Hybrid intelligent machine systems : design, modeling and control

To further improve performances of machine systems, mechatronics offers some opportunities. Traditionally, mechatronics deals with how to integrate mechanics and electronics without a systematic approach. This thesis generalizes the concept of mechatronics into a new concept called hybrid intelligent machine system. A hybrid intelligent machine system is a system where two or more elements combine to play at least one of the roles such as sensor, actuator, or control mechanism, and contribute to the system behaviour. The common feature with the hybrid intelligent machine system is thus the presence of two or more entities responsible for the system behaviour with each having its different strength complementary to the others. The hybrid intelligent machine system is further viewed from the system’s structure, behaviour, function, and principle, which has led to the distinction of (1) the hybrid actuation system, (2) the hybrid motion system (mechanism), and (3) the hybrid control system. This thesis describes a comprehensive study on three hybrid intelligent machine systems. In the case of the hybrid actuation system, the study has developed a control method for the “true” hybrid actuation configuration in which the constant velocity motor is not “mimicked” by the servomotor which is treated in literature. In the case of the hybrid motion system, the study has resulted in a novel mechanism structure based on the compliant mechanism which allows the micro- and macro-motions to be integrated within a common framework. It should be noted that the existing designs in literature all take a serial structure for micro- and macro-motions. In the case of hybrid control system, a novel family of control laws is developed, which is primarily based on the iterative learning of the previous driving torque (as a feedforward part) and various feedback control laws. This new family of control laws is rooted in the computer-torque-control (CTC) law with an off-line learned torque in replacement of an analytically formulated torque in the forward part of the CTC law. This thesis also presents the verification of these novel developments by both simulation and experiments. Simulation studies are presented for the hybrid actuation system and the hybrid motion system while experimental studies are carried out for the hybrid control system

Master of Science

thesisA repair technique for damaged precast reinforced concrete bridge column to pier cap joints constructed with grouted splice sleeve connections has been developed using plastic hinge relocation. Undamaged column to pier cap specimens constructed with grouted splice sleeve connections were tested to failure using quasi-static cyclic loads applied in the horizontal direction at the top of the column. The column's plastic hinge region was subsequently repaired using prefabricated carbon fiber-reinforced polymer shells, epoxy anchored headed mild steel bars, and nonshrink or expansive concrete to increase the moment of inertia at the column base and relocate the plastic hinge in the column to a region with minor damage. Follow up quasi-static cyclic tests of the repaired specimens were performed to verify the effectiveness of the repair technique. Analytical strut and tie models of both the original and repaired specimens were developed and verified using the test results. In addition to destructive tests, acoustic emission monitoring of grouted splice sleeves, the original specimens, and the repaired specimens were performed to correlate acoustic emissions to damage. To obtain an appropriate damage assessment of grouted splice sleeve connections using acoustic emissions monitoring, the acoustic emission characteristics of two different grouted splice sleeve systems were obtained by performing tension tests of the sleeves to failure. The acoustic emission monitoring system was then implemented on the original and repaired specimens to demonstrate the effectiveness of relating acoustic emissions to damage

Creative design and modelling of large-range translation compliant parallel manipulators

Compliant parallel mechanisms/manipulators (CPMs) are parallel manipulators that transmit motion/load by deformation of their compliant members. Due to their merits such as the eliminated backlash and friction, no need for lubrication, reduced wear and noise, and monolithic configuration, they have been used in many emerging applications as scanning tables, bio-cell injectors, nano-positioners, and etc. How to design large-range CPMs is still a challenging issue. To meet the needs for large-range translational CPMs for high-precision motion stages, this thesis focuses on the systematic conceptual design and modelling of large-range translational CPMs with distributed-compliance. Firstly, several compliant parallel modules with distributed-compliance, such as spatial multi-beam modules, are identified as building blocks of translational CPMs. A normalized, nonlinear and analytical model is then derived for the spatial multi-beam modules to address the non-linearity of load-equilibrium equations. Secondly, a new design methodology for translational CPMs is presented. The main characteristic of the proposed design approach is not only to replace kinematic joints as in the literature, but also to replace kinematic chains with appropriate multiple degrees-of-freedom (DOF) compliant parallel modules. Thirdly, novel large-range translational CPMs are constructed using the proposed design methodology and identified compliant parallel modules. The proposed novel CPMs include, for example, a 1-DOF compliant parallel gripper with auto-adaptive grasping function, a stiffness-enhanced XY CPM with a spatial compliant leg, and an improved modular XYZ CPM using identical spatial double four-beam modules. Especially, the proposed XY CPM and XYZ CPM can achieve a 10mm’s motion range along each axis in the case studies. Finally, kinematostatic modelling of the proposed translational CPMs is presented to enable rapid performance characteristic analysis. The proposed analytical models are also compared with finite element analysis

