To keep millions of American bowlers stocked with the
highest performing, top-of-the-line equipment, the U.S.
Bowling Congress (USBC) has led the charge of bowling research and testing
technology at the International Bowling Campus. The latest USBC milestone marks
the age of the higher-performance bowling robot, a technological curiosity with
a concrete purpose dubbed E.A.R.L. (Enhanced Automated Robot Launcher)
developed by the engineering firm ARM
ARM Automation, based in
Austin, TX, develops custom automation solutions for industrial applications.
Through the years, ARM has developed and built multi-axis orthopedic implant
testing systems, modular robots for handling nuclear materials, underwater
robotics for the world's largest fountain shows, packaging and assembly lines
for PC production, mobile robots for warehouse automation and laser
micro-machining tools for semiconductor photomask production.
So it should come as no
surprise that perhaps the company's most unique robot project of 2010 was
E.A.R.L. the bowling robot.
"E.A.R.L's abilities will aid us in quantifying the data relating
to ball motion and overall scoreability, helping us maintain the credibility of
our sport," says Neil Stremmel, managing director of the USBC National
Governing Body. "E.A.R.L has the ability to replicate virtually any bowler's
style, which will aid coaching staff by showing how conditions change as
individual bowlers compete and how to properly adjust to the ever-changing
One of the ways the USBC serves its members is by testing bowling
equipment to ensure that it adheres to its published specifications. To
eliminate the variation that a human bowler would introduce during the tests,
the USBC turned to automation and robotics.
"The biggest challenge overall for the
mechanical and electrical controls development was getting the timing of the
bowling ball release within 1 ms," says Greg Wiese, project engineer for ARM
Automation. "Considering the 24 mph velocity for the ball release that USBC
required, if the system dithered 1 ms, it equated to roughly a degree in
difference for ball loft and 0.5-inch difference relative to the foul line. Any
additional dither and the ball could be thrown into the ceiling or slammed into
the bowling lane."
With what may seem like a
simple swing of an arm, there are actually a wide range of parameters that go
into 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 of
gravity; release point of the ball relative to the bowling lane (height,
position relative to foul line, position across the width of the lane, loft
angle, ball trajectory); and ball release speed and rotation speed. E.A.R.L.'s
motion system consists of a linear axis to position the ball across the width
of the lane, a 5-axis positioning robot, a ball spinner and release mechanism
installed on a gripper. PC-based Controls over Ethernet
To tackle the tight precision
requirements of this robot application, ARM Automation selected an EtherCAT-
and PC-based control system from Beckhoff
. Via a Beckhoff HMI, USBC personnel can input their test setup
on E.A.R.L. and adjust up to 11 variables for configuring different throws via
the HMI to control speed and pick-up orientation. The E.A.R.L. robot with
Beckhoff controls can be reconfigured for different parameters in less than 10
The system includes a Beckhoff C6920 Industrial PC running
TwinCAT NC PTP software and Windows CE operating system along with EtherCAT as
the I/O and drive fieldbus. For the HMI, E.A.R.L. is equipped with a Beckhoff
CP6901 Control Panel display with touchscreen and visualization functions
developed with TwinCAT software.
Position of the E.A.R.L. robot's end effector is communicated to
the EtherCAT drives to determine the exact time at which the ball needs to be
released. That position measurement is precise (within 1 ms) and creates the
correct loft of the ball each time. E.A.R.L. is able to release a bowling ball
under test within 250 µs of a scan of the position.
"EtherCAT also allows us
to diagnose the bus to detect broken links on the physical layer and easily
determine exactly where the problem is located along the line," says Joe
Geisinger, ARM Automation's CTO.
"Traditionally ARM used SERCOS for high-end servo systems, but
switched to EtherCAT years ago for several reasons," he continues. "These
include a common physical layer, a drastic increase in performance, declining
interest in legacy fieldbuses, an increasing interest in Ethernet-based
networks, and the ability to combine motion and I/O on same network."
"E.A.R.L. required the ability to flexibly gather the inputs from
a range of devices and communicate easily with the drives in one flexible
environment," Geisinger adds. "TwinCAT System Manager and EtherCAT allow us to
do just that; we can pull together different platforms easily. With this
system, we can also run multiple tasks such as the I/O and drives at different
scan rates, which provided a significant efficiency boost."
ARM Automation used the TwinCAT software platform to develop the
robot motion controller and to coordinate the acquisition of I/O and position
data from the drives, perform inverse kinematics, generate the next joint
position commands, and output the new position commands and data to the drives.
"We utilized the path programming functionality within TwinCAT for the
multi-axis platform on E.A.R.L.," Geisinger explains. "With NC PTP, we control
the motion axes and constantly monitor the status of the EtherCAT drives."
There's also a safety system implemented
in E.A.R.L. with TwinCAT monitoring all the safety devices. If anything goes
wrong during operation, the drives are disabled and the robot immediately goes
into a safe state until the system is reset properly. E.A.R.L. is also enclosed
in a protective cage with safety sensors, light curtains and safety relays
installed all around to ensure optimum safety.
"We now have more options
and better resolution for release height, trajectory, ball speed, RPMs and
loft," USBC's Stremmel says. "E.A.R.L is able to handle a larger range of ball
diameters and RPMs. Moving E.A.R.L and changing his settings is much simpler
and far more accurate than our previous robot solution."
Shane Novacek is marketing communications manager
for Beckhoff Automation.