Miniaturized, High-accuracy, Radiation-hardened Rotary Angle Sensors

Navy SBIR 23.2 - Topic N232-114
SSP - Strategic Systems Programs
Pre-release 4/19/23   Opens to accept proposals 5/17/23   Closes 6/14/23 12:00pm ET    [ View Q&A ]

N232-114 TITLE: Miniaturized, High-accuracy, Radiation-hardened Rotary Angle Sensors

OUSD (R&E) CRITICAL TECHNOLOGY AREA(S): Microelectronics;Nuclear;Space Technology

The technology within this topic is restricted under the International Traffic in Arms Regulation (ITAR), 22 CFR Parts 120-130, which controls the export and import of defense-related material and services, including export of sensitive technical data, or the Export Administration Regulation (EAR), 15 CFR Parts 730-774, which controls dual use items. Offerors must disclose any proposed use of foreign nationals (FNs), their country(ies) of origin, the type of visa or work permit possessed, and the statement of work (SOW) tasks intended for accomplishment by the FN(s) in accordance with the Announcement. Offerors are advised foreign nationals proposed to perform on this topic may be restricted due to the technical data under US Export Control Laws.

OBJECTIVE: Develop miniaturized rotary angle sensors (e.g. resolvers or encoders) of high accuracy that are radiation hardened and capable of performing in space flight in a contested environment.

DESCRIPTION: Requirements driving the reduction of size of the next-generation, guidance systems dictate the need for size-reduction of all componentry without a relaxation of performance requirements. These competing concerns drive the need for innovation in the componentry used throughout the system.

One component technology that is of chief interest is rotary angle sensor technology; this component measures the angular position and rotational speed and direction of a rotating member. The technology must be precise, accurate, and stable over a long product lifetime, capable of surviving shock, vibration, and radiation characteristic of space flight through a contested environment, as well as small, lightweight, and low in power dissipation.

There are a variety of technology approaches that may prove viable for improving currently employed capabilities, some examples include capacitance encoders, optical encoders, inductive encoders, magnetic encoders, ultrasonic encoders, and rotary resolvers [Refs 1-5]. Many devices, across this range of technologies, are available commercially and have found widespread use in both industrial and defense applications on the ground as well as in space. Miniaturized rotary angle sensor technology sought by this SBIR holds the promise, provided that smaller variants can be developed that meet the both the unique accuracy and packaging and environmental requirements. The following is a list of these requirements:

Measurement range: 360 degrees

Measurement type: Absolute

Accuracy: < 20 arc second

Max Rotation Speed (at full accuracy) = 25 rpm

Interrogation rate = ~2.5 kHz

Power (Total)= < 2 watts

Power (Sense Head) = < 0.25 watts

Size (sense head): 1 inch diameter x 0.5 inches height (max)

Size (electronics): 0.5 in3 (max)

Operation Temperature Range: 5 C to 60 C

Storage Temperature Range: -40 C to 80 C

Operating Pressure: 0 to 75 psia

Humidity: 0 90% RH

Outline path toward meeting the performance requirements of a space launch environment for vibration and shock and a space radiation environment

PHASE I: Develop a design for a miniaturized rotary angle sensor based on the above requirements. Perform a study/analysis and show how the design should be able to fulfill the requirements. Define a test plan that will be used in Phase II to test the rotary encoder that exceeds the accuracy requirement listed.

The Phase I Option, if exercised, will include the initial design specifications and capabilities description to build a prototype solution in Phase II.

PHASE II: Based on the design and results from Phase I, build a small lot of three functional, highly accurate, miniaturized rotary angle sensors and control electronics. Characterize the performance of the batch of sensors according to the test plan outlined in Phase I. Delivery of not less than two (2) devices to the government for additional testing at the conclusion of Phase II.

PHASE III DUAL USE APPLICATIONS: Based on the prototypes developed in Phase II, continue development leading to productization of highly accurate, miniaturized rotary angle sensors suitable for a variety of applications for the defense, aerospace, and commercial markets. Such sensors would be applicable for use in seeker heads, radar fire controls, stabilized platforms, robotic joint feedback, vehicle surface feedback and/or flight control surface feedback. Specific detailed design guidance will be provided during Phase III.


  1. A. S. A. Kumar, B. George and S. C. Mukhopadhyay, "Technologies and Applications of Angle Sensors: A Review," in IEEE Sensors Journal, vol. 21, no. 6, pp. 7195-7206, 15 March15, 2021, doi: 10.1109/JSEN.2020.3045461
  2. D. Zheng, S. Zhang, S. Wang, C. Hu and X. Zhao, "A Capacitive Rotary Encoder Based on Quadrature Modulation and Demodulation," in IEEE Transactions on Instrumentation and Measurement, vol. 64, no. 1, pp. 143-153, Jan. 2015, doi: 10.1109/TIM.2014.2328456
  3. S. Das and B. Chakraborty, "Design and Realization of an Optical Rotary Sensor," in IEEE Sensors Journal, vol. 18, no. 7, pp. 2675-2681, 1 April1, 2018, doi: 10.1109/JSEN.2018.2794822
  4. K. Miyashita, T. Takahashi and M. Yamanaka, "Features of a magnetic rotary encoder," in IEEE Transactions on Magnetics, vol. 23, no. 5, pp. 2182-2184, September 1987, doi: 10.1109/TMAG.1987.1065634
  5. Z. Han, N. Wang, X. Zhu, Z. Li, Y. Cui and X. Jian, "A Miniature High-Frequency Rotary Ultrasonic Encoder for Internal Ultrasound Imaging," in IEEE Sensors Journal, vol. 21, no. 12, pp. 13137-13145, 15 June15, 2021, doi: 10.1109/JSEN.2021.3069433

KEYWORDS: rotary angle sensor; encoder; rotary resolver; capacitance encoder; optical encoder; inductive encoder; magnetic encoder; ultrasonic encoder


The Navy Topic above is an "unofficial" copy from the Navy Topics in the DoD 23.2 SBIR BAA. Please see the official DoD Topic website at for any updates.

The DoD issued its Navy 23.2 SBIR Topics pre-release on April 19, 2023 which opens to receive proposals on May 17, 2023, and closes June 14, 2023 (12:00pm ET).

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Topic Q & A

5/11/23  Q. What type of outputs from the encoders are acceptable? Would an analog output be accepatble?
   A. Either digital or analog outputs are acceptable. If analog, requirements for an analog to digital converter needed to obtain the stated accuracy should be provided.
5/11/23  Q. What level of radiation hardness is required?
   A. Performers should assume the space radiation environment associated with an equivalent 5 year mission on orbits in upper LEO (~2,000 km) to GEO (~36,000 km).

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