Development of an Adaptive Flap/Flaperon Flight Control System with Shape Memory Alloy Actuation

This thesis discusses the design, manufacturing and testing of a new kind of adaptive airfoil using Shape Memory Alloy (SMA) actuation. An antagonistic arrangement of SMA wires was used in a Post-Buckled Precompressed (PBP) kind of actuator that was employed in an adaptive flap system. The thesis opens with a short survey on the history of the PBP mechanism and a literature research on different flap systems actuated by adaptive materials. The conceptual design of the SMAPBP actuator and its evolution to the actuator employed in an adaptive aerostructure is discussed in the first chapters. Experiments showed that the SMAPBP actuator could obtain tip rotations up to 65°, which nearly quadrupled the levels achieved by piezoelectric PBP actuators. In the following, former developed theory for piezoelectric PBP actuators was modified to account for the trapezoidal shape of the SMAPBP actuator. The developed theory was then compared to experimental results. A FEM model was also developed and evaluated to prove the PBP concept for this actuator numerically. In the second section of the thesis the author gives a detailed explanation of the design concept and the manufacturing of the airfoil. A NACA0012 airfoil with a chord length of 150mm and a width of 100mm was used to prove the concept of the adaptive flap system. The thesis continues with a description of the test setup, the CFD model assumptions and the results of wind tunnel tests. The developed adaptive airfoil proved its capabilities during the numerical and experimental tests and showed that the employment and actuation of the SMAPBP actuator could more than doubled the lift coefficient of the airfoil. The architecture and employment of a closed loop position feedback system to overcome the nonlinear behavior of the SMA material and the PBP mechanism is also discussed. The thesis closes with an overview over the adaptive airfoil with SMAPBP actuator and gives recommendations for future work in this field

Destructive Testing and Finite-Element Modeling of Full-Scale Bridge Sections Containing Precast Deck Panels

Full-depth, precast panel deck systems are becoming more common in bridge installation and repair. The objective of these systems is to achieve the performance of cast-in-place systems while simultaneously saving time and money. The structural behavior of these systems has been the subject of scrutiny in recent research. The Utah Department of Transportation demolished a steel I-girder bridge containing a precast panel deck system and provided two full-scale specimens for this project. Destructive testing was performed at Utah State University on the specimens to investigate three failure modes: flexural, beam shear, and punching shear. Finite-element models were created using ANSYS software to replicate experimental behavior. Overall, it was found that the elastic, post-elastic, and ultimate behavior of the full-scale bridge sections containing precast panel deck systems can be accurately predicted in analytical models. Another aspect of this project was to investigate changes in dynamic behavior as the system was subjected to flexural yield and failure. Point loads were applied and removed in increments, and dynamic testing was conducted at each load level. It was found that significant damage is somewhat noticeable by monitoring the changes in natural frequencies

