MiniRHex is an open-source, low-cost hexapod developed by the Robomechanics Lab. I recently updated the mechanical and electrical design to be higher performance, more robust, and far easier to assemble. The updated design will officially be released soon! In the meantime, you can read about MiniRHex V1 here.
My primary PhD research is on using models of wheel-soil manipulation to develop strategies for planetary rovers to alter soft-soil terrain. Nonprehensile terrain manipulation has the capability to enhance sampling, augment mobility, and much more. In 2018 I earned a NASA Space Technology Research Fellowship to pursue this research. I collaborate frequently with engineers at NASA Ames Research Center, and in fall 2019 accompanied a group of NASA scientists to Chile’s Atacama Desert to perform terrain manipulation experiments there.
Publications related to this project:
C. Pavlov and A. M. Johnson, “Soil Displacement Terramechanics for Wheel-Based Trenching with a Planetary Rover,” 2019 International Conference on Robotics and Automation (ICRA), Montreal, QC, Canada, 2019, pp. 4760-4766. Link.
Youtube video demonstrating nonprehensile terrain manipulation on Ames’ KREX-2 rover.
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In 2020 I constructed a testbed in my apartment for measuring wheel-soil interaction forces. This testbed is modeled on one developed at NASA Ames, and is fabricated nearly entirely with rapid prototyping methods and precut material. The testbed has a 6-axis force-torque sensor, four motors for controlling a soil preparation mechanism and wheel travel speed, rotational speed, and angle, and wheel depth measurement. It contains 4kg of PLA worth of custom brackets and mounts and about 250 lbs of sand.
I use this testbed in my work modeling wheel-soil interaction forces for Nonprehensile Terrain Manipulation.
In April 2020 I contributed to efforts to rapidly scale ventilator manufacturing by making a fully machinable ventilator based on the Go2Vent. Fortunately, these were never needed, but I got the chance to design a neat manometer that is easily fabricated with manual machining and does not require calibration.
The device measures lung pressure by using a main air intake channel to pressurize an array of vertical channels, each of which has one to five steel dowel pins. The channels are open at the top so that air pressure from below can raise each stack of pins until they contact the top, sealing off airflow in that column. The manometer is read by viewing which pins are at the top, with each channel representing an increment in pressure.
Inspired by my previous work on Volcanobot, myself and several friends developed a microspine-enhanced hexapod robot based on the RHex architecture. While not yet able to climb vertical walls, the robot can scale inclines up to 55 degrees and statically cling to overhangs far beyond vertical. I contributed the overall leg architecture as well as a novel way of rapidly fabricating embedded microspine structures through the use of FDM 3d printing.
Publications related to this project:
Our Youtube video created as a part of the course
Matt Martone, Catherine Pavlov, Adam Zeloof, Vivaan Bahl, Aaron M. Johnson. Enhancing the Vertical Mobility of a Robot Hexapod Using Microspines. arXiv preprint, last revised September 2019. Link.
Paul Nadan, Dinesh K. Patel, Catherine Pavlov, Spencer Backus, and Aaron M. Johnson. Microspine Design for Additive Manufacturing. IEEE/RSJ International Conference on Intelligent Robots and Systems 2022. Link.
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In summer 2016, I worked under Professor David Wettergreen of CMU’s field robotics center to design a rover rocker capable of push-roll locomotion. Push-roll locomotion is a novel mobility concept in which a rover is able to expand and contract each rocker such that the front and rear wheels can be moved relative to another (resembling the motion of an inchworm, but performed with wheels). I designed a mechanism for testing the efficacy of push-roll locomotion by analyzing the platform’s drawbar pull. I also developed an experimental plan for testing the mechanism in the FRC’s soft soil testbed.
In 2015-2016 I had the opportunity to work on JPL’s AAReST project through Caltech’s Aerospace Engineering course. I served on the team working on the boxes housing the telescope’s mirrors. We developed assembly procedures for the box, assembled a prototype, and performed vibrational testing to simulate response during a launch.
This project was conducted for Caltech’s course Design for Independence from Disability. My team designed and fabricated a prototype mechanism for converting a standard mechanical wheelchair into one operable by a person with hemiplegia. Hemiplegia, in which one half of the body is full or partially paralyzed, is common in stroke victims. While wheelchairs capable of one-arm operation exist, there are limited models and all are high cost. This device allows the user to select a (much less expensive) standard wheelchair of their preference, and convert it to a single-arm operable wheelchair -without permanent modification. Our designed device is able to bolt onto a wheelchair with no need for technical fabrication – only a hex wrench is required for installation.
This was my senior design project at Caltech. Our team constructed 3 robots with a budget of just $1.5k for a “robot soccer” competition, in which teams had several minutes to score as many goals as possible. The game had 12 balls, three goals on each side, and obstacles in the center of the field. We used chain and sprocket drive train, fabricating all sprockets from stock with a waterjet. While we did not win the competition, our robots were so powerful that the instructor required we add bumpers, lest we damage the playing field.
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Volcanobot refers to a series of robots designed for 3D mapping of post-eruptive volcanic fissures, with the aim of analyzing their geometry to discover their formation mechanism.
In the summers of 2014 & 2015 I designed, fabricated, and tested generations 2 and 3 of Volcanobot. I also assisted in field testing during spring of 2015, where we deployed Volcanobot 2 at Mount Kilauea’s 1969 fissure system in Hawaii.
I performed all mechanical and electrical design and fabrication for the robots, which were designed to be highly mobile, compact, tethered platforms capable of steering themselves along a vertical wall. The robots used a short-range 3D depth sensor to record point cloud data of the fissure during descent and ascent.
Publications related to this project:
Carolyn E. Parcheta, Catherine A. Pavlov, Nicholas Wiltsie, Kalind C. Carpenter, Jeremy Nash, Aaron Parness, Karl L. Mitchell. A robotic approach to mapping post-eruptive volcanic fissure conduits. Journal of Volcanology and Geothermal Research,
Volume 320, 2016, Pages 19-28. Link.
Carolyn E. Parcheta, Jeremy Nash, Aaron Parness, Karl L. Mitchell, Catherine A Pavlov. Narrow Vertical Caves: Mapping Volcanic Fissure Geometries. 2nd International Planetary Caves Conference, held 20-23 October, 2015 in Flagstaff, Arizona. LPI Contribution No. 1883, p.9010. Link.
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Catherine Pavlov 