SABCA is a leading Belgian aerospace company that has been in business for over 90 years. One of the company’s core businesses is the development of high-precision electromechanical systems for the aerospace market. Control of such systems is a key technology that has since long moved over from analog to digital for obvious reasons.
By the end of the 1990’s, SABCA developed a DSP called BRISC-11 (Bi floating-point unit Reduced Instruction Set Computer) that was dedicated to closed-loop motor control. The major ideas behind it were the following:
- The processor performs floating point operations in parallel and keeps all data in internal registers that are immediately available without external memory access. To be noted is that the number of registers that are needed for a control algorithm is relatively limited (typically 100).
- Processing is completely deterministic and is driven by an internal synchronisation mechanism that cannot be interrupted.
BRISC-11 was successfully deployed for various applications and was later on, under sponsorship of ESA via the GSTP-2 program, further transformed into HBRISC2 (radiation-Hardened BRISC). Qualified models of HBRISC2 were available by 2005.
HBRISC2 added the following features:
- It is possible to directly compile a control model, designed in Simulink, into executable software. The design and the implementation of the control model are intrinsically the same. No knowledge of HBRISC2 internal architecture is required for the generation of the executable software;
- The processor has circuitry on board for immediate interfacing with peripherals such as sensors and motor power electronics, and it is also capable to generate and exchange synchronization signals with the outside world.
- It is radiation-hardened. It is capable to detect and correct SEU events as a result of heavy ion impacts. The detection mechanism is transparent for the executing software.
HBRISC2 was successfully deployed in the field, with the Thrust Vector Control systems of the VEGA launcher being the most notorious example.
VEGA lifting off under HBRISC2 control
The BRISC-11 and HBRISC2 technology has in the mean time been deployed in the following areas:
- Launcher Thrust Vector Control (VEGA).
- Spacecraft re-entry flap control (IXV).
- Fine pointing mechanisms (TIP/TILT).
- Actuator for civil aviation Airbus A320 (EHA).
- Military aviation (pointing device).
- Strategic defense.
It has in the mean time also been selected for an advanced attitude and orbit control system (ELSA).
ESA is executing the ASSP (Application Specific Standard Product) program, aiming at providing a number of dedicated processors as a standard commercial-of-the-shelf product to the European Space industry. With the further development of HBRISC2 into the Control Loop Processor, the Agency is acknowledging the fact that this technology certainly merits its place on the market.