On-line multiobjective automatic control system generation by evolutionary algorithms

Evolutionary algorithms are applied to the on- line generation of servo-motor control systems. In this paper, the evolving population of controllers is evaluated at run-time via hardware in the loop, rather than on a simulated model. Disturbances are also introduced at run-time in order to pro- duce robust performance. Multiobjective optimisation of both PI and Fuzzy Logic controllers is considered. Finally an on-line implementation of Genetic Programming is presented based around the Simulink standard blockset. The on-line designed controllers are shown to be robust to both system noise and ex- ternal disturbances while still demonstrating excellent steady- state and dvnamic characteristics

Metamodelling of multivariable engine models for real-time flight simulation.

Sophisticated real-time distributed flight simulation environments may be constructed from a wide range of modelling and simulation tools. In this way accuracy, detail and model flexibility may be incorporated into the simulator. Distributed components may be constructed by a wide range of methods, from high level environments such as Matlab, through coded environments such as C or Fortran to hardware-in-the- loop. In this paper the Response Surface Methodology is combined with a hyper-heuristic (evolutionary algorithm) and applied to the representation of computationally intensive non-linear multivariable engine modelling. The paper investigates the potential for metamodelling (models of models) dynamic models which were previously too slow to be included in multi-component, high resolution real-time simulation environments. A multi-dimensional gas turbine model with five primary control inputs, six environmental inputs and eleven outputs is considered. An investigation has been conducted to ascertain to what extent these systems can be approximated by response surfaces with experiments which have been designed by hyper-heuristics as a first step towards automatic modelling methodology

On the response surface methodology and designed experiments for computationally intensive distributed aerospace simulations

Distributed real-time simulation is the focus of intense development with complex systems being represented by individual component simulations interacting as a coherent model. Commercial off the shelf (COTS) and Freeware real-time software exists to provide data communication channels between he components subject to adequate system bandwidth. However, if the individual models are too computationally intensive to run in real-time, then the performance of the real-time simulation architecture is compromised. In this paper, model representations are developed from dynamic simulation by the Response surface Methodology, allowing complex systems to be included in a real-time environment. A Permanent Magnet AC motor drive simulation with model reference control for a more electric aircraft application is examined as a candidate for inclusion in a realtime simulation environment

Novel field equipment for assessing the stability of natural and hybrid turfs

Natural turf pitches are used for many outdoor sports. Turf is a complex network of interacting organic material, soil textures and water content. Turf is susceptible to damage under large surface forces, caused by intensive player movements in rugby union and football. To assess and monitor surface stability, there needs to be a reliable test method for ground staff and other stakeholders. At present, no turf stability mechanical test method exists that represents player–surface interaction, especially to represent a linear movement across the surface such as in a rugby scrummage. This paper describes the development of a novel device for assessing turf stability. Verification was undertaken in the laboratory on a variety of controlled soil samples, and during a field study. The device measurements were shown to be sensitive to the shear strength of a high clay content soil at varying water content and to the density and type of sandy soils. A programme of field data on high quality pitches suggested a large effect of the turf root reinforcement. A conceptual model of soil failure induced by the device was developed to identify the key soil variables and support experimental data interpretation

