1、Lessons Learned Entry: 1617Lesson Info:a71 Lesson Number: 1617a71 Lesson Date: 2005-06-02a71 Submitting Organization: DFRCa71 Authored by: Jonathan BrownSubject: Fin Actuator System (FAS)/High Current Transients in Digital Circuits Abstract: The Pegasus actuator system was redesigned to accommodate
2、the need for greater hinge torque. The decision to re-utilize, as much as possible, of the existing legacy actuator drive system is not necessarily a poor choice. However, one must understand that significantly increasing the performance requirements will stress all components in the (sub)system. In
3、stantaneous currents associated with digital switching of power components can far exceed the steady-state values. When considering undertaking a significant redesign of a system or sub-system, extreme care must be taken to ensure that reutilization of existing components, i.e. motherboards, power s
4、upplies, cabling, etc., doesnt pose a greater risk than the initial cost and schedule impact of a complete (sub)system redesign.Description of Driving Event: Following the recommendations from the X43A Flight 1 MIB, the Pegasus actuator system was redesigned to accommodate the need for greater hinge
5、 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 provide the necessary torque including margins, and the power supply was increased to provide the required 80+ amps, instead of the
6、 previous 40 amp capability. The decision to re-utilize, as much as possible, of the existing legacy actuator drive system is not necessarily a poor choice. However, one must understand that significantly increasing the performance requirements will stress all components in the (sub)system. The effe
7、cts of the “passive” components of the (sub)system - motherboards, printed circuit boards, cabling - are often under appreciated. Instantaneous demands of digital circuits can be many times their steady-state values, and this misunderstanding can lead to design decisions that can have significant im
8、pact upon project schedule/mission success later in the project. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Lesson(s) Learned: Instantaneous currents associated with digital switching of power components can far exceed the steady-state values. T
9、hese high current transients strain the ground and power planes, adequate for lower slew rate analog systems, but leading to increased noise levels and deleterious ground bounce in digital circuits. Recommendation(s): When considering undertaking a significant redesign of a system or sub-system, ext
10、reme care must be taken to ensure that reutilization of existing components, i.e. motherboards, power supplies, cabling, etc., doesnt pose a greater risk than the initial cost and schedule impact of a complete (sub)system redesign. Evidence of Recurrence Control Effectiveness: N/ADocuments Related t
11、o Lesson: N/AMission Directorate(s): a71 Exploration Systemsa71 Aeronautics Researcha71 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: 2008-06-27a71 Approval Name: mbella71 Approval Organization: HQProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
