When the U.S. Bowling Congress (USBC), the national governing body for bowling, approached ARM Automation with a request to develop an automated bowling system capable of reproducing virtually any type of throwing style to a high degree of accuracy, the company’s creative wheels started turning. In their quest to build the ultimate testing platform for balls, lanes, and related equipment, the USBC had approached several different machine builders and had evaluated using many off-the-shelf robotic systems to no avail. What had to be done is for the ARM Automation team to break down the many different challenges presented and come up with a solution that met all of the performance criteria—within a strict budget.

The team had to consider multiple elements in a bowling test, including different ball masses, ball grip orientations, spin, velocity, release point, and throw vector parameters. Any single bowl requires specification and execution of up to over a dozen variables all interacting at once.

The Enhanced Automated Robot Launcher (EARL) is essentially a purpose-built seven-degree-of-freedom robot and tightly calibrated control system that allows for precision motion (± 2mm) and split second (± 1ms) timing accuracy. That’s what was ultimately required of the system to provide throwing a bowling ball at speeds up to 25 miles per hour time after time for test after test. 

Some of the key attributes of EARL include high robot tip speeds, high precision motion, fast spin speeds of unbalanced balls, and a simple touch-panel setup with flexible programmability. EARL is built for portability and rigidity. It’s mounted on air bearings, which double as vacuum chucks to secure the frame while throwing the ball. 

One of the key challenges of the project was the development of a suitable combination ball gripper/spindle/release mechanism. Each ball must be captured in a user-defined grip orientation (gripper spin axis relative to the ball’s rotationally non-homogenous coordinate frame) and clamped with significant pressure despite small variances in allowable ball size. 

To achieve required ball spin speeds of up to 900 rpm, a spindle motor system was incorporated into the scissor like gripper apparatus. Finally, in order to achieve precise release points while traveling at maximum arm speed, the gripper mechanism needed to open in a manner that imparted no adverse motion to the ball’s instantaneous trajectory and needed to do so in a very tight window of time, ±1 millisecond. This free-release grip solution required that the clamp forces on the ball be almost instantaneously reversed. 

To achieve this function, the ARM team of designers created a reversible scissor mechanism which once set closed was held in place by a multi-stage hair trigger release. Once set, the clamping cylinder loading was reversed, which attempted to open the mechanism. This allowed a fast-acting solenoid—combined with an accurate look-ahead control scheme—to release the spindle jaws at precisely the right moment and see that they swung wide and clear of the departing ball.

EARL’s capabilities were so repeatable that it limited its own ability to bowl a perfect game. During an initial competition against a top professional bowler, EARL’s programmed perfect throw rubbed a dry streak on the oiled lane, which resulted in a progressively decreasing score. Tom Frenzel, USBC Senior Director of Equipment Specifications said, “Something I say about E.A.R.L. when I showcase him is: Due to the range of release variables E.A.R.L. can be adjusted with, it gives us a bowler for our research that can emulate any bowling style from the standard league bowler hobbyist all the way up to the top-level professionals by just pushing a few buttons. That allows us to study how our equipment specifications affect all levels of the sport.” 

Bonus video of EARL playing against Chris Barnes, 2007–2008 PBA Bowler of the Year:

For more information, visit ARM Automation.

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