SZ DJI Technology Co Ltd v. Bell Textron Canada Ltd

I. Executive Summary and Procedural Information

• Parties & Counsel:
  • Plaintiff: SZ DJI Technology Co. Ltd. (China)
  • Defendant: Bell Textron Canada Ltd. (Canada)
  • Plaintiff’s Counsel: Goulston & Storrs PC; Xsensus, LLP; Bejin Bieneman PLC
• Case Identification: 1:23-cv-02642, S.D.N.Y., 03/29/2023
• Venue Allegations: Plaintiff alleges venue is proper because Defendant is a foreign entity that has committed acts of patent infringement in the Southern District of New York.
• Core Dispute: Plaintiff alleges that Defendant’s Bell 505 Helicopter infringes patents related to assisted takeoff procedures and aircraft attitude control methods.
• Technical Context: The patents-in-suit relate to advanced flight control systems for aerial vehicles, a field of technology critical to the stability, safety, and performance of both unmanned drones and modern aircraft.
• Key Procedural History: The complaint does not mention any prior litigation, inter partes review proceedings, or licensing history relevant to the patents-in-suit.

Case Timeline

Date	Event
2014-03-27	U.S. Patent No. 9,126,693 Priority Date
2014-05-30	U.S. Patent No. 9,958,874 Priority Date
2015-09-08	U.S. Patent No. 9,126,693 Issued
2018-05-01	U.S. Patent No. 9,958,874 Issued
2023-03-29	Complaint Filed

II. Technology and Patent(s)-in-Suit Analysis

U.S. Patent No. 9,126,693 - "Assisted Takeoff," Issued September 8, 2015 (’693 Patent)

The Invention Explained

• Problem Addressed: The patent describes how feedback control systems in aerial vehicles, particularly those using proportional-integral-derivative (PID) controllers, can cause instability during takeoff due to interactions with ground forces, leading to a higher probability of crashing. (Compl. Ex. A, ’693 Patent, col. 1:17-28).
• The Patented Solution: The invention proposes a two-stage takeoff method. Initially, the vehicle operates under a first, simplified control scheme (e.g., one that disables integral control) to prevent instability while on the ground. Once the vehicle’s onboard processor determines a "takeoff threshold" has been met (indicating it is airborne) based on internal data like motor output or acceleration, it seamlessly switches to a second, normal flight control scheme (e.g., full PID control). (’693 Patent, col. 1:36-46, col. 2:24-36).
• Technical Importance: This approach is designed to enhance the safety and reliability of takeoffs, especially for unmanned aerial vehicles (UAVs) in challenging conditions or operated by inexperienced users, by mitigating control system errors induced by ground effect. (’693 Patent, col. 5:6-15).

Key Claims at a Glance

• The complaint asserts independent claim 18. (Compl. ¶12).
• The essential elements of claim 18, a system claim, include:
  • An actuator for increasing the altitude of an aerial vehicle.
  • One or more processors configured to determine if a "takeoff threshold" has been met based on actuator output or vehicle velocity/acceleration.
  • The determination is performed without using signals from an external source and without using reflected signals.
  • The processors generate a signal to control the actuator using a first control scheme before the threshold is met, and a second control scheme after the threshold is met.
• The complaint expressly reserves the right to assert additional claims. (Compl. ¶13).

U.S. Patent No. 9,958,874 - "Aircraft Attitude Control Methods," Issued May 1, 2018 (’874 Patent)

The Invention Explained

• Problem Addressed: The patent identifies shortcomings in conventional cascaded PID flight controllers, noting that their tuning process is complex, lengthy, and specific to each aircraft design. Performance of the entire system is highly dependent on the accuracy of the inner angular velocity loop, and these systems primarily react to disturbances after they have already affected the vehicle. (’874 Patent, col. 1:12-32).
• The Patented Solution: The invention describes a control method that first calculates "aircraft configuration parameters" (e.g., moment of inertia, center of gravity) based on the aircraft's physical characteristics. This aircraft-specific model is then used in a feedback control scheme that explicitly incorporates an "angular acceleration loop with angular acceleration feedback." This allows the controller to more directly and preemptively manage the aircraft's attitude. (’874 Patent, col. 1:39-56; Fig. 6A).
• Technical Importance: This method aims to create a more robust, adaptive, and higher-performance attitude control system that can be more easily configured for different aircraft and can suppress disturbances more rapidly than traditional designs. (’874 Patent, col. 7:46-54, col. 8:6-13).

Key Claims at a Glance

• The complaint asserts independent claim 1. (Compl. ¶17).
• The essential elements of claim 1, a method claim, include:
  • Calculating aircraft configuration parameters from physical characteristics.
  • Receiving a signal for a target attitude.
  • Generating a command signal for an actuator based on both the target attitude and the calculated configuration parameters.
  • This generation uses a feedback control scheme that includes an angular acceleration loop with angular acceleration feedback.
  • Measuring the aircraft's resulting dynamics with sensors.
  • Feeding the measured dynamics back to the processor to adjust or confirm the command signal.
• The complaint expressly reserves the right to assert additional claims. (Compl. ¶18).

III. The Accused Instrumentality

Product Identification

The Bell 505 Helicopter. (Compl. ¶11).

Functionality and Market Context

The complaint identifies the accused instrumentality but does not provide details regarding the specific functionality of its flight control, stability, or automation systems. (Compl. ¶11, ¶16). The complaint alleges that Plaintiff DJI is a "commanding market leader of UAVs," but makes no specific allegations regarding the market position of the Bell 505 Helicopter. (Compl. ¶2).

