Initial work on path generation routines for the University of Surrey Manipulator demonstrated the need for an improved control strategy. In view of the difficulties encountered in obtainins such a strategy by analytical means it was decided to investigate the feasibility of seneratins switching profiles for individual degrees of freedom of the manipulator by a suitable computer simulation. A computer implementation of an exponential constant volume pressure transient formed the basis for a simulation of one degree of freedom of the manipulator that requires a minimum of experimental data for its operation. Using this approach a simulation of the trajectory of a single axis of the manipulator under the control of a simple switch-over sequence was carried out in forward and reverse time It was argued that such a simulator package is suitable for the generation of switching profiles for the axis and a number of suggestions were made concerning the use of such simulators as the basis for the control of the arm.

This thesis documents the research that has led to the development, in prototype form, of a modular sensing system for use in a robot's work cell. The system implemented overcomes one of the major limitations of existing sensing systems, that is the difficulty of altering their sensing characteristics. The majority of sensing systems that are currently available are inflexible in that the addition of extra sensors requires, at the very least, substantial changes to both hardware and software. What these systems require is a facility through which users can easily, and readily, make changes to the configuration of the sensors they employ. In the modular system described, the sensors that provide the information about the robot's work cell are independent of the algorithms that make use of the information. That is, the sensors do not need any knowledge as to when or how the information they provide will be used. Similarly, the algorithms that make use of the data do not need any knowledge as to the provider of the data. This separation of data provider from data user enables the software that controls the sensors (and even the sensors themselves) to be upgraded without corresponding changes to the data user software. Additional sensors can easily be added to the system while redundant sensors can simply be removed. The location of objects within the robot's workspace is achieved by building a model of the workspace using the information provided by a number of sensors. As a prerequisite to model construction three problems had to be addressed. Firstly, the information extracted from different sensors is generally at different resolutions. Secondly, the representation of 3-D space requires large amounts of computer memory. Thirdly, the production of the 3-D model, particularly when a large number of sensors are involved requires a substantial amount of processor time. The first two problems were addressed using a data structure that allowed compact data storage, while the final problem was reduced by identifying parallel aspects of the processing and implementing them on a network of transputers. After the objects within the robot's workspace have been located, the next stage is to identify them. The identification is achieved by calculating the degree of match between measurable characteristics of the object to be identified and the same measurable characteristics of known objects. The degree of match, which is similar but not identical to the correlation function, between the object to be identified and each known object is then used to determine, if possible, the required identity of the object. The work contained within the thesis not only demonstrates the feasibility and benefits of a modular sensing system, over traditional sensing system, but has brought to light some points that will need further thought before a fully functional system is produced. The last chapter contains, in addition to a full and detailed list of conclusions made during the research, a summary of some of these areas that still require further work.

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abstract: Human running requires extensive training and conditioning for an individual to maintain high speeds (greater than 10mph) for an extended duration of time. Studies have shown that running at peak speeds generates a high metabolic cost due to the use of large muscle groups in the legs associated with the human gait cycle. Applying supplemental external and internal forces to the human body during the gait cycle has been shown to decrease the metabolic cost for walking, allowing individuals to carry additional weight and walk further distances. Significant research has been conducted to reduce the metabolic cost of walking, however, there are few if any documented studies that focus specifically on reducing the metabolic cost associated with high speed running. Three mechanical systems were designed to work in concert with the human user to decrease metabolic cost and increase the range and speeds at which a human can run. The methods of design require a focus on mathematical modeling, simulations, and metabolic cost. Mathematical modeling and simulations are used to aid in the design process of robotic systems and metabolic testing is regarded as the final analysis process to determine the true effectiveness of robotic prototypes. Metabolic data, (VO2) is the volumetric consumption of oxygen, per minute, per unit mass (ml/min/kg). Metabolic testing consists of analyzing the oxygen consumption of a test subject while performing a task naturally and then comparing that data with analyzed oxygen consumption of the same task while using an assistive device. Three devices were designed and tested to augment high speed running. The first device, AirLegs V1, is a mostly aluminum exoskeleton with two pneumatic linear actuators connecting from the lower back directly to the user's thighs, allowing the device to induce a torque on the leg by pushing and pulling on the user's thigh during running. The device also makes use of two smaller pneumatic linear actuators which drive cables connecting to small lever arms at the back of the heel, inducing a torque at the ankles. Device two, AirLegs V2, is also pneumatically powered but is considered to be a soft suit version of the first device. It uses cables to interface the forces created by actuators located vertically on the user's back. These cables then connect to the back of the user's knees resulting in greater flexibility and range of motion of the legs. Device three, a Jet Pack, produces an external force against the user's torso to propel a user forward and upward making it easier to run. Third party testing, pilot demonstrations and timed trials have demonstrated that all three of the devices effectively reduce the metabolic cost of running below that of natural running with no device. / Dissertation/Thesis / Masters Thesis Engineering 2014

