Aquatic animal movement results from a complex balance between muscular actuation, swimmer's inertia, damping, and stiffness; as well as, the effects from the fluid environment. Most aquatic animals utilize undulatory propulsion methods during swimming. Propulsion mode transition involves a variation of these parameters, and to better investigate the variation of these parameters during propulsion mode switching, and provide guidance for swimming robot design, we studied propulsion mechanism of undulation locomotion by combining biological investigation, mathematical simulation and experimental validation. A modular robot platform, with assembling function, was built based on the obtained biological features to realize the corresponding propulsion methods. Then a modular dynamic modeling method was proposed to simulate robot locomotion using a CPG based algorithm and a PD control method, further revealing the underlying mechanism for undulatory locomotion. Finally, experiments were conducted using the robotic platform to validate the found conclusions as well as enhance the propulsion mechanism of undulatory motion, providing a generic guidance for swimming robot design.

Due to challenges, such as information collection in huge water, propulsion at different scales and manipulation in extreme fluid environments, wide application of unmanned underwater vehicles (UUVs) is limited. In this paper, an alligator modular robot, composed by 14 small robots, was inspired from the locomotion and morphologies of alligators and microorganisms. With the undulatory body and beating legs, the assembled large robot was able to maintain fast and maneuverable swimming for tasks executions at large Reynolds number. With a biologically optimized body aspect ratio (3.47), small modular robots achieved effective propulsion in viscous fluid. Facilitated by a dissembling system, small robots were automatically released from the large robot frame and swam around with independent actuation systems. Hydrodynamic model for the large and small robot were formulated, based on which the propulsion for the modular robot in large and low Reynolds numbers (Res) were simulated. Experiments were conducted to compare with the simulation results to further validate the proposed modular robot design.

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.

Wearable inertial tracking is well accepted due to its convenience for free-style motion tracking with high accuracy. Traditionally, complicated high-order calculations for human kinematic modeling and inaccurate estimation of sensor placement are interfering the efficiency of real-time tracking. In order to tackle the challenges, a wearable human motion tracking system is developed by applying twists and exponential maps techniques. When the body segments are articulated by product of exponential maps, joint positions are continuously updated based on these techniques and their rotational angles are represented individually within the global frame. It is more efficient to achieve real-time motion tracking with low-order calculations. Meanwhile by applying the well-designed calibration procedure, it is more convenient to estimate a sensor's position and orientation regardless of knowing its placement. This paper presents our approach and exemplifies the assessment of proposed motion tracking system by several tests of limb and full body motion tracking. The comparisons with Vicon and OptiTrack motion capture systems verify satisfactorily high accuracy.

Whirligig beetle, claimed in the literature to be one of the highest measured for a thrust-generating apparatus within the animal kingdom, has evolved a series of propulsion strategies that may serve as a source of inspiration for designing highly efficient propulsive systems. First, a robotic platform was developed to test an energy-efficient propulsion mechanism inspired by the whirligig beetle. Second, a mathematical model for the robot was proposed to account for the fluid dynamics generated by the robotic swimming. Third, an optimal problem was formulated and solved for the propulsor and beating pattern design. The results indicated that soft middle, stiff end propulsor, and alternating, asymmetrical beating pattern will improve the propulsion efficiency for a swimming robot with four propulsors. Finally, simulation and experiments were conducted to further analyze the effect of beating pattern to the robotic propulsion efficiency. It was found that the oscillated body movement and S-shaped trajectory introduced by the optimal beating pattern would improve the propulsion efficiency for the designed robot.

This paper provides the design of a low cost master controller for teleoperation systems. The system consists of a center handle and four off the shelf haptic devices. The control law of the four devices coordinates them to provide six degree-of-freedom(DOF) force feedback. The relative position and the dimension of the handle are designed to maximize the range of motion. The system actuation redundancy problem is formulated into a standard convex optimization problem and resolved. The squared sum of the force provided by all the haptic devices are defined as the optimization function and the desired force and torque feedback is used as the linear constraints. Experiments in teleoperation and haptics projects were carried out to verify the theoretical results about system.

