Analysis, design, and control of an omnidirectional mobile robot in rough terrain

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2008.Includes bibliographical references (leaves 49-52).An omnidirectional mobile robot is able, kinematically, to move in any direction regardless of current pose. To date, nearly all designs and analyses of omnidirectional mobile robots have considered the case of motion on flat, smooth terrain. In this thesis, an investigation of the suitability of an active split offset caster driven omnidirectional mobile robot for use in rough terrain is presented. Kinematic and geometric properties of the drive mechanism are investigated along with guidelines for designing the robot. An optimization method is implemented to explore the design space. These analyses can be used as design guidelines for development of an omnidirectional mobile robot that can operate in unstructured environments. A simple kinematic controller that considers the effects of terrain unevenness via an estimate of the wheel-terrain contact angles is also presented. It is shown in simulation that under the proposed control method, near-omnidirectional tracking performance is possible even in rough, uneven terrain.by Martin Richard Udengaard.S.M

Mechanical Design of Cylindrical Track for Sideways Motion

Proceedings of 2008 IEEE International Conference on Mechatronics and Automatio

A modified footplate for the Kerrison rongeur

Use of the Kerrison rongeur for bone removal in spinal surgery is associated with dural tears and cerebrospinal fluid (CSF) leaks. We report a modification of the Kerrison rongeur footplate designed to reduce the risk of dural tears. A novel footplate was designed by incorporating the following parameters: (1) tapering the footplate to deflect soft tissue downward during positioning of the rongeur underneath the bone, and (2) making the footplate longer and wider than the cutting element to prevent soft tissue from entering into the cutting surface. Stereolithography models of the modified footplate were made and tested in a cadaver. A stainless steel modified footplate was then incorporated into an existing Kerrison rongeur as a working prototype, and tested in 20 laminectomy cases to clinically validate its design. The modified footplate prevented soft tissue from entering the cutting surface of the Kerrison rongeur in the manner intended by its design. No dural tears or CSF leaks were encountered in any instance. Potential soft tissue compression caused by an increase in footplate dimensions was not a significant issue in the rongeur size tested. This modification, however, might not be practical in rongeurs larger than 3 mm. The risk of dural tears and cerebrospinal fluid leaks in spinal surgery may be reduced by this footplate modification of the Kerrison rongeur. Soft tissue compression may limit the incorporation of this modification to rongeurs of 3 mm or smaller. The promising results warrant further tests with a wider range of sizes.Center for Integration of Medicine and Innovative Technology (U.S. Army Medical Research Acquisition Activity Cooperative Agreement No. DAMD17-02-2-0006

Health Survey of Pet Rabbits in Norway

In Norway, the Animal Welfare Act aims to promote good animal welfare and respect towards animals

Speed-Dependent Eigenmodes for Efficient Simulation of Transverse Rotor Vibration

Accurate, computationally efficient simulations enable engineers to design high-performing, cost-efficient, lightweight machines that can leverage models of predictive controls and digital twin predictive maintenance schedules. This study demonstrates a new speed-dependent eigenmode method for accurately and efficiently simulating shaft transverse vibrations. The method involves first independently computing shaft eigenmodes over a range of operating speeds, then correlating the eigenmodes across the different speeds during compilation, and finally adjusting modal properties gradually in accordance with a lookup method during simulation. The new method offers several distinct advantages over the traditional static eigenmodes and Craig-Bampton methods. The new method maintains accuracy over a large range of shaft rotation speeds whereas the static eigenmodes method does not. The new method typically requires fewer modal degrees of freedom than the Craig-Bampton method. Whereas the Craig-Bampton method is limited to modeling changes at the boundaries, the new method is suitable for modeling changing body properties as well as boundary-based changes. For this paper, a fluid-bearing-supported 10 MW direct-drive wind turbine drive shaft is tested virtually in a simulation model developed in Simscape™ Driveline™. Using the simulation statistics, this study compares the accuracy and computational efficiency of the speed-dependent eigenmode method to the traditional finite lumped element, static eigenmode, and Craig–Bampton methods. This paper shows that the new method simulates the chosen system 5 times faster than the traditional lumped mass method and 2.4 times faster than the Craig-Bampton method