Systems Control and Flight Dynamics
SACSO,
Active Suspension for Wind Tunnel Tests
Creation of the Demonstrator
Models
To debug the control mechanisms, we used a skid (figure 8) fitted with sensors (gyros and accelerometers) and on-board electronics. The carbon fiber sting to which the nine cables are attached was linked to the skid by a false balance of the same mass and stiffness as the balance used with the real model (figure 9). These models were made in Lille by the "Model Design and Production Department" (M. Deschamps).
Figures 8 and 9 : the instrumented pad and the real model
External Bearing Structure
The plans for the mechanical part were drawn up by A. Dillinger (Toulouse center). The mechanical engineering was partly sub-contracted and partly done by A. Dejean and B. Fasano (Toulouse center).
The external bearing structure is made of eight mechanically welded posts supporting the nine cable tension control motors. The cables are wound on a drum (figure 10) and pass over guide pulleys fitted with a damping system and a tension measuring system (figure 11).
Figures 10 and 11: motor, drum, pulleys, damper and tension measuring device.
The model is fixed in its reference position by an initial position arm (figure 12). Figure 13 shows the pad suspended by the nine cables in the DCSD's laboratory in Toulouse.
Figure 12: initial position arm
Figure 13 : pad suspended by the cables
Electronics
These were designed and made by P. Carton. The measurements from the three gyros, nine accelerometers, six balance components and three potentiometers associated with the control surfaces are conditioned, processed and digitized locally, on board the model, to limit interference better. The commands intended for the three control surface servos are amplified on board. All these signals are managed, multiplexed and transmitted by a coaxial cable that supplies power to the model and transfers data in both directions. The on-board electronics (figure 14) consist of nine cards connected by a bus. At the other end of the service cable they are complemented by an interface card (figure 15) that controls the data transmission (according to the serial RS422 standard at 1.5 Mbauds) and power transmission.
To improve the model positioning precision, which is important for control but also for the accuracy of the trajectory restitution used when identifying the coefficients of flight mechanics models, we hybridize the data from the accelerometers, gyros, cable lengths and from an optical location system using two cameras aimed at reflective markers glued on the model (J.C. Barral).
Figures 14 and 15: on-board electronics and interface card
Control and Operating Programs
The control and operating programs were designed by P. Carton, C. Lambert and M. Llibre. They are run on two separate workstations for controlling the system and conducting and processing the tests (figure 16).
Figure 16 : conducting and processing the tests
