Braking system is an important part of aircraft, which has strong time-varying and non-linear characteristics. The main function is to realize the safe, reliable, smooth and efficient braking under the condition of landing and taxiing or RTO (Reject Take Off) , and to ensure certain directional maneuverability of the aircraft. Generally include normal braking system (including automatic braking) , backup braking system and emergency/stop braking system, etc. . Common Brake Systems include wheel speed sensor, brake command sensor, (automatic brake selector) , anti-skid Brake Control Unit, electro-hydraulic Servo Valve, hydraulic safety, shuttle Valve SHV, pressure sensor PT, wheel and brake device.

The anti-skid brake control unit outputs the corresponding brake pressure according to the request obtained by the brake pedal sensor or the automatic brake selector from the pilot’s brake command signal, and at the same time monitors the wheel speed signal and calculates the aircraft reference speed, according to the change of the wheel speed signal, the wheel skidding state is judged, the anti-skidding signal is calculated, and the output of brake pressure is adjusted, so as to release the wheel lock-up and restore the normal rolling state. Therefore, the safe, stable and efficient braking of aircraft is realized. Aircraft Braking relies on the friction provided by the tires and the ground when braking (also known as the binding force) , which converts the Kinetic Energy of the aircraft into the heat energy of the braking devices (brake discs) and consumes it, while also preventing excessive wear or “Blowout”of the tires, to achieve the safety of aircraft braking. The friction varies non-linearly with the tire load, the slip ratio and the runway state.

The hardware-in-the-loop simulation test platform designed and developed by SSD technology can satisfy both the digital simulation of the brake system and the hardware-in-the-loop simulation. And a comprehensive simulation of aircraft landing conditions (multi-wheel, single theory, symmetric, asymmetric, variable load, cross-wind, dry, wet, water, snow, etc.) under the aircraft braking situation, and with the following test functions:

1) the simulation and verification of the input-output relationship of a single product;

2) the Simulation and verification of the structural principle and design parameters of a single product (except for electronic products, the electrical parts of mechanical and electrical products are simulated by mathematical models or control modules, and the mechanical parts of mechanical and electrical products and hydraulic products are built by using simulation software module library according to the actual structure of the products) ;

3) Simulation and verification of Control Law Design of Brake Control Unit

4) Simulation and verification of function and performance of hydraulic and Electric Brake System (including digital and semi-physical Simulation) ;

5) failure of system and accessory products-safety simulation verification;

6) data recording, storage, processing system and real-time scene display;

7) capable of state simulation with two (or six) degrees of freedom (expandable option) ;

8) ability to simulate driver control.

The simulation test-bed system is used to simulate the actual working condition of the aircraft anti-skid braking system, real-time software simulation of aircraft motion and dynamic process, runway condition, landing gear mechanical characteristic and brake device pressure-moment characteristic is realized. Take the relevant accessories of the brake as the object, the rest part can be either hardware or software, and carry on the comprehensive simulation test of the large system. The hardware-in-the-loop simulation test of aircraft braking system realizes the simulation of takeoff and landing in various environments, which provides theoretical and experimental basis for product design, improvement and parameter optimization design. The hardware-in-the-loop Simulation test-bed of the brake system is composed of the physical part of the system, the measurement and control part, the simulation and control part and the cockpit simulation part.

Physical Part:

This part includes: Brake Control Unit, hydraulic/all-electric simulation system, visual part, etc. 

The hydraulic simulation part mainly simulates the relevant parts of the aircraft brake system which uses the traditional hydraulic pressure as the control power

All-electric simulation system for the new aircraft design, including all-electric actuator, feedback sensors, brakes, and so on.

Measurement and control:

It is the core part of the test-bed, responsible for the collection, processing, operation, reality, model establishment, solution, control, correction and so on.

Simulation control part:

It is mainly composed of simulation computer and control software. Responsible for aircraft brake system modeling, software real-time simulation and debugging. And can be separated from the real part of the system for digital simulation.

COCKPIT SIMULATION:

Brake control part, monitor and display part, brake control part.

The brake control part simulates the pilot’s brake control part, which changes the pilot’s pedal brake into the corresponding hydraulic pressure relief type control pressure, or the corresponding proportional electric control signal.

The Monitor display part is to monitor the status of each part of the system, and the image is displayed in front of the audience.

The brake control part mainly simulates the brake control and the hydraulic system remote control in the cockpit

Category: Electronic System Simulation