Roshena MacPherson

Contacts:

Roshena MacPherson

Roshena MacPherson is a graduate student in Mechanical Engineering. She received her B.S. in Mechanical Engineering from the University of California, Berkeley in 2015. At the Center for Interdisciplinary Biological Inspiration in Education and Research (CiBER) at UC Berkeley, she worked on understanding the role of flexible tails in the fast turning capabilities of lizards. She is currently a Gabilan Fellow and an NSF Fellow.

Roshena’s research interests include control theory, mechatronics, robotics, and analysis of systems with complex and interesting dynamics. Her current research explores the use of gecko-inspired controllable dry adhesives for grasping and manipulation in space. She has been involved in the characterization of the grasping envelopes of compliant wrists equipped with gecko inspired adhesives, as well as the design of a controller to guarantee successful grasping of a spinning object. She plans to extend this research to develop a full control architecture to enable dynamic grasping in space.

In her spare time Roshena enjoys playing ultimate frisbee, rock climbing, yoga, drawing, playing music, and escaping to the mountains.

ASL Publications

R. MacPherson, B. Hockman, A. Bylard, M. A. Estrada, M. R. Cutkosky, and M. Pavone, “Trajectory Optimization for Dynamic Grasping in Space using Adhesive Grippers,” in Field and Service Robotics, Zurich, Switzerland, 2017.
[BibTeX] [Abstract]

Abstract: Spacecraft equipped with gecko-inspired dry adhesive grippers can dynamically grasp objects having a wide variety of featureless surfaces. In this paper we propose an optimization-based control strategy to exploit the dynamic robustness of such grippers for the task of grasping a free-floating, spinning object. First, we extend previous work characterizing the dynamic grasping capabilities of these grippers to the case where both object and spacecraft are free-floating and comparably sized. We then formulate the acquisition problem as a two-phase optimal control problem, which is amenable to real time implementation and can handle constraints on velocity, control, as well as integer timing constraints for grasping a specific target location on the surface of a spinning object. Conservative analytical bounds on the set of initial states that guarantee persistent feasibility are derived.
```
@inproceedings{MacPhersonHockmanEtAl2017,
  author = {MacPherson, R. and Hockman, B. and Bylard, A. and Estrada, M. A. and Cutkosky, M. R. and Pavone, M.},
  title = {Trajectory Optimization for Dynamic Grasping in Space using Adhesive Grippers},
  booktitle = {{Field and Service Robotics}},
  year = {2017},
  address = {Zurich, Switzerland},
  month = sep,
  url = {/wp-content/papercite-data/pdf/MacPherson.Hockman.Bylard.ea.FSR17.pdf},
  owner = {bylard},
  timestamp = {2018-01-16}
}
```
A. Bylard, R. MacPherson, B. Hockman, M. R. Cutkosky, and M. Pavone, “Robust Capture and Deorbit of Rocket Body Debris Using Controllable Dry Adhesion,” in IEEE Aerospace Conference, Big Sky, Montana, 2017.
[BibTeX] [Abstract]

Abstract: Removing large orbital debris in a safe, robust, and cost-effective manner is a long-standing challenge, having serious implications for LEO satellite safety and access to space. Many studies have focused on the deorbit of spent rocket bodies (R/Bs) as an achievable and high-priority first step. However, major difficulties arise from the R/Bs’ residual tumble and lack of traditional docking/grasping fixtures. Previously investigated docking strategies often require complex and risky approach maneuvers or have a high chance of producing additional debris. To address this challenge, this paper investigates the use of controllable dry adhesives (CDAs), also known as gecko-inspired adhesives, as an alternative approach to R/B docking and deorbiting. CDAs are gathering interest for in-space grasping and manipulation due to their ability to controllably attach to and detach from any smooth, clean surface, including flat and curved surfaces. Such capability significantly expands the number and types of potential docking locations on a target. CDAs are also inexpensive, are space-qualified (performing well in a vacuum, in extreme temperatures, and under radiation), and can attach and detach while applying minimal force to a target surface, all important considerations for space deployment. In this paper, we investigate a notional strategy for initial capture and stabilization of a R/B having multi-axis tumble, exploiting the unique properties of CDA grippers to reduce maneuver complexity, and we propose alternatives for rigidly attaching deorbiting kits to a R/B. Simulations based on experimentally verified models of CDA grippers show that these approaches show promise as robust alternatives to previously explored methods.
```
@inproceedings{BylardMacPhersonEtAl2017,
  author = {Bylard, A. and MacPherson, R. and Hockman, B. and Cutkosky, M. R. and Pavone, M.},
  title = {Robust Capture and Deorbit of Rocket Body Debris Using Controllable Dry Adhesion},
  booktitle = {{IEEE Aerospace Conference}},
  year = {2017},
  address = {Big Sky, Montana},
  month = mar,
  url = {/wp-content/papercite-data/pdf/Bylard.MacPherson.Hockman.ea.AeroConf17.pdf},
  owner = {bylard},
  timestamp = {2017-03-07}
}
```