Mechatronics

The purpose of this study was to investigate the validity of linear position
transducers (LPTs), The Open Barbell System (OBS) and Tendo Weightlifting Analyzer
System (TWAS), in comparison to criterion measure Optotrak Certus (OC3D). Further,
we aimed to compare LPTs against each other. Twenty-five resistance-trained males were
recruited, and reported to the laboratory for one day of data collection. Subjects
performed one-repetition maximum (1 RM) testing of the squat, then had a standardized
rest before completing one set to failure with 70% 1 RM. There was no significant
difference in average velocity (AV) between either LPT vs. OC3D. T-tests revealed
significant differences between LPTs and OC3D peak velocity (PV) (OBS: p=0.02080;
TWAS: p<0.01). A significant difference was detected between OBS and TWAS PV
(p<0.01). OBS and TWAS demonstrated concurrent validity compared to OC3D for AV
(OBS: p=0.2014; TWAS: p=0.5466). Neither LPT was a valid measure ofPV (OBS:
p=0.0208; TWAS: p<0.01).

novel approach to extend the decision-making capabilities of unmanned surface vehicles
(USVs) is presented in this work. A multi-objective framework is described where separate
controllers command different behaviors according to a desired trajectory. Three behaviors
are examined – transiting, station-keeping and reversing. Given the desired trajectory, the
vehicle is able to autonomously recognize which behavior best suits a portion of the
trajectory. The USV uses a combination of a supervisory switching control structure and a
reinforcement learning algorithm to create a hybrid deliberative and reactive approach to
switch between controllers and actions. Reinforcement learning provides a deliberative
method to create a controller switching policy, while supervisory switching control acts
reactively to instantaneous changes in the environment. Each action is restricted to one
controller. Due to the nonlinear effects in these behaviors, two underactuated backstepping
controllers and a fully-actuated backstepping controller are proposed for each transiting, reversing and station-keeping behavior, respectively, restricted to three degrees of freedom.
Field experiments are presented to validate this system on the water with a physical USV
platform under Sea State 1 conditions. Main outcomes of this work are that the proposed
system provides better performance than a comparable gain-scheduled nonlinear controller
in terms of an Integral of Absolute Error metric. Additionally, the deliberative component
allows the system to identify dynamically infeasible trajectories and properly
accommodate them.

This thesis discusses the coupling of a mechanical and electrical oscillator, an arrangement that is often encountered in mechatronics actuators and sensors. The dynamics of this coupled system is mathematically modeled and a low pass equivalent model is presented. Numerical simulations are then performed, for various input signals to characterize the nonlinear relationship between the electrical current and the displacement of the mass. Lastly a framework is proposed to estimate the mass position without the use of a position sensor, enabling the sensorless control of the coupled system and additionally providing the ability for the system to act as an actuator or a sensor. This is of value for health monitoring, diagnostics and prognostics, actuation and power transfer of a number of interconnected machines that have more than one electrical system, driving corresponding mechanical subsystems while being driven by the same voltage source and at the same time being spectrally separated and independent.