This paper briefly describes a surgical telerobot designed to provide enhanced dexterity to doctors performing minimally invasive surgical procedures. The rationale for a full 7-degree-offreedom master-slave system is presented along with a discussion of the resulting computational architecture and recent clinical applications.
This paper deals with several of the basic concepts in the kinematics of mechanical hands. Several different types of finger contacts are modeled and used in a number synthesis of three-fingered hands. Screw theory is used to show which finger configurations allow complete immobilization of the gripped object relative to the fingers, and also allow for the manipulation of the object by the fingers while maintaining the grasp. Shown in this paper is how to determine the forces applied by the fingers on the object, and also how to compute the velocities of the fingers and the object. The analysis developed in this paper is shown to lead to a hand with three fingers, each with three turning joints, and having friction contacts with an object at three separate points.
Haptic display is the process of applying forces to a h u m a n "observer" giving the sensation of touching and interacting with real physical objects. Touch is unique among the senses because it allows simultaneous exploration and manipulation of a n environment. A haptic display system has three m a i n components.T h e first is the haptic interface, or display devicegenerally s o m e type of electro-mechanical system able t o exert controllable forces on the user with one or more degrees of freedom. T h e second is the object model -a mathematical representation of the object containing its shape and other properties related to the way it feels. T h e third component, the haptic rendering algorithm, joins the first two components to compute, in real time, the model-based forces to give the user the sensation of touching the simulated objects. This paper focuses o n a n e w haptic rendering algorithm f o r generating convincing interaction forces f o r objects modeled as rigid polyhedra (Fig. 1). W e create a virtual model of the haptic interface, called the god-object, which conforms to the virtual environment. T h e haptic interface can then be servo-ed to this virtual model. This algorithm is extensible to other functional descriptions and lays the groundwork f o r displaying n o t only shape information, but surface properties such as friction and compliance.
Continuumrobotic manipulators articulate due to their inherent compliance. Tendon actuation leads to compression of the manipulator, extension of the actuators, and is limited by the practical constraint that tendons cannot support compression. In light of these observations, we present a new linear model for transforming desired beam configuration to tendon displacements and vice versa. We begin from first principles in solid mechanics by analyzing the effects of geometrically nonlinear tendon loads. These loads act both distally at the termination point and proximally along the conduit contact interface. The resulting model simplifies to a linear system including only the bending and axial modes of the manipulator as well as the actuator compliance. The model is then manipulated to form a concise mapping from beam configurationspace parameters to n redundant tendon displacements via the internal loads and strains experienced by the system. We demonstrate the utility of this model by implementing an optimal feasible controller. The controller regulates axial strain to a constant value while guaranteeing positive tendon forces and minimizing their magnitudes over a range of articulations. The mechanics-based model from this study provides insight as well as performance gains for this increasingly ubiquitous class of manipulators.
The book presents the most current research in manipulator design and control of direct-drive robot arms. In direct-drive robots the shafts of revolute joints are directly coupled to the
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