Obviousness

Obviousness Analysis of US Patent 8515637 Under 35 U.S.C. § 103

This analysis assesses the obviousness of US patent 8515637 under 35 U.S.C. § 103, considering combinations of prior art references identified as highly relevant in the preceding "Prior Art" section. A person having ordinary skill in the art (POSITA) in the field of machine control systems, particularly for heavy machinery with hydrostatic transmissions, would have been motivated to combine these references to achieve predictable results, such as improved torque load management, enhanced machine stability, and prevention of engine stalling.

The core inventive concept of US8515637, as articulated in its independent claims (Claims 1, 12, and 17), revolves around a machine control system and method for hydrostatic transmissions that adjusts operator requests using a factor derived from torque inputs, thereby ensuring the torque load on the power source remains within a desired range. This system often incorporates elements like torque load limits, actual torque, torque error, and filtering with a filter factor.

Combination 1: US20090319136A1 (Torque load control) in view of US4593555A (Speed and torque sensor)

• US20090319136A1 ("Torque load control system and method"): This reference is highly relevant as it explicitly describes a "torque load control system and method." It is highly likely to disclose receiving torque inputs, an operator request, the determination of an adjustment factor, and the sending of a command to a transmission (potentially hydrostatic, given the general nature of torque control) to keep the torque load on a power source within a desired range.
• US4593555A ("Speed and torque sensor for hydraulic motor"): This patent specifically discloses a speed and torque sensor for a hydraulic motor, which is a key component for providing "torque inputs" to a control system.

Motivation for Combination and Obviousness:
A POSITA, when seeking to implement or improve a torque load control system for a machine, such as that described in US20090319136A1, would have been explicitly motivated to use sensors to obtain the necessary torque inputs. US20090319136A1 teaches a torque load control system, but specific details on how to obtain the torque inputs might be broadly described or implied. US4593555A directly provides the means to achieve the "input receiving portion configured to receive torque inputs related to a hydrostatic transmission" (Claim 1) and "obtaining inputs including: torque inputs related to the hydrostatic transmission" (Claim 12). For a machine (Claim 17) comprising a power source and a hydrostatic transmission, the control system would inherently need to "receive a limit on a torque load... and a torque load the hydrostatic transmission exerts on the power source." The US4593555A reference explicitly discloses sensors for hydraulic motors, which are integral to hydrostatic transmissions, thereby providing a clear and obvious means to obtain these torque inputs.

Combining these references, a POSITA would arrive at a system and method where:

• Claim 1: An input receiving portion (using sensors from US4593555A) receives torque inputs related to a hydrostatic transmission (e.g., actual torque load) and an operator request (as taught by US20090319136A1). A processor (from US20090319136A1) determines a factor based on these torque inputs to adjust the operator request and determine a command to keep the torque load within a desired range. An output sending portion (from US20090319136A1) sends this command.
• Claim 12: Inputs (including torque inputs from US4593555A and operator requests from US20090319136A1) are obtained. A factor is determined based on torque inputs to adjust the operator request, and a command is determined to maintain torque load within a desired range, then sent to the hydrostatic transmission (all taught by US20090319136A1).
• Claim 17: A machine with a power source and hydrostatic transmission (as generally known in the art for heavy machinery, and implied by the function of US20090319136A1 for a "work machine") includes a control system. This system has an input receiving portion (from US4593555A for torque sensing and US20090319136A1 for operator requests) to receive torque load limits, actual torque load, and operator requests. A processor (from US20090319136A1) determines a factor based on these to adjust the operator request and determine a command to keep the torque load within a desired range, sent by an output sending portion (from US20090319136A1).

This combination predictably results in a torque load control system that effectively measures and manages torque loads, addressing a known problem in the art (preventing stalling, improving stability).

Combination 2: US20090112415A1 (Torque limiting control for IVT) in view of US4444286A (Torque-control with overspeed regulation and hydrostatic drive)

• US20090112415A1 ("Work Machine With Torque Limiting Control For An Infinitely Variable Transmission"): This reference is highly relevant as it describes "torque limiting control" for an "infinitely variable transmission" (IVT). Hydrostatic transmissions are a type of IVT. This application likely discloses a control system and method for receiving torque inputs and operator requests, determining an adjustment factor, and issuing commands to an IVT to ensure the torque load is within a desired range.
• US4444286A ("Torque-control with overspeed regulation and method of controlling a hydrostatic drive"): This reference explicitly addresses "torque-control" and a "method of controlling a hydrostatic drive," including "overspeed regulation." This directly relates to managing torque and speed in a hydrostatic system.

Motivation for Combination and Obviousness:
A POSITA seeking to implement a robust torque limiting control for an infinitely variable transmission (IVT), as taught by US20090112415A1, would naturally consider specific types of IVTs and proven control strategies. Given that US20090112415A1 covers IVTs generally, a POSITA would find it obvious to apply its teachings to a hydrostatic transmission, a common type of IVT in work machines. US4444286A provides a specific example of "torque-control" for a "hydrostatic drive," including "overspeed regulation," which functions to keep the power source within a desired operating range, aligning with the "desired range" limitation in US8515637's claims.

The motivation would be to combine the general "torque limiting control" principles for IVTs from US20090112415A1 with the specific and well-known "torque-control" and "overspeed regulation" techniques for hydrostatic drives from US4444286A. This combination offers a predictable improvement by applying a recognized torque limiting strategy to a specific, relevant transmission type using known control methods.

