William R. Hamel

Accurate Human Navigation Using Wearable Monocular Visual and Inertial Sensors

This paper presents a novel visual-inertial integration system for human navigation in free-living environments, where the measurements from wearable inertial and monocular visual sensors are integrated. The preestimated orientation, obtained from magnet, angular rate, and gravity sensors, is used to estimate the translation based on the data from the visual and inertial sensors. This has a significant effect on the performance of the fusion sensing strategy and makes the fusion procedure much easier, because the gravitational acceleration can be correctly removed from the accelerometer measurements before the fusion procedure, where a linear Kalman filter is selected as the fusion estimator. Furthermore, the use of preestimated orientation can help to eliminate erroneous point matches based on the properties of the pure camera translation and thus the computational requirements can be significantly reduced compared with the RANdom SAmple Consensus algorithm. In addition, an adaptive-frame rate single camera is selected to not only avoid motion blur based on the angular velocity and acceleration after compensation, but also to make an effect called visual zero-velocity update for the static motion. Thus, it can recover a more accurate baseline and meanwhile reduce the computational requirements. In particular, an absolute scale factor, which is usually lost in monocular camera tracking, can be obtained by introducing it into the estimator. Simulation and experimental results are presented for different environments with different types of movement and the results from a Pioneer robot are used to demonstrate the accuracy of the proposed method.

Grand Challenges in Bioengineered Nanorobotics for Cancer Therapy

One of the grand challenges currently facing engineering, life sciences, and medicine is the development of fully functional nanorobots capable of sensing, decision making, and actuation. These nanorobots may aid in cancer therapy, site-specific drug delivery, circulating diagnostics, advanced surgery, and tissue repair. In this paper, we will discuss, from a bioinspired perspective, the challenges currently facing nanorobotics, including core design, propulsion and power generation, sensing, actuation, control, decision making, and system integration. Using strategies inspired from microorganisms, we will discuss a potential bioengineered nanorobot for cancer therapy.

Control strategies for teleoperated Internet assembly

Teleoperated systems are increasingly being used to perform tasks over the Internet. This paper discusses this general idea in terms of the control needs, constraints and concepts that are associated with the notion of Internet-based assembly. A discrete-event simulation is used to investigate several supervisory control strategies used for the assembly of a standardized fixture (the Cranfield) using teleoperated commands issued over the Internet. Results are presented relating the assembly performance, control strategy and Internet communication performance.

Observations concerning Internet-based teleoperations for hazardous environments

Teleoperated systems are used to perform remote maintenance functions in hazardous environments usually with the fundamental objective of reducing, or eliminating, human worker exposure to dangers. Researchers are now considering how might Internet capabilities be used in such operations. The paper discusses this general idea in terms of the practical needs, constraints, and concepts that are associated with the notion of Internet-based teleoperations.

Elements of telerobotics necessary for waste clean up automation

A promising way to achieve increased remote worksystem efficiency is to layer telerobotic technologies onto teleoperated remote systems. The research being reported here will enable the teleoperation baseline to be supplemented with operator-selective telerobotic modes of operation that allow automatic performance of subtasks that are either repetitive, require high precision, or involve extreme patience. Before subtask automation can be exploited, however, it is necessary to explicitly represent the 3D geometry of the task space scene surrounding the remote worksystem. The Robot Task Space Analyzer (RSTA) is a tool for remote equipment operators that combines infrared laser and visible stereo imaging, human-interactive modeling and computer-based object recognition to build 3D models of the immediate work zone in which a robot system is operating. This paper presents the hardware and software design of the RTSA system. Human factors aspects the system operation and design are discussed.