Micro motion stages with flexure hinges-design and control

The developments in micro and nano technologies brought the need of high precision micropositioning stages to be used in micro/nano applications such as cell manipulation, surgery, aerospace, micro fluidics, optical systems, micromachining and microassembly etc. Micro motion stages with flexible joints called compliant mechanisms are built to provide the needed accuracy and precision. This thesis aims to build compliant planar micro motion stages using flexure hinges to be used as micropositioning devices in x-y directions by applying new control methods. First 3- RRR planar parallel kinematic structure is selected which is also popular in the literature. Then the mechanism is developed to have a new structure which is a 3-PRR mechanism. The necessary geometric parameters are selected by using Finite Element Analysis (FEA). The displacement, stress and frequency behaviors of the mechanisms are compared and discussed. Modeling of the flexure based mechanisms is also studied for 3-PRR compliant stage by using Kinetostatic modeling method which combines the compliance calculations of flexure hinges with kinematics of the mechanism. Piezoelectric actuators and optical 2d position sensor which uses a laser source are used for actuation and measurement of the stages. After the experimental studies it's seen that the results are not compatible with FEA because of the unpredictable errors caused by manufacturing and assembly. We have succeeded to eliminate those errors by implementing a control methodology based on Sliding Mode Control with Disturbance Observer which is also based on Sliding Mode Control using linear piezoelectric actuator models. Finally, we have extracted experimental models for each actuation direction of the stage and used those models instead of piezoelectric actuator models which lowered our errors in the accuracy of our measurement and ready to be used as a high precision micro positioning stage for our micro system applications

Non-contact measurement machine for freeform optics

The performance of high-precision optical systems using spherical optics is limited by aberrations. By applying aspherical and freeform optics, the geometrical aberrations can be reduced or eliminated while at the same time also reducing the required number of components, the size and the weight of the system. New manufacturing techniques enable creation of high-precision freeform surfaces. Suitable metrology (high accuracy, universal, non-contact, large measurement volume and short measurement time) is key in the manufacturing and application of these surfaces, but not yet available. In this thesis, the design, realization and testing of a new metrology instrument is described. This measurement machine is capable of universal, noncontact and fast measurement of freeform optics up to Ø500 mm, with an uncertainty of 30 nm (2s). A cylindrical scanning setup with an optical distance probe has been designed. This concept is non-contact, universal and fast. With a probe with 5 mm range, circular tracks on freeform surfaces can be measured rapidly with minimal dynamics. By applying a metrology frame relative to which the position of the probe and the product are measured, most stage errors are eliminated from the metrology loop. Because the probe is oriented perpendicular to the aspherical best-fit of the surface, the sensitivity to tangential errors is reduced. This allows for the metrology system to be 2D. The machine design can be split into three parts: the motion system, the metrology system and: the non-contact probe. The motion system positions the probe relative to the product in 4 degrees of freedom. The product is mounted on an air bearing spindle (??), and the probe is positioned over it in radial (r), vertical (z) and inclination (¿) direction by the R-stage, Z-stage and ¿- axis, respectively. The motion system provides a sub-micrometer repeatable plane of motion to the probe. The Z-stage is hereto aligned to a vertical plane of the granite base using three air bearings, to obtain a parallel bearing stage configuration. To minimize distortions and hysteresis, the stages have separate position and preload frames. Direct drive motors and high resolution optical scales and encoders are used for positioning. Mechanical brakes are applied while measuring a track, to minimize power dissipation and to exclude encoder, amplifier and EMC noise. The motors, brakes and weight compensation are aligned to the centres of gravity of the R and Zstage. Stabilizing controllers have been designed based on frequency response measurements. The metrology system measures the position of the probe relative to the product in the six critical directions in the plane of motion of the probe (the measurement plane). By focussing a vertical and horizontal interferometer onto the ¿-axis rotor, the displacement of the probe is measured relative to the reference mirrors on the upper metrology frame. Due to the reduced sensitivity in tangential direction at the probe tip, the Abbe criterion is still satisfied. Silicon Carbide is the material of choice for the upper metrology frame, due to its excellent thermal and mechanical properties. Mechanical and thermal analysis of this frame shows nanometer-level stabilities under the expected thermal loads. Simulations of the multi-probe method show capabilities of in process separation of the spindle reference edge profile and the spindle error motion with sub-nanometer uncertainty. The non-contact probe measures the distance between the ¿-axis rotor and the surface under test. A dual stage design is applied, which has 5 mm range, nanometer resolution and 5° unidirectional acceptance angle. This enables the R and Z-stage and ¿-axis to be stationary during the measurement of a circular track on a freeform surface. The design consists of a compact integration of the differential confocal method with an interferometer. The focussing objective is positioned by a flexure guidance with a voice coil actuator. A motion controller finds the surface and keeps the objective focused onto it with some tens of nanometers servo error. The electronics and software are designed to safely operate the 5 axes of the machine and to acquire the signals of all measurement channels. The electronics cabinet contains a real-time processor with many in and outputs, control units for all 5 axes, a safety control unit, a probe laser unit and an interferometry interface. The software consists of three main elements: the trajectory planning, the machine control and the data processing. Emphasis has been on the machine control, in order to safely validate the machine performance and perform basic data-processing. The performance of the machine assembly has been tested by stability, single track and full surface measurements. The measurements focus on repeatability, since this is a key condition before achieving low measurement uncertainty by calibration. The measurements are performed on a Ø100 mm optical flat, which was calibrated by NMi VSL to be flat within 7 nm rms. At standstill, the noise level of the metrology loop is 0.9 nm rms over 0.1 s. When measuring a single track at 1 rev/s, 10 revolutions overlap within 10 nm PV. The repeatability of three measurements of the flat, tilted by 13 µm, is 2 nm rms. The flatness measured by the uncalibrated machine matches the NMi data well. Ten measurements of the flat tilted by 1.6 mm repeat to 3.4 nm rms. A new non-contact measurement machine prototype for freeform optics has been developed. The characteristics desired for a high-end, single piece, freeform optics production environment (high accuracy, universal, non-contact, large measurement volume and short measurement time) have been incorporated into one instrument. The validation measurement results exceed the expectations, especially since they are basically raw data. Future calibrations and development of control and dataprocessing software will certainly further improve these results

