Master of Science in Electrical Engineering (MSEE), Wright State University, 2023, Electrical Engineering

Stochastic resonance (SR) is a phenomenon that can enhance the detection or transmission of weak signals by adding random noise to a non-linear system. SR introduced into the human motor control system as a subthreshold mechanical vibration has shown promise to improve sensitivity to haptic feedback. SR can be valuable in a laparoscopic surgery application, where haptic feedback is critical. This research sought to find if applying SR to the human motor control system improves performance in a laparoscopic probing task, if the performance differs based on the location of stochastic resonance application, and if there are sustained effects from SR after its removal. Subjects were asked to perform a palpation task using a laparoscopic probe to determine whether a series of simulated tissue samples contained a tumor. Subjects in the treatment groups were presented with a series of samples under the following conditions: Pre-SR, SR applied to the forearm or elbow, and Post-SR. Subjects in the control group did not have SR applied at any point. Performance was measured through the accuracy of tissue assessment, subjects' confidence in their assessment, and assessment time. Data from 27 subjects were analyzed to investigate the application of stochastic resonance and its sustained effects to improve haptic feedback sensitivity in a simulated laparoscopic task. The forearm group was shown to have significant improvement in the accuracy of tissue identification and sensitivity to haptic feedback with the application of SR. Additionally, the forearm group showed a greater improvement in accuracy and sensitivity than the elbow group. Finally, after SR was removed, the forearm group showed sustained significant improvement in accuracy and sensitivity. Therefore, the experiment results supported the hypotheses that stochastic resonance improves subjects' performance and haptic perception, that performance improvement differs based on application location, and that subjec (open full item for complete abstract)

Committee: Luther Palmer III, Ph.D. (Advisor); Caroline Cao Ph.D. (Committee Member); Katherine Lin M.D. (Committee Member) Subjects: Biomedical Engineering; Biomedical Research; Engineering; Health; Health Care; Mechanical Engineering; Surgery

Master of Science (M.S.), University of Dayton, 2015, Mechanical Engineering

An active, feedback vibration control strategy with the goal of abating gear whine noise in rear-wheel and all-wheel drive vehicles is developed. The control strategy was implemented using two small inertial (proof mass) actuators, mounted on the rear subframe of a luxury all-wheel drive sedan with independent rear suspension, as the active elements in this application. Acceleration information measured by accelerometers nearly-collocated with the actuators was used as the feedback signal. The effectiveness of active vibration control was successfully demonstrated by examining the extent of reduction in the shaker induced vibration of the rear subframe as well as the sound pressure inside the vehicle. The evaluation of the active control scheme was extended to rolling dynamometer tests, during which effective reduction of vibration of rear subframe and the pressure inside the vehicle were demonstrated.

Committee: Reza Kashani Ph.D. (Committee Chair); Dave Myszka Ph.D. (Committee Member); David Perkins Ph.D. (Committee Member) Subjects: Mechanical Engineering

Master of Science, The Ohio State University, 2005, Mechanical Engineering

While piezoelectric driven actuators offer many attractive characteristics, the limited strain of piezoelectric materials necessitates the use of an actuation mechanism to amplify stroke for many applications. Screw-type stick-slip actuators offer the attractive characteristics of large stroke, fine resolution, high power-off holding force, and relative simplicity to manufacture. However, the actuation speed of current rotary stick-slip actuators limits their applications. This research seeks to expand the application of screw-type stick-slip actuators by increasing actuation speed. Three approaches for meeting this objective are evaluated, resulting in three actuator concepts. Two of these concepts are then developed, constructed, tested, and compared with two commercial actuators: the Picomotor and the Inchworm. Actuator characterization is critical for the modeling, optimization, and comparison of actuator designs. This research also reviews performance metrics proposed by various authors and expands an existing actuation efficiency model to incorporate an amplification mechanism.

Committee: Gregory Washington (Advisor) Subjects: Engineering, Mechanical

Doctor of Philosophy, The Ohio State University, 2005, Industrial and Systems Engineering

The dynamic behavior of the PZT-5H Bimorph bender actuator is studied by applying driving waveforms with higher harmonics. Due to the large dynamic displacement the actuator providing at its tip, the trajectory of the actuator response is emphasized instead of stroke of the response. The mathematical model of the actuator (combined the mechanical cantilever bin and electrical model of the actuator) is derived and a computer simulation is used to describe the dynamic behavior of the actuator under different frequencies. Since both significant delay and hysteresis effect of the actuator are induced by its large capacitance and dynamic ferroelectric property, how to reduce the undesired deformation and handle the coupling between delay and hysteresis is emphasized in our research. To acquire a precise hysteresis model of the actuator independent of the system delay, the major loop and minor loop of the actuator is studied both statically and dynamically. Experimentally, an optical interferometer is employed to sense both the static and dynamic displacement of the actuator and the results are compared with the mathematical simulations. Once the precise model is acquired, an inversion-based adaptive control algorithm is employed. Since the operation system is varying with time, the plant model used in control needs to be detected continuously. The recursive Least Square method is used in dynamic system identification. A FIR filter is designed to decouple the linear and nonlinear noise and bring the response of the actuator to desired trajectory. After fundamental frequency adaptation and disturbance suppression, great improvement has been detected in the waveform tracking. Finally, the controlled piezo actuator is applied to a one-dimensional vibratory feeding system and the precision of the actuating system is analyzed. It is proved experimentally that the feeding speed of decoupled vibratory feeder can be adjusted dynamically and no hopping and backsliding are detected (open full item for complete abstract)

Committee: Garp Maul (Advisor) Subjects: Engineering, Industrial

Master of Science, University of Akron, 2007, Electrical Engineering

This thesis presents a charge feedback method for linear control of a piezoelectric stack actuator. The charge feedback control system incorporates a high-impedance, high-voltage charge sampling circuit, a window comparator, and a low-resistance, switched-mode (non-PWM) actuator drive circuit. The system design and modeling are discussed in detail. A describing function stability analysis is performed to determine the allowable variations in the comparator dead zone and the actuator drive circuit propagation delay. Experiments were conducted to compare the responses of the stack actuator under voltage and charge control and to determine the frequency and amplitude limits of operation. The experimental data show that the charge control provides nearly linear actuator operation from 0.1 Hz to 10 Hz over 66.7% of the actuator operating range, and from 0.1 Hz to 100 Hz over 56.7% of the operating range. The constrained displacement range is found to be a function of the actuator drive circuit and charge sampling circuit implementations, and therefore not a general limitation of the presented charge control design.

Committee: Robert Veillette (Advisor) Subjects: