Designing and Implementing a Model Vehicle Platoon with Longitudinal Control

Decreasing fuel consumption and increasing road capacity are both desired in regards to heavy duty vehicles. One proposed way of doing this is by having vehicles travelling at close distances to reduce the air drag, and thereby reducing their fuel consumption. This thesis address the platooning problem on model-scale vehicles as they are a desirable demonstration platform since they can be driven indoors. This thesis considers the implementation and evaluation of the longitudinal control of a model-scale vehicle platoon where Model Predictive Control is utilised. The concept of platooning on real full-size vehicles is briefly discussed and some of its benefits are described. The thesis then discusses and evaluates what sensors are necessary to equip the model vehicles with and how to implement them, in addition to a discussion and evaluation of inter-vehicular communication in an indoor environment is provided. Then, based on the available sensors, a heuristic feedback controller and a model-based controller is designed as distance controllers, as well as a feedback controller used for speed control, and then connected in a cascading structure. The two controllers are then evaluated in simulations based on different scenarios and finally results from a working implementation on the model-scale vehicles are presented. The end results from this thesis are a demonstration platform of two model-scale electrical vehicles as well as two different distance control algorithms both based on using the cruise control developed in the vehicles

AN EVALUATION OF THE TRAVELING WAVE ULTRASONIC MOTOR FOR FORCE FEEDBACK APPLICATIONS

The traveling wave ultrasonic motor is considered for use in haptic devices where a certain input-output relation is desired between the applied force and the resulting motion. Historically, DC motors have been the standard choice for this purpose. Owing to its unique characteristics, the ultrasonic motors have been considered an attractive alternative. However, there are some limitations when using the ultrasonic motor for force-feedback applications. In particular, direct torque control is difficult, and the motor can only supply torque in the direction of motion. To accommodate these limitations we developed an indirect control approach. The experimental results demonstrate that the model reference control method was able to approximate a second order spring-damper system

The Roles of Piezoelectric Ultrasonic Motors in Industry 4.0 Era: Opportunities & Challenges

Piezoelectric Ultrasonic motors (USM) are based on the principle of converse piezoelectric effect i.e., vibrations occur when an electrical field is applied to piezoelectric materials. USMs have been studied several decades for their advantages over traditional electromagnetic motors. Despite having many advantages, they have several challenges too. Recently many researchers have started focusing on Industry 4.0 or Fourth Industrial revolution phase of the industry which mostly emphasis on digitization & interconnection of the entities throughout the life cycle of the product in an industrial network to get the best possible output. Industry 4.0 utilizes various advanced tools for carrying out the nexus between the entities & bringing up them on digital platform. The studies of the role of USMs in Industry 4.0 scenario has never been done till now & this article fills that gap by analyzing the piezoelectric ultrasonic motors in depth & breadth in the background of Industry 4.0. This article delivers the novel working principle, illustrates examples for effective utilization of USMs, so that it can buttress the growth of Industry 4.0 Era & on the other hand it also analyses the key Industry 4.0 enabling technologies to improve the performance of the USMs

Climbing and Walking Robots

With the advancement of technology, new exciting approaches enable us to render mobile robotic systems more versatile, robust and cost-efficient. Some researchers combine climbing and walking techniques with a modular approach, a reconfigurable approach, or a swarm approach to realize novel prototypes as flexible mobile robotic platforms featuring all necessary locomotion capabilities. The purpose of this book is to provide an overview of the latest wide-range achievements in climbing and walking robotic technology to researchers, scientists, and engineers throughout the world. Different aspects including control simulation, locomotion realization, methodology, and system integration are presented from the scientific and from the technical point of view. This book consists of two main parts, one dealing with walking robots, the second with climbing robots. The content is also grouped by theoretical research and applicative realization. Every chapter offers a considerable amount of interesting and useful information

Reconfigurable Fiducial-Integrated Modular Needle Driver For MRI-Guided Percutaneous Interventions