Design and analysis of a monolithic flexure atomic force microscope

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2008.Includes bibliographical references (p. 175-178).This thesis details the design, manufacture, and testing of a sub-nanometer accuracy atomic force microscope. It was made to be integrated into the Sub-Atomic Measuring Machine (SAMM) in collaboration with the University of North Carolina at Charlotte (UNCC). The microscope uses a tuning fork sensor to gauge its proximity to the sample surface. The sensor is fixed to a stage that is guided to move in one degree of freedom by a monolithic flexure. A piezoelectric actuator drives the moving stage while three capacitance sensors provide a non-contact direct measurement of the displacement. A decoupling flexure prohibits the error motions of the actuator from propagating into the moving stage. A digital control system uses closed loop control to regulate the vertical displacement of the stage. The positioning system demonstrated a 450 Hz -3db closed loop bandwidth and 0.249 RMS noise positioning. A new probe named after its inventor Dr. Terunobu Akiyama is implemented in a feedback control system that adjusts the displacement of the stage in order to maintain a constant gap between the probe and the sample. The system displayed an 8.3 nm RMS positioning noise when set to measure a stationary block of aluminum. The dynamics of the feedback control loop indicate that the system can operate at 27 Hz upon application of a proportional controller. Advanced methods to self excite the tuning fork sensor at resonance by use of a phase locked loop are explored. Follow-up work to integrate the atomic force microscope into the SAMM stage, diminish the electrical noise in the tuning fork, and to implement the phase locked loop circuit are suggested.by Dean Marko Ljubicic.S.M

