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This thesis focuses on the methods and results of the workspace formulation of wire-actuated parallel manipulators. Four methods of workspace generation are studied. The null space method, based on the calculation of wire tensions, is used to formulate the workspaces of example manipulators. The results of this method are used to verify the results of the following methods. This thesis presents that the convex hull workspace formulation method, a geometric analysis of the manipulator’s Jacobian matrix, can be extended to manipulators that have an external wrench and/or gravity applied to the mobile platform. The convex hull method is applied to the example manipulators investigated with the null space method. The workspace envelope characterization, an analytical approach of defining the borders of the workspace using the formulation of the kernel of the manipulator’s Jacobian matrix, is applied to the example planar manipulators investigated with the previous methods. A new process, presented in this thesis, of identifying the contribution of each set of four wires/forces of a planar manipulator allows the workspace envelope characterization to be applied to redundant planar manipulators and planar manipulators that have an external wrench and/or gravity applied to the mobile platform. The discrete and analytical antipodal methods, based on theorems from multi-fingered grasping manipulators, are presented and applied to the example planar manipulators investigated with the previous methods. This research generalizes the use of these theorems, which determine wrench-closure poses of planar four-wire manipulators that share wire-connection points on the base or mobile platform, to the discrete and analytical workspace formulation of planar three-degree-of-freedom wire-actuated manipulators with no restrictions on the number of wires or the configuration of the manipulator. Comparing all methods investigated in this thesis, the null space method results in the workspace that takes into account the maximum and minimum wire tensions and is recommended for use in the design of both spatial and planar wire-actuated parallel manipulators. All the other methods presented in this thesis, have similar results when compared to the null space method but formulate the maximum workspace which assumes the wires can operate with very high to infinite wire tension. / Thesis (Master, Mechanical and Materials Engineering) -- Queen's University, 2009-10-14 09:02:25.562

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Sensorless control strategies were first suggested well over a decade ago with the aim of reducing the size, weight and unit cost of electrically actuated servo systems. The resulting algorithms have been successfully applied to the induction and synchronous motor families in applications where control of armature speeds above approximately one hundred revolutions per minute is desired. However, sensorless position control remains problematic. This thesis provides an in depth investigation into sensorless motor control strategies for high precision motion control applications. Specifically, methods of achieving control of position and very low speed thresholds are investigated. The developed grey box identification techniques are shown to perform better than their traditional white or black box counterparts. Further, fuzzy model based sliding mode control is implemented and results demonstrate its improved robustness to certain classes of disturbance. Attempts to reject uncertainty within the developed models using the sliding mode are discussed. Novel controllers, which enhance the performance of the sliding mode are presented. Finally, algorithms that achieve control without a primary feedback sensor are successfully demonstrated. Sensorless position control is achieved with resolutions equivalent to those of existing stepper motor technology. The successful control of armature speeds below sixty revolutions per minute is achieved and problems typically associated with motor starting are circumvented.

Humanoid robots have proven to be very useful and could revolutionize the way humans live. Knowing human anatomy and behaviour helps improve a robotic mechanisms ability to perform human tasks. The following thesis introduces the concept of a threefingered robot hand and its driving mechanism. The hand includes two fingers and a thumb. Using the concept of “an under actuated system”, each finger consists of three revolute joints which are driven by two actuators and tooth belt transmission system. The thumb has two joints but only one joint is active and actuated by one motor. The passive joint is designed to set the initial position of the thumb on the piano key if necessary. Required angle of rotation for each joint has been calculated through Inverse Kinematics. Once the fingertip presses the piano key, it should apply 1N force to play a note. Force Sensing Resistors at each finger tip, as a control method, are introduced to the system to accurately measure the amount of applied force from the finger tip on the key and increase the angle of rotation of the motor if needed. Stress and deformation of the joints have been studied through Finite Element Analysis. A prototype model, consisting of a single finger was built to better understanding the functionality of the concept. Analysis of this model, led to necessary modification of the transmission system and some design revisions to each link. Genetic Algorithm using MATLAB was used to optimize the performance Index of a finger. Finally the hand assembly including all the components and driving mechanism was constructed and experimented in the playing mode. / UOIT

