DIMLab Stander Symposium Projects

2017

The RASSO - A Robotic Assistant for Surgical LaparoScopic Operations
The Rasso robot is a biomimetic robot expected to be used in place of standard laproscopic surgery. Being inserted through a 3-4 cm incision, the robot is designed to navigate along the top of the abdominal wall. This is made possible due to the stomach being inflated by a gas throughout the surgery. The Robot, having pads attached to its legs that mimic a gecko's limbs, allow for the robot to adhere itself upside down to the wall of the inflated stomach. The microstructure of this material allows for adhesion to a wet surface just as a gecko's would. Utilizing a peeling motion to detract the legs, the robot is capable of moving across the surface without dropping towards the surgical area. It is hoped that eventually laproscopic tools can be attached to the robot that will allow this surgery to be performed remotely. My contribution specifically involves the introduction of a new kinematic design that allows for improved movement along the abdominal wall. Within that redesign I also am working towards improving the necessary peeling motion of the gecko-like material so as to minimize reactionary forces acting on the robot.

Design and Prototyping of a Shape-changing Rigid-body Human Foot in Gait
This project focuses on the design and prototyping of a practical, multi-segment rigid body foot mechanism capable of matching the dynamic change in profile of a human foot throughout multiple stages of gait. Dynamic models of the human foot often replicate the physiological change in shape of the foot during gait using compliant mechanisms. While rigid body foot models exist, these models are often simplified as single-segment bodies incapable of accurately representing the geometry and kinematics of the human foot. Multi-segment rigid body systems offer certain advantages over compliant systems which may be desirable in the design of ankle-foot devices, including the ability to withstand greater loading, the ability to achieve more drastic shape change, and the ability to be synthesized from the kinematics, allowing for realistic functionality without consideration of the complex internal kinetics of the human foot.

Assessing Shape Repeatability in Variable Geometry, Polymer Extrusion Dies
Die extrusion is a manufacturing process to create parts with a fixed cross-sectional profile by passing melted plastic through a die of the desired cross-section. The resulting plastic piece then hardens as it is pulled through a water trough and is then cut into pieces with the desired length. Extrusion has significant cost savings over other plastic processing methods. In current technology, the dies have a fixed geometry creating parts with a constant cross-section. The objective of this project is to create a die that can change shape by actuating a lever resulting in a part with variable cross sections. In order to determine the feasibility of variable geometry extrusion, dies have been designed and constructed. The process is tested by the use of a laser scanner that captures data points of the cross sections at multiple locations along the variable extruded part. The data is analyzed by a numerical process to determine the repeatability accuracy by comparing multiple profiles of the same extrusion.

Analysis of Joint Leakage in Variable Geometry Die
This project presents a computational analysis of multiple joint types used in variable geometry dies that enable the extrusion of polymer plastic parts with a varying cross-sectional area. Polymer extrusions account for nearly half of all manufactured plastic parts due to it being a high production and low cost process. Traditional polymer extrusion is limited to fixed dies that produce plastic products of continuous cross-sectional area defined by the die exit profile. A variable geometry die allows the cross-sectional area of the extruded polymer part to vary while being extruded. To allow for a change in shape, multiple links move around various joints. Clearances in the joints are required for the joints to properly function and to be able to properly manufactured the joints. These clearances create leakage paths for the melted polymer to escape through and potentially damage the quality of the plastic part. Computational fluid dynamics models have been constructed and used to assess the effect of the various clearance sizes on the leakage through the joints. The goal of this analysis is to optimize the clearance require in the geometry of the joints.

Design of an Opposed-piston, Opposed-stroke Diesel Engine for Utility Aircraft 
An opposed piston, opposed stroke is a unique diesel engine design as each cylinder contains two pistons which means that the combustion chamber is captured between the two pistons as they move towards each other. In this thesis project, an opposed piston, opposed stroke diesel engine was designed for use in utility aircraft. Utility aircraft are used for commercial purposes with a maximum takeoff weight of 12,500 lbs and commonly powered by gas turbine engines that drives a propeller. Compared to the turboprop alternative, opposed piston diesel engines offer a greater power density, weight reduction, and increases in fuel, thermal, and combustion efficiencies. In conjunction with the Foundation for Applied Aviation Technology, specifications for the engine have been prepared, including a required 800 hp at takeoff. As part of the research project, an analytical simulation model was formulated to determine the appropriate physical dimensions and a virtual prototype was produced. 

Spherical Linkages Analysis and Synthesis by Special Unitary Matrices for Solution via Numerical Algebraic Geometry 
Numerical algebraic geometry is the field that studies the computation and manipulation of the solution sets of systems of polynomial equations. The goal of this research is to formulate spherical linkages analysis and design problems via a method suited to employ the tools of numerical algebraic geometry. Specifically, equations are developed using special unitary matrices that naturally use complex numbers to express sphysical and joint parameters in a mechanical system. Unknown parameters expressed as complex numbers readily admit solution by the methods of numerical algebraic geometry. This work illustrates their use by analyzing the spherical four-bar and Watt I linkages. I addition, special unitary matrices are utilized to solve the five orientation synthesis of a spherical four-bar linkage. Additionally, synthesis equation were formulated for Watt I linkage. The numerical algebraic geometry software used throughout is Bertini.

Energy Analysis of a Two Degree of Freedom Robotic System
Energy usage is increasing in manufacturing operations. One reason for the increase is the shift to automation and robotics. Robots use an array of motors to manipulate objects, and each motor uses energy to operate and move the robot. In most cases, the motors use energy even when holding an object still or while the robot sits idle between tasks. This project focuses on the design and efficiency of a robot that requires fewer motors than a typical industrial robot yet is capable of performing many of the same industrial tasks. A CAD model of the robot is developed to perform an energy analysis during a typical operation cycle and then to optimize this cycle. Additionally, experimentation will augment the analysis through the use of a microprocessor controlled motor to measure current requirements while performing specified motions.

Simulation of an Automatic Commercial Ice Maker
Automatic commercial ice making machines that produce a batch of cube ice at regular intervals are known as “cubers”. Such machines are commonly used in food service, food preservation, hotel, and health service industries.The machines are typically rated for the weight of ice produced over a 24 hour period at ambient air temperatures of 90 °F and water inlet temperature of 70 °F. These cubers typically utilize an air-cooled, vapor-compression cycle to freeze circulating water flowing over an evaporator grid. Once a sufficient amount ice is formed, a valve switches to enable a harvest mode. The U.S. Department of Energy has set a target of reducing energy usage by 10 - 15% by 2018. Engineering models are not publicly available to assist designers in achieving the new energy regulations. This work presents an engineering simulation model that addresses this need. This model simulates the transient operation of a cuber ice machine based on fundamental principles and generalized correlations. The model calculates time-varying changes in the system properties and aggregates performance results as a function of machine capacity and environmental conditions. Rapid “what if” analyses can be readily completed, enabling engineers to quickly evaluate the impact of a variety of system design options. Simulation results from the model were compared with the experimental data of a fully instrumented, standard 500 lb capacity ice machine, operating under various ambient air and water inlet temperatures. Key aggregate measures of the ice machine’s performance are: 1) cycle time (duration of freeze plus harvest cycles), 2) energy input per 100 lb of ice, and 3) energy usage during 24 hours. For these measures, the model’s accuracy is within 5% for a variety of operating conditions.