Mike Duke

Studies of control strategies for Building Integrated Solar Energy System

Research and development work on Building Integrated Solar Energy Systems (BISES) has become an area of growing interest, not only in New Zealand (NZ) but worldwide. This interest has led to a significant growth in the use of solar energy to provide heating and electricity generation. This paper presents the theoretical and experimental results of a novel building integrated solar hot water system developed using commercial long run roofing materials. This work shows that it is possible to achieve effective integration that maintains the aesthetics of the building and also provides useful thermal energy. The results of a 6.73m2 glazed domestic hot water systems are presented. The key design parameters of the Building Integrated Thermal (BIT) system were identified and implemented in a TRansient SYstem Simulation (TRNSYS) model. Validation results comparing the simulation in TRNSYS and real experimentation show that experimental and simulation responses are close to each other. The coupling of TRNSYS and Matlab/Simulink shows the possibility to use Matlab/Simulink for developing appropriate control strategies for BIT roofing systems. Preliminary Fuzzy Logic (FL) intelligent controller was implemented in a Fuzzy Integrated System (FIS) toolbox in a Matlab/Simulink model and linked into TRNSYS model. Further work is needed to identify and design advanced predictive control strategies for the Building Integrated Photovoltaic Thermal (BIPVT) solar system and determine how the performance can be optimized.

Electromagnetic damper control strategies for light weight electric vehicles

An investigation is conducted into the performance of passive, semi-active and active electromagnetic dampers. Theoretical models are constructed of the dampers and these are included in two degree of freedom models of the suspension. The passive and semi-active electromagnetic dampers are significantly heavier than commercial hydraulic dampers. In the case of active electromagnetic damper, the reduction in passenger acceleration is 88 percent when compared to passive damper and 61 percent when compared to a semi-active damper. The power consumption is similar to a magnetorheological semi-active damper.

Convection suppression in an attic shaped enclosure

In recent times there has been growing interest in the integration of solar collectors, for water heating, into the facade of buildings. However, the design methodology of these devices remains largely the same as typical “stand-alone” collectors. As such it is still common for materials with a high thermal resistance to be used for insulating the rear surface of these collectors. Unlike a “stand-alone” solar collector that is exposed to the atmosphere at all faces; a building integrated system allows the opportunity for air to act as an insulator at the rear surface of the solar collector. The use of convection suppression devices has been widely discussed in the literature as a means of reducing natural convection heat loss from the front surface of glazed solar collectors. However in this study the use of baffles in an attic was examined as a means of suppressing heat loss by natural convection from the rear surface of a roof-integrated solar collector. The aim of the study was to examine whether the use of baffles would allow the cost of building integrated collectors to be reduced by removing the cost of insulating material. To determine the effect of baffles in the attic space at the rear surface of the collector, a 3-dimensional triangular cross sectioned enclosure with a vertical aspect ratio of 0.5 and a horizontal aspect ratio of 3.3 was modelled. The flow patterns and heat transfer in the enclosure were determined for Grashof Numbers in the range of 106 to 107 using a commercially available finite volume CFD solver. It was found that the use of a single adiabatic baffle mounted vertically downwards from the apex, and extending the length of the enclosure, would alter the flow such that the heat transfer due to natural convection was reduced with respect to the length of the baffle. Furthermore, it was observed that a series of convection cells, not previously reported in the literature, appeared to exist along the length of the enclosure. As such, it may be possible to derive additional benefit in reducing the heat transfer by adding lateral baffles in addition to the single longitudinal baffle modelled in this study.

Model Building and Simulation of the Suspension System for a Robotic Asparagus Harvester

The demand for high accuracy on automated harvesters is getting higher. While system accuracy is lowered by vibration resulted when a robot with sensors and arms is running on the field. Applying suspension system onto these automated harvesters is a solution to reduce the vibration effects and assure required accuracy. This paper presents a model of the suspension system for a robotic asparagus harvester. The simulation results showed that the peak value of vibration was reduced to an acceptable level. Most importantly, the peak deflection of a vibrated platform was decreased to a required range as well. At the end of this paper, a conclusion is drawn. A suspension system is suggested to reduce vibration effects and improve the accuracy of both sensors and picking arms for mobile manipulators. In the future, this suspension system will be fabricated and installed onto a robotic asparagus harvester to validate this proposed model.

Overview of Sensor Technologies Used for 3D Localization of Asparagus Spears for Robotic Harvesting

Advances in agricultural automation, coupled with a general decline of available labour hasgenerated interest in automated harvesting of various crops. Paramount to the success of such systemsis the development of accurate, robust detection technologies and localization strategies. This paperpresents an overview of sensor technologies used in the detection and localization of green aspara-gus spears for robotic harvesting. Tactile, photoelectric, machine vision and time-of-flight sensors areinvestigated and their applicability for use in robotic asparagus harvesting is evaluated. Investigationof previous asparagus harvesting devices has revealed that no such device has yet achieved commer-cial viability. It was identified that this is likely due to weaknesses in currently employed detectiontechnologies, namely slow response times, high sensitivity to changes in ambient lighting conditionsand requirement for frequent manual calibration. Of the sensor technologies investigated it was foundthat time-of-flight cameras, such as the Microsoft Kinect V2 are the most feasible for the detectionof asparagus spears for robotic harvesting. It was concluded that further research would be conductedinto the application of such sensors into a commercially viable harvester.

