Abstract: The technology relates to aerial vehicle launch and land site selection. A method for determining beneficial launch and land sites may include computing a launch delay for a desired time period for each cell in a grid map with a target zone and an existing site located on the grid map, computing a flight time to target for a delay time that accounts for a launch delay, computing a launch time to target based on the launch delay and the flight time to target, receiving geographical restrictions data, and determining an efficiency benefit over the existing site based on the geographical restrictions data and a comparison of the launch time to target of each cell with the launch time to target of the existing site for the desired time period.

Abstract: The technology relates to real-time state estimation and sensor management. A method for real-time state estimation and sensor management may include receiving telemetry from a fleet of aerial vehicles, storing telemetry in a telemetry buffer, generating a real-time state estimate of an aerial vehicle in the fleet using a group of estimators, the estimators being of one or more types, such as a sensor management estimator, a bias and noise management estimator, and a physical modeling estimator, and providing the real-time state estimate of the aerial vehicle to a job in a fleet management system.

Abstract: The technology relates to a storm avoidance system for a lighter than air (LTA) vehicle. The storm avoidance system can include a mechanical actuation system, a balloon envelope comprising a ballonet, and a valve configured to allow air to escape the ballonet. When the storm avoidance system is engaged, the mechanical actuation system can open the valve, thereby allowing air to escape the ballonet and causing the LTA vehicle to ascend to an altitude above a storm altitude. In some cases, a state of the LTA vehicle can be detected, and the storm avoidance system can be engaged in response to the detected state. In some cases, a proximity of the LTA to a low population area can be determined, and the LTA vehicle can be caused to land in the low population area.

Abstract: The technology relates to techniques for an aquatic energy discharge system for an energy storage system of an aircraft. An aquatic energy discharge system can include an energy storage system, a pair of electrodes coupled to the energy storage system, and a water detection system configured to detect a water landing. The electrodes can be configured to submerge in a body of water after the aircraft has landed in the body of water, and cause a hydrolysis reaction that drains energy from the energy storage system in response to the water detection system detecting the water landing. A method of discharging an energy storage system of an aircraft can include detecting that an aircraft (or portion thereof) has landed in a body of water, and discharging the energy storage system by powering a hydrolysis reaction using a pair of electrodes.

Abstract: The technology relates to techniques for redundant power distribution and monitoring for lighter than air (LTA) vehicles. A power distribution and monitoring system for an LTA vehicle, can include two or more redundant controllers coupled to a multiplexer in a crossbar architecture. Each controller can control the multiplexer and inhibit the other controller in the case of a failure of the other controller. Each controller can control a power switch to direct power from a power source to an electronic component, and can monitor the power source. In some cases, a first controller receives a signal indicting a failure in a second controller, and the first controller inhibits the second controller and directs power from the power source to the electronic component.

Abstract: The technology relates to health and lifetime estimation for a lighter-than-air vehicle. A method for vehicle health and lifetime estimation may include receiving flight data inputs associated with a vehicle, determining a gas temperature based on the flight data inputs, estimating a gas amount remaining in a balloon envelope of the vehicle, estimating a gas leak rate based on the gas amount, estimating a component lifetime representing an estimated lifetime of a component of the vehicle, and determining a remaining lifetime output based on one or both of the gas leak rate or the component lifetime, the remaining lifetime output indicating a remaining lifetime estimate for the vehicle. The method also may include simulating a terminal event and causing the vehicle to take an action based on the remaining lifetime estimate.

Abstract: The technology relates to health and lifetime estimation for a lighter-than-air (LTA) vehicle. An LTA vehicle health and lifetime estimation system may include a processor and a memory storing instructions executable by the processor to cause the processor to implement an estimation service for determining a remaining lifetime output and a simulator for simulating a terminal event based on the remaining lifetime output. The estimation service may include a thermal model configured to determine a gas temperature, a gas and air estimator configured to estimate a gas amount and an air amount remaining in a balloon of the LTA vehicle, a leak rate estimator configured to estimate a leak rate, and a zero pressure estimator configured to determine the remaining lifetime output based on the leak rate. The system also may include an air flow estimator configured to determine an air mass flow rate based on the air amount.

