As of June 21, 2021, Ingenuity Mars Helicopter has successfully flown its 8th flight, traveling about 525 feet (160 meters) south-southeast from Airfield D to the new Airfield E! This marks the third flight in the Operations Demonstration Phase of Ingenuity, in which the team will continue to push the flight envelope of the aircraft while learning valuable operational lessons. Flight 8 was also the first flight the vehicle executed since performing an update of its Flight-Controller flight software and all telemetry indicates that the update was a success!
- Climb to 10 meters
- Translate ~160 meters SSE from Airfield D to Airfield E
- Descend and land
- Flight time ~78 seconds
Fixing the Watchdog Issue – Regaining Reliability in Flight Planning
Ingenuity first encountered its watchdog issue during commissioning on Sol 49, April 9, 2021. The symptom of the problem is that the helicopter cannot transition into the “flight-state” within the software. Without this internal state transition, the helicopter cannot spin its blades up to full speed, and, therefore, cannot fly. The issue stems from a computer protection and reliability feature between our Flight Controller microcontrollers and our Field Programmable Gate Array (FPGA). When attempting to transition to the “flight-state,” the watchdog on the FPGA would detect violations to its strict timing requirements and prevent Ingenuity from continuing with its planned spin/flight. The team identified a sequence workaround that would allow us to proceed with flight activities, but we have a 15% probability of needing re-attempts if the watchdog triggered again.
A timeline of the watchdog events is below, along with related blog posts.
- April 9, 2021 - Sol 49 High-Speed Spin Attempt 1 – First instance of the Watchdog
- April 16, 2021 - Sol 55 High-Speed Spin Attempt 2 – Success
- April 17, 2021 - Preparation for Flight 1
- April 29, 2021 - Sol 68 Flight 4 Attempt 1
- June 4, 2021 - Sol 105 Flight 7 Attempt 1
The Ingenuity team is proud to say that last week we completed a flight software update of the Flight Controller microcontrollers on the helicopter, with the intent of permanently fixing the watchdog issue. This patch provides much needed reliability in the operations demonstration, ensuring that the heli and rover teams can plan for successful flights in the future. Following a 50 rpm slow-speed spin regression test on June 18, 2021, or Sol 116, Flight 8 confirmed that the FC flight software update was a success and that Ingenuity is ready to proceed with confidence into the next flights of the ops demo.
Up next for the Ingenuity team is to tackle the only remaining flight software update, which will update a large portion of the Ingenuity’s navigation-computer software. This update will address the Flight 6 anomaly, where image timing delays manifested into aircraft estimation and control challenges.
During the course of analyzing the Flight 6 anomaly, the team determined that the process of capturing color RTE camera images may have been inducing the imaging pipeline glitch, which resulted in the instability encountered during Flight # 6. The team’s hypothesis is that the large CPU load involved in capturing the RTE’s 13-megapixel color images, could result in rare instances of navigation camera images being dropped in the pipeline. Those nav. camera image drops are what caused the Flight #6 anomaly. That is why Flights 7 and 8 did not have any color images captured. This update will provide a mechanism for the Helicopter to detect and correct when image timestamps in the pipeline become out-of-synch/are dropped/skipped, while also re-enabling the capture of high-resolution 13-megapixel color images. This update is planned to occur in the coming days, followed by Ingenuity’s ninth flight on Mars.