This thesis presents the development of a contactless sensing system and the dynamic evaluation of an air-bearing based precision wafer positioning system. The contactless positioning stage is a response to the trend seen in the high-tech industry, with the substrates becoming thinner and larger to reduce the cost and increase the yield. With contactless handling, it is possible to avoid damage and contamination. The system works by floating the substrate on a thin film of air. A viscous traction force is applied on the substrate by steering the airflow. A cascaded control structure has been implemented to the contactless positioning system, where the Inner Loop Controller (ILC) controls the actuator which steers the airflow and the Outer Loop Controller (OLC) controls the position of the substrate by controlling the reference of the ILC. The dynamics of the ILC are evaluated and optimized for the performance of the positioning of the substrate. For the OLC a linear charge-coupled device (CCD) has been implemented as a contactless sensing system. The sensing concept is implemented in the contactless actuation system and the results are presented.

Computer vision has been on the rise over the last decades. The applications of computer vision are mostly found within the domain of robotics and Unmanned Aerial Vehicle's. The use of computer visions in precision industry is new and offers both opportunities and challenges. In high performance precision systems the demands on sensors is set high in terms of precision, delay and sample rate. In previous work a computer vision sensor was developed for the control of a microscopy stage. This development opened a path for computer vision sensors in precision systems. However, the limitations of computer vision sensors are challenging in the domain of control. A computer vision sensor needs to process an image before it can estimate the position of an object. This processing requires time which introduces a time delay into the control system. Due to the nature of the computer vision algorithm and computing devices, the delay in the sensor is time varying. Furthermore, since a controller typically requires a tenfold sample rate of the control bandwidth the limited frame rate of computer vision sensors imposes additional challenges. In previous work, the delay and limited sample rate of the computer vision sensor limited the control bandwidth of a microscopy to 0.87Hz in translational range. Since high performance precision systems require higher bandwidths a new computer vision sensor is developed in this thesis. An existing microscopy stage is used to test the performance of a computer vision sensor. Ground vibrations in a laboratory environment have a peak value at 10Hz which defines the target bandwidth. In order to reach this target bandwidth a new computer vision sensor is proposed. The sensor uses a cost-effective camera and a computer to run the computer vision algorithm. By decreasing the delay from 60ms to 10ms a control bandwidth of 7Hz, using PID, is obtained in this work. Since the target bandwidth is 10Hz time delay compensation is considered to improve the performance. By implementing a Filtered Smith Predictor the target bandwidth of 10Hz is reached. The maximum control bandwidth of the controller, 15Hz, was derived in order to inspect the limit of computer vision sensors in precision systems.

The application of actively controlled micrometer precision positioning stages in products that are accessible to start-ups, individual consumers or third world countries is currently limited by their price and size. To solve this problem, the use of low-cost and compact components in stages is investigated. Earlier research done in the MSD group already showed that relatively low-cost sensor concepts and mechanical designs can be applied to significantly reduce the price of stages, while still achieving sub-micrometer precision. In this research, the applicability of the Arduino Due micro-controller (€40) and amplifiers based on Pulse Width Modulation (PWM, €6) in precision stages is investigated. The use of cheap components doesn’t come without its drawbacks. To name a few examples, the Analog-to-Digital Converter (ADC) in the Arduino doesn’t have the resolution of higher quality components, PWM adds frequency content to the output of the amplifier and the Arduino processor isn’t as fast. In this research project, an extensive theoretical analysis is done to reveal how the components affect the overall performance of the stage, which can then be used to optimize system parameters to circumvent the performance losses that are inevitable with cheap components. This way much of the overall system performance can be maintained. The theory is experimentally validated and the Arduino and PWM based amplifiers are successfully implemented into a working prototype with a precision of 1.5μm.

Reset control is a "simple" nonlinear control strategy that has the potential of being widely adopted and improving the performance of systems traditionally controlled with PIDs. Lack of suitable methods for proving stability, that are in line with the current industrial practice, hampers the wider acceptance of reset control. In this thesis, novel sufficient conditions for stability of reset control systems, that can be evaluated using measured frequency response function of a system to be controlled, are derived using the hybrid passivity and finite-gain framework. A method for analysing the hybrid passivity and finite-gain parameters of reset systems, that can be extended to other classes of nonlinear systems, is developed. Additionally, a variant of the “Constant in Gain Lead in Phase” reset element, that facilitates the use of the proposed method for the stability analysis, is introduced. Stability of several precision positioning systems with reset controllers, designed for different objectives, is studied to demonstrate the applicability of the proposed hybrid passivity and finite-gain approach for the stability analysis of reset control systems. Guidelines for design of reset systems such that their stability can be concluded using the hybrid passivity and finite gain method are shown. This thesis presents a new view on the stability of reset systems and addresses the need for frequency-domain tools for stability analysis of nonlinear control systems in precision mechatronics applications.

High Tech industry is looking to push the bounds of what is possible, this requires machines that run with ever increasing speed and precision for longer amount of time under progressively more hostile environments. These requirements necessitate the use of compliant mechanisms/flexures instead of traditional rigid body counterparts. However, as these flexures are pushed to operate at ever higher speeds, high frequency modes affect precision and hence require better damping. Currently active damping relies on a single or small amount of actuators which makes their placement for multimode damping inefficient. To this end, the MetaMech project was created which aims to combine the disciplines of mechatronics and metamaterials to create flexures with integrated cells housing sensors, active and passive dampers in optimal positions and orientations. This will enable more efficient placement and orientation of dampers, reducing the force and thus the size and weight needed to damp the system. This thesis takes the first step in this direction and is concerned with developing the first prototype demonstrator of a metamaterial flexure with integrated damping using currently available technology. The presentation will cover the design, Finite Element Analysis and practical tests of a hexagonal patterned metamaterial flexure with integrated piezo patches. It also presents the design and finite element analysis of a more advanced hexagonal cell able to exert force in three different directions. The results provide proof of concept for the MetaMech project with insights for future work.