A comparison of two real-time control schemes for redundant manipulators with bounded joint velocities

A comparison of two real-time control schemes for redundant manipulators is presented. Both schemes are developed in the framework of resolved rate control, and were presented by the authors in earlier articles (R.V. Dubey et al., 1988, J.A. Euler et al., 1988, and S.M. Babcock, 1988). The first scheme is the gradient projection scheme, which determines only the direction of the self-motion for the optimization of a scalar performance criterion. The second scheme determines the direction as well as the magnitude of the self motion. However, when the magnitude of the self-motion is limited by the hardware bounds on joint velocities, the results obtained using the two schemes are remarkably similar when the computational frequency is high (above 100 Hz). Therefore, the gradient projection scheme, which is computationally more efficient, is recommended. An explanation for the similarity of results is presented. Scheme 1 was implemented in real-time on a Motorola 68020 VME bus-based controller of the seven-degree-of-freedom manipulator at the Center for Engineering Systems Advanced Research.<<ETX>>

Energy-Efficient Surface Propulsion Inspired by Whirligig Beetles

The whirligig beetle, claimed to be one of the most energy-efficient swimmers in the animal kingdom, has evolved a series of propulsion strategies that may serve as a source of inspiration for the design of propulsion mechanisms for energy-efficient surface swimming. In this paper, we introduce a robot platform that was developed to test an energy-efficient propulsion mechanism inspired by the whirligig beetle. A propulsor-body-fluid interaction dynamics model is proposed, and based on this model, the propulsor flexural rigidity and beating patterns are optimized in order to achieve energy-efficient linear swimming and turning. The optimization results indicate that a propulsor with decreasing flexural rigidity enhances vortex shedding and improves thrust generation. It has also been found that an alternating asymmetrical beating sequence and optimal beating frequency of 0.71 Hz improves propulsion efficiency for linear swimming of the robot. The alternating beating of the outboard propulsors and the unfolded inboard propulsors working as brakes results in efficient turning with a smaller turning radius. Both simulation and experimental studies were conducted, and the results illustrate that decreasing flexural rigidity along the propulsor length, an oscillating body motion, and an S-shaped trajectory are critical for energy-efficient propulsion of the robot.

Robotics in Hazardous Applications

Robotics researchers have worked hard to realize a long-awaited vision: machines that can eliminate the need for people to work in hazardous environments. Chapter 60 is framed by the vision of disaster response: search and rescue robots carrying people from burning buildings or tunneling through collapsed rock falls to reach trapped miners. In this chapter we review tangible progress towards robots that perform routine work in places too dangerous for humans. Researchers still have many challenges ahead of them but there has been remarkable progress in some areas. Hazardous environments present special challenges for the accomplishment of desired tasks depending on the nature and magnitude of the hazards. Hazards may be present in the form of radiation, toxic contamination, falling objects or potential explosions. Technology that specialized engineering companies can develop and sell without active help from researchers marks the frontier of commercial feasibility. Just inside this border lie teleoperated robots for explosive ordnance disposal (EOD ) and for underwater engineering work. Even with the typical tenfold disadvantage in manipulation performance imposed by the limits of today’s telepresence and teleoperation technology, in terms of human dexterity and speed, robots often can offer a more cost-effective solution. However, most routine applications in hazardous environments still lie far beyond the feasibility frontier. Fire fighting, remediating nuclear contamination, reactor decommissioning, tunneling, underwater engineering, underground mining and clearance of landmines and unexploded ordnance still present many unsolved problems.

e-maintenance robotics in hazardous environments

Robotic systems are used to perform maintenance functions in hazardous environments usually with the fundamental objective of reducing, or eliminating, human worker exposure to dangers. An obvious thought is how might Internet capabilities be used in such operations. This paper considers this general idea in terms of the practical needs, constraints, and concept that are associated with the notion of using the emerging Internet to reduce costs and enhance overall performance in robotic maintenance in hazardous environments.

Dynamic modeling and analysis of a transmission-based robot servoactuator

This paper addresses aspects of the feasibility of extending high performance brushless DC motor torque-speed capabilities by using multi-speed transmissions. Initial dynamic modeling and simulation results show that a transmission-based electrical servo actuator can have similar load capabilities with widely used hydraulic actuator in robot manipulators.