Industrial networks: CAN, CANopen find new applications, including wind power
Besides traditional industrial machines, this serial bus system for embedded control is in wind power systems, medical machines, and more.
CANopen networks are gaining new applications. Besides use in traditional industrial machines, this serial bus system for embedded control is in wind power systems, medical machines, and more.
In the June 2009 issue of the CAN newsletter, Editor-in-chief Holger Zeltwanger, says, “At Hanover Fair, everybody talked about energy: Energy efficiency of drives and motion controllers, wind power, and photovoltaic. CANopen is involved in most of these topics.” CiA 402 is the “dominating motion control profile” he says, and is gaining market acceptance in frequency inverters.
“ Pitch-control in wind power makes use of CANopen networks to connect actuators and sensors,” says Zeltwanger. “Another application is temperature supervision of gears and other wind power components. Although there is a need for wind power specific CANopen profiles, [none] of the suppliers takes the initiative to start profile standardization (codename: WINDopen). The same is in the photovoltaic industry: CiA has already developed dedicated profiles for photovoltaic devices (CiA 437 series), but just a few companies support the profile. But some companies met to promote the profile (nickname: SUNopen).”
CAN was internationally standardized (ISO 11898–1) in 1993, and more than two billion CAN nodes have been sold since the protocol's development in the early 1980s. Approximately 500 companies are members of the nonprofit CAN in Automation (CiA) , headquartered in Nuremberg, Germany.
This month, CiA’s Indian office of Global Technology in Mumbai is completing a series of CAN/CANopen in Wind Power Systems seminars there. The seminars introduced the CANopen system design options for wind power systems and covered basics of CAN lower-layer-protocols as well as CANopen application-layer-protocols. Mr. Anat Khadkikar from Bachmann Electronic Industrial Automation in Pune as well as Mr. Tushar Joshi from Kübler Automation India, Pune were speakers. More information is available at CiA’s website .
Five-finger robot-hand with CAN
An important advance in service robotics applications was also reported by Zeltwanger in June. : Based on the technique of DLR-Hand II, Harbin Institute of Technology (HIT) in China and the German Aerospace Center (DLR) Department for Robotics and Mechatronics developed a smaller, multi-sensor robotic hand called DLR-HITHand II.
The robot-hand features five fingers with four finger joints each. Each finger has three degrees of freedom: It may be moved forward and backward (1st joint), to the left and right (2nd joint) and be extracted/retracted (3rd and 4th joints). Commercially available brushless dc motors with analog Hall sensors (for commutation) are used as drives.
The motors are integrated in the fingers and in the carpus (wrist) of the hand. Each joint is equipped with an angle sensor and a strain gauge-based torque sensor.
According to Peter Meusel from DLR, the complete hand is controlled via a signal-processor, previously mounted on a PCI plug-in card. “Using optimized control functions and more powerful signal processors, it is now possible to embed the complete control on printed circuit board in the hand,” Meusel says. “There with the amount of communicated data was reduced and interconnection of devices via CAN was realized in a prototype solution.”
Separately, the first applications for intrinsically safe CAN (IS- CAN) communication are proving feasible, Zeltwanger says. “In the past, CANopen has not been used in process automation very often. This may change in the future,” he says. “Interesting is that the first IS-CAN implementation has been realized in USA. It might be that European manufacturers have not detected the CiA 103 physical layer suitable for intrinsic safe applications.”
The CAN application layer also is increasingly used in outdoor-machines, says Zeltwanger. He says CiA has recently established the CANopen SIG for aerial working platforms (AWP). This group is going to develop a recommended practice for CANopen devices (joysticks, remote control units, hydraulics, etc.) used in AWPs. A similar CANopen recommended practice under development will describe the truck interface (CiA 413) for cranes.
– Edited by Renee Robbins, senior editor
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