Determining the volumetric characteristics of a passive linear electromagnetic damper for vehicle applications.

Abstract Previous research has shown that passive electromagnetic damping could be feasible for automotive applications, but there would be a severe weight penalty, particularly in light weight vehicles. With modern advances in permanent magnets the feasibility of passive electromagnetic dampers is re-examined. A model of a permanent magnet and coil system is developed and validated in small scale. This magnet model is used to model a dynamic damper system which is again tested. This dynamic model is then scaled up to a two degree of freedom system to determine the damping for a quarter car model. Two damper designs are created each of which would produce a damping coefficient of 1,600 Ns/m. The proposed dampers require more than three times the volume of the equivalent hydraulic dampers.

Investigation of electroless nickel plating on rapid prototyping material of acrylic resin

Purpose – This paper aims to investigate the layer of material deposited on a sample of acrylic resin by electroless nickel plating process. Acrylic resin is a popular material in rapid prototyping (RP) which uses the additive manufacturing technique to build prototypes for visual inspection, assembly, etc. Metallization of the RP materials can extend application envelop of RP techniques, as they can be used in decorative or functional applications. Design/methodology/approach – Unlike electroless nickel plating on a metal substrate, the plating process for an acrylic resin substrate is different, as there is no metal ion for the auto-catalytic electroless reaction. Pre-treatment processes are performed on an acrylic resin sample to initiate electroless nickel plating. The morphology, chemical composition and structure of the layer deposited on the sample are examined using scanning electron microscopy, energy-dispersive spectroscopy and X-ray diffraction. Findings – The investigation shows that a nickel ...

The implementation in VISSIM REALTIME of an active electromagnetic damper controller for lightweight electric vehicles

The use of linear electromagnetic active damper units in the suspension system of a lightweight electric vehicle offers many advantages over conventional passive, semi-active and active hydraulic dampers. While full active hydraulic systems have been commercially available in automobiles for many years, the linear electromagnetic active damper offers a lower weight system with a much reduced power demand. However an active system requires the use of a controller to adjust the power output to the damper unit. This unit must process signal inputs and provide an output solution within a short time period, often 5 milliseconds or less. By using VISSIM REALTIME, a controller was built that controlled a scale linear electromagnetic damper using Karnopps Skyhook algorithm. This had to deal with issues such as accelerometer drift and signal to noise ratio. These required simple but fast techniques to provide useful information to the damper in a useful timeframe. This controller-damper combination proved effective in reducing the vibration experienced by the sprung mass and was more effective than an ideal passive damper at all frequencies tested by at least a factor of three.

Active electromagnetic damping for lightweight electric vehicles

Due to the low weight of most current electric vehicles, the effectiveness of commercial passive dampers is reduced when compared to current production automobiles. Active dampers allow for a significant reduction in the amount of road signal that affects the passenger body. However current active hydraulic dampers tend to be heavy and to have a power consumption that precludes their use in electric vehicles. By use of a linear electromagnetic element it is possible to create an active damper that has enough authority to provide active damping with a fraction of the weight and power consumption of a hydraulic system. A computer model of an active electromagnetic damper was constructed and the results were compared to a physical prototype. This verified the effectiveness of the damper and the low power consumption. This computer model was then scaled up for the simulation of a real world quarter car model. This simulation demonstrated that the use of the active linear electromagnetic damper was more effective at all frequencies when compared to an ideal passive damper. It was also demonstrated that the active electromagnetic damper had a similar mass to a passive damper and had a power consumption of more than an order of magnitude less than a comparable active hydraulic damper.

Numerical determination of series and shunt resistances using the Lambert W-function

A number of methods currently exist to determine the values of series and shunt resistance of a solar cell which are generally unpublished and necessary for modeling of photovoltaic systems. A new method is proposed to numerically locate these values using the popular Newton-Raphson technique at maximum power point from data predominantly provided by manufacturer data sheets. Equations based on the Lambert W-function and their partial derivatives are provided so that all calculations can be performed in a Matlab or similar environment. The results of this new method are presented and compared with one current method and the analytical results obtained by Charles et al. [1] for a blue and grey type solar cells which were selected based on their largely varying characteristics. Values determined with the proposed method agreed with benchmark results in all cases and with greater accuracy over the alternative method studied. Additionally, values for both series and shunt resistance were determined quickly with quadratic convergence.