In re Trovato, 1994
Just when it seemed like at least the Federal Circuit supported patents for software related inventions came the troubling case of In re Trovato.
The problem of finding the shortest distance between two points is a recurring one, and is of particular interest to students of the computer science field known as graph theory. Trovato’s inventions work within this area, attempting to solve the “shortest path problem” by finding the optimal path between two locations, whether in terms of distance, cost, capacity, time or other criteria. The inventions model possible object movements in the real world–the “physical task space”–by a graph called a “configuration space.” Each node of the graph represents a discrete state, or set of conditions, such as location or orientation. Edges connect the graph nodes and indicate the cost of transferring from one state to another.
Representative claims of the application included method claims 1 and 2, which recite:
1. A method for determining motion of an object comprising the steps of:
a) storing a configuration space data structure representing a physical task space, the configuration space data structure including representations of the object and its environment; and
b) propagating cost waves, in the configuration space data structure, to fill the configuration space data structure with cost values according to a space variant metric.
2. The method of claim 1, further comprising the steps of:
a) deriving a sequence of object pose representations within the configuration space data structure, using the cost values, which representations represent physical poses defining a least cost path from a start pose to a goal pose in the physical task space; and
b) providing a series in electronic form usable by the object to follow the path.
Claim 33 provides an example of an apparatus claim within the application:
33. Apparatus for planning a least cost path comprising:
a) means for storing a discretized representation of a physical task space;
b) means for assigning at least one respective cost to at least one neighboring position of any given position, based on
i) a cost assigned to the given position; and
ii) a measure which varies according to position within the discretized representation, so that a least cost path from the neighboring position to the given position is established;
c) means for starting the assigning means at a first position of known cost;
d) means for causing the assigning means to iterate, so that all positions within the discretized representation are assigned respective costs, in waves propagating outward from the first position; and
e) means for identifying a least cost path between two positions in the discretized representation based on the respective costs.
These claims were somewhat similar in style to those of Alappat. However, there was not as much detail in the specification as to the structure behind each means.
The court upheld application of the Freeman-Walter-Abele test.
The Federal Circuit found both method and machine claims to be unstatutory subject matter. and stated that Trovato’s applications failed to explain how the claimed inventions actually employ the numbers to control movement, and that the absence of even a cursory description of how the computed values were implemented further indicated that the claimed methods comprised only numerical manipulation.
After this case, the best solution seemed to be to write claims to recite some sort of tangible product or to apply results to a physical solution, and to try to recite structure to better define respective means.