Robotics and Automation Expert
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Shared Control of Teleoperated Robots (page 6)

In the configuration advisor application, a single set of joint displacements is one trial configuration. The algorithm generates the displacements for the redundant joints (five for the DAWM) randomly and then solves for the remaining joint displacements (twelve for the DAWM) using inverse kinematics. Performance criteria values associated with the trial configuration are the equivalent of energy in the algorithm. The example application calculates the energy as the weighted sum of two elementary criteria, though continuing work is investigating more sophisticated criteria fusion schemes. One of the criteria measures the approach to joint travel limits and the other criteria measures the approach to collisions. If the trial exceeds a travel limit or would result in a collision, the algorithm rejects the configuration immediately.

Shared Control - There is a quantum leap in complexity as the interaction between operator and machine progresses from the level of intelligent assistance to the level of shared control. The coupled-Cartesian control mode is an example of shared control. A computer algorithm is automatically controlling extra kinematic resources. To reasonably deploy these resources, the computer algorithm needs a great deal of information about the task at hand and the robotís environment. The location of obstacles in the environment is of primary importance. Implementing the coupled-Cartesian control mode for the DAWM requires a solution of the inverse kinematics problem in the redundant case. A number of researchers have developed and implemented solutions to this problem. Whitney was quite influential with his resolved motion rate control that suggests the use of the pseudo-inverse to resolve redundancy. Liegeois showed the extension of this method to include self-motions via the null-space. The coupled-Cartesian control mode implemented a solution based on direct constraint tracking and multicriteria optimization, though the concept of the control mode is generic with respect to the particular solution method.

Conclusions - A spectrum of tasks in unstructured environments characterizes the D&D mission. Telemanipulators represent a technology for accomplishing a portion of the missionís task spectrum. Giving these telemanipulators extra kinematic resources enables them to perform a wider range of tasks, thus further amortizing costs. The extra kinematic freedom also poses new user interface questions because the operator must now control a more complex system.

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