To keep millions of American bowlers stocked with thehighest performing, top-of-the-line equipment, the U.S.Bowling Congress (USBC) has led the charge of bowling research and testingtechnology at the International Bowling Campus. The latest USBC milestone marksthe age of the higher-performance bowling robot, a technological curiosity witha concrete purpose dubbed E.A.R.L. (Enhanced Automated Robot Launcher)developed by the engineering firm ARMAutomation.

ARM Automation, based inAustin, TX, develops custom automation solutions for industrial applications.Through the years, ARM has developed and built multi-axis orthopedic implanttesting systems, modular robots for handling nuclear materials, underwaterrobotics for the world's largest fountain shows, packaging and assembly linesfor PC production, mobile robots for warehouse automation and lasermicro-machining tools for semiconductor photomask production.

So it should come as nosurprise that perhaps the company's most unique robot project of 2010 wasE.A.R.L. the bowling robot.

"E.A.R.L's abilities will aid us in quantifying the data relatingto ball motion and overall scoreability, helping us maintain the credibility ofour sport," says Neil Stremmel, managing director of the USBC NationalGoverning Body. "E.A.R.L has the ability to replicate virtually any bowler'sstyle, which will aid coaching staff by showing how conditions change asindividual bowlers compete and how to properly adjust to the ever-changingbowling environment."

One of the ways the USBC serves its members is by testing bowlingequipment to ensure that it adheres to its published specifications. Toeliminate the variation that a human bowler would introduce during the tests,the USBC turned to automation and robotics.

Microsecond Measurements

"The biggest challenge overall for themechanical and electrical controls development was getting the timing of thebowling ball release within 1 ms," says Greg Wiese, project engineer for ARMAutomation. "Considering the 24 mph velocity for the ball release that USBCrequired, if the system dithered 1 ms, it equated to roughly a degree indifference for ball loft and 0.5-inch difference relative to the foul line. Anyadditional dither and the ball could be thrown into the ceiling or slammed intothe bowling lane."

With what may seem like asimple swing of an arm, there are actually a wide range of parameters that gointo a single ball throw test. A typical E.A.R.L. test setup consists of:orientation of the robot gripper relative to the bowling ball's center ofgravity; release point of the ball relative to the bowling lane (height,position relative to foul line, position across the width of the lane, loftangle, ball trajectory); and ball release speed and rotation speed. E.A.R.L.'smotion system consists of a linear axis to position the ball across the widthof the lane, a 5-axis positioning robot, a ball spinner and release mechanisminstalled on a gripper.

PC-based Controls over Ethernet

To tackle the tight precisionrequirements of this robot application, ARM Automation selected an EtherCAT-and PC-based control system from BeckhoffAutomation. Via a Beckhoff HMI, USBC personnel can input their test setupon E.A.R.L. and adjust up to 11 variables for configuring different throws viathe HMI to control speed and pick-up orientation. The E.A.R.L. robot withBeckhoff controls can be reconfigured for different parameters in less than 10seconds.

The system includes a Beckhoff C6920 Industrial PC runningTwinCAT NC PTP software and Windows CE operating system along with EtherCAT asthe I/O and drive fieldbus. For the HMI, E.A.R.L. is equipped with a BeckhoffCP6901 Control Panel display with touchscreen and visualization functionsdeveloped with TwinCAT software.

Position of the E.A.R.L. robot's end effector is communicated tothe EtherCAT drives to determine the exact time at which the ball needs to bereleased. That position measurement is precise (within 1 ms) and creates thecorrect loft of the ball each time. E.A.R.L. is able to release a bowling ballunder test within 250 mus of a scan of the position.

"EtherCAT also allows usto diagnose the bus to detect broken links on the physical layer and easilydetermine exactly where the problem is located along the line," says JoeGeisinger, ARM Automation's CTO.

"Traditionally ARM used SERCOS for high-end servo systems, butswitched to EtherCAT years ago for several reasons," he continues. "Theseinclude a common physical layer, a drastic increase in performance, declininginterest in legacy fieldbuses, an increasing interest in Ethernet-basednetworks, and the ability to combine motion and I/O on same network."

"E.A.R.L. required the ability to flexibly gather the inputs froma range of devices and communicate easily with the drives in one flexibleenvironment," Geisinger adds. "TwinCAT System Manager and EtherCAT allow us todo just that; we can pull together different platforms easily. With thissystem, we can also run multiple tasks such as the I/O and drives at differentscan rates, which provided a significant efficiency boost."

ARM Automation used the TwinCAT software platform to develop therobot motion controller and to coordinate the acquisition of I/O and positiondata from the drives, perform inverse kinematics, generate the next jointposition commands, and output the new position commands and data to the drives."We utilized the path programming functionality within TwinCAT for themulti-axis platform on E.A.R.L.," Geisinger explains. "With NC PTP, we controlthe motion axes and constantly monitor the status of the EtherCAT drives."

Onboard Safety

There's also a safety system implementedin E.A.R.L. with TwinCAT monitoring all the safety devices. If anything goeswrong during operation, the drives are disabled and the robot immediately goesinto a safe state until the system is reset properly. E.A.R.L. is also enclosedin a protective cage with safety sensors, light curtains and safety relaysinstalled all around to ensure optimum safety.

"We now have more optionsand better resolution for release height, trajectory, ball speed, RPMs andloft," USBC's Stremmel says. "E.A.R.L is able to handle a larger range of balldiameters and RPMs. Moving E.A.R.L and changing his settings is much simplerand far more accurate than our previous robot solution."

Shane Novacek is marketing communications managerfor Beckhoff Automation.