工程學

Double Parallelogram Lifting Mechanism (DPLM) is a compact and stable lifting mechanism with a large extension range widely adopted in robot designs. Rubber bands and springs are often installed on the DPLM to lighten the motors' load and maintain its height, yet the installation positions are often obtained through trial and error. This project aims at finding the optimal rubber band installation positions for DPLM using modeling and optimization techniques. A mathematical model which describes the forces and moments acting on all the linkages of DPLM was derived based on the conditions for the static equilibrium and verified with a 3D simulation software. A genetic algorithm (GA) was implemented to optimize rubber band installation positions, which managed to find solutions with the overall root-mean-square- error (RMSE) of the net moment less than 2 for 2 to 6 rubber bands. A further statistical analysis of 50000 random rubber band samples showed that installing rubber bands in triangles is the best solution with the overall lowest RMSE. A test was conducted with a prototype of the DPLM and the results were consistent with our model and optimization. This project derived and verified a mathematical model for the DPLM, and found the optimal way and positions to install rubber bands. The results of this project provides a theoretical basis for controlling DPLM with rubber bands, allowing it to be further adopted in industrial robots that require repetitive lifting and lowering such as inspection robots and aerial work platforms.

Cycling is a very popular mode of transport as well as a famous sport around the world. Many people enjoy this sport either professionally or recreationally. Cycling in the UK alone has grown up to 200% since lockdown in 2020. (Chandler, 2020) Cyclists make use of a broad selection of products to enhance their performance. Those products range from wireless gear shifting, advanced geometry, smart suspension. This project is aimed to indicate the importance of tire pressure and to introduce a product which will be able to adjust tire pressure while cycling. This product will give cyclist an advantage on different terrains as well as eliminate some common problems amongst cyclists. Flat tires are one of these problems. It occurs commonly amongst cyclists and can happen due to a variety of reasons. Another problem is wrongly inflated tires. This causes unnecessary loss in a cyclist’s power and speeds due to the high rolling resistance between the tires and the surface. This then results in losing time whether racing or commuting. In an article published in 2014 in Velonews.com, Lennard Zinn states: “Whether on tarmac or singletrack, a tire with lower rolling resistance reduces the power required to move forward while also providing a better quality ride. The tire absorbs small bumps by not transferring them into the bicycle and rider, resulting in a smoother ride, faster speeds, and better cornering." (Zinn, 2014) Taking this in consideration it becomes clear that it is important to develop a system which is able to control tire pressure.

The present research has as main objective to degrade the post-cured photopolymer of the stereolithography 3D printer resin using Galleria mellonella larvae. It is necessary to consider that the use of materials from 3D printers tends to increase considerably and in approximately seven years about 10% of everything that will be produced in the world will come from this type of printing. Considering also that the increase in population growth and technological development are directly linked to the increase of solid waste on the planet, in particular to polymeric materials, there is a need to degrade and give an adequate end to waste, avoiding a notorious accumulation along the time. For this purpose, Galleria mellonella larvae will be used because of it's comprovated capacity to degrade polyethylene, to find out if it is capable of biodegrading the post-cured resin of the printer. To carry out the research, compositional tests were done in partnership with the SENAI Institute for Innovation in Polymer Engineering, located in São Leopoldo, Rio Grande do Sul, and the creation of the larvae and degradation of the photopolymer will be carried out in partnership with the University Federal University of Health Sciences of Porto Alegre (UFCSPA). The data analysis will be based on the crystallinity determination tests by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and attenuated total reflectance spectroscopy (ATR) that will also be applied in the larvae feces after contact with the polymer to assess for degradation. As a result of the compositional tests, the ATR showed predominantly characteristic absorptions of acrylic resin; in the TGA test, the loss of mass described in the test is related to the loss of mass of organic material, mainly polymer. Finally, in the DSC test a thermal event was observed in the heating of the sample, with peaks at 125 ° C (Tpm), characteristic of fusion, and a thermal event in the cooling of the sample, in 112 ° C (Tpc), characteristic of crystallization. Based on the analysis of the results obtained, it is possible to infer that most of the composition of the photopolymer is acrylic resin, widely used in stereolithography 3D printers. The research has the future objective of isolating the substance into the larvae responsible for degradation so that it can be degraded on industrial scales. The research started in March 2020 and is still under development due to the COVID-19 pandemic, which compromised the planned tests.