Design and development of a novel natural turf shear stability tester

The stability of natural Rugby Union pitches continues to be a recurring problem at all levels of the game. The effects of poor stability are seen when the pitch surface shears under player loading, creating unsightly divots and an uneven and potentially injurious surface. This observed instability is a real concern for many stakeholders, from the groundsmen to the revenue-generating television companies, and is arguably increasing caused by greater popularity of sports, more intensive use of natural turf pitches and advances in player physical conditioning. However, perhaps surprisingly, no objective quantitative mechanical test method currently exists for assessing the shear stability of the natural turf prior to games being played. This paper presents the findings from a (ongoing) research study into the design and development of a prototype turf stability apparatus (‘Turf Tester’). The key aim was to measure the shearing stability of natural and hybrid turf in order to assess a recurring failure problem. In order to be relatable to sporting performance, this failure imitates conditions to simulate player(s) interaction. The prototype and test method was developed with properties suggested from published papers discussing rugby and agronomists’ experience. It was theorized that there was a potential zone susceptible to failure within the top 100 mm of the sports turf. The position of this zone was variable and depended on pitch construction. The prototype was built to explore this variable failure zone using a 50 mm and 100 mm pin that sheared through the soil when a known load was applied to it. Both the Clegg Impact Hammer (CIH) and the rotational traction (RTD) were suggested to be relatable to penetration and shear stability; however, their relatability to the failure zone was an unknown. This paper details the background behind the study, the prototype design and principle, the observed failure mechanisms of sports turf, and presents the results of the prototype apparatus trailed on a range of turf constructions at venues used for the 2015 Rugby World Cup. Data was collected at each venue using Labosport’s Scoreplay system detailing full agronomic classifications and a suite of industry standard player performance tests. The combined data from 13 of the venues provided a powerful data set to evaluate and refine the prototype apparatus, providing validity of its conceptual design. The findings show that the shear tester assessed the upper level of ability of pitches with a 50 mm depth pin and the lower ability with the 100 mm pin. There was some evidence of a relationship to the CIH and RTD, albeit weak, and it was concluded the shear tester was assessing a characteristic of the sport turf not currently measured by standard industry tests currently utilized. The shear tester differentiated between the high stability of the hybrid pitch constructions and the weaker natural pitches. The shear tester rankings for pitch quality also approximated well the ranking from the Scoreplay pitch quality system. Incorporation of the shear tester into routine pitch evaluations could benefit a scoring system approac

Investigating shear stability of rugby union natural turf pitches

The stability of natural Rugby Union pitches continues to be a recurring problem at all levels of the game. The effects of poor turf stability are seen when the pitch surface shears under player loading, creating divots and an uneven surface. However, perhaps surprisingly, there is no objective quantitative mechanical test method for assessing the stability of the natural turf, with regard to shear resistance. This paper details initial work undertaken to assess the effectiveness of current shear testing apparatus in predicting stability for Rugby Union. It has been suggested there are two failure areas in pitch constructions: One on the surface and one deeper in the soil. The results show variability in natural turf constructions, and that current shear test methods are less effective in sandy soils. Penetration readings were relatable to hardness, however shear stability testing requires development

Investigating shear stability of rugby union natural turf pitches

The stability of natural Rugby Union pitches continues to be a recurring problem at all levels of the game. The effects of poor turf stability are seen when the pitch surface shears under player loading, creating divots and an uneven surface. However, perhaps surprisingly, there is no objective quantitative mechanical test method for assessing the stability of the natural turf, with regard to shear resistance. This paper details initial work undertaken to assess the effectiveness of current shear testing apparatus in predicting stability for Rugby Union. It has been suggested there are two failure areas in pitch constructions: One on the surface and one deeper in the soil. The results show variability in natural turf constructions, and that current shear test methods are less effective in sandy soils. Penetration readings were relatable to hardness, however shear stability testing requires development

