DCT
6:23-cv-00169
Iron Bird LLC v. Autel Robotics Ltd
I. Executive Summary and Procedural Information
- Parties & Counsel:
- Plaintiff: Iron Bird LLC (Texas)
- Defendant: Autel Robotics Ltd. and Autel Robotics USA LLC (Delaware)
- Plaintiff’s Counsel: Sand, Sebolt & Wernow Co., LPA
- Case Identification: 6:23-cv-00169, W.D. Tex., 07/10/2023
- Venue Allegations: Plaintiff alleges venue is proper in the Western District of Texas because Defendants conduct business in the district through online stores and authorized resellers, deriving revenue from sales to customers located there.
- Core Dispute: Plaintiff alleges that Defendant’s EVO Lite+ drone infringes a patent related to using optical sensor data to stabilize the flight of an airborne vehicle.
- Technical Context: The technology concerns optical flow sensing, where an airborne vehicle uses a camera to track movement relative to the ground to maintain a stable position, particularly during hover.
- Key Procedural History: The complaint does not mention any prior litigation, licensing history, or post-grant proceedings involving the patent-in-suit.
Case Timeline
| Date | Event |
|---|---|
| 2002-09-23 | U.S. Patent No. 7,400,950 Priority Date |
| 2008-07-15 | U.S. Patent No. 7,400,950 Issued |
| 2023-07-10 | Complaint Filed |
II. Technology and Patent(s)-in-Suit Analysis
U.S. Patent No. 7,400,950 - "Optical sensing system and system for stabilizing machine-controllable vehicles"
- Patent Identification: U.S. Patent No. 7,400,950, "Optical sensing system and system for stabilizing machine-controllable vehicles," issued July 15, 2008.
The Invention Explained
- Problem Addressed: The patent describes the difficulty and complexity of controlling remote-controlled helicopters, which previously relied on stabilization systems that only controlled yaw or used instruments that could not provide a ground-related control for stationary hovering (’950 Patent, col. 1:24-28, 1:44-49). Achieving a stable hover required controlling both inclination (roll/pitch) and velocity relative to the ground, which was difficult for pilots and prior art systems (’950 Patent, col. 1:60-65).
- The Patented Solution: The invention proposes using an "opto-electronical shift sensor," similar to that in an optical mouse, to view a section of the ground and detect "optical flow"—the apparent motion of surface features (’950 Patent, Abstract). This optical flow signal, which represents the vehicle's lateral movement, is fed into an electronic circuit that generates a control signal in a negative feedback loop to drive an actuating element (e.g., rotor blades) and stabilize the vehicle's roll attitude, enabling a stable hover (’950 Patent, col. 2:6-8; col. 11:10-22).
- Technical Importance: The invention provided a method for achieving precise ground-relative flight stabilization that was potentially lower in cost and complexity than systems requiring complex image processing or multiple conventional instruments (’950 Patent, col. 5:10-22).
Key Claims at a Glance
- The complaint asserts independent claim 13 and dependent claim 15 (Compl. ¶¶19-20).
- Independent Claim 13 requires:
- A system for controlling at least a roll attitude for stabilizing hovering flight of an airborne object.
- An optoelectronical sensing means for obtaining an optical flow measurement signal from a section of a ground image.
- An electronic circuit adapted for generating from the optical flow signal a control signal in the manner of a negative feedback loop.
- The generated control signal being adapted for driving an actuating element affecting roll movements.
- The complaint does not explicitly reserve the right to assert other claims but notes its infringement theories may be modified during discovery (Compl. ¶42).
III. The Accused Instrumentality
Product Identification
- The "EVO Lite+" drone (Compl. ¶25). Plaintiff reserves the right to add other products (Compl. ¶25, n.1).
Functionality and Market Context
- The complaint describes the EVO Lite+ as a four-rotor UAV capable of "indoor and outdoor steady hovering" and "intelligent flight" (Compl., Ex. B, p. 31, 33).
- Its relevant technical functionality includes a "binocular vision system" and ultrasonic sensors that "use the image data to calculate the distance between the aircraft and the potential obstacles" (Compl., Ex. B, p. 32, 34). The vision system is also used for positioning in poor GPS signal conditions (Compl., Ex. B, p. 35).
- The complaint highlights the "Dynamic Track 2.1" feature, where the drone automatically follows a selected object and "hovers until the target starts moving again" (Compl., Ex. B, p. 36).