21st century manufacturing machines: Design, fabrication and controls

Advances in nanotechnology, microfabrication and new manufacturing processes, the revolution of open electronics, and the emerging internet of things will influence the design, manufacture, and control of manufacturing machines in the future. For instance, miniaturization will change manufacturing processes; additive and rapid prototyping will change the production of machine components; and open electronics offer a platform for new control architectures for manufacturing systems that are open, modular, and easy to reconfigure. Combined with the latest trends in cyber-physical systems and the internet of things, open architecture controllers for CNC systems can become platforms, oriented for numerical control as a service (NCaaS) and manufacturing as a service, tailored to the creation of cyber-manufacturing networks of shared resources and web applications. With this potential in mind, this research presents new design-for-fabrication methodologies and control strategies to facilitate the creation of next generation machine tools. It provides a discussion and examples of the opportunities that the present moment offers. The first portion of this dissertation focuses on the design of complex 3D MEMS machines realized from conventional 2.5D microfabrication processes. It presents an analysis of an example XYZ-MEMS parallel kinematics stage as well as of designs of the individual components of the manipulator, integrated into a design approach for PK-XYZ-MEMS stages. It seems likely that this design-for-fabrication methodology will enable higher functionality in MEMS micromachines and result in new devices that interact, in three full dimensions, with their surroundings. Novel and innovative research exemplifies the opportunities new and economical manufacturing technologies offer for the design and fabrication of modern machine tools. The second portion of this dissertation describes the demonstration of a new flexural joint designed with both traditional and additive manufacturing processes. It extrapolates principles based on the design of this joint that alleviate the effects of low accuracy and poor surface finishing, anisotropy, reductions in material properties of components, and small holding forces. Based on these results, the next section presents case examples of the construction of mesoscale devices and machine components using multilayered composites and hybrid flexures for precision engineering, medical training, and machine tools for reduced life applications and tests design-for-fabrication strategies. The results suggest the strategies effectively address existing problems, providing a repertory of creative solutions applicable to the design of devices with hybrid flexures. The implications for medical industry, micro robotics, soft robotics, flexible electronics, and metrology systems are positive. Chapter number five examines to positive impact of open architectures of control for CNC systems, given the current availability of micro-processing power and open-source electronics. It presents a new modular architecture controller based on open-source electronics. This component-based approach offers the possibility of adding micro-processing units and an axis of motion without modification of the control programs. This kind of software and hardware modularity is important for the reconfiguration of new manufacturing units. The flexibility of this architecture makes it a convenient testbed for the implementation of new control algorithms on different electromechanical systems. This research provides general purpose, open architecture for the design of a CNC system based on open electronics and detailed information to experiment with these platforms. This dissertation’s final chapter describes how applying the latest trends to the classical concepts of modular and open architecture controllers for CNC systems results in a control platform, oriented for numerical control as a service (NCaaS) and manufacturing as a service (MaaS), tailored to the creation of cyber-manufacturing networks of shared resources and web applications. Based on this technology, this chapter introduces new manufacturing network for numerical control (NC) infrastructure, provisioned and managed over the internet. The proposed network architecture has a hardware, a virtualization, an operating system, and a network layer. With a new operating system necessary to service and virtualize manufacturing resources, and a micro service architecture of manufacturing nodes and assets, this network is a new paradigm in cloud manufacturing

Flexure-based nanopositioning systems : integrated design and control

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2010.Cataloged from PDF version of thesis.Includes bibliographical references (p. 209-219).This thesis deals with the design and control of flexure-based mechanisms for applications requiring multi-degree-of-freedom positioning and alignment. Example applications include positioning a probe or sample in atomic force microscopy, alignment of tool and sample in stamping processes, and fine-positioning of wafer steppers in semiconductor manufacturing. Such applications necessitate nanopositioning systems that satisfy critical functional requirements, such as load-capacity, bandwidth, resolution, and range. Therefore, a systematic approach for design and control is an important tool for research and development for flexure-based nanopositioning systems. In this thesis, a novel methodology is presented for generating flexure-based topologies that can meet performance requirements, such as those dictating structural strength or dynamical behavior. We present performance metrics that allow for the generation of topologies that are tuned for a desired level of structural strength or modal separation. The topology generation is aimed as a valuable addition to the design toolkit, facilitating novel designs that could not have been conceived otherwise. The parameters within any particular topology could be adjusted at a subsequent phase through a detailed shape and size optimization. The thesis also proposes a controller generation approach. Unlike existing controller parameterizations, a novel parameterization formulated in this thesis allows for directly tuning the sensitivity transfer function of the closed-loop system. Tuning sensitivity is critical in mitigating the effects of disturbances affecting the system, as well as those arising from cross-coupling and parasitic error motions. Further, an integrated methodology for design and control is presented. This methodology uses the design topology generation approach and controller generation approach proposed in the thesis. The key distinction of our design for control approach is that the design is iterated over topologies and not just parameters within a selected topology. A simple one-degree-of-freedom positioning system example is worked out to detail the steps of the proposed integrated design and control methodology. A novel design topology that is ideally suited for achieving a desired design and control performance is derived using this methodology. Finally, the hardware design and control of a novel flexure-based nanopositioner implementation for scanning probe microscopy are presented to illustrate the effectiveness of the approaches discussed in this thesis.by Vijay Shilpiekandula.Ph.D