A low-computation, high-bandwidth, inverse-based hysteresis compensation and control strategy, not needing a priori knowledge of the desired trajectory, is presented. The resulting two degree-of-freedom controller is applied to a dynamic mirror with antagonistic piezoelectric stack actuation. Hysteresis compensation is performed by a finite-state machine activating polynomials for hysteresis inversion based on input signal slope. Residual error after hysteresis compensation is corrected by an LQR feedback controller. Experimental results demonstrate effectiveness of the hysteresis compensator and closed-loop system. For the input signal tested, a 91.5% reduction in hysteresis uncertainty is achieved at a 60 kHz sample rate.

In this study, we developed a perception-based quantitative model to relate broadband vibrations transmitted through a motorcycle handlebar to a rider’s hands. The test apparatus consisted of the handlebar of a motorcycle rig assembly driven by a computer-controlled actuator. Participants were instructed to hold the handlebar and maintain a sitting posture as they would while riding a motorcycle. In Exp. 1, psychophysical detection thresholds for 10 participants were estimated at ten test frequencies between 20–300 Hz using a two-interval one-up two-down adaptive procedure. The interpolated threshold vs. frequency function specified the minimum acceleration required before a user could perceive the vibration at a particular frequency. In Exp. 2, participants were asked to rate 15 representative handlebar vibrations using a magnitude estimation procedure. The vibration patterns were measured on an actual motorcycle handlebar while the motorcycle traveled at speeds ranging from 25 to 75 mph. Several weighting functions, including the ISO-5349 standards, were applied to the broadband vibration signal in the frequency domain to estimate the total vibration energy by summing up all weighted components. The best weighting function, in the sense that the estimated total energy correlated linearly with the subjective magnitude ratings obtained in Exp. 2, were based on the detection threshold data obtained in Exp. 1. Specifically, the strength of each vibration component was calculated relative to the human detection threshold at the same frequency, thereby taking into account human sensitivity to vibration signals at different frequencies. The resulting weighting function can be applied to other recorded vibration signals to predict user rating of perceived vibration intensities.

This paper presents a multi-course problem-based learning (PBL) experience to foster the entrepreneurial mindset in the junior and senior mechanical engineering curriculum. Previous senior project students designed, fabricated, and validated a fluid-powered gantry crane that exhibited areas for improvement. To improve upon the project gantry crane, junior-and senior-level students implemented concurrent problem-based learning activities in three courses: Fluid Mechanics, Heat Transfer, and Mechatronics. Even though the PBLs targeted both technical and entrepreneurial objectives, only the results of entrepreneurial mindset attributes are discussed in this paper. Assessment results including student commentary are detailed and discussed in the paper. Preliminary results indicate extensive student practice of entrepreneurial skills.

Tapered roller bearings used to support pinion and differential gears in automotive drive axles perform best with accurate assembled preload. One of the most common high volume production assembly methods relies on bearing friction to adjust preload; however torque is an indirect measure of load, can be influenced by the raceway condition, and is difficult to control. A new method to measure preload utilizes frequency response to estimate axial preload from system stiffness. The stiffness can be measured dynamically and an assembly method automated to set preload without the need for torque or dimensional measurements. By eliminating the need for a torque signal, the raceway conditions which contribute to setting torque do not contribute to the preload setting accuracy. This study demonstrates the effectiveness of using frequency response to measure stiffness and estimate preload.

His research interests include mechatronics, dynamic systems, and control with applications to piezoelectric actuators, hysteresis, and perception. He serves as the faculty advisor for the LTU Baja SAE team.

A dynamic mirror actuator utilizing antagonistic piezoelectric stack actuators is presented for use in laser printers. Exhibiting hysteresis and other nonlinearities in open-loop operation, the dynamic mirror actuator (DMA) requires a control structure to achieve accurate mirror positioning. A linear DMA model is developed for extending operational bandwidth under closed-loop control, employing explicit piezoelectric stack actuator (PESA) charging dynamics and incorporating two modes for single input control of opposing PESA drives. Compared to constitutive models from literature, the proposed model displays a comparable fit with experimental frequency response data while retaining a lower model order. As further validation, simulated step response data are shown to agree with experimental data.