Development of a Two-Wheel Inverted Pendulum and a Cable Climbing Robot

The research work in this thesis constitutes two parts: one is the development and control of a Two-wheel inverted pendulum (TWIP) robot and the other is the design and manufacturing of a cable climbing robot (CCR) for suspension bridge inspection. The first part of this research investigates a sliding mode controller for self-balancing and stabilizing a two-wheel inverted pendulum (TWIP) robot. The TWIP robot is constructed by using two DC gear motors with a high-resolution encoder and zero backlashes, but with friction. It is a highly nonlinear and unstable system, which poses challenges for controller design. In this study, a dynamic mathematical model is built using the Lagrangian function method. And a sliding mode controller (SMC) is proposed for auto-balancing and yaw rotation. A gyro and an accelerometer are adopted to measure the pitch angle and pitch rate. The effect on the sensor’s installation location is analyzed and compensated, and the precision of the pose estimation is improved accordingly. A comparison of the proposed SMC controller with a proportional-integral-derivative (PID) controller and state feedback controller (SFC) with linear quadratic regulation (LQR) has been conducted. The simulation and experimental test results demonstrate the SMC controller outperforms the PID controller and SFC in terms of transient performance and disturbance rejection ability. In the second part of the research, a wheel-based cable climbing robotic system which can climb up and down the cylindrical cables for the inspection of the suspension bridges is designed and manufactured. Firstly, a rubber track climbing mechanism is designed to generate enough adhesion force for the robot to stick to the surface of a cable and the driving force for the robot to climb up and down the cable, while not too big to damage the cable. The climbing system includes chains and sprockets driven by the DC motors and adhesion system. The unique design of the adhesion mechanism lies in that it can maintain the adhesion force even when the power is lost while the system works as a suspension mechanism. Finally, a safe-landing mechanism is developed to guarantee the safety of the robot during inspection operations on cables. The robot has been fully tested in the inspection of Xili bridge, Guangzhou, P.R. China

Vision-based methods for relative sag measurement of suspension bridge cables

Main cables, comprising a number of wire strands, constitute a vital element in long-span suspension bridges. The determination of their alignment during construction is of great importance, and relative sag is commonly measured for the efficient sag adjustment of general strands. The conventional approach uses the caterpillar method, which is inconvenient, difficult-to-implement, and potentially dangerous. In order to realize the high-precision measurement of cable alignment in a strong wind environment, a vision-based method for relative sag measurement of the general cable strands is proposed in this paper. In the proposed measurement system, images of pre-installed optical targets are collected and analyzed to realize the remote, automatic, and real-time measurement of the relative sag. The influences of wind-induced cable shaking and camera shaking on the accuracy of the height difference measurement are also theoretically analyzed. The results show that cable strand torsion and camera roll have a great impact on the measurement accuracy, while the impacts of the cable strand swing and vibration, camera swing and vibration, and camera pitch and yaw are insignificant. The vision-based measurement system tested in the field experiment also shows a measurement error within 3 mm, which meets the requirements for cable adjustment construction. At the same time, the vision-based measurement method proposed and validated in this paper can improve the measurement accuracy and efficiency of strand alignment in a strong wind environment. Potential risks involved in the manual measurement, e.g., working at heights and in strong wind environments, can be eliminated, facilitating the automation of the cable erection process

Design and Manufacturing of Pole Climbing Unmanned Fire Extinguisher

May it be the destruction of Jerusalem temple in 587BC or the infamous disaster in a mall in Philippines in December 2017, fire was the major culprit. Fire is one of the most severe and frequent disasters faced by the mankind especially in the machine age. Our project focuses on extinguishing such city fires with the help of a specially designed robot. The proposed robot would climb up a pole which can easily be constructed with minimal expenditures and efforts during or after the construction of the building. The robot being able to climb pole, would be able to traverse upwards, no matter at what height the fire is set. This versatility would eliminate the problems posed due to insufficiently long ladders (100 feet maximum) with the firefighting department. The robot is also equipped with a motor controlled nuzzling arrangement which will allow spraying the water jet in all possible directions. Such use of technology also safeguards the lives of firefighters which in conventional methods are put in danger. The robot will be equipped with a camera at the top which would enable the controller to judge the intensity and severity of the fire. The robot can be wirelessly controlled using radio controlled device which can control the locomotion of robot, direction control of water jet and an LCD which can display the camera sight

Surface and Sub-Surface Analyses for Bridge Inspection

The development of bridge inspection solutions has been discussed in the recent past. In this dissertation, significant development and improvement on the state-of-the-art in the field of bridge inspection using multiple sensors (e.g. ground penetrating radar (GPR) and visual sensor) has been proposed. In the first part of this research (discussed in chapter 3), the focus is towards developing effective and novel methods for rebar detection and localization for sub-surface bridge inspection of steel rebars. The data has been collected using Ground Penetrating Radar (GPR) sensor on real bridge decks. In this regard, a number of different approaches have been successively developed that continue to improve the state-of-the-art in this particular research area. The second part (discussed in chapter 4) of this research deals with the development of an automated system for steel bridge defect detection system using a Multi-Directional Bicycle Robot. The training data has been acquired from actual bridges in Vietnam and validation is performed on data collected using Bicycle Robot from actual bridge located in Highway-80, Lovelock, Nevada, USA. A number of different proposed methods have been discussed in chapter 4. The final chapter of the dissertation will conclude the findings from the different parts and discuss ways of improving on the existing works in the near future

