Timothy G. McGee

A collaborative BCI approach to autonomous control of a prosthetic limb system

Existing brain-computer interface (BCI) control of highly dexterous robotic manipulators and prosthetic devices typically rely solely on neural decode algorithms to determine the users intended motion. Although these approaches have made significant progress in the ability to control high degree of freedom (DOF) manipulators, the ability to perform activities of daily living (ADL) is still an ongoing research endeavor. In this paper, we describe a hybrid system that combines elements of autonomous robotic manipulation with neural decode algorithms to maneuver a highly dexterous robotic manipulator for a reach and grasp task. This system was demonstrated using a human patient with cortical micro-electrode arrays allowing the user to manipulate an object on a table and place it at a desired location. The preliminary results for this system are promising in that it demonstrates the potential to blend robotic control to perform lower level manipulation tasks with neural control that allows the user to focus on higher level tasks thereby reducing the cognitive load and increasing the success rate of performing ADL type activities.

Approaches to robotic teleoperation in a disaster scenario: From supervised autonomy to direct control

The ability of robotic systems to effectively address disaster scenarios that are potentially dangerous for human operators is continuing to grow as a research and development field. This leverages research from areas such as bimanual manipulation, dexterous grasping, bipedal locomotion, computer vision, sensing, object segmentation, varying degrees of autonomy, and operator control/feedback. This paper describes the development of a semi-autonomous bimanual dexterous robotic system that comes to the aid of a mannequin simulating an injured victim by operating a fire extinguisher, affixing a cervical collar, cooperatively placing the victim on a spineboard with another bimanual robot, and relocating the victim. This system accomplishes these tasks through a series of control modalities that range from supervised autonomy to full teleoperation and allows the control model to be chosen and optimized for a specific subtask. We present a description of the hardware platform, the software control architecture, a human-in-the-loop computer vision algorithm, and an infrastructure to use a variety of user input devices in combination with autonomous control to compete several dexterous tasks. The effectiveness of the system was demonstrated in both laboratory and live outdoor demonstrations.

APLNav: Development Status of an Onboard Passive Optical Terrain Relative Navigation System

Over much of the last decade, the Johns Hopkins Applied Physics Laboratory has developed and tested passive optical on-board terrain relative navigation for precision landing on the moon or small planetary bodies. This paper summarizes the development history and current status of the APLNav system that was first prototyped in 2006 and has been matured in the subsequent years under the ALHAT and Robotic Lunar Lander Development Programs. Development activities have included multiple field tests, performance tests on flight processors, and integration with guidance, navigation, and control systems.

Performance Analysis of the APLNav System for Passive Optical Lunar Navigation

The Autonomous Landing and Hazard Avoidance Technology (ALHAT) program is a NASA technology development program working to advance capabilities needed to perform precision landing on the Moon. The Johns Hopkins University Applied Physics Laboratory (APL) is developing the Autonomous Precision Landing Navigation Algorithm (APLNav), a passive optical terrain sensing system, as part of this program. A wide variety of simulationbased tests have performed on the APLNav system to study the effects of various operational, noise, and design parameters on the performance, robustness, and processing requirements of the APLNav algorithm. Overall the algorithm performed very well within its expected parameter ranges. The testing also illustrated some of the potential engineering trade-offs that can be made in the algorithm design to optimize its performance for specific mission requirements.

Analysis of Spinning Spacecraft with Wire Booms Part 3: Spin-Plane Dynamics, Maneuvers, and Deployment

