The disadvantages of non-minimum-phase (NMP) systems for control applications are well known. Prior research has shown that a NMP system can be discretized to an minimum-phase (MP) system using either a zero-order hold or square-pulse sample and hold input. First the research focused on the MP characteristics of the discrete-time system that obtained from a continuous-time single-input-single-output NMP system by using different sample and hold inputs. Two new sample and hold inputs (forward and backward triangular) are studied in addition to the square pulse. Numerical simulations were adopted for studying the MP property of the resulting discrete-time system as a function of sample and hold parameters. The simulation results show that it is possible to find a smaller sampling period that results in an MP discrete-time system using the proposed sample and hold inputs compared to zero-order hold. The q-Markov Cover system identification with pseudo-random binary signal (PRBS) was then used for a hardware-in-the-loop (HIL) simulation study. A resistor-capacitor filter was used to represent the implementation error of the sample and hold input due to unmodeled actuator dynamics. HIL simulation results show that the proposed sample and hold input scheme is robust to actuator modeling error. The MP properties of the discrete-time systems with three sample and hold inputs are compared. The results show that the forward triangle sample and hold input has the best performance due to its robustness to unmodeled actuator dynamics and the capability of retaining MP property of the discretized system at small sampling periods.Based on the analytical result, the advantages of using the SHIs for the single inverted pendulum through simulations and experiments were studied. In particular, it is shown that the performance of the stabilized closed-loop system can be improved by designing an dual-loop controller based on the MP discrete system obtained using the SHIs. Simulation results in the presence of Coulomb friction show that the additional controller reduces cart oscillations significantly; for a particular SHI, the steady state amplitude of oscillation was reduced by up to 68.95%. Experiments confirmed the results obtained in simulations.The dual-loop control technique is also demonstrated for performance improvement on a mini Segway (MS), a robot developed for an undergraduate mechatronics class which equipped with an extremely low cost microcontroller (Arduino). It is important to show that the special SHIs can be implemented in a low cost micro-controller. A dual-loop control tuning method was also developed to optimize the overall closed-loop system performance. Experimental result shows that the low cost microcontroller can be used for the dual-loop SHI control scheme and the MS cart displacement oscillation is significantly reduced by more than 60\\% over the baseline controller. A solid-set canopy delivery system (SSCDS) is developed to deliver water and chemical solutions to high-density fruit trees with the support from USDA-SCRI (US Department of Agriculture Specialty Crop Research Initiative). For the purpose of detecting SSCDS faults, two methods were proposed and they are flow and/or pressure sensors based in-line detection method and thermal image based detection method. A FLIR thermal camera was mounted on a modified commercial Unmanned Aerial Vehicle (UAV) so that any plug, partial plug, and gusher faults can be captured by the thermal camera during the water and chemical spray process. With the help of a image processing software, the thermal video is stitched into one panorama image. By comparing it with a baseline panorama image, the SSCDS faults can be detected. The main advantage of the proposed fault detection method is the ability of distinguishing all three types of faults over a huge area within a fairly short amount of time, utilizing only a UAV equipped with both regular and thermal video cameras. The future work is to fly the UAV automatically based on a pre-planned route, collect the thermal video, process the panorama image and diagnose the SSCDS faults.
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