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Mechanical System Simulation

Technology Category: Intelligent Robotics

Description: The Applied Mechanics, Measurements and NDE Group at Pacific Northwest National Laboratory (PNNL) designs and analyzes mechanical systems using a suite of simulation tools in concert to develop effective engineering simulations of these systems. The group has state-of-the-art high-speed computer workstations and an extensive library of computer codes that support these kinds of simulation. The group has the knowledge and experience to step into any phase of the design process and use simulation to provide the results required to move on to the next phase of design. The simulations can supplant physical prototypes in many cases, thus streamlining the design process. More importantly, the simulation can model system usage, including the entire process and other devices with which the machine interacts. The analyst uses this simulation to evaluate timing, potential collisions, machine and operator interactions and other issues that would be difficult or impossible to understand prior to system integration. This comprehensive modeling approach allows the system designer to focus on the process that is being designed, then the tools that carry out the process, and finally the details of the design and fabrication.

When kinematic issues are important analysts will use the IGRIP kinematic simulation code to develop an animated three-dimensional graphical representation of the system under consideration. These models provide excellent visualization capabilities, collision detection features, and can model the dynamics of certain types of rigid-body mechanical systems. IGRIP can also be used to perform robotic reachability studies, develop robot control programs off-line, and study the ergonomics of tasks performed by humans. A representative graphic from an IGRIP model is shown at left. The system in the graphic is a Stewart platform-based teleoperated pneumatic manipulator. This system was developed entirely using computer simulation and rapid prototyping - very few paper drawings were used.

The DADS code is a dynamic modeling package that handles more complex dynamics calculations for systems including hydraulic actuators, impact, flexibility, and interactions with road surfaces, control systems, and other complex nonlinear effects. Flexible analysis results from the ANSYS code can be imported into DADS, allowing rigorous simulation of flexibility effects. The DADS code can also be interfaced with the MATLAB controls development code. This allows the MATLAB-developed controller to operate directly on the nonlinear DADS model.

Point of Contact: Carl Baker (509) 375-3614