Several science spacecraft use long wire booms as electric-field antennas and the spacecraft spins to maintain the orientation of these flexible wires. These booms account for a majority of the total spacecraft inertia while weighing only a small fraction of the total mass. The spacecraft dynamics is therefore dominated by these booms. The analysis of such spacecraft is further complicated by other flexible appendages and the presence of damping in the system, both inherent in the system and from damping mechanisms deliberately added into the system. This paper and two companion papers analyze such spacecraft. The first of these derives the governing nonlinear equations from first principles. Under certain conditions, the dynamics neatly separate into spin-plane and out-of-plane dynamics. The second companion paper examines the out-of-plane dynamics and maneuvers. This paper examines the spin-plane dynamics of such a spin-stabilized spacecraft. It analyzes the fundamental modes and mode-shapes of the system, spin-plane maneuvers, and the effects of boom deployment. While this analysis is applicable to any spin-stabilized spacecraft with flexible radial booms, the analysis was driven by the needs of the Radiation Belt Storm Probes (RBSP) spacecraft currently being designed at the Johns Hopkins University Applied Physics Laboratory, as part of NASAs “Living With a Star” program. This paper provides an analytical treatment of the spacecraft dynamics. These theoretical predictions are verified using fully non-linear six degree-of-freedom simulations.

Analysis of Spinning Spacecraft with Wire Booms Part 1: Derivation of Nonlinear Dynamics

Algebraic expressions for the governing equations of motion are developed to describe a spinning spacecraft with flexible appendages. Two limiting cases are investigated: appendages that are self-restoring and appendages that require spacecraft motion to restore. Solar panels have sufficient root stiffness to self-restore perturbations. Radial wire antennae have little intrinsic root stiffness and require centripetal acceleration from spacecraft rotations to restore perturbations. External forces applied for attitude corrections can displace spacecraft appendages from their steady-state position. The Radiation Belt Storm Probe (RBSP) satellite is used as an example to explore numerical results for several maneuvers.

Demonstration of force feedback control on the Modular Prosthetic Limb

The Johns Hopkins University Applied Physics Laboratory (APL) led the development of the Modular Prosthetic Limb (MPL), an advanced upper-extremity prosthetic limb, under the DARPA Revolutionizing Prosthetics program. In addition to its use as an advanced prosthetic, APL is also exploring more advanced autonomy including closed-loop force feedback control with the MPL. This short paper provides an overview of the MPL system and summarizes two demonstrations performed at APL using fingertip force sensors to perform autonomous writing and fingertip grasping.

Analysis of Spinning Spacecraft with Wire Booms Part 2: Out-of-Plane Dynamics and Maneuvers

An analysis of the dynamics for a spin stabilized spacecraft consisting of a rigid central hub with four long exible wire booms is presented. The analysis focuses on the dynamics out of the spin plane of the spacecraft. Companion papers will focus on the derivations of the full nonlinear dynamics and analysis of the in plane dynamics. A linear analysis is used to estimate the mode shapes of the free response of the system, the eects of various damping mechanisms on these modes, and the dynamic response of the system to various maneuvers. The results of an independent simulation of the full nonlinear dynamics of the system are also provided to support the linear analysis. While the dynamics and analysis approach presented can be applied to the general class of spin stabilized spacecraft having multiple exible wire booms, the numeric parameters studied represent those of the satellites from the Radiation Belt Storm Probe (RBSP) mission. The mission, part of NASA’s Living With a Star Geospace Program, will launch two Earth-orbiting spacecraft to investigate how populations of relativistic electrons and ions in the region known as the Radiation Belts are formed and change in response to variable inputs of energy from the Sun.

Design considerations for a Guidance, Navigation, and Control sensor system for a robotic lunar lander

With the goal of developing a preliminary hardware and software design of a Guidance, Navigation and Control Subsystem of a robotic lunar lander for various potential missions including the International Lunar Network (ILN), navigation sensor technologies are researched and their maturity is assessed. 12The results of the broad technology assessment are compared with requirements generated from known or estimated design constraints, modeling and simulation results, and subject-matter expert consultations to validate the assembly design. The results identify the current baseline and some alternative components for the lander. The nominal sensor configuration baselines assume that precision landing is desired for the mission even though some of the mission concepts, including the ILN mission, could be achieved without precision landing. In these cases, the specific sensors used for precision terrain relative position measurements are removed from the configuration.