A teleoperation system with kinesthetic feedback can provide operators with information so that they can make proper judgments as if they were in direct contact with the slave robot work environment. This paper presents the idea of testing the same haptics exploration tasks in both direct and teleoperation scenarios. This provides the advantage that lessons learned in experimental psychology can be used for future teleoperation systems' control and hardware design. One preliminary experiment is presented in this paper to demonstrate the concept. This experiment comprised of three sets of weight perception tasks. One set of direct hand exploration experiments were carried out first. Two sets of teleoperator based experiments, one with a basic two channel controller and the other with three channel controllers, were used to replicate the same set of experiments. Results from the experiments were compared and analyzed.

A new class of fluoroscopy, using a robotic mobile platform, is being developed. The Tracking Fluoroscope System (TFS) is intended to be an orthopedic diagnostic tool that provides more accurate and detailed in vivo pre-operative and post-operative information for surgeons. This is accomplished through the ability to fluoroscope natural and uninterrupted human joint motion during level walking, step climbing, and ramp walking. This overall functionality requires independent tracking of the position and orientation of the body with respect to the robotic platform, as well as the position of the joints with respect to the body. The overall robotic system, embodied in the TFS, necessary to accurately perform real-time imaging of joints in motion is discussed. Recent subject and joint tracking experimental results are presented.

This paper describes a basic passive-versus-aggressive defense model and analyzes it in terms of defense strategies against an intelligent enemy. In response to varying combinations of passive and aggressive defense, we assume that the enemy can up or down regulate the growth activity. This leads to a differential game formulation of battle scenarios. First, we examine military counterterrorist activities in a civilian population. We then consider immune defense against hepatitis B in the liver. The underlying principles in these two examples are similar, although the model features are slightly different. Simulation results are provided to demonstrate the benefits and limitations of the proposed model in terms of understanding biological systems and developing strategic army defense plans.

This paper describes a basic passive vs. aggressive defense model, and analyzes it in terms of defense strategies against an intelligent enemy. In response to varying combinations of passive and aggressive defense, we assume that the enemy can up- or down-regulate recruitment activity. This leads to a differential game formulation of battle scenarios that we analyze for a warfare situation. Specifically, we consider military counterterrorist activities in a civilian population. Simulation results, including uncertainty and sensitivity analyses, are provided to demonstrate the benefits and limitations of the proposed model in terms of understanding army defense plans.

Large multi-fingered end-effectors have promise to provide the added dexterity needed for manipulation while decreasing the amount of special fixturing required for tooling and object manipulation common to remote handling operations in hazardous and unstructured environments such as those in the nuclear domain. This paper presents the integration of a heavy-duty three-fingered articulated hand with a Schilling Titan hydraulic manipulator that is part of a comprehensive telerobotics test bed. Experiments demonstrated that a multi-fingered end effector approach has distinct benefits and advantages.

This paper discusses the tracking algorithms and approach used to control the tracking fluoroscope system. It is a mobile platform equipped with an on-board fluoroscope system to perform real-time imaging of human joints in motion: ankles, knees and hips. In order to record the natural and uninterrupted joint motion, the person has to be able to walk freely while being followed by the robot. It requires independent tracking of the position and orientation of the body with respect to the platform as well as joint positions with respect to the trunk of the body. This paper investigates the problem of tracking position and orientation of a walking person with respect to the following robotic platform.

This paper investigates a perimeter patrol control problem in which multiple agents travel back and forth defending a border. A decentralized control inspired from the adaptive immune system TH1/TH2 differentiation mechanism has been proposed. The resulting patrol control exhibits robustness under adversarial conditions. This is primarily because the motion period can be arbitrary, which makes it difficult for intruders to find weak spots for attack. Moreover, this immuno-inspired control can avoid collision and automatically recover from agent failure.

