Flooding, by which the sink node broadcasts messages to the entire network, is an important and common operation in wireless sensor networks (WSNs). The emerging synchronous duty-cycled wakeup schedules together with the unreliable communication of WSNs post new challenges for efficient broadcast protocol design, and the existing methods are not appropriate to address this problem. This paper proposes a delay-aware energy-optimized flooding algorithm (DEF) tailored for synchronous duty-cycled WSNs, which can act as an enhanced scheme for most flooding trees. DEF globally adjusts a constructed flooding tree, to maximize the energy efficiency improvement while following the delay constraint. To this end, we first remodel the flooding problem in the new context mathematically. Then, we introduce a routing metric, which fully utilizes the features of synchronous duty-cycled WSNs for energy optimization, and design an effective delay-aware tree adjusting approach. Extensive evaluation results demonstrate that DEF could save considerable energy, while the flooding delay keeps unchanged or even decreases slightly. In addition, a modified minimum spanning tree (MMST) is proposed to indicate the approximate energy lower bound. Compared with MMST, DEF achieves comparable energy efficiency and better latency performance.

Contact detection based on computing minimum distance is a fundamental issue important to many applications. A largely unsolved problem is how to detect multiple contacts that are formed simultaneously between non-convex and non-polyhedral general objects both accurately and in real-time. This paper presents an effective solution to the problem. Our approach first locates the pairs of closest components by fast intersection checking based on hybrid bounding volume hierarchies of surface components. For each pair of such components, it then finds the pairs of closest points and corresponding pairs of closest parametric features by combining collision detection or minimum distance query between polygonal meshes of those components and exact distance computation between the parametric features. Implementation results show that this approach can compute multiple simultaneous contacts between general objects both very accurately and efficiently in the order of several milliseconds regardless of the numbers of features on the objects

Haptic rendering has the potential to increase the quality of human-computer interaction with virtual environment by accommodating the sense of touch. In this paper, a 7 DOF arm type exoskeleton device is designed and implemented. Human user can haptically interact with virtual environment by using this light-weight device. The principles of measuring user's arm motions are presented, which include the dimensional mechanism. The motion of each joint of the proposed haptic device is nearly independent. The virtual contact force is also calculated in real time to meet the stringent requirement of real time haptic rendering. Experiments results show promising feasibility of the arm type exoskeleton device.

Telesurgery is an interdisciplinary field of teleoperated robotics and robot-assisted minimally invasive surgery, and has good promising future. In this work, the structure and work flow of the tele-neurosurgery are addressed at first. Then the key technologies involved, including our newly developed surgical robot, untouched methodology in localizing marks for registration, video overlay and surgical simulation, video transmission and network communication, and safeguards, are discussed, which guarantee the safety and feasibility of the clinical telesurgery. In the end, the first remote clinical stereo tactic neurosurgery is presented.

A computer and robot assisted telesurgical system for stereotactic neurosurgery is presented in this paper. Using the user friendly interface for surgical planning, the surgeons can make the surgical planning on the model reconstructed in the computer, and marker registration is used to create the mapping between the patient's head and the 3D-brain model. When appropriate entrance position on the skull and entrance trajectory are determined through the surgical planning, they are exported to remote physical medical robotic system, via the Internet, for real-world execution. Remote robotic system is not only used as a navigational tool to direct the surgery planning, but also used as an instrument platform to assist surgeons to accomplish the operation. This computer and robot assisted tele-neurosurgery system has been successfully used in clinical application.

The surgical training system presented in this paper provides the surgeon a virtual surgical practice environment for the robot assisted minimally invasive neurosurgery, which includes collision detection, deformation of soft issue and haptic rendering. The 3D model of the brain structure of the patient is reconstructed based on the 2D images. After the virtual robot move to the entrance pose that is planned by the user, it is fixed, and the user can control the virtual needle to insert into the virtual head to verify his planning. During needle insertion, the inner structure of patient head is displayed, and the resistance force between the needle and organs is calculated and reflected to surgeon by haptic device. An improved collision detection scheme is also proposed to meet the need of real time haptic rendering. Using this virtual training system, the surgeon can make virtual neurosurgery to take cost-effective practice and training.

This paper presents the formulation of the inverse kinematics and dynamics of the 3-RRS parallel platform with three degrees of freedom. For inverse kinematics, the position analysis is first performed. Then the differential motion constraint equations of the movable platform are established, based on which the velocity and acceleration formulae of leg actuators are derived. In the inverse dynamic analysis, the parallel platform is decomposed into two parts through parting the three spherical joints, and the forces acting on the parted joints are determined according to the moment (and force) equilibrium's of the legs and the movable platform. Subsequently, the analytic expressions of the driving moments of the leg actuators are derived by means of the moment equilibrium of the legs. Although only the 3-RRS parallel platform is analyzed, the presented method and process can also be applied to other less DOF parallel platforms.

Teleoperation is a viable alternative to project a human operator's intelligence into the places that are inaccessible or dangerous to people, or where expertise and resources are not available. Due to the distance between the human operator and remote environment, the human-machine interface is an important component for the overall system performance capabilities and efficiency. The paper proposes a new design method of multimodal interface for teleoperation. A distributed graphic predictive display subsystem based on virtual reality is implemented, and all kinds of feedback information acquired from a remote environment, such as actual live images, audio and force information are organized and presented to human operators in an appropriate, way. Experimental results demonstrate that the multimodal human-machine interface can reduce a human operator's mental workload and facilitate teleoperation. Some key technologies concerned with this multimodal interface, such as the synchronization mechanism of the distributed predictive simulation subsystem and the real time transmission of actual live multimedia via the Internet under narrow bandwidth are also developed.