A traditional helicopter requires 60 - 80% more power to hover than when in forward or lateral flight, making the manoeuvre extremely power inefficient. To maximise efficiency, industrially many properties of the helicopter and rotor have been changed and tested, for example: optimising blade shape, fuselage shape and changing weights of different helicopter components. This report in particular aims to find a relationship between power efficiency and angular velocity for a twin bladed hovering helicopter with a single rotor. The angular velocity of a blade measures the frequency of its revolution about a fixed point. A theoretical approach was first taken and then justified with empirical data. Firstly, a model for power efficiency was derived with William Froude’s momentum and blade element theory. The efficiency equations incorporated the thrust and power coefficients. Therefore, the research focused on determining values for these coefficients by manipulating equations, using industrial specifications and simulations from the XFOIL software. In order to validate the accuracy for such theoretically generated data, an experiment was conducted for a comparison. The theoretical and empirical data were concurrent, as they followed a similar trend and the empirical values overlapped within the theoretical error bars. The power efficiency for different angular velocities were then found by substituting values for the coefficients. The results demonstrated a positive relationship; where, as angular velocity increases, power efficiency increases too, then plateaus and repeats the same trend once again. The research raises many questions and could be extended by determining if a similar relationship exists for tri-copters and quadcopters.

Double Parallelogram Lifting Mechanism (DPLM) is a compact and stable lifting mechanism with a large extension range widely adopted in robot designs. Rubber bands and springs are often installed on the DPLM to lighten the motors' load and maintain its height, yet the installation positions are often obtained through trial and error. This project aims at finding the optimal rubber band installation positions for DPLM using modeling and optimization techniques. A mathematical model which describes the forces and moments acting on all the linkages of DPLM was derived based on the conditions for the static equilibrium and verified with a 3D simulation software. A genetic algorithm (GA) was implemented to optimize rubber band installation positions, which managed to find solutions with the overall root-mean-square- error (RMSE) of the net moment less than 2 for 2 to 6 rubber bands. A further statistical analysis of 50000 random rubber band samples showed that installing rubber bands in triangles is the best solution with the overall lowest RMSE. A test was conducted with a prototype of the DPLM and the results were consistent with our model and optimization. This project derived and verified a mathematical model for the DPLM, and found the optimal way and positions to install rubber bands. The results of this project provides a theoretical basis for controlling DPLM with rubber bands, allowing it to be further adopted in industrial robots that require repetitive lifting and lowering such as inspection robots and aerial work platforms.

921地震震波對高11-15層大樓產生重大危害。本研究以模型模擬11層大樓建築物，頂樓設置水塔配合陽台天花板設置水撲滿的雙阻尼消能系統設計，探討不同震度震波在雙阻尼系統減震成效。模擬之設備利用3D列印機自製水撲滿、不同形式網狀隔間液體阻尼零件，自製地震模擬器以電流調整器控制怠速馬達，進行模擬不同震度下高樓產生擺動與震盪之狀態與特性。 實驗發現單一阻尼消能元件的減震阻尼效能較差，雙阻尼消能系統可提升39％至58％減震阻尼效能。其中雙阻尼消能系統若有網狀隔間，水波擾動震盪越明顯，阻尼效能提升 6％至14％。11層大樓於頂樓設置平行器壁網狀隔間正方形水塔，並配合在第9至11層樓處，設置隔間距離較短網狀隔間水撲滿，二者水位設定六分滿，此液體雙阻尼減震消能系統，可抑制模擬震度5至7級震波對大樓產生的順向波動共振與大樓結構體的自主扭轉共振。

Food sustainability is key to human survival. Robotic solutions have started playing large roles in automating farming tasks in order to assist with crop yield and the efficiency of production. Due to the unreliability of and lack of manual labour in many parts of the world, Agribots are playing bigger roles. One of the biggest advantages of Agribots is that they can operate 24/7, 365 days a year without payment. Agribots are being used more often in dairy farms to milk cows while others are used to shear sheep. Agribots are fast becoming very important to farmers by gathering valuable data; milking cows; automating animal feed; measuring the right amount of pest control, detecting weeds and pests, harvesting and ploughing with unmanned tractors. In many parts of the world farm labour is scarce and difficult to come by. In 南非 for example farm labourers endure gruesome attacks. These attacks on farmers result in the closure of the farm for an extended period of time resulting in the loss of large quantities of crops. Food sustainability is dire in Africa and many parts of the world. “Each day, 25,000 people, including more than 10,000 children, die from hunger and related causes. Some 854 million people worldwide are estimated to be undernourished, and high food prices may drive another 100 million into poverty and hunger. . 90 percent of the world’s farms produce over 80 percent of the world’s food. They also manage about 75 percent of farmland worldwide. Yet, paradoxically, these farmers are often poor and food insecure themselves. Due to the increase in the world’s population annually, there is a growing demand for food. This has led to increasing pressure on farmers to produce crops. In order to meet this demand, farming innovations are vital for the future of food and agriculture. Constant innovations in agriculture is thus needed to constantly feed a growing and increasing population. Innovation in agriculture is also critical to help farmers use resources in better and more efficient ways. “Innovation is one of our best tools for creating a #ZeroHunger world.

