TRAS — Two-Rotor Aerodynamical System
The Two-Rotor Aerodynamical System (TRAS) is built for control experiments. It behaves loosely like a helicopter.
The rig is a beam pivoted on a base so it can rotate freely in the horizontal and vertical planes. At each end of the beam sits a rotor (one main, one tail) driven by a DC motor. A counterbalance arm with a weight sits at the pivot.
The beam state has four process variables: horizontal angle, vertical angle (both read by encoders at the pivot), and the two corresponding angular velocities. Two more state variables are the rotor angular velocities, read by speed sensors coupled to the DC motors.
In a real helicopter the aerodynamic force is set by changing the angle of attack. On TRAS the angle of attack is fixed, and the aerodynamic force is controlled by varying the rotor speed.
Specifications
| Dimensions | 50 × 50 × 60 cm |
|---|---|
| Structure | Rigid frame holding the pivoted beam |
| Motors | 12 V DC, PWM controlled |
| Sensors | Angular position, angular velocity, angular acceleration |
| Control software | Scilab-based code |
Learning outcomes
- System modelling: physical modelling, linear vs nonlinear systems, solid mechanics, aerodynamics, linearisation, model validation, system identification.
- System control: stability analysis, classical controllers (on/off, PID), more advanced controllers, fault diagnosis and fault-tolerant strategies.