Phase I demonstrated key technologies and development work for the Rad Hard ½ U Compact Precision Inertial Measurement Unit (CIMU). Optimized gyro bias compensation including switched drive achieving navigation grade performance using a commercially available TRL9 piezo-transduced Coriolis Vibratory Gyroscope (CVG) sensor integrated with IW’s digital IWAG control algorithm demonstrated rate noise necessary to attain Attitude Determination with <0.1 arc second pointing and arc second level control. IW further demonstrated navigation grade north-finding capabilities with a representative IMU block mounted CVG. Temperature testing and optimization of thermal bias compensation was also demonstrated.
IW successfully replaced the bulky discrete analog CVG controller electronics with IW’s digital-based low noise ASIC using IW’s patent pending embedded IWAG control algorithm. Full digital closed loop Rate Gyro operation with excellent bias stability was demonstrated. Efficacy of IW’s Radiation Hard by Design (RHBD) method in the ASIC’s CMOS process was demonstrated with successful Mega-Rad level Co60 chamber testing of IW’s sensor analog front-end (AFE). Significant analysis and simulation of Single Event Effects and efficacy of planned SEE hardening for the full RHBD ASIC in planetary orbit and interplanetary radiation environments was completed.
A full mechanical design and FEA analysis and system design of the IMU was completed with integrated 3-axis ASIC-based CVG’s, COTS MEMS accelerometers, interface electronics, and mechanical assembly. Mechanical modes and thermal characteristics were verified, with more work planned for vibration isolation in Phase II.
Phase II will design and fabricate a complete RHBD version of the CVG ASIC control. We shall then integrate it to resonators and build and test the complete CIMU, achieving significantly smaller size, lighter weight, and much lower power than state-of-the-art space IMUs (e.g. MIMU, SIRU).
This revolutionary navigation-grade RadHard IMU technology provides low cost, flexible, and resilient capabilities for NASA's strategic goal of autonomy with assured navigation. It enables navigation & north finding functions for robotic missions, in-situ resource prospecting & surveying; multi-mode operation for spacecraft interplanetary navigation, ascent, entry, descent, & landing; and newly realized pointing stability for next generation low cost satellites carrying out complex coordinated missions (distributed SAR & optical imaging).
This robust navigation-grade IMU significantly lowers cost for assured navigation enabling wide adoption in the emerging autonomous vehicle market, missile applications, commercial space communications, and down-hole navigation capabilities in the energy/mining sector. The re-configurable ASIC controller enables new inertial sensors and ever-improving C-SWaP, ensuring a long product life cycle.