Design and development of a novel natural turf shear stability tester

The stability of natural Rugby Union pitches continues to be a recurring problem at all levels of the game. The effects of poor stability are seen when the pitch surface shears under player loading, creating unsightly divots and an uneven and potentially injurious surface. This observed instability is a real concern for many stakeholders, from the groundsmen to the revenue-generating television companies, and is arguably increasing caused by greater popularity of sports, more intensive use of natural turf pitches and advances in player physical conditioning. However, perhaps surprisingly, no objective quantitative mechanical test method currently exists for assessing the shear stability of the natural turf prior to games being played. This paper presents the findings from a (ongoing) research study into the design and development of a prototype turf stability apparatus (‘Turf Tester’). The key aim was to measure the shearing stability of natural and hybrid turf in order to assess a recurring failure problem. In order to be relatable to sporting performance, this failure imitates conditions to simulate player(s) interaction. The prototype and test method was developed with properties suggested from published papers discussing rugby and agronomists’ experience. It was theorized that there was a potential zone susceptible to failure within the top 100 mm of the sports turf. The position of this zone was variable and depended on pitch construction. The prototype was built to explore this variable failure zone using a 50 mm and 100 mm pin that sheared through the soil when a known load was applied to it. Both the Clegg Impact Hammer (CIH) and the rotational traction (RTD) were suggested to be relatable to penetration and shear stability; however, their relatability to the failure zone was an unknown. This paper details the background behind the study, the prototype design and principle, the observed failure mechanisms of sports turf, and presents the results of the prototype apparatus trailed on a range of turf constructions at venues used for the 2015 Rugby World Cup. Data was collected at each venue using Labosport’s Scoreplay system detailing full agronomic classifications and a suite of industry standard player performance tests. The combined data from 13 of the venues provided a powerful data set to evaluate and refine the prototype apparatus, providing validity of its conceptual design. The findings show that the shear tester assessed the upper level of ability of pitches with a 50 mm depth pin and the lower ability with the 100 mm pin. There was some evidence of a relationship to the CIH and RTD, albeit weak, and it was concluded the shear tester was assessing a characteristic of the sport turf not currently measured by standard industry tests currently utilized. The shear tester differentiated between the high stability of the hybrid pitch constructions and the weaker natural pitches. The shear tester rankings for pitch quality also approximated well the ranking from the Scoreplay pitch quality system. Incorporation of the shear tester into routine pitch evaluations could benefit a scoring system approac

The science of sports surface interactions for synthetic turf surfaces

The introduction and acceptance of new (3rd) generation long pile filled synthetic turf surfaces in sports such and football and rugby has led to these surfaces becoming widely used at all levels of the game. The interaction of a sports person and/or ball with these surfaces is of great importance in terms of player safety, comfort and playing performance. The specification for these surfaces, and the constituent materials used, are known to vary within the industry. Recent field measurements of unfilled ‘water based’ pitches highlighted significant spatial and temporal changes in the playing characteristics both over the surface of a single pitch and between (similar) pitches, including the test results for traction. It has been suggested that synthetic turf surfaces increase the traction produced at the shoe-surface interface causing a greater number of sports specific injuries. However, as part of a PhD research programme at Loughborough University, a comprehensive review of published literature was performed which highlighted a significant lack of quantified research and data regarding the surface properties influencing the traction developed at the shoe-surface interface. There has been no attempt to date to measure and quantify the role of the individual components of a surface on the traction that can be achieved. If the underlying material science of the surface components were better understood, decisions and judgements based on the desired characteristics required for surfaces could be optimised. This paper reviews the available information regarding 3rd generation synthetic turf surfaces and establishes the primary parameters influencing traction during the interaction between a player and the surface, with a focus on the mechanics of the surface components and their interaction, and the influence of potential changes during the pitch lifetime, such as degradation. The proposed research and methods required to address these knowledge gaps is presented

Using Experience and Case History Data to Enhance the Design of Piled Foundations and Predict Behaviour Characteristics

This paper explores the process of piled foundation design and how it can benefit from the inclusion of previous test data and case histories from nearby or geologically similar sites. The interaction between the soil and the structure is critical to the behaviour of a pile and is a function of both the ground conditions and the method of pile construction. An accurate model of the ground conditions is required for the design, as is a detailed knowledge of the method of pile installation and its subsequent interaction with the soil. Where case histories are available they can be utilised to refine the design or to reduce the risk associated with a solution. This is currently often done in a subjective manner by the application of engineering judgement and personal experience. This paper discusses a quantitative method which can be used to employ data from case histories and provide an objective approach to the inclusion of existing knowledge and experience. Bayesian updating is utilised to improve the model of the ground conditions and subsequently the degree of uncertainty is reduced. The probability of failure has been seen to be reduced by this process, as demonstrated through the application an example situation