This paper presents a PID control of a prototype transmission-based robot servo-actuator system (TBA) and its implementation using real time application interface (RTAI) under Linux. The PID control presented can achieve stability and performance requirement in terms of attenuation of disturbance due to gear shift. The control software has a real time multithread design. Verification test shows the new control software has a deterministic control loop time, and significant performance improvement is achieved compared with the implementation using Labview Express under Windows XP

This paper described an error analysis of a camera/laser range finder sensor head to characterize the effects of an error of the sensor head components, and a calibration of the sensor head. The sensor head of the telerobotic system, which is being developed for D&D operation of nuclear facilities, improves the work efficiency of a human operator through visual guidance and 3D modeling of the task space. For successful and accurate task executions, three subsystems must be calibrated:1) calibration of the sensor head, 2) calibration of the homogeneous transformation matrix from the sensor head frame to the manipulator frame, and 3) calibration of the manipulator. This paper determined dominant error sources of the sensor head through the analysis of error propagation, and calibrated the sensor head by compensating the dominant error sources

Sensors such as cameras and range finders provide flexibility and safety to telerobotic manipulations. However, in order to use their supportive features, sensor-based telerobotic control requires that both the sensors and the robot arm be calibrated so that the manipulator can target and articulate objects in the environment easily and effectively. The scope of this paper is to define the sensor-manipulator calibration issue, outline the system errors, describe the calibration methods, and explain the algorithms necessary to provide compensation. The problem was divided into three steps: acquisition of calibration data of the sensor and the arm, numerical analysis and determination of needed parameters, and validation of obtained results. Since the task is to find parameters that represent the object position accurately, the problem is treated as multidimensional least squares optimization problem with simple bounds. The function to minimize is the distance between the target and its calculated position. Two approaches are applied to represent kinematics parameters: Euler angles and quaternions. Solutions are analyzed to determine the best method for future planned online calibration checks as well as to perform teleoperation tasks on the calibrated system

Online modeling or estimating tooling interaction of teleoperation is complicated and difficult. Classic analytical and numerical modeling methods are not suitable for real-time modeling. In this paper, a grey prediction model GM(1,1) was developed for predicting tooling interactions of teleoperation since grey modeling has the following characteristics: (i) small data set, (ii) less computation, (iii) online real-time modeling, and (iv) any kind of data distribution. The developed GM(1,1) was successfully applied to model bandsawing interaction forces.

A novel actuator concept has been developed and prototyped. By integrating a multi-speed transmission with a high performance permanent magnet DC servomotor, it has been shown that an electrical drive can provide power/torque density and physical size that approaches the capabilities of electrohydraulics. Preliminary experimental tests of the prototype are encouraging and the first steps toward verifying the concept.

This paper proposes a methodology for the operational fault detection (OFD) of telerobotic systems using discrete wavelet transform and AC analysis. For the generalization of the proposed methodology, the sensor considered in this study is confined to the sensor, which is usually installed in the standard or general configuration of telerobots, such as joint position sensors. Also, the common characteristics and limitations of telerobots are considered in the development of the algorithms.

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.

This paper addresses the issues of developing fault tolerant control system for telerobotic systems in operational space. First, the characteristics of operational faults and the relevant sensor signals are studied and classified. Secondly, the framework for FDI and the associated supervisory control scheme are proposed to effectively integrate the FDI approaches into telerobotic systems.

In this paper, a methodology to integrate sensor and model based computer assistance into a class of human controlled teleoperator systems called human machine cooperative telerobotics (HMCTR) is presented. In this strategy, the human operator is retained at all phases of the operation, and is assisted, but never superseded, with sensor and model information. This strategy is presented along with the task planner that connects the system to the results of the task space scene modeling. A controller using this strategy in its three control modes: pure teleoperation, autonomous operation, and teleoperation with assistance, was built for use with a Titan II/spl trade/ manipulator that is often used in remote operations at radioactive sites. An experiment was performed that demonstrates the shorter execution times using HMCTR over standard teleoperation procedures are achievable.

