Jet Propulsion LaboratoryCalifornia Institute of Technology

Mars 2020 Project

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).

Mars 2020 Project

Jet Propulsion LaboratoryCalifornia Institute of Technology

First Pair Tracking

Second Pair Tracking

LVS is an extension of MER-DIMES

MER-DIMES (2004) was the first use of descent images for navigation during EDL.

descentimage

referencemap

positionknowledge error

before TRN

positionknowledge error after

TRN

TRN automatically matches features in a descent image to landmarks in a map to obtain a position fix.

landmarks

image features

Champollion, MER, NMP/ST9, Mars Tech Program

DIMES tracked features between descent images to estimate velocity.

TRN is an extension of MER-DIMES to estimate position for accurate landing.

Horizontal Velocity

:  For Planning and Discussion Purposes Only.

Mars 2020 Project

Jet Propulsion LaboratoryCalifornia Institute of Technology

outlier

Image 1Image 2

Image 3

IMU

x x

x

x xx

xx x

outlier

Re

sid

ua

ls

Timex xx x xxTRON: coarse matches

x xx xxxThreshold

IMU

IMU

Image 4

TRON:coarsematches

TRON:coarsematches

Image 5

IMU

TRON: finematches

TRON:finematches

VISINAV: Batch Initialization VISINAV: Extended Kalman Filter

coarse matchimage templates

fine matchimage templates

Propagate

Batch update

EKF update

EKF update

LVS TRN Implementation

Propagate Propagate Propagate

IMU

Map

Camera Image 10

Remove Large Position Uncertainty (50m 1-σ) Improve Position Accuracy (20m 1- σ):  For Planning and Discussion Purposes Only.

Mars 2020 Project

Jet Propulsion LaboratoryCalifornia Institute of Technology

LVS Compute Element

Prototype LVS Block Diagram

LVS IMU

LVS Camera

Lander GN&C

initial state(p+perr,q,v+verr,A)M_B

accel, angular rates

grayscale image

LEON 3 Flight ProcessorRTEMS OS

Batch Init EstimatorExtended Kalman Filter

Image Processing ControlHomography Generation

Outlier RejectionData Sequencing

com

pact

PC

I bac

kpla

ne

Virtex 5 FPGAAMBA Bus

Homography WarpImage NormalizeFFT Correlation

Interest OperatorSpatial Correlation

Sensor TimingCamera I/F

IMU I/F

LVSLVS Technology

S/C

legend

SDRAM with map

Data Logger

(position correction)M_B

data products, data

:  For Planning and Discussion Purposes Only.

Mars 2020 Project

Jet Propulsion LaboratoryCalifornia Institute of Technology

• Hardware

Implementation on a Cubesat

:  For Planning and Discussion Purposes Only.

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

Mars 2020 Project

Jet Propulsion LaboratoryCalifornia Institute of Technology

• 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…!

Possible Mission Applications

:  For Planning and Discussion Purposes Only.