A large number of bilateral teleoperation control architectures in the literature have been designed based on assumed impedance models of the master and slave manipulators. However, hydraulic or heavily geared and many other manipulators cannot be properly described by impedance models. In this paper, a common four-channel bilateral control architecture designed for the above impedance models is extended to teleoperation systems with master and slave manipulators of either the admittance or impedance type. Furthermore, control parameters that provide perfect transparency under ideal conditions are found for each type of teleoperation system. Because in practice such parameters may not lead to systems that are robust to time delays and model uncertainties, an analysis of the stability and performance robustness of this very general architecture and two-channel architectures is also presented. The analysis uses the passivity-based Llewellyn two-port network absolute stability criterion, as well as bounds on the minimum and range of values of the impedance transmitted to the operator. The results of these evaluations provide design guidelines on choosing a particular control architecture and its parameters given different master and slave manipulator structures.

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Earth-moving machines such as hydraulic excavators are usually used for carrying out contact tasks. Impedance control can be employed as an approach for achieving compliant motion in such tasks. This paper describes a position-based impedance controller that has been developed in our laboratory for excavator-type manipulators, and presents supporting experimental results. First, the problem of impedance control for a single hydraulic cylinder is addressed and a method is presented to analyze the system stability. The steady-state position and force tracking accuracy of the closed-loop system is also studied. Next, the problem of impedance control for a multilink hydraulic excavator is addressed and the arm Jacobian and accurate estimates of the arm inertial terms are employed to map the desired impedance of the end-effector (bucket of the excavator) onto the hydraulic cylinders. Various contact experiments carried out using an instrumented mini-excavator demonstrate that the proposed impedance controller has very good performance for both single-link and multilink cases.

A novel shared control architecture is presented for dual-user haptic training simulation systems for enhanced interaction between the users and between each user and the virtual environment. The coupled stability of the proposed control architecture against uncertainties in the environment and the user's dynamics is investigated using the three-port master-slave network model of the dual-user haptic simulation system. For this purpose, Llewellyn's unconditional stability criterion is applied to an equivalent two-port network model obtained from the corresponding three-port network, considering the environment as a load termination. The kinesthetic performance of the proposed architecture is numerically analyzed for transparency and evaluated against a benchmark control architecture under different operating conditions, such as various types of environments, users' grasps, and levels of dominance of users over the task. An experimental user study is carried out to assess the effectiveness of the proposed architecture in terms of users' perception of environment stiffness sensing, device agility, and haptic guidance reception.

This paper presents the prototype for an augmented reality haptic simulation system with potential for spinal needle insertion training. The proposed system is composed of a torso mannequin, a MicronTracker2 optical tracking system, a PHANToM haptic device, and a graphical user interface to provide visual feedback. The system allows users to perform simulated needle insertions on a physical mannequin overlaid with an augmented reality cutaway of patient anatomy. A tissue model based on a finite-element model provides force during the insertion. The system allows for training without the need for the presence of a trained clinician or access to live patients or cadavers. A pilot user study demonstrates the potential and functionality of the system.