REG NASA-LLIS-1608--2005 Lessons Learned - Fin Actuator System Guard bands Design in Critical Timing Circuits.pdf

1、Lessons Learned Entry: 1608Lesson Info:a71 Lesson Number: 1608a71 Lesson Date: 2005-06-02a71 Submitting Organization: DFRCa71 Authored by: Jonathan BrownSubject: Fin Actuator System/Guard bands Design in Critical Timing Circuits Abstract: Variations in component production lots; Low-inductance groun

2、d and power planes/paths within (sub)systems are essential for proper operation. Following the recommendations from the X43A Flight 1 MIB, the Pegasus actuator system was redesigned to accommodate the need for greater hinge torque. The analog-based legacy actuator system was redesigned for digital d

3、rive of the power output stage to the actuators, an additional actuator was incorporated to provide the necessary torque including margins, and the power supply was increased to provide the required 80+ amps, instead of the previous 40 amp capability. Multiple failures during qualification testing,

4、and the subsequent technical investigations, proved the lack of understanding between the ideal circuit operation and the impact of system implementation. Low-inductance ground and power planes/paths within (sub)systems are essential for proper operation. Description of Driving Event: Following the

5、recommendations from the X43A Flight 1 MIB, the Pegasus actuator system was redesigned to accommodate the need for greater hinge torque. The analog-based legacy actuator system was redesigned for digital drive of the power output stage to the actuators, an additional actuator was incorporated to pro

6、vide the necessary torque including margins, and the power supply was increased to provide the required 80+ amps, instead of the previous 40 amp capability. Multiple failures during qualification testing, and the subsequent technical investigations, proved the lack of understanding between the ideal

7、 circuit operation and the impact of system implementation. Lesson(s) Learned: Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Guard-bands, and other critical timing periods, of the output switching circuits must accommodate the various parasitic imp

8、edances caused by the printed circuit board, and variations in component parameters due to different manufacturing production lots. Recommendation(s): The design and determination of adequate guard-bands, or “dead” bands in critical timing circuits must account for variations in component production

9、 lots, temperature stability, and circuit board construction and trace layout. Dont assume that a circuit will perform ideally in the real world. Evidence of Recurrence Control Effectiveness: N/ADocuments Related to Lesson: N/AMission Directorate(s): a71 Exploration Systemsa71 Aeronautics Researcha7

10、1 Space OperationsAdditional Key Phrase(s): a71 Accident Investigationa71 Flight Equipmenta71 Hardwarea71 Safety & Mission Assurancea71 Test & VerificationAdditional Info: Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Approval Info: a71 Approval Date: 2006-04-18a71 Approval Name: dkruhma71 Approval Organization: HQProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-