臺灣已進入高齡社會，步態復健對於亞健康及慢性病族群極為重要，以帕金森氏症患者為例，他們常行走困難且容易跌倒。提升跨步品質的視覺提示是非常有效的協助方式，但臨床多仰賴治療師在地上貼膠帶或擺物件，調整不易且只受限於特定場所，因此居家自行照顧困難。先前已有研究開發出輕便可攜的裝置，能調整視覺提示，但每位使用者對不同提示模式的反應不一。本研究提出創新方法解決治療師手動調整的問題。以低成本周邊所建置的系統已能即時無線的變換不同提示模式、調控其參數，和自動計算各步態參數。其使用MG90s伺服機調整投射角度、霍爾式旋轉角度計裝在輪子上測量位移、Wi-Fi無線接收及操控參數。已經完成自動化探索使用者能力，並作最佳化的視覺提示設定。讓使用者不必出門，居家使用時，皆有最佳的視覺提示設定，得以更短的時程達到更好的復健效果。

臨床手術中常有骨釘植入位置偏差之情形，且目前並無研究針對骨釘植入位置對椎體力學反應之探討，故本研究使用CAD軟體Solidworks建立11個不同骨釘植入位置的人體第三節腰椎模型，利用有限元素分析軟體ANSYS進行力學模擬分析，計算不同骨釘植入位置於不同負載條件以及有無骨整合情況下，腰椎椎體的應力情形與整體結構之穩定度。研究結果顯示，在不考慮傷及神經或是骨釘穿出骨頭的情況下，當椎體與骨釘若受前彎(flexion)、後仰(extension)、側彎(lateral bending)、旋轉(rotation)及無軸向負載(pure bending)時，骨釘螺帽中點至棘突中軸的垂直投影距離越小，椎體位移亦越小，結構越穩定；且不論有無骨整合都呈現相似走勢。骨科醫師表示仍會選擇打在目前最普遍的植入位置最為保險；但依照本研究結果，當臨床手術醫師面臨植入常規位置困難度較高時，骨釘植入位置若稍偏外側穩定度並不會有顯著差異，且可避免傷及中樞神經系統。

Originally, the Tesla transformer was developed to transmit energy and messages wirelessly. But it did not prove itself for either of these applications, so today it is only used for research purposes. Over time, the Tesla transformer has evolved and improved. Today it is possible with Tesla transformers to generate powerful and highly precise controlled discharges. During operation, impressive high-voltage discharges occur at the transformer. A tesla transformer is basically a high voltage generator that achieves a voltage boost by using two magnetically coupled LC series resonant circuits of the same resonant frequency. The Dual Resonant Solid State Tesla Coil (DRSSTC) built in this work has a high power IGBT half bridge module to excite the primary resonant circuit at the resonant frequency. The IGBTs are driven in such a way that audible pressure waves, and therefore music, are generated by the electrical discharges at the high voltage electrode. Within the scope of this work were the following two questions: - How is a DRSSTC designed and built? The DRSSTC system realized in this work is about 80 cm high and reaches about one-meter-long discharges. The design, development, and construction of the transformer are documented in detail and extensively in this thesis. - How does one measure an electrical voltage of 200,000 V, which changes sign more than 100,000 times per second? Two approaches have been taken to measure the voltages. Derived from the energy balance of an ideal capacitor and an ideal coil, a secondary voltage of about 200 kV was calculated via secondary current measurement. The second approach uses a voltage measurement via an in-house developed measuring electrode and a calculated divider ratio between the measured voltage and the secondary voltage. A relatively unrealistic secondary voltage of about 750 kV was measured since the divider ratio depends on approximate values. Nevertheless, the measuring electrode can be used for investigations of the voltage curve, or the divider ratio can be calibrated via the secondary current measurement. The development of such a transformer laid the foundation for much further research and scientific analysis.