Abstract: The technology relates to health and lifetime estimation for a lighter-than-air vehicle. A method for vehicle health and lifetime estimation may include receiving flight data inputs associated with a vehicle, determining a gas temperature based on the flight data inputs, estimating a gas amount remaining in a balloon envelope of the vehicle, estimating a gas leak rate based on the gas amount, and determining a remaining lifetime output based on the gas leak rate, the remaining lifetime output indicating a remaining lifetime estimate for the vehicle. The method also may include simulating a terminal event and causing the vehicle to take an action based on the remaining lifetime estimate.

Abstract: The technology relates to managing nighttime power for solar-powered vehicles. A system may include a sunrise estimator for estimating a time until a next sunrise, a battery state estimator for estimating a battery state, a critical battery estimator for determining a battery threshold, below which subsystems may be powered off, and an alert monitor to determine, and communicate to the solar-powered vehicle, a charge threshold and a restart charge threshold. A method may include operating a vehicle in an operational power mode, estimating a time until a next sunrise, estimating a battery state, determining a preservation battery threshold based on the estimated time until the next sunrise and the estimated battery state, determining a minimum charge threshold based on the preservation battery threshold, monitoring a battery charge level of the vehicle throughout the night, and if the battery charge level drops below the minimum charge threshold, implementing a preservation power mode.

Abstract: The technology relates to techniques for lighter than air vehicle redundant pressure sensor calibration. A lighter than air (LTA) vehicle can include a redundant pressure sensor calibration system, including a high precision pressure sensor onboard the LTA vehicle and two or more additional pressure sensors onboard the LTA vehicle, where the two or more additional pressure sensors are each redundant with the high precision pressure sensor. The two or more additional pressure sensors can be calibrated based on pressure measurements from the high precision pressure sensor and the two or more additional pressure sensors at two or more altitudes, wherein the high precision pressure sensor is calibrated before a flight of the LTA vehicle.

Abstract: Aspects of the disclosure relate to an aerial vehicle. The aerial vehicle may include an envelope having a plurality of tendons and formed from a first plurality of gores. The aerial vehicle may also include one or more ballonets arranged within the envelope. An outer membrane may be arranged around at least part of the envelope and formed from a second plurality of gores. The outer membrane may include at least one panel attached at one side to the outer membrane between a pair of the second plurality of gores and attached at an opposite side to the envelope. The outer membrane may be arranged to improve aerodynamics of the envelope when the aerial vehicle is in flight.

Abstract: The technology relates to techniques for a dynamic threshold for a pressure or altitude trigger for a lighter than air vehicle. A method of operating a system of an LTA vehicle can include setting a dynamic threshold of a system to a first value based on one or both of a first measured pressure altitude and a first measured absolute pressure, receiving an indication that the LTA vehicle has increased its altitude, and setting the dynamic threshold of the system to a second value based on one or both of a second measured pressure altitude and a second measured absolute pressure. A flight termination system for an LTA vehicle can include mechanical actuation systems configured to be triggered based on dynamic thresholds. A method of terminating the flight of an LTA vehicle can include triggering the mechanical actuation systems based on dynamic thresholds.

Abstract: The technology provides a launch rig structure capable of filling a very large balloon envelope while the balloon is arranged vertically. The filled balloon is capable of staying aloft in the stratosphere with its payload for months or longer. The launch rig structure is configured to rotate up to 360° in response to current wind conditions. It includes an integrated lifting boom and gas handling system to fill the envelope. A payload release assembly is configured to couple with a rigid connection member of the balloon, enabling the envelope to be filled while in a vertical orientation. The payload release assembly is part of a launch cart that is positioned within the interior space of the launch rig. A gripper assembly engages with the rigid connection member. Once the envelope is filled, the gripper assembly disengages from the connection member so that the balloon floats away from the launch rig.

Abstract: The technology described here relates to LTA vehicle launch configuration and in-flight optimization. A method for automated ballast dropping by an LTA vehicle in flight may include receiving, by an in-flight ballast model, an initial lift gas fill amount and an initial ballast amount, generating altitude ranges based on a remaining lift gas amount and a current system mass of the LTA vehicle to determine whether the remaining lift gas amount is within a ballast drop lift gas range, determining whether a convergence criterion for the remaining lift gas amount is met, the convergence criterion indicating a convergence between a remaining lift gas estimate and a remaining lift gas model, determining that dropping a ballast increment will not decrease an overall ballast amount below a target ballast amount corresponding to the remaining lift gas amount, and causing the LTA vehicle to drop the ballast increment.