IV. Analysis of Infringement Allegations
'950 Patent Infringement Allegations
| Claim Element (from Independent Claim 13) | Alleged Infringing Functionality | Complaint Citation | Patent Citation |
|---|---|---|---|
| System for controlling at least a roll attitude for stabilizing hovering flight of an airborne object, | The Autel EVO Lite+ drone supports "indoor and outdoor steady hovering and intelligent flight." The complaint alleges that in certain modes, such as when tracking a target that stops, the roll attitude of the drone is controlled to maintain a hover. | ¶25; Ex. B, p. 33 | col. 1:4-10 |
| wherein an optoelectronical sensing means is provided for obtaining an optical flow measurement signal from a section of a ground image; | The accused drone is equipped with a "binocular vision system" that includes multiple cameras, including a downward-facing one. This system uses image data to calculate position and enable accurate hovering, particularly in poor GPS conditions. A diagram in the complaint shows the drone's vision system. (Compl., Ex. B, p. 34) | ¶26; Ex. B, p. 34 | col. 11:1-9 |
| the system comprising an electronic circuit adapted for generating from the optical flow signal ... a control signal in the manner of a negative feedback loop; | The complaint provides an image of an electronic circuit board within the EVO Lite+ drone. (Compl., Ex. B, p. 38) It alleges this circuit processes the optical flow signal to generate a control signal to stabilize the drone during hover. | ¶27-28; Ex. B, p. 38 | col. 11:10-14 |
| the generated control signal being adapted for driving an actuating element affecting roll movements of the airborne object. | The accused drone uses brushless motors and an Electronic Speed Controller (ESC) to operate. The complaint alleges the ESC regulates motor speed to control the drone's movements, including roll, thereby acting as the claimed actuating element. | ¶29; Ex. B, p. 42 | col. 11:15-19 |
- Identified Points of Contention:
- Technical Question: The complaint alleges the "binocular vision system" provides the claimed "optical flow measurement signal" (Compl. ¶26). However, the complaint's own exhibits describe this system as using "image data to calculate the distance between the aircraft and the potential obstacles" (Compl., Ex. B, p. 32). The infringement analysis may turn on whether a system described as measuring distance can be shown to also generate a signal measuring lateral movement, which is the core of "optical flow" as described in the patent (’950 Patent, col. 2:6-8).
- Scope Question: The claim requires a system for "stabilizing hovering flight." The complaint points to the drone's ability to "realize the accurate hovering" using its vision system (Compl., Ex. B, p. 35). A question for the court will be whether the vision system is the primary means of stabilization as claimed, or if it serves a secondary role (e.g., position-hold assist) to a primary GPS-based or inertial stabilization system not covered by the patent.
V. Key Claim Terms for Construction
The Term: "optical flow measurement signal"
Context and Importance: This term is the central input to the claimed control system. Its construction is critical because the accused product is described as using its vision system to calculate "distance" (Compl., Ex. B, p. 32), whereas the patent specification appears to define "optical flow" in terms of measuring the shift of an image to determine relative velocity or movement (’950 Patent, col. 11:1-9). Practitioners may focus on whether "distance" calculation from image data falls within the scope of an "optical flow measurement signal."
Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: The patent states that the invention measures "motion-related measurands," which could be argued to encompass more than just velocity (’950 Patent, col. 8:38-39). The patent also discusses measuring distance as a possible, albeit separate, application (’950 Patent, col. 8:9-16).
- Evidence for a Narrower Interpretation: The patent's abstract and detailed description consistently describe the core inventive concept as measuring the "shift of the image" to determine vehicle movement, akin to an optical mouse (’950 Patent, Abstract; col. 11:4-9). The claims themselves tie the signal to "lateral movement direction" (Claim 13) and "velocity" (Claim 14), suggesting a focus on motion, not static distance.
The Term: "a control signal in the manner of a negative feedback loop"
Context and Importance: This term defines how the optical signal is used. The infringement case depends on showing that the accused drone's flight controller implements this specific type of feedback control using the optical data. The defense may argue that while the drone has a flight controller, it does not generate a control signal "from the optical flow signal" in the specific negative feedback manner required by the claim to stabilize hover.
Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: The term is functional, and any circuit that uses an optical input to generate an opposing control output could arguably meet the limitation.
- Evidence for a Narrower Interpretation: The patent provides a detailed block diagram (Fig. 5) showing a specific control architecture where the optical sensor signal (3) is a direct input that is compared against a target value to generate a control signal for the rotor blades (8) (’950 Patent, Fig. 5; col. 12:50-63). This detailed embodiment may be used to argue for a narrower construction requiring a similar, direct feedback pathway.
VI. Other Allegations
- Indirect Infringement: The complaint makes conclusory allegations of induced infringement by "encouraging infringement" (Compl. ¶37) and contributory infringement by selling a product that is not a "staple article of commerce" (Compl. ¶38). The facts alleged to support these claims appear to be limited to the act of selling the accused drone.
- Willful Infringement: The complaint alleges Defendants have had knowledge of infringement "at least as of the service of the present Complaint" (Compl. ¶35). This allegation, on its face, supports only a claim for post-filing willfulness and does not allege pre-suit knowledge of the patent or infringement.
VII. Analyst’s Conclusion: Key Questions for the Case
- A core issue will be one of technical operation: Does the accused EVO Lite+ drone's "binocular vision system," which is described in marketing materials as a distance-measuring and obstacle-avoidance feature, actually function by generating an "optical flow measurement signal" based on lateral ground movement, as required by the patent's claims?
- A central evidentiary question will be one of functional causality: Is the accused drone's hovering capability "stabilized" by means of the claimed optical feedback loop, or is its hovering primarily achieved through other means (e.g., GPS, inertial sensors), with the vision system serving a different, potentially non-infringing purpose?
- A key question of claim scope will be whether the term "optical flow measurement signal" can be construed broadly enough to read on a system that primarily calculates object distance, or if it is limited by the specification to systems that measure the rate of image shift to determine velocity.