SBIR-STTR Award

A low cost ½ U CubeSat Compact Inertial Reference Unit (CIRU) is proposed comprising of a patent-pending, digitally-controlled, low power, ASIC-based, piezoelectrically-transduced, Coriolis Vibratory Gyroscope (CVG). Demonstrated at TRL 4 in a lab environment, it has very low Angle White Noise (AWN), Angle Random Walk (ARW) and Bias Stability enabling Attitude Determination with <0.1 arc second pointing and arc second level control. The small size is enabled by our Radiation Hard By Design (RHBD) commercial CMOS ASIC. This results in 4X smaller size, 4X lower weight, and 20X lower power vs. state of the art IRUs, (e.g. MIMU, NGC SIRU). The same ASIC also interfaces accelerometers to complete an IMU for relative or absolute navigation. The macroscale PZT metal cylinder resonator's very low mechanical thermal noise, digitally controlled with our low-noise ASIC and patent-pending IWAG electronics overcomes the limited range and noise of current analog rate demodulation and digitization. Digital vs. analog control allows low-cost, parameter-based adaptation for more applications and modes of operation such as Whole Angle for high rates, IWAG self-precession for asymmetry detection and switched drive axis operation for bias self-calibration. Eliminating bulky discrete electronics yields a low-cost, lower power, compact CVG with lower parasitic impedance. Our ASIC is collocated and thermal-mechanically isolated with the resonator for precise temperature compensation/control. Gyros are mechanically tuned, balanced, and vibration isolated. The IMU also has vibration isolation for external source suppression. The Phase 1 project will extend bias compensation and thermal mechanical packaging design to TRL 5 performance in a relevant environment. For Phase 2, we will build the newly designed mechanical package and integrate full RHBD ASIC electronics and optional accelerometers into a compact IRU/IMU assembly with the result being a TRL 6 CIRU/CIMU performance demonstration. Potential NASA Applications The CIRU enables spacecraft from CubeSat to mid-size to have the same sub-arc-second knowledge and control as large spacecraft at a fraction of the cost. Smaller size and lighter weight also benefits larger satellites and interplanetary missions by lowering cost and increasing payload. Telescope and other pointing payloads can also benefit from smaller mass IRU sensors. Entry, descent, and landing missions can also benefit from the lower cost, light weight, and high performance IMU. Potential Non-NASA Applications Commercial low earth orbit, geosynchronous, and constellations of spacecraft can benefit from the CIRU smaller size, light weight, and performance at lower cost. Payload pointing, autonomous spacecraft safing, and other space applications are envisioned. Terrestrial applications include aircraft attitude sensing, autonomous vehicles, north finding, down-hole navigation, and other pointing applications. The large quantity potential of terrestrial uses may further reduce cost for all users.

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). Potential NASA Applications (Limit 1500 characters, approximately 150 words) 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). Potential Non-NASA Applications (Limit 1500 characters, approximately 150 words) 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.