Combining these references, a POSITA would arrive at a system and method where:

• Claim 1: A machine control system for an IVT (specifically, a hydrostatic transmission, as taught by US4444286A) with torque limiting control (from US20090112415A1). The system receives torque inputs (from US4444286A's torque control) and an operator request (from US20090112415A1). A processor determines a factor for adjusting the operator request and determines a command (guided by US4444286A's control of a hydrostatic drive) to ensure the torque load on a power source is within a desired range (achieved by US20090112415A1's torque limiting and US4444286A's overspeed regulation).
• Claim 12: A method for controlling an IVT (specifically a hydrostatic transmission, from US4444286A). It involves obtaining torque inputs (from US4444286A) and operator requests (from US20090112415A1). A factor is determined based on torque inputs to adjust the operator request, and a command is determined for actuating the hydrostatic transmission (per US4444286A's control) such that the torque load on the power source is within a desired range (per US20090112415A1's torque limiting and US4444286A's overspeed regulation).
• Claim 17: A machine with a power source and a hydrostatic transmission (from US4444286A, and common in work machines from US20090112415A1). The control system includes an input receiving portion configured to receive a torque load limit and the actual torque load (as part of US20090112415A1's torque limiting and US4444286A's torque control) and an operator request (from US20090112415A1). A processor determines a factor based on the torque load limit and exerted torque load to adjust the operator request, and determines a command for the hydrostatic transmission (from US4444286A) to keep the torque load within a desired range (from US20090112415A1 and US4444286A).

This combination yields a system for managing torque load on a power source in a hydrostatic drive, which is directly analogous to the claims of US8515637.

Combination 3: US4802336A (Hydrostatic transmission with torque/power limit regulation) in view of US20100127654A1 (Machine control system and method)

• US4802336A ("Hydrostatic transmission having a control and regulating device for adjusting the driving torque with superimposed output power limit regulation"): This reference is highly relevant, specifically describing torque adjustment and power limit regulation for a hydrostatic transmission. This directly addresses the core objective of US8515637 to manage torque load within a desired range.
• US20100127654A1 ("Machine control system and method"): This patent application has the identical title as US8515637 and is by the same assignee, Caterpillar Inc., and includes one of the same inventors (Randall T. Anderson). This strongly suggests it is a related or earlier application disclosing a similar or foundational control system and method for machines. It is highly likely to disclose receiving torque inputs, operator requests, determining adjustment factors, and issuing commands to a transmission (likely hydrostatic given the context) to manage torque load.

Motivation for Combination and Obviousness:
A POSITA, particularly one working for Caterpillar Inc. (the common assignee), would have been well aware of the concepts disclosed in US20100127654A1, which describes a "machine control system and method" for managing torque. When developing or refining such a control system, it would be obvious to integrate specific, known control techniques for hydrostatic transmissions, especially those focused on "adjusting the driving torque with superimposed output power limit regulation," as taught in US4802336A. The motivation would be to apply the general control framework of US20100127654A1 to a specific and highly relevant application—hydrostatic transmissions—using established torque and power limiting techniques already known in the art (US4802336A). Given the common assignee and inventor, this represents an explicit motivation to combine related internal developments or prior art.

Combining these references, a POSITA would arrive at a system and method virtually identical to the claims of US8515637:

• Claim 1: A machine control system (from US20100127654A1) having an input receiving portion to receive torque inputs (from US20100127654A1 and US4802336A's control and regulating device) related to a hydrostatic transmission (from US4802336A) and an operator request (from US20100127654A1). A processor (from US20100127654A1) determines a factor (from US20100127654A1's adjustment mechanisms) based on the torque inputs for adjusting the operator request, and determines a command for actuating the hydrostatic transmission (from US4802336A's control device) such that a torque load to be exerted on a power source is within a desired range (achieved by US4802336A's output power limit regulation and US20100127654A1's torque management). An output sending portion (from US20100127654A1) sends the command.
• Claim 12: A method for controlling a machine including a power source and a hydrostatic transmission (from US4802336A and US20100127654A1). The method obtains inputs including torque inputs related to the hydrostatic transmission (from US4802336A) and an operator request (from US20100127654A1). It determines a factor based on torque inputs for adjusting the operator request and determines a command for actuating the hydrostatic transmission based on the adjusted request (all from US20100127654A1 and US4802336A) such that the torque load is within a desired range (from US4802336A's power limit regulation). The command is then sent to the hydrostatic transmission.
• Claim 17: A machine with a power source and a hydrostatic transmission (from US4802336A). A control system (from US20100127654A1) includes an input receiving portion to receive a limit on torque load and the exerted torque load (from US4802336A's power limit regulation and torque adjustment) and an operator request (from US20100127654A1). A processor (from US20100127654A1) determines a factor based on these torque inputs to adjust the operator request, and determines a command for actuating the hydrostatic transmission (from US4802336A) to keep the torque load within a desired range. An output sending portion sends the command.

This combination is particularly strong due to the explicit description of relevant control mechanisms in US4802336A for hydrostatic transmissions and the highly analogous "machine control system and method" of US20100127654A1. The common assignee and inventor further bolster the argument that a POSITA would have been motivated to combine these teachings.