A little less than a year after finding that claims of U.S. Patent No. 6,474,159, directed to an inertial tracking system, were patent-eligible under the Alice abstract idea test, the Federal Circuit has affirmed a decision of the USPTO’s Patent Trial and Appeal Board (PTAB) that claims of the ’159 patent have not been shown to be obvious under 35 U.S.C. § 103. Elbit Systems of America, LLC. v. Thales Visionix, Inc., No. 2017-1355 (Fed. Cir. Feb 6, 2018) (precedential) (opinion by Judge Wallach, joined by Judges Moore and Stoll).
Dependent claim 3 of the ’159 patent was representative, That claim, including base claims 1 and 2, recites:
1. A system for tracking the motion of an object relative to a moving reference frame, comprising:
a first inertial sensor mounted on the tracked object;
a second inertial sensor mounted on the moving reference frame; and
an element adapted to receive signals from said first and second inertial sensors and configured to determine an orientation of the object relative to the moving reference frame based on the signals received from the first and second inertial sensors.
2. The system of claim 1 in which the first and second inertial sensors each comprises three angular inertial sensors selected from the set of angular accelerometers, angular rate sensors, and angular position gyroscopes.
3. The system of claim 2, in which the angular inertial sensors comprise angular rate sensors, and the orientation of the object relative to the moving reference frame is determined by integrating a relative angular rate signal determined from the angular rate signals measured by the first and second inertial sensors.
There was no dispute that the prior art did not disclose the claimed method of calculating the “relative angular rate signal.” The PTAB credited the patent owner’s expert, who explained that the prior art used a three-step method, whereas the claims recited a two-step method. The opposing expert’s testified that these two methods were “mathematically equivalent” and practically the same. But this opinion was entitled to little weight, the PTAB had said, because the expert “did not address or account for the recited relative angular rate signal limitation anywhere in his opinion.”
The Federal Circuit sided with the patent owner, whose expert had explained the benefits of the two-step-method over the three-step method. And arguments that the PTAB improperly failed to acknowledge expert testimony that one of ordinary skill in the art would have understood prior art as disclosing the recited integration were merely an attempt to create legal error by looking at PTAB statements in isolation.
Lessons for Practice
It is interesting to observe that the claims that here survived an obviousness challenge were previously held patent-eligible. One is tempted to draw the lesson that obviousness and patent-eligibility go hand in hand. But those are murky waters. Perhaps a clearer lesson here is that obviousness requires prior art to show what claims recite, not simply steps that might be functionally equivalent.