Abstract: The technology described here relates to LTA vehicle launch configuration and in-flight optimization. A method for optimizing for an objective of an LTA vehicle launch may include receiving a desired objective, receiving known parameters of the LTA vehicle, including a pressure threshold, performing probabilistic calculations based on the desired objective and the known parameters, the probabilistic calculations configured to model setup parameters and to output probabilities for the setup parameters, the output indicating probabilities that a simulated vehicles would achieve the desired objective. The method also includes selecting a setup parameter value based on a high probability indicated in the output. Also described is an LTA vehicle launch configuration system implementing a thermal model, a physics model, and a fill and ballast tool, including an altitude range estimator, a gas-air estimator, and a pre-flight ballast model.

Abstract: The technology relates to a scalable power system. A scalable power system includes battery modules connected in parallel, a network of diodes, a battery management system that may be localized or centralized, a localized battery management system configured to control an individual battery module, a centralized battery management system configured to control all of the battery modules in the scalable power system. In a system with localized battery control, a parallelizing circuit board may connect battery modules to a system bus in parallel. The battery modules can be charged and discharged by the system bus. A method of adding a battery module to a scalable power system includes discharging a highest-charged battery module, then discharging a next highest-charged battery module until there are no remaining charged battery modules, then adding an additional battery module in parallel, and charging the connected battery modules in parallel.

Abstract: Aspects of the technology employ real-time monitoring and feedback for a printed circuit board fabrication system. An x-ray simulator can be used to aid in understanding metallurgical phase transformations in real time to ensure acceptable and reliable solder connections. This includes real-time data gathering and evaluation of solder-related printed circuit board data, including peak temperature, time above liquidus (TAL), ramp up and ramp down rates. Such information is used to identify the exact melting point and view specific soldering behavior in order to achieve an optimized soldering solution. This approach can provide effective solder joint analysis, which can reduce the likelihood of failure of a circuit board intended to operate in extreme environments for an extended period of time, such as the stratosphere.

Abstract: The technology relates to simulating a dynamic hybrid network. A method for simulating a dynamic hybrid network includes modeling a transmission supply of a mesh network of moving stations on aerial vehicles in flight at each time step in a time series, modeling capacity demand as a function of user distribution data and user behavior data, and computing an aggregate network metric for the dynamic hybrid network including throughput. A method for optimizing throughput of a dynamic hybrid network includes modeling a dynamic hybrid network, including a transmission supply of a mesh network of moving stations, modeling capacity demand as a function of user distribution data and user behavior data, and computing an aggregate network metric; then providing feedback to a controller and causing a change to a station in the network to increase throughput.

Abstract: The technology relates to techniques for an electromagnetic inertial switch. An electromagnetic inertial switch can include an electrically conductive and magnetic mass located within a cavity, where portions of the cavity are electrically conductive and are electrically coupled to terminals of the electromagnetic inertial switch. A first magnetic field can be configured to apply a first force on the mass to attract the mass towards a first location, and a second magnetic field can be configured to apply a second force on the mass to attract the mass towards a second location. The electromagnetic inertial switch can be in a first electrical state when the mass is in the first location, and in response to an acceleration event greater than a threshold acceleration, the mass can move to the second location, thereby changing the electromagnetic inertial switch to a second electrical state.

Abstract: An antenna for wireless communication includes a spherical reflector and one or more feeds. The spherical reflector includes an inner portion made of material that reflects radiofrequency (RF) beams, and an outer portion positioned on an edge of the inner portion, the outer portion being made of metamaterials that can be controlled to be reflective of or transparent to RF beams. The one or more feeds are configured to form one or more RF beams reflected off the spherical reflector. In some implementations, the antenna includes one or more processors configured to form one or more RF beams using the one or more feeds, and control at least a part of the outer portion of the spherical reflector to reflect an RF beam of the one or more RF beams or be transparent to the RF beam based on the one or more RF beam.