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4:15pm, Adamson Wing, Baker Hall
The speaker will describe the sensing, calibration, and actuator system used to convert an existing 30-ton high bay bridge crane at NIST to computer control for automated placement of construction components. The system is being designed to permit either telepresent or fully autonomous assembly of a subset of a full-scale process plant. In order to achieve six degree-of-freedom manipulation of the individual components the traditional bridge crane cable and hook has been replaced by TETRA, an inverted cable operated Stewart platform equipped with various manipulators attached to a suspended triangular platform. The sensing systems are largely concentrated into three categories: displacement, force, and state sensors. What makes this application unique is the scale of the robot: the crane spans 23 m, has a run length of 32 m and a working volume height of 24 m. This scale, and a need for clean operation without power and communications wires, has led to a control system based on discrete sensing packets. The packets consist of one or several force, displacement, or state sensors (limit switches, hall effect chips) which receive their power locally and are connected to local microcontrollers. Each microcontroller, in turn, broadcasts its data via wireless ethernet to a master controller which then communicates with the world via a high speed ATM link. Issues relating to selection, implementation, and calibration of the sensor array needed to operate this large construction robot will be discussed.
For appointments, please contact the host, Jim Osborn: firstname.lastname@example.org, 412.268.6553
You can also visit the Construction Automation home page.
This appears on the World Wide Web at http://www.frc.ri.cmu.edu/~mcm/seminar.html