply registration corrections (or position ad- enters a few key parameters, such as Label Pitch, Pad justments) to both axes to ensure that the label is applied Length, and Tray Size, then runs the machine slowly in precisely in an indentation on the tray. “teach mode” for 5 cycles. Based on position readings and At the end of the Lug Chain, the trays are stacked calculations, the recipe parameters are automatically using a mechanical re-nester. Fig.4 shows the Tray determined by “AML”. Re-Nester. 4. Evolution of the Design The Servo-driven Pad Placing & Labeling Machine was originally conceived as a 3-axis machine, with the label applicator controlled by a single servo. GEA of Texas and AI customer support engineers worked with Waldrop to specify the control system and to develop the application, a process that took only 8 weeks from initial specification until successful demonstration at the International Poultry Exposition in Atlanta, GA in January, 2002. However, it became apparent very quickly that the ex- isting label applicator would prevent the machine from operating consistently at the desired speeds. After the successful show, Waldrop enlisted the help of AI's system integration group to rework the label appli- cator. Collaboration between Waldrop, GEA of Texas, and AI engineers resulted in a new labeler concept that Fig.4 Tray Re-Nester was quickly fabricated by Waldrop. Tommy Thompson, Staff Controls Engineer at AI, made several trips to the Waldrop facility to help write the AML application pro- gram for the new 2-axis label applicator. He also worked 13|SANYO DENKI Technical Report No.14 Nov. 2002 with Waldrop engineers to add exception handling to the 6. Conclusion existing application and to add functionality such as the “teach mode”. The combination of AI and SDC technology, and the The first machine is now in production at a meat know-how and ingenuity of the machine builder packing facility with additional machines produced on an (Waldrop), the distributor (GEA of Texas), and the AI ongoing basis. Waldrop is now evaluating the benefits of support and integration engineers, all came together in th adding a 5th servo axis for de-nesting the trays and a 6 this application to produce a successful machine. servo axis for controlling the knife. Both of these addi- Through this cooperative effort, all parties are on the tional axes would be mapped to the Lug Chain, running winning side. electronic cam profiles to improve the product handling AI wishes to thank Waldrop for their participation and capabilities. cooperation in the writing of this article. They have been a pleasure to work with in all regards. Also, many thanks 5. Features and Benefits to GEA of Texas for recognizing the opportunity, and for providing continued support and service throughout the The servo-driven machine, controlled by Sanyo Denki’s process. “SMS-10” with “AML” and the “PV” drives with SER- COS interface, offers numerous advantages over the traditional mechanical version of this machine as follows: Ann Hamil Director of Engineering 1) The most obvious benefit is the ease of product Ann received her BSEE from Georgia In- changeover. This not only provides enormous flexi- stitute of Technology. After graduation, she bility to the end user, but it simplifies the design worked for Lockheed and a small engi- requirements of Waldrop. With only two machine neering firm, where she began working with configurations (the lug pitch differs to accommodate custom, high-speed servo controlled pack- different tray sizes) to design, manufacture, and aging equipment. In 1983, after two of her support, they can satisfy the diverse needs of their associates started Automation Intelligence, customer base. a system integrator specializing in high-speed servo control systems, Ann joined them as the VP of Engineering. 2) The SERCOS interface for communication between At AI, she has been involved with many of the controller, servo drives, and I/O simplifies panel the company's integration projects, primar- fabrication by reducing the wiring complexity and ily writing application software. As the electrical noise concerns. A single fiber-optic ring development of the machine control prod- links all the components, providing high-speed data ucts began, Ann shifted her focus to the transfer in a digital and noise-immune environment. product development, focusing on real-time motion control. She is now Director of En- gineering & Marketing, defining and 3) The HMI with color touch-screen makes the system managing the “AML” product development, simple to operate and set up. This includes the “teach while continuing to develop software and mode” along with extensive adjustment and solve tough application problems. diagnostic capabilities. 4) Use of servo systems provides more precise control of Tommy Thompson the mechanical assemblies, allowing the machine to Staff Control System Engineer run at higher speeds as compared to the traditional mechanical machine. Tommy is an Electrical Engineer with an undergraduate degree from the Georgia Institute of Technology. At the beginning of 5) Finally, the simplified mechanics that result from the Tommy's 20-year career in engineering, he use of servo drives makes for more quiet operation worked with the Lockheed Company as a and reduced maintenance. systems engineer. For the past thirteen years, Tommy has been with Automation Combined, these features make the Servo-driven Pad Intelligence. As a project engineer, Tommy Placing & Labeling Machine a higher-performance and has designed and implemented countless more cost-effective solution when compared to the tradi- control systems using both digital and ana- log servo motion systems. He was also in- tional mechanical machine. Also, Waldrop has a machine strumental in the design and implementa- that has capabilities that the competition cannot provide tion of Automation Intelligence's motion in one machine at this time. controller, “AML”. SANYO DENKI Technical Report No.14 Nov. 2002|14