Science & Technology

Docking the Robotic Arm on NASA’s Mars Perseverance Rover

Mars Perseverance Sol 87 – Left Navigation Digicam: First time docking on Mars, on Sol 87 [May 18th, 2021]. This picture was acquired by Perserverance’s left navigation digicam shortly after the arm completed docking. The Bit Carousel is the conical object in the heart of the picture. Credit: NASA/JPL-Caltech

Docking occurs twice throughout pattern assortment. First, the robotic arm docks to drop off the currently-chucked abrading bit and choose up a coring bit with an empty pattern tube. Then, after accumulating a rock pattern, it docks once more to drop off the coring bit with a now-filled sample tube, which might be processed, sealed, and saved by the caching meeting.

Mars Perseverance Sol 21 – WATSON Digicam: An summary image of the dock on the entrance of Perseverance, taken by the WATSON digicam on the Robotic Arm. A door in entrance of the bit carousel was nonetheless closed when this picture was acquired and has since been opened. Credit: NASA/JPL-Caltech

Docking works by guiding a set of small posts on the finish of the robotic arm into an identical set of cones on the dock. Think about plugging your charger into your cellphone or laptop – even in case you don’t give it some thought, you rely lots on the tactile suggestions out of your hand and fingertips to really feel if it is advisable slide the plug to the aspect, to line it up somewhat higher, and to know when it’s reached the backside. Docking works the similar method. A drive sensor on the finish of the robotic arm tells Perseverance how laborious it’s pushing and during which instructions, and Perseverance makes use of this information to information the arm into place and to find out when docking is full. (The dock additionally consists of microswitches at the backside of every cone that are pressed when the arm is sort of docked, which function an additional verification). As soon as the posts attain the backside of the cones, the robotic arm pushes more durable into the dock with nearly 650N (146 lbs) of drive to verify it stays docked throughout bit alternate.

I’ve labored on docking for many of my 6-year profession at JPL, and my purpose has been to make it dependable and straightforward – similar to plugging in your cellphone. Getting thus far required a number of design and testing (together with docking nearly 2000 occasions in numerous testbeds right here on Earth), and it’s been a privilege to see docking occur efficiently many occasions on Mars already. I’ll all the time be somewhat nervous each time we acquire a pattern, however my fingers are crossed for a lot of extra profitable and straightforward docking makes an attempt.

Written by Sawyer Brooks, Docking Methods Engineer at NASA/JPL.

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