Security and defence technology: control experts are scarce

Flight controllers for safety-critical vehicles must hold everywhere

What happens. The controller works in the simulator and in calm test flights. Then the vehicle meets gusts, a different payload, a heavier battery or a damaged actuator, and the behaviour changes. Each new case brings another round of gain changes and another flight campaign.

What it costs. Flight days, test hardware and time to qualification. In safety-critical programmes every change to the control law also means new evidence, so late changes are expensive.

Why the usual fix fails. More gain schedules and more margin cover the cases already seen, not the next one. A controller tuned at a few points tells little about the space in between, and reviewers ask exactly about that space.

How a fixed-price remote diagnosis checks it. From your models, control structure and flight or simulation logs I check where the controller loses margin, which uncertainties matter most and whether a model-based design would cover the envelope with fewer special cases. The fixed-price remote diagnosis says what it would take to show robustness, not just hope for it.

Background: Predictive control for aerial vehicles

Lead roles for vehicle dynamics and control stay open for months

What happens. The programme needs someone who owns the dynamics model, the control laws and the link to flight test. The post is advertised for months; meanwhile the few people who know the system carry everything.

What it costs. Milestones slip, design reviews are postponed, and decisions on the control architecture are taken late or by whoever is free.

Why the usual fix fails. Recruiting for this profile takes long, and security clearance or relocation makes it slower. Spreading the work over generalists keeps the lights on but leaves the hard questions open.

How a fixed-price remote diagnosis checks it. I review the state of models, control laws and test plans and name the open technical questions in order of risk. The fixed-price remote diagnosis gives your team a clear list of what needs a specialist now and what can wait, with freelance support or temporary agency work as options for the gap.

Actuator control and test benches wait for a specialist

What happens. Electromechanical or hydraulic actuators need position and force control that is fast, stable and repeatable, and test benches that prove it. The role behind this stays vacant, and bench tests are run with old settings.

What it costs. Tests that have to be repeated, actuators that are qualified late, and a bench that shows symptoms without explaining them.

Why the usual fix fails. Retuning the loop on the bench until it looks good fixes one load case. Friction, backlash and temperature change the behaviour, and the next load case brings the problem back.

How a fixed-price remote diagnosis checks it. From bench logs, actuator data and the current control structure I identify where friction, backlash or saturation limit the loop and whether a model-based controller and an observer would hold across load cases. The fixed-price remote diagnosis shows what a robust actuator loop and a meaningful bench test would need.

Fast, agile aircraft push flight control to the edge of the envelope

What happens. Small, fast vehicles with thrust vectoring or strong control surfaces fly close to the limits of their actuators. Manoeuvres that matter most are the ones where the linear models no longer hold.

What it costs. Departures from controlled flight, lost airframes in testing, and a flight envelope that is opened slowly and cautiously.

Why the usual fix fails. Linear controllers designed at trim points and blended together work in the middle of the envelope. At the edges, where actuators saturate and couplings grow, the blending is guesswork.

How a fixed-price remote diagnosis checks it. From your aerodynamic and actuator models and flight logs I check where saturation and coupling decide the behaviour and whether a controller that plans within actuator limits would hold there. At SkySails I developed the flight automation of large towing kites, a fast vehicle flown at its limits in rough weather. The fixed-price remote diagnosis says which approach fits your vehicle and what it would take.

Flight data is stored but does not explain the behaviour

What happens. Every flight produces large amounts of logs. They are checked for alarms and then archived. Why the vehicle oscillated in one manoeuvre or drifted in another stays a matter of opinion.

What it costs. The same questions are raised after every campaign, and model and controller are improved by trial instead of by evidence.

Why the usual fix fails. More sensors and more plots give more data, not a model. Without identifying the dynamics from the data, the simulator and the real vehicle drift apart.

How a fixed-price remote diagnosis checks it. From a few representative flights I check which model parameters can be identified, how well the current simulation matches and where the gaps are. The fixed-price remote diagnosis shows how flight data can update the model routinely, so that the next design step rests on measured dynamics.

The way from flight dynamics model to first flight test is long

What happens. The dynamics model, the controller, the state estimator and the test plan are built by different people at different times. When the first flight approaches, the pieces do not fit, and the date moves.

What it costs. Months between a working simulation and a working vehicle, and a test team waiting for software.

Why the usual fix fails. Adding people late to a chain that was never designed as one adds interfaces, not speed. Each piece is tested on its own, the gaps between them are not.

How a fixed-price remote diagnosis checks it. I review model, controller, estimator and test plan as one chain and name where assumptions differ and which tests would catch it before flight. The fixed-price remote diagnosis gives you an ordered list of what to close before the first flight.

Sensors on moving platforms must stay on target

What happens. A camera, antenna or optical sensor sits on a vehicle, ship or aircraft that moves, vibrates and turns. The line of sight has to stay steady and follow a target that moves too, while the gimbal has friction, end stops and delays.

What it costs. Blurred images, lost tracks and a system that meets its specification only in calm conditions.

Why the usual fix fails. Stiffer mounts and faster motors help up to a point. A controller that only reacts to the error is always a step behind the platform motion and the target.

How a fixed-price remote diagnosis checks it. From gimbal and inertial data I check how much of the error comes from platform motion, friction or delay, and whether estimating the motion and controlling ahead of it would keep the line of sight steadier. The fixed-price remote diagnosis shows what a stabilisation with estimation and predictive control would need.

Background: Computing unmeasured states for control