Needle-based interventions are pervasive in Minimally Invasive Surgery (MIS), and are often used in a number of diagnostic and therapeutic procedures, including biopsy and brachytherapy seed placement. Magnetic Resonance Imaging (MRI) which can provide high quality, real time and high soft tissue contrast imaging, is an ideal guidance tool for image-guided therapy (IGT). Therefore, a MRI-guided needle-based surgical robot proves to have great potential in the application of percutaneous interventions. Presented here is the design of reconfigurable fiducial-integrated modular needle driver for MRI-guided percutaneous interventions. Further, an MRI-compatible hardware control system has been developed and enhanced to drive piezoelectric ultrasonic motors for a previously developed base robot designed to support the modular needle driver. A further contribution is the development of a fiber optic sensing system to detect robot position and joint limits. A transformer printed circuit board (PCB) and an interface board with integrated fiber optic limit sensing have been developed and tested to integrate the robot with the piezoelectric actuator control system designed by AIM Lab for closed loop control of ultrasonic Shinsei motors. A series of experiments were performed to evaluate the feasibility and accuracy of the modular needle driver. Bench top tests were conducted to validate the transformer board, fiber optic limit sensing and interface board in a lab environment. Finally, the whole robot control system was tested inside the MRI room to evaluate its MRI compatibility and stability

Pjezorobotų trajektorijų valdymas nanopalydovų stabilizavimui

Rapid industrial advancement requires novel ideas, new scientific approaches and effective technologies that would ensure quality and precision. Application of piezoelectric actuators in robotics opens many possibilities to create systems with extreme precision and control. A very important step in the development of autonomous robots is the formation of motion trajectories. Classical interpolation methods used for formation of the trajectories are suitable only when robots have wheels, legs or other parts for motion transmission. Piezorobots that are analyzed in this dissertation have no additional components that create motion, only contact points with the static plane. Therefore, traditional motion formation methods are not suitable and a problem arises how to define motion trajectory of such device. The aim of this work is to create a trajectory control algorithm of multi-degrees-of-freedom piezorobot used for nanosatellite stabilization. In order to achieve the objective, the following tasks had to be solved: to analyze constructions of precise piezorobots, their operating principles and motion formation methods; to analyze stabilization problems of satellites and application of multi-degrees-of-freedom piezorobots for nanosatellite stabilization; to create piezorobots’ motion formation algorithms according to electrode excitation schemes, to perform an experimental research; to determine quantitative characteristics of the constructed piezorobots and their motion trajectories. The introduction describes the importance and novelty of this thesis, goals of this work, its practical value and defended statements. The first chapter analyses the principals of ultrasonic devices, gives a thorough review of constructions of ultrasonic devices with multi-degrees-of-freedom. The second chapter provides a review of satellite stabilization principles and how multi-degrees-of-freedom piezorobots can be applied for nanosatellite stabilization. Motion formation methods for ultrasonic devices with multi-degrees-of-freedom are presented. The third chapter presents the detailed analysis of different piezorobots. In the fourth chapter experimental results are provided. Trajectory planning of piezorobot is shown, results are compared to numerical calculations performed in the third chapter. The conclusions about applicability of piezorobots’ motion formation algorithms according to electrode excitation schemes are given. Seven articles focusing on the subject of the dissertation have been published, two presentations on the subject have been presented in conferences at international level. The research for the dissertation has been funded by the Lithuanian State Science and Studies Foundation: European Regional Development Fund, Project No. DOTSUT-234 and Research Council of Lithuania, Project No. MIP-084/2015.Dissertatio

Modelling and Evaluation of Piezoelectric Actuators for Wearable Neck Rehabilitation Devices

Neck pain is the most common neck musculoskeletal disorder, and the fourth leading cause of healthy years lost due to disability in the world. Due to the need of hands-on physical therapy and Canada’s aging population, access to treatment will become highly constrained. Wearable devices that allow at-home rehabilitation address this future limitation. However, few have emerged from the laboratory setting because they are limited by the use of conventional actuators. An overlooked type of actuation technology is that of piezoelectric actuators, more specifically, travelling wave ultrasonic motors (TWUM). In this work, a clear procedure that outlines how the required parameters within the hybrid TWUM model can be identified, as well as an assessment of the use of TWUMs within wearable devices for the neck, is presented. The procedure includes custom testing setups that were designed to identify the stator motion parameters, and the Coulomb coefficient of friction. The accuracy of the determined parameters were confirmed when the angular velocity of the hybrid model at different duty cycles was compared to the real TWUM being modelled, producing a coefficient of determination of 0.974. The model was then used to create a position control system that controlled the joints of a virtual robotic manipulator that modelled the neck. The manipulator exhibited a maximum absolute mean error of only 0.0289 m when simulating the required trajectories of range of motion exercises. This performance, in addition to the exemplary traits TWUMs express, demonstrate their potential to advance the field of wearable mechatronic devices

