Cello servo drives in a CANopen network to facilitate motion control
Elmo Motion Control has streamlined an application for trimming and cutting meat in a sophisticated machine that incorporates a 3D laser scanner and water jet robotics. The Elmo solution uses Cello servo drives in a CANopen network to facilitate motion control over up to eight separate axes.
In beef, poultry and fish processing applications, a complex series of tasks is required in order to analyze each piece of meat and subsequently trim and cut it into clean units of similar size or weight. Elrad Ltd. has implemented a solution using its CompuScan 300 robotic water-jet system, which uses a 3D laser scanner, powerful computerized analysis programs and an X-Y robotic water-jet cutter to trim and cut the meat.
The system processes fish, beef, pork and turkey, trimming and cutting through bone, fat and tissue. The actual machine . custom tailored to each specific application . processes meat on a moving conveyor belt.
Each piece is first imaged by a triple-CCD camera head, and subsequently analyzed in order to determine the shape and topography of the piece, including locating fat lines and blood spots. From this information, a central processing unit interpolates the shape and the motions required to trim and cut the meat into sections of similar size or weight. Water jets mounted on linear slides assembled above the conveyor belt perform the actual slicing according to the processed information.
To operate the many axes of the system, a multi-axis controller was originally used in a centralized system to send analog current commands to current mode amplifiers on the axes. This scheme, while successful, required a mass of wires and connectors for the many encoders, current commands, Enable/Disable commands and various I/O commands, resulting in a very rigid and costly system. An attempt to streamline this configuration using RS-232 communication was thwarted by the need to multiplex up to eight ports and increase communication speed. It also was unable to support advanced motion requirements.
A solution was required to manage six to eight different axes with fast communication, while reducing the amount and complexity of the cabling, and providing flexibility in design for upcoming customer applications.
Elrad meat processing line configured with Elmo Cello servo drives
Elmo Cello digital servo drives were configured to control the back-and-forth operation of each water-jet slicing head mounted above the conveyer. An additional Cello controls the motion of the motor of the conveyor transporting the meat. The optical head that executes the 3D visualization is connected to the PC that performs vision analysis, determines the motion trajectory and manages the man-machine interface. In order to streamline and improve communication to the axes of the conveyor and robotics, Elmo Motion Control assisted the Elrad system designers. in implementing a CANopen access layer for distributed networking, installed on the same control-and-analysis PC. Implementing the Elmo Interlude API, with its field-proven CANopen communication libraries, helped reduce the time to full operation to one single week.
Fast and Flexibility
Using Elmo’s innovative multi-axis networking solution together with Elmo Cello digital servo drives, the Elrad food processing system has been streamlined for a boost in speed, flexibility and cost savings. The CANopen network has solved the communication speed problem, while providing tremendous adaptability to new configurations, which may include added axes and different I/O requirements. Control of single axes is direct and highly efficient, as is interpolation of motion between multiple axes.
Replacing the “bulky” multi-axis controller with CANopen networking has done away with the complex maze of wiring, which translates into cost savings in hardware as well as in the entire time-to-build process. The configuration of Elmo Cello servo drives and the Elrad Compuscan, integrating CANopen, has proven to be an extremely successful solution.