PID is the most popular controller in the industry. PID controllers are linear, and thus have fundamental limitations, such that certain performance criteria cannot be achieved. To overcome these limitations, nonlinear reset control can be used. Reset control can achieve less overshoot and a faster response time than linear controllers. However, the resetting mechanism has a jump function which causes jumps in the control input, which can result in limit cycles. Linear filters and controllers are designed in the industry using loop shaping, which is done in the frequency domain. In this study it is investigated how to analyse reset systems in the frequency domain. A reset system is nonlinear, so transfer functions needs to be approximated by describing functions. The sinusoidal input describing function considers only the first harmonic of the output and therefore does not capture all the dynamics of the element. The effects of the higher order harmonics are important in precision systems, since unwanted dynamics should not be excited nor should performance be affected. In this thesis, the higher order sinusoidal input describing functions (HOSIDF) are derived analytically. The HOSIDF shows the magnitude and phase response per harmonic, such that stability and performance analysis can be improved. Because the HOSIDF shows multiple responses, it is not trivial how to do loop shaping. The information from the HOSIDF is combined, creating a combined magnitude and combined phase response. It is seen that the combined magnitude looks promising, but the combined phase has jumps. It is concluded that the combined magnitude and combined phase are not mature enough to rely on during loop shaping and further work in this direction is required.

Stringent control demands from the high-tech mechatronics industry have warranted the need to explore potentially advantageous non-linear controllers. Variable Fractional Order (VFO) calculus provides one such avenue to build non-linear PID-like controllers. VFO calculus is the generalization of integer order differentiation and integration, where, in addition to the possibility of orders being real or even complex, the orders can vary as a function of a variable like time, temperature, etc. However, in this nascent field of VFO control, the focus has mainly been on controller tuning by time domain optimization of the performance for certain specific trajectories or cost functions. On the other hand, Frequency domain tools allow for analysis and tuning of controllers for performance over a wide range of exogenous inputs. For smooth adoption into industry, it is important to develop a frequency domain framework for working with VFO control. Describing function (DF) analysis is a method to obtain an approximate Frequency Response Function (FRF)-like function for non-linear systems. In this thesis, DF analysis is used for developing VFO PID controllers in the frequency domain from an industry compatibility point of view and the closed loop performance of these controllers in controlling a precision positioning stage is examined.

To push the performance of the next generation Ultimaker 3D printers further, a new positioning system is required to improve the printing speed, print accuracy and print repeatability. The expectation is that a linear motor positioning system will perform significantly better than a conventional belt driven system. For this reason, the aim of this MSc thesis is to demonstrate the feasibility of a low-cost linear motor positioning system for use in a 3D printer. A single axis experimental set-up is realized to evaluate the performance of the positioning system using different linear motors, sensors, guides and controllers. Using a single sided ironless linear motor, Hall effect encoder, linear ball bearing and an open-source controller, a positioning system is realized that can reach a speed of 3.7 m/s, an accuracy of 14 µm and a repeatability of 3 µm. A 2DOF system using these components can be realized with an overall cost of € 854.

PID is the most commonly used technique in industrial motion control. It consists of three components - lead, lag and low pass filter (LPF). PID, being a linear control method is inherently bounded by waterbed effect due to which there exists a trade-off between precision, tracking, and stability. Reset control is a nonlinear technique which shows promise in overcoming certain limitations. Despite the promise shown, the use of reset elements other than integrator within the framework of PID for improved performance has not been well investigated. This thesis work focuses on implementing reset in lead part and in LPF in order to reduce the severity of the waterbed effect in PID. Three controllers have been developed that provide improvements in bandwidth, precision, and tracking. The controllers were implemented in a Lorentz-actuated nanometer precision stage and the performance has been validated in both time and frequency domain.

Floor vibrations are a common problem in high tech engineering where good tracking, precision and bandwidth have utmost importance. They are mainly present at low frequencies, and they need to be suppressed. PID control is the go-to controller in the industry because of its ease of design, simple implementation and good performance. However, PID is subjected to the fundamental limitations of linear control theory - the waterbed effect and bode's gain-phase relationship. Therefore, it is not possible to improve one performance criterion, like stability, without negatively influencing the other. The need for overcoming the fundamental limitations of linear control initiates research towards nonlinear controllers. Reset control is a type of nonlinear controller as a solution to overcome the limitations of a linear control. It reduces phase lag within the system, gives the advantage to reach higher bandwidth and results in lower overshoot or a faster settling time compared to linear controllers. However, using reset control comes with a price of unwanted dynamics due to the higher order harmonics. The main focus of this thesis is to improve disturbance rejection performance against floor vibrations by attenuating the power of high order harmonics. This problem has been tackled within the thesis, and a band-pass reset control is proposed. Proposed reset controller applies reset only within the frequency range where floor vibrations are present, and it uses integrator as a reset variable. Results show reset controller that has a broadband phase compensation, like CgLp, is more advantageous towards phase lag reduction methods. CgLp is a reset element, which is an abbreviation of Constant-Gain Lead Phase. It gives broadband phase compensation within the desired range of frequencies by using generalized first order reset element. Also, CgLp controller achieved disturbance rejection performance of PI extsuperscript{2}D with the phase behavior of Clegg.