Model, design & development of piezoelectric ultrasonic motor

Ph.DDOCTOR OF PHILOSOPH

Application of ultrasonic motors to MR-compatible haptic interfaces

Functional Magnetic Resonance Imagery (fMRI) is an imaging technique allowing the observation of brain activity. Haptic interfaces can be used in conjunction with fMRI to stimulate the subject while measuring brain activity. Using robotic stimulation over conventional methods offers repeatability, flexibility and the possibility of logging of different experiment variables. Such system becomes a powerful tool for neuroscience study, diagnostic and rehabilitation. The MR scanner with its high magnetic fields and radio frequency pulses is a harsh environment for a robotic system. Robots that can operate safely and do not induce disturbances in the imaging of the scanner are qualified as MR-compatible. The actuation of these robots is an important issue. Electrical power brought to the actuator represents an important source of interferences with the scanner. Since electrical motors cannot be introduced in the MR room, haptic interfaces are conventionally remotely actuated over a long transmission with the actuators placed outside of the MR room. In particular cases, such as the study of finger motion, small haptic interfaces with limited force ranges are required. Remote actuation methods impose transmission lengths and means that cannot be reduced nor scaled down thus imposing a trade-off between performances and size reduction in these applications. This work investigates an alternative actuator that can achieve high-quality force-interactions with the fingers. The Ultrasonic Motor (USM) is MR-compatible and offers good performances. But it is not well suited for force-feedback and may be hazardous for the users. To address these issues, mechanical solutions are investigated by using an electrical analogy applied to mechanical systems. A novel actuation system using the USM as a power source and a clutch to control the output torque is proposed: the Hybrid USM Clutch Actuator (HUCA). The first prototype validates the different mechanical concepts developed in this work. The second, MR-compatible, integrates a clutch based on electrorheological fluids (ER). MR-compatibility has been validated and performances evaluated. Since the HUCA has the unique property of behaving both like a force source and a velocity source, dedicated control schemes have been developed to implement impedance and admittance force control. These enable the display of stiff walls and the rendering of a wide range of impedances thanks to the overlap of their range of displayable impedances. Compared to the hydrostatic transmission actuation, the HUCA shows higher performances and user safety. Furthermore, the powering through electrical wires allows developments of multi-DOF interfaces

Dynamics of Ultrasonic Motors

This thesis is treating theory, modeling, model analysis and experiments of traveling wave type ultrasonic motors. A framework to derive models for ultrasonic motors is given here, which is based on the continuum theory of electromechanical solids. This includes the modeling of the stator-rotor contact and the electromechanical behavior of piezoceramic stators. The principle of virtual power is stated for electromechanical systems, where the terms of virtual power due to normal and tangential contact stresses are expressed explicitly. Using this principle and a symbolic equation manipulation tool, a planar motor model based on BERNOULLI-EULER kinematics is derived. Subsequently, a scaling analysis is carried out. Then, a model analysis scheme is given, based on the derived motor model at steady-state. Contact boundary and transition conditions, continuity equations at the contact boundaries and contact search equations are stated. After that, a spatial discretization is carried out, using a GALERKIN discretization method with both, global and local Ansatz-functions. Compared to Finite-Element-Methods this reduces the number of degrees of freedom drastically, thus saving computer time. For the resulting algebraic equations, a contact algorithm is given. Using the computer code developed from this, numerical analyses are carried out. Particular resonance curves and speed-torque characteristics are computed and discussed. In the experimental part, the focus is on the resonance, the temperature and the steady-state motor operation behavior of a typical ultrasonic motor. Resonance curves of the electric admittances of stator and motor were measured and discussed as well as those of the velocity of surface points of both, stator and rotor. The resonance curves show a non-linear softening behavior. For sufficiently high stator vibration amplitudes this goes along with a jump phenomenon. It is found that material non-linearities in the piezoceramics may be the reason for this effect. Furthermore, the influence of the temperature rise due to the frictional contact mechanism is investigated. Speed-torque characteristics were measured and their dependence on various external parameters is investigated. At the same time, the time histories of different motor quantities like rotational speed, motor torque, electric current or velocity of surface points were recorded. Different effects in the motor behavior were observed, among them overhang speed-torque characteristics and hysteretic behavior. Finally, resistive and reactive power components as well as efficiencies along the speed-torque characteristics were computed