Conceção, produção e validação experimental de um dispositivo trepador para inspeção não destrutiva de cabos

Os robôs trepadores têm sido alvo de desenvolvimento nos últimos anos devido às várias vantagens que apresentam. Estes permitem aumentar a eficiência de várias operações, reduzir os custos das mesmas e ainda salvaguardar os operadores de locais potencialmente perigosos. Estes podem ser caracterizados pelo seu método de movimentação e pela técnica de fixação. O objetivo deste trabalho consistiu em conceber, produzir e testar um robô trepador para ser utilizado como uma ferramenta de inspeção para cabos e tubos, com recurso a correntes induzidas (CI), em locais altos e de difícil acesso. O dispositivo foi concebido com recurso à manufatura aditiva. Este encontra-se dividido em 3 partes e engloba todo o perímetro da superfície. Para a inspeção de defeitos, acoplou-se ao dispositivo uma sonda de correntes induzidas, produzido em PCB flexível. Para validar o desempenho do dispositivo, foi utilizado um varão de latão com 25 mm de diâmetro, onde foram realizados 3 defeitos artificiais para serem detetados pela sonda. O dispositivo, com uma massa aproximada de 1,5 kg, conseguiu trepar o varão de forma fiável com velocidades até 4100 mm/min. Com diferentes velocidades, a sonda foi também capaz de detetar os diferentes defeitos impostos sobre o varão.Climbing robots have been a development subject in recent years due to the several advantages they present. These allow the efficiency increase of various works, lower operations costs and even safeguard workers from potentially dangerous scenarios. These can be characterized by their locomotion method and by their attachment technique. The goal of this work was to develop a climbing robot to be used as an inspection tool for cables and pipes, using eddy currents (EC), at great heights and difficult to access spots. The device was designed using additive manufacturing. The device is divided in 3 parts and involves the entire surface perimeter. For the defect inspection, an eddy currents probe, produced with flexible PCB, was coupled to the device. To validate the device performance, a 25 mm diameter brass rod was used, where 3 artificial defects were made to be detected by the probe. The device, with an approximate mass of 1,5 kg, was able to reliably climb the rod up to speeds of 4100 mm/min. With different frequencies, the probe was also able to detect the different defects imposed on the rod

Long-duration robot autonomy: From control algorithms to robot design

The transition that robots are experiencing from controlled and often static working environments to unstructured and dynamic settings is unveiling the potential fragility of the design and control techniques employed to build and program them, respectively. A paramount of example of a discipline that, by construction, deals with robots operating under unknown and ever-changing conditions is long-duration robot autonomy. In fact, during long-term deployments, robots will find themselves in environmental scenarios which were not planned and accounted for during the design phase. These operating conditions offer a variety of challenges which are not encountered in any other discipline of robotics. This thesis presents control-theoretic techniques and mechanical design principles to be employed while conceiving, building, and programming robotic systems meant to remain operational over sustained amounts of time. Long-duration autonomy is studied and analyzed from two different, yet complementary, perspectives: control algorithms and robot design. In the context of the former, the persistification of robotic tasks is presented. This consists of an optimization-based control framework which allows robots to remain operational over time horizons that are much longer than the ones which would be allowed by the limited resources of energy with which they can ever be equipped. As regards the mechanical design aspect of long-duration robot autonomy, in the second part of this thesis, the SlothBot, a slow-paced solar-powered wire-traversing robot, is presented. This robot embodies the design principles required by an autonomous robotic system 1in order to remain functional for truly long periods of time, including energy efficiency, design simplicity, and fail-safeness. To conclude, the development of a robotic platform which stands at the intersection of design and control for long-duration autonomy is described. A class of vibration-driven robots, the brushbots, are analyzed both from a mechanical design perspective, and in terms of interaction control capabilities with the environment in which they are deployed.Ph.D

Performance analysis for wireless G (IEEE 802.11G) and wireless N (IEEE 802.11N) in outdoor environment

This paper described an analysis the different capabilities and limitation of both IEEE technologies that has been utilized for data transmission directed to mobile device. In this work, we have compared an IEEE 802.11/g/n outdoor environment to know what technology is better. The comparison consider on coverage area (mobility), throughput and measuring the interferences. The work presented here is to help the researchers to select the best technology depending of their deploying case, and investigate the best variant for outdoor. The tool used is Iperf software which is to measure the data transmission performance of IEEE 802.11n and IEEE 802.11g

Performance Analysis For Wireless G (IEEE 802.11 G) And Wireless N (IEEE 802.11 N) In Outdoor Environment

This paper described an analysis the different capabilities and limitation of both IEEE technologies that has been utilized for data transmission directed to mobile device. In this work, we have compared an IEEE 802.11/g/n outdoor environment to know what technology is better. the comparison consider on coverage area (mobility), through put and measuring the interferences. The work presented here is to help the researchers to select the best technology depending of their deploying case, and investigate the best variant for outdoor. The tool used is Iperf software which is to measure the data transmission performance of IEEE 802.11n and IEEE 802.11g