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Patel, Nikunj

Publications and source records attributed to Patel, Nikunj.

5 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS2022

Assessing Mars Curiosity Rover Wheel Damage

An alarming rate of wheel skin cracks were first observed on the Mars Science Laboratory (MSL) Curiosity rover about 14 months after the start of its surface mission. Nine years later (as of August 2, 2021), Curiosity has four broken wheelgrousers, three on the left middle wheel and one on the right middle wheel. There are a substantial number of wheel skin cracks on the left front, left middle, and right middle wheels such that the number of grousers on each that are consideredat risk of breaking are 10, 7, and 11, respectively. Although the current level of wheel damage does not significantly limit Curiosity’s mission objectives, a higher damage rate could impact surface operations, so the damage rate is closely monitored. OnNovember 30, 2013, the MSL Surface Operations team began periodically acquiring images of Curiosity’s wheels. In this paper, we describe the process the Mobility Operations team uses to assess wheel damage, the current state of Curiosity’swheels, and how the wheel damage assessments have influenced driving guidelines and wheel imaging frequency.

Rink, Kimberly↗
NASA NTRS2022

Visual Odometry Thinking While Driving for the Curiosity Mars Rover's Three-Year Test Campaign: Impact of Evolving Constraints on Verification and Validation

Over the first 9 years of the Mars Science Laboratory (MSL) Curiosity rover's surface mission, more than 87\% of its driving has been performed using Visual Odometry (VO). The benefits of using VO during driving are that it minimizes rover position uncertainty and can be used to monitor wheel slip, halting a drive if excessive wheel slip is occurring. The VO implementation on board Curiosity acquires and processes VO images in between drive steps while the rover is stationary. A VO Thinking While Driving (VTWD) flight software capability has been developed which enables the processing of VO images during rover driving, increasing the distance Curiosity can drive with VO in a given time period up to as much as 1.75x total distance. Verification and Validation (V\&V) of the capability has been challenging due to impacts from the COVID-19 pandemic and unavailability of the JPL Mars Yard outdoor test site. The VTWD V\&V test procedures were modified to use a small indoor space with Mars-like terrain. This paper describes the 3 year V\&V effort under challenging conditions to approve the VTWD capability for use on the Curiosity rover.

Rankin, Arturo↗
NASA NTRS2020

Driving Curiosity: Mars Rover Mobility Trends During the First Seven Years

NASA’s Mars Science Laboratory (MSL) mission landed the Curiosity rover on Mars on August 6, 2012. As of August 6, 2019 (sol 2488), Curiosity has driven 21,318.5 meters over a variety of terrain types and slopes, employing multiple drive modes with varying amounts of onboard autonomy. Curiosity’s drive distances each sol have ranged from its shortest drive of 2.6 centimeters to its longest drive of 142.5 meters, with an average drive distance of 28.9 meters. Real-time human intervention during Curiosity drives on Mars is not possible due to the latency in uplinking commands and downlinking telemetry, so the operations team relies on the rover’s flight software to prevent an unsafe state during driving. Over the first seven years of the mission, Curiosity has attempted 738 drives. While 622 drives have completed successfully, 116 drives were prevented or stopped early by the rover’s fault protection software. The primary risks to mobility success have been wheel wear, wheel entrapment, progressive wheel sinkage (which can lead to rover embedding), and terrain interactions or hardware or cabling failures that result in an inability to command one or more steer or drive actuators. In this paper, we describe mobility trends over the first 21.3km of the mission, operational aspects of the mobility fault protection, and risk mitigation strategies that will support continued mobility success for the remainder of the mission.

Rankin, Arturo↗