No description available.

This thesis describes the design, development and implementation of a robot mounted active stereo vision system for adaptive robot arm guidance. This provides a very flexible and intelligent system that is able to react to uncertainty in a manufacturing environment. It is capable of tracking and determining the 3D position of an object so that the robot can move towards, and intercept, it. Such a system has particular applications in remotely controlled robot arms, typically working in hostile environments. The stereo vision system is designed on mechatronic principles and is modular, light-weight and uses state-of-the-art dc servo-motor technology. Based on visual information, it controls camera vergence and focus independently while making use of the flexibility of the robot for positioning. Calibration and modelling techniques have been developed to determine the geometry of the stereo vision system so that the 3D position of objects can be estimated from the 2D camera information. 3D position estimates are obtained by stereo triangulation. A method for obtaining a quantitative measure of the confidence of the 3D position estimate is presented which is a useful built-in error checking mechanism to reject false or poor 3D matches. A predictive gaze controller has been incorporated into the stereo head control system. This anticipates the relative 3D motion of the object to alleviate the effect of computational delays and ensures a smooth trajectory. Validation experiments have been undertaken with a Puma 562 industrial robot to show the functional integration of the camera system with the robot controller. The vision system is capable of tracking moving objects and the information this provides is used to update command information to the controller. The vision system has been shown to be in full control of the robot during a tracking and intercept duty cycle.

Off-line programming techniques have been developed to improve productivity of advanced robot systems. In the manufacturing industry, they enable robot workcells to be simulated and robot programs to be generated without interrupting the production process. However, due to the poor structural integrity of present-day robots, discrepancies exist between the CAD model used in the off-line programming system and the real robot. These discrepancies severely limit the effectiveness of off-line programming techniques, since manual operator intervention is required to modify the off-line generated trajectories required for the robot to operate in the manufacturing cell. The work presented here addresses the problems associated with some of these discrepancies to enhance off-line programming systems, by concentrating on two aspects of robot kinematic performance. Identification of the 'actual' kinematics of the manipulator using a new calibration methodology enables the static positioning accuracy of the device to be improved. Validation experiments have been performed using the new kinematic calibration methodology. Identification of the 'actual' kinematics of a Puma-560 industrial robot has shown that this robot's average positioning error can be reduced by approximately 93%. By providing the workcell designer with a new performance index known as the Condition Vector as an indication of the variation in robot kinematic performance throughout its workspace, workcells can be arranged and robot postures selected based on desired robot characteristics for prescribed tasks. Validation experiments for the Condition Vector, undertaken on two industrial robots, were not conclusive but provided promising results.