Teleoperation performance can be improved through methods that combine remote operation with robotic techniques and lessen the inefficiencies and complexities inherent in teleoperation. The human machine cooperative telerobotics (HMCT) project uses robotic control techniques, called assistance functions, to enhance the ability of the human operator by modifying the operator's commands. This paper presents the concept of HMCT using the force assistance function based on fuzzy control.

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.

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.

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.

This paper is a continued investigation of a new concept for extending the payload-power range of electrical servoactuators. The fundamental idea is to combine small, high power motors with multispeed or continuously variable transmissions such that the effective torque-speed characteristics of the motor are "spread" across a wider output speed range. This has the effect of allowing smaller, high speed motors to also deliver high torque at low speeds. Use of a multispeed transmission allows motor size to be reduced while increasing overall actuator power density in the process. This power density increase can be used to allow a much greater range of electrically-actuated robots to be implemented with distributed actuators and can be used to drastically reduce overall manipulator complexity. This paper discusses the transmission-based actuator concept from a low-level control standpoint, and demonstrates that the "shifting action" of the transmission occurs in a way that is minimally obtrusive to the overall joint servo-control. It is shown that the gear-ratio only changes in situations where high acceleration is desired; the shifting of the transmission happens early in the move, occurs very rapidly, and settles to a final, fixed gear ratio very quickly. For the majority of the move, control objectives are essentially identical to those for available actuators. These results encourage further development of the concept for both robotics and automation applications.

Concerns a concept for extending the payload-power range of electrical servoactuators. The fundamental idea is to combine small, high power motors with multispeed transmissions such that the effective torque-speed characteristics of the motor are "spread" across a wider output speed range, This has the effect of allowing smaller motors to deliver high torque at low speeds. Use of a multispeed transmission allows motor size to be reduced while increasing overall actuator power density in the process. This increase can drastically reduce overall manipulator complexity and can be used to allow a greater range of electric robots to be implemented with distributed actuators. This paper discusses the transmission-based actuator concept from a low-level control standpoint, and demonstrates that the "shifting action" of the transmission occurs in a way that is minimally obtrusive to the overall joint servocontrol. It is shown that the gear-ratio only changes in situations where high acceleration is desired; the shifting of the transmission happens early in the move, occurs very rapidly, and settles to a fixed gear ratio very quickly. For the majority of the move, control objectives are essentially identical to those for available actuators. These results encourage further development of the concept for robot applications.

This paper explores a new approach for extending the operating range of electrical servoactuators in applications such as high payload robotics and remote handling systems where, at present, only hydraulic systems are used. The fundamental idea is to incorporate a multi-speed transmission to "spread" a servomotor's torque-speed characteristics across a wider output speed range. This has the effect of allowing smaller high power motors to also deliver high torque at low speeds. Incorporating a multi-speed transmission allows motor size to be reduced while increasing the overall actuator power density in the process. The hypothesis of this research was that this power density increase would be sufficient to allow a greater range of electrically-actuated robot manipulators to be designed with distributed actuators such that the cost and complexity of centralized actuators with power transmissions could be avoided. An existing articulated manipulator design is used as a baseline to evaluate potential benefits of this concept for robotics. Among these are increased performance, dramatic reductions in manipulator complexity and reduced manufacturing and implementation costs.

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.>

The US Department of Energy has provided support to four universities and the Oak Ridge National Laboratory (ORNL) to pursue research leading to the development and deployment of robotic system(s) for advanced nuclear power stations. The scope of the program and the R&D effort contributed by ORNL are reported.>

The National Aeronautics and Space Administration (NASA) Space Station Program marks the beginning of a new era in space utilization and habitation. Extensive use of remote manipulation and robotics to reduce astronaut extra-vehicular activity is expected. Emphasis on teleoperator technology in early space station phases, followed by growth of autonomous robotics capabilities, is planned. A new telerobot concept has been developed at Oak Ridge National Laboratory (ORNL), under NASA Langley Research Center sponsorship, to address the technical needs of both teleoperations and robotics for these future NASA programs. The concept is based on traction drives, redundant kinematics, modular construction, and a state-of-the-art distributed, hierarchical control system.