IV. Analysis of Infringement Allegations

The complaint alleges that the Bell 505 Helicopter infringes the ’693 and ’874 patents and refers to claim charts attached as Exhibits C and D, respectively. (Compl. ¶12, ¶17). These exhibits were not provided with the complaint document. As a result, a detailed element-by-element analysis of the Plaintiff's infringement theory is not possible.

No probative visual evidence provided in complaint.

Identified Points of Contention

• Scope Questions: Both patents were developed in the context of unmanned aerial vehicles (UAVs). A primary legal and technical question will be whether the claims, as written and supported by the specification, can be construed to read on the flight control architecture of a conventional manned helicopter. This may raise the question of whether a person of ordinary skill in the art of helicopter flight control systems would understand the claim terms in the same way as a person of ordinary skill in the art of UAVs.
• Technical Questions (’693 Patent): The infringement analysis will likely focus on whether the Bell 505's flight control system employs a distinct two-stage takeoff control scheme as claimed. Further, it will require determining if the helicopter's system for detecting liftoff relies exclusively on on-board, non-reflected signals (as required by claim 18), or if it incorporates data from sources like radio altimeters (which use reflected signals) or GPS (an external source).
• Technical Questions (’874 Patent): A key factual dispute may be whether the Bell 505's flight control system performs the specific steps of claim 1, including calculating "aircraft configuration parameters" from physical data and using them in a feedback loop that specifically includes an "angular acceleration loop." The analysis will require evidence of the helicopter's control system architecture and whether it maps onto the patented method.

V. Key Claim Terms for Construction

’693 Patent (Claim 18): "without (1) using signals from a source external to the aerial vehicle, or (2) using signals reflected to the aerial vehicle"

Context and Importance

This negative limitation is central to defining the invention's self-contained nature. The viability of the infringement claim will depend heavily on whether any part of the Bell 505's takeoff monitoring process uses data from sources that fall within these two excluded categories.

Intrinsic Evidence for Interpretation

• Evidence for a Broader Interpretation: Plaintiff may argue that the specification’s focus is on avoiding reliance on external positioning systems like GPS, and that the term should be interpreted in that context. Language such as, "the switch may be made without requiring any signals from outside the aerial vehicle," could be framed as distinguishing the invention from systems dependent on external infrastructure for the core takeoff determination. (’693 Patent, col. 6:32-34).
• Evidence for a Narrower Interpretation: Defendant may argue for a plain meaning, where any signal originating externally (e.g., GPS timing signals) or any signal that is transmitted and reflected (e.g., from a radio altimeter) used in the takeoff determination would place the system outside the claim scope. The patent repeatedly highlights the advantage of not needing signals from "external devices, such as global positioning system (GPS) satellites." (’693 Patent, col. 12:51-54).

’874 Patent (Claim 1): "feedback control scheme that includes an angular acceleration loop with angular acceleration feedback"

Context and Importance

This term describes the core architectural novelty of the claimed control method. Practitioners may focus on this term because the dispute will likely turn on whether the accused flight control system has this specific feature, as opposed to a more conventional control scheme that may only implicitly account for acceleration.

Intrinsic Evidence for Interpretation

• Evidence for a Broader Interpretation: The specification describes the functional benefit: "the angular acceleration loop can act as direct control, response time may be short with strong disturbance resistance characteristics." (’874 Patent, col. 8:9-11). Plaintiff may argue that any system that directly measures and feeds back angular acceleration to achieve this stated purpose meets the limitation, regardless of its specific diagrammatic representation.
• Evidence for a Narrower Interpretation: The patent illustrates this concept with a specific block diagram showing a distinct "angular acceleration a_Err" being fed into a PI or PID controller. (’874 Patent, Fig. 6A, element 626). Defendant may argue that the claim requires this specific architecture—a dedicated loop for processing angular acceleration error—and not merely a system where acceleration is calculated as a derivative of a velocity signal within a different loop.

VI. Other Allegations

Indirect Infringement

The complaint does not allege any facts to support claims for either induced or contributory infringement. It pleads only direct infringement. (Compl. ¶11, ¶16).

Willful Infringement

The complaint does not contain a count for willful infringement or allege specific facts suggesting Defendant had pre-suit knowledge of the patents-in-suit. The prayer for relief includes a request for a finding of an exceptional case under 35 U.S.C. § 285, but the factual basis is not articulated in the complaint body. (Compl. p. 5).

VII. Analyst’s Conclusion: Key Questions for the Case

• A core issue will be one of technological applicability: Can claim limitations conceived and described in the context of unmanned aerial vehicles (UAVs)—such as a two-stage takeoff controller using only onboard sensors or an attitude controller based on pre-calculated physical parameters—be construed to cover the integrated and mature flight control systems of a modern, manned helicopter?
• A central evidentiary question will be one of architectural correspondence: Does the Bell 505’s flight control system, in its actual operation, implement the specific "angular acceleration loop" required by the ’874 patent, or does it achieve flight stability through a technically distinct method?
• For the ’693 patent, the case may turn on the scope of a negative limitation: Does the Bell 505’s takeoff process use any inputs, such as from a radio altimeter or GPS, that would qualify as "reflected signals" or "signals from a source external to the aerial vehicle," thereby placing its system outside the literal scope of the asserted claim?