This thesis is devoted to the study and extension of screw image space and its application to kinematic restraint and robotic grasping. In the study of restraint and robotic grasping, problems arise in relation to how to map the conditions and requirements of restraint in a special representational space, and how to map an object in the same space, so that all analysis and synthesis can be performed and further developed in such a space. Meanwhile, it is desirable that such a space would allow us to establish a relationship between equilibrium and geometry of a restraint circumstance, and also a relationship between geometry and algebra. The study is to introduce the restraint mapping in a newly extended screw image space. With the help of a new look at the properties of screws and screw systems, the screw image space is extended with its relevant spaces, the relationship among them is clarified together with a set of definitions. The screw image space is further completed with the study of its entities including hyperplanes, simplexes and polytopes, and further with the partition of the space. A framework is thus established and associated to restraint mapping and the extension of screw image space, and a set of theories is developed to study the entities in screw image space and to apply them to the restraint mapping. The study is based on the linear dependence of screws with detailed algebraic reasoning, which puts forward new properties of zero pitch screw combinations and theory of linear dependence of reciprocal screw systems together with algebraic and geometric reasoning. The study is successfully applied to kinematic restraint and robotic grasping with a set of theorems and methodologies, not only by mapping the restraint of an object, but also by mapping a set of restraint screws along the surface of an object. The graspability of an arbitrary object can thus be determined, the planning and optimisation can be carried out in the screw image space, together with three new invariant quality measures. An optimal grasp is hence achieved with isotropic resistance to arbitrary externally applied forces. The mapping and entities in screw image space are further weighted to account for the stiffness of contacts in dealing with frictional restraint, and planning is thus based on a stiffness weighted mapping. The planning and optimisation are further given in the concept of normal related restraint, and are achieved in the relevant screw image spaces. An augmented space is then established with the introduction of an affine condition. The relationship between the affine solution and the volumetric ratios of sub-simplexes to an n-simplex reconciles the quality measures with the optimisation. With the further introduction of elastic compatibility, frictional grasps are decomposed, and the force equation of equilibrium is augmented. The approach makes it possible to plan grasps in screw image space and to solve them in augmented space. The approach is further used to predict the failure of a specific case of grasping, and gives a satisfactory result, when compared with an experimental result. The final phase of the study is applied to the unknown grasping of unknown objects. By aggregating contact normals and their position vectors of an unknown object by means of newly developed tactile fingertip detectors, and by mapping them into screw image space, the description of an unknown object is completed. The planning and optimisation can thus operate in screw image space, giving a sufficient prediction of a grasp to be applied on the object. Examples and case studies are given through the thesis. Experiments are quoted to demonstrate the implementation of the new system of theories and methodologies in this Thesis. Further, a set of strategies and their methodology is given and incorporated into a package in C++ with a general application to the study of restraint in screw image space. The thesis ends with a concluding chapter reviewing the contents of the thesis and the main achievements of the study, proposing suggestions for further work.

The thesis describes a distributed software environment designed for the development, evaluation and comparison of new techniques in knowledge based control of robot assembly work cells. It has characteristics which fulfil deficiencies within previous systems and contains within it new techniques in task specification, distributed control[1,2], object recognition[3,4] and path planning[5]. The control of the resources within the cell is based upon an extension of the facilities of a classical blackboard architecture to include plan execution. Unlike previous schemes, these additions allow Plethora to reason about the intent of an action, the current state of the cell and asynchronous events within a single framework. It is this seamless operation and extended representational adequacy that allows Plethora to explore new techniques dealing with the uncertainty inherent in a flexible work cell. The task is specified in domain terms and interpreted to produce a partially ordered set of goals. This new technique is based upon a two-stage ordering process using constructional constraints and necessary collision avoidance. Two new methods, one for object identification and the other for path planning, have also been developed using the system. These have two advantages, efficiency and the ability to operate on data from a vision system or Plethora's geometric modeller. Both methods can be completed within the critical times typical of an assembly work cell. Finally, results of an experiment using the system on a laboratory work cell illustrate how it encompasses previous techniques and can be used to develop new techniques not possible with earlier architectures.

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