Terrain Relative Navigation for Pinpoint Landing using Cubesats Mars Cubesat Workshop Swati Mohan, Andrew Johnson, Nikolas Trawny November 21, 2014 Copyright 2014 California Institute of Technology. Government sponsorship acknowledged. For planning and discussion purposes only. Cleared for unlimited release (CL#14-4997).

LVS is an extension of MER-DIMES MER-DIMES (2004) was the first use of descent images for navigation during EDL. descent image reference map position knowledge error before TRN knowledge error after TRN TRN automatically matches features in a descent image to landmarks in a map to obtain a position fix. landmarks image features DIMES tracked features between descent images to estimate velocity. Champollion, MER, NMP/ST9, Mars Tech Program First Pair Tracking Second Pair Tracking TRN is an extension of MER-DIMES to estimate position for accurate landing. Horizontal Velocity :  For Planning and Discussion Purposes Only.

LVS TRN Implementation VISINAV: Batch Initialization VISINAV: Extended Kalman Filter x outlier Threshold x x x x x x x Residuals x x x x x x x x x x x x x Time TRON: coarse matches TRON: coarse matches TRON: coarse matches TRON: fine matches TRON: fine matches fine match image templates coarse match image templates IMU IMU Image 1 IMU Image 2 IMU Camera Image 3 Image 10 Image 4 Image 5 Map move later add performance requirements outlier IMU Batch update EKF update EKF update Propagate Propagate Propagate Propagate Remove Large Position Uncertainty (50m 1-σ) Improve Position Accuracy (20m 1- σ) :  For Planning and Discussion Purposes Only.

Prototype LVS Block Diagram LVS Compute Element compact PCI backplane LEON 3 Flight Processor RTEMS OS Batch Init Estimator Extended Kalman Filter Image Processing Control Homography Generation Outlier Rejection Data Sequencing Lander GN&C initial state (p+perr,q,v+verr,A)M_B (position correction)M_B data products, data Data Logger Virtex 5 FPGA AMBA Bus Homography Warp Image Normalize FFT Correlation Interest Operator Spatial Correlation Sensor Timing Camera I/F IMU I/F accel, angular rates LVS IMU grayscale image LVS Camera SDRAM with map legend LVS LVS Technology S/C :  For Planning and Discussion Purposes Only.

Implementation on a Cubesat Hardware Compute Element: Existing TRN boards are larger than Cubesat scale Requires time and money to scale down to scale to a Cubesat size JPL developed IRIS radio includes Cubesat scale Virtex 5 implementation Deep space Cubesat processor in development in JPL Sec. 349 IMU: Current TRN designs use LN200 or MIMU Cubesat scale IMUs exist with similar performance Examples are BCT MEMS gyro, KVH FOG gyro Camera: Current TRN design use a 1024x1024 array with 90 deg field of view Cubesat scale detectors exist with similar performance Example: KAI-04022 (2048x2048) Optics would need to be designed for each mission Software TRN algorithms have been implemented and field tested Mission specific development needs to occur: Porting to the mission processor Interfacing with the mission GN&C Obtaining and implementing maps for mission landing site :  For Planning and Discussion Purposes Only.

Possible Mission Applications Technology Advancement Technology demonstration of pinpoint landing Technology demonstration of hazard detection Science Precision placement of probes ( seismometers, weather stations, etc.) Mapping of Phobos or Deimos Landing Site Support Pre-cursor probes to confirm “worthiness” of potential landing site targets And many more…! :  For Planning and Discussion Purposes Only.