This dissertation analyzes two unsolved problems to fulfill the gap in the literature: (1). What is the vehicle delay and intersection capacity considering left-turn traffic at a pre-timed signal? (2). What are the mean and variance of delay to vehicles at a vehicle-actuated signal? The first part of this research evaluates the intersection performance in terms of capacity and delay at an isolated pre-timed signal intersection. Despite of a large body of literature on pre-timed signals, few work has examined the interactions be- tween left-turn and through vehicles. Usually a protected left-turn signal phase, before (leading) or after (lagging) through signal, is applied to a signalized inter- section when the traffic demand is relatively high. A common problem for leading left-turn operation is the blockage to left-turn vehicles by through traffic, particularly at an intersection with a short left-turn bay. During the peak hour, some vehicles on the through lane might not be able to depart at the end of a cycle, resulting in an increased probability of left-turn blockage. In turn, the blocked left-turn vehicles may also delay the through traffic to enter the intersection during the following cycle. Those problems may not exist for a lagging left-turn operation, since left-turn vehicles intend to spill out of the bay under heavy traffic. In this case, the through capacity is reduced, leading to an increase of total delay. All of these factors contribute to the difficulties of estimating the delay and capacity for an isolated intersection. In order to examine this missing part of study on the signalized intersection, two probabilistic models are proposed to deal with the left-turn bay blockage and queue spillback in a heuristic manner. Numerical case studies are also provided to test the proposed models. The second part of this research studies an isolated intersection with vehicle-actuated signal. Typically an advanced detector is located at a distance prior to the intersection such that an arriving vehicle triggers a green time extension in or- der to pass through without any stop. This extended time period actuated by the vehicle is called unit extension in this study. If no vehicle actuation occurs during a unit extension, the green phase would terminate in order to clear queues in other approaches. In this way, the actuated system dynamically allocates the green time among multiple approaches according to vehicle arrivals. And the unit extension is the only control parameter in this case. We develop a model to study the vehicle delay under a general arrival distribution with a given unit extension. Our model allows optimizing the intersection performance over the unit extension. The third part of this research applies graphical methods and diffusion approximations to the traffic signal problems. We reinterpret a graphical method which is originally proposed by Newell in order to directly measure the variance of the time for the queue clearance at a signalized intersection, which remains yet to be carefully examined in practice and would be rather challenging if only using the conventional queuing techniques. Our results demonstrate that graphical method explicitly presents both the deterministic and stochastic delay. We also illustrate that the theoretical background for the graphical methods in this particular application is inherently the diffusion approximation. Furthermore, we investigate the problems of disruptions occurred during a pre-timed traffic signal cycle. By diffusion approximation, we provide quantitative estimation on the duration that the effects of disruptions would dissipate.

Most spacecraft are designed to be maneuvered to achieve pointing goals. This is generally accomplished by designing a three-axis control system. This work explores new maneuver strategies when only two control inputs are available: (i) sequential single-axis maneuvers and (ii) three-dimensional (3D) coupled maneuvers. The sequential single-axis maneuver strategies are established for torque, time, and fuel minimization applications. The resulting control laws are more complicated than the equivalent results for three-axis control because of the highly nonlinear control switch-times. Classical control approaches lead to optimal, but discontinuous control profiles. This problem is overcome by introducing a torque-rate penalty for the torque minimization case. Alternative approaches are also considered for achieving smooth continuous control profiles by introducing a cubic polynomial multiplicative control switch smoother for the time and fuel minimization cases. Numerical and analytical results are presented to compare optimal maneuver strategies for both nominal and failed actuator cases. The 3D maneuver strategy introduces a homotopy algorithm to achieve optimal nonlinear maneuvers minimizing the torque. Two cases are considered: (i) one of the three-axis control actuators fails and (ii) two control actuators fail among four control actuators. The solution strategy first solves the case when all three actuators are available. Then, the failed actuator case is recovered by introducing a homotopy embedding parameter, ε, into the nonlinear dynamics equation. By sweeping ε, a sequence of neighboring optimal control problems is solved that starts with the original maneuver problem and arrives at the solution for the under-actuated case. As ε approaches 1, the designated actuator no longer provides control inputs to the spacecraft, effectively modeling the failed actuator condition. This problem is complex for two reasons: (i) the governing equations are nonlinear and (ii) ε fundamentally alters the spacecraft’s controllability. Davidenko’s method is introduced for developing an ordinary differential equation for the costate variable as a function of ε. For each value of ε, the costate initial conditions are iteratively adjusted so that the terminal boundary conditions for the 3D maneuver are achieved. Optimal control applications are presented for both rest-to-rest and motion-to-rest cases that demonstrate the effectiveness of the proposed algorithm.

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This thesis is a development project for a myoelectric prosthetic hand. That means a mechanical hand that is controlled and actuated by the user's own muscles on the residual limb. The thesis has led to a theoretical concept of a complete prosthesis and a non-complete physical prototype that provides proof of concept and functions. The thesis was as a means of providing the mechanical development of an alternative model of the prosthesis that is more functional and has the ability to offer the users a lower price than current models. The foundation of the project is that the development has been done on a user needs basis. This leads to customer requirements that are derived from the users themselves. The development begun with a wide research to obtain user feedback as well as technical data of different mechanical solutions. The focal point of the thesis is the mechanical aspect of the prosthetic while the electronic and sensory systems were implemented with the use of standardized components.

El texto completo de este trabajo no está disponible en el Repositorio Académico UPC por restricciones de la casa editorial donde ha sido publicado. / The fully actuated signal control detects the pedestrian density using sensors and, according to that, it prioritizes pedestrians crossing. One major problem, worldwide, is using fixed time traffic light as a traffic regulator at intersections with high pedestrian and vehicular volume. Lima is no exception, continuing to use this kind of traffic lights completely harms pedestrian accessibility, it increases their waiting and crossing times, it also affects road safety and service levels at the structures. The proposal on this article is to design a fully actuated signal control using logical controls that are able to perceive the pedestrian density on the refuge islands, making everything more accessible. In order to do this, a study to identify the pedestrian and vehicle volume was conducted on the Lima Panamerican highway. There was a total of 7506 pedestrians during rush hour, proving there is a large amount of people at the intersection at that time. Thereby, by using the VisVap module of the Vissim, the study managed to simulate and validate the priority control required. All in all, the results showed a remarkable improvement, the pedestrian crossing time was reduced by 6.84% and the service level of the intersection went from E to D.