Description:
This paper presents a new algorithm for the control of a B-double truck–trailer with steerable trailer wheels and active hitch angles, designed to minimize both off-tracking and scuffing. Each trailer has six autonomously steered double wheels, although each double wheel is modelled by a centrally placed single wheel. Each hitch point, joining truck to first trailer and first trailer to second trailer, as well as a nominated point central to the axles of the second trailer, traverses the same path which is determined by an operator controlling the path curvature and truck speed. The algorithm approximates the ideal solution in which all wheels on each trailer have the same centre of curvature. The actively controlled hitch angles, satisfying the path-following constraints, provide a further level of cooperative redundancy of steering systems. Simulations are carried out to show the effects of changing curvature and front hitch speed on hitch path, wheel angles, and hitch angles as well as the accuracy of the algorithm. Further simulation is carried out to show the improvement in off-tracking of the new control system over current B-double fixed-wheel systems.
Description:
This paper presents a new algorithm for the control of a B-double truck–trailer with steerable trailer wheels and active hitch angles, designed to minimize both off-tracking and scuffing. Each trailer has six autonomously steered double wheels, although each double wheel is modelled by a centrally placed single wheel. Each hitch point, joining truck to first trailer and first trailer to second trailer, as well as a nominated point central to the axles of the second trailer, traverses the same path which is determined by an operator controlling the path curvature and truck speed. The algorithm approximates the ideal solution in which all wheels on each trailer have the same centre of curvature. The actively controlled hitch angles, satisfying the path-following constraints, provide a further level of cooperative redundancy of steering systems. Simulations are carried out to show the effects of changing curvature and front hitch speed on hitch path, wheel angles, and hitch angles as well as the accuracy of the algorithm. Further simulation is carried out to show the improvement in off-tracking of the new control system over current B-double fixed-wheel systems.
Description:
The authors have previously proposed a solution to the twin problems of wheel scuffing and off-tracking of B-double truck–trailer vehicles thereby reducing tyre wear and environmental damage as well as improving maneuverability. The solution to the scuffing problem requires that trailer axles in excess of one per trailer must have steerable wheels. However, if all trailer wheels are steerable, then the off-tracking problem can also be solved. The previous work devised an algorithm for a B-double in forward motion, whereby an on-board computer would be used to calculate the correct wheel and hitch angles and a control system would implement these angles. The purpose of the present technical note is to complete the study of a numerical algorithm for navigating a B-double truck–trailer vehicle by considering travel in the reverse direction. In this case the angle of the front wheels of the truck must also be controlled by the on-board computer. The algorithm for determining the effective angle of the truck’s steerable wheels is derived using an innovative combination of vector geometry and calculus and completes the total control system for these B-double vehicles. The paper concludes with a simulation study of the control algorithm demonstrating its versatility for reversing along twisting paths and effectiveness in reducing off-tracking.
Description:
The authors have previously proposed a solution to the twin problems of wheel scuffing and off-tracking of B-double truck–trailer vehicles thereby reducing tyre wear and environmental damage as well as improving maneuverability. The solution to the scuffing problem requires that trailer axles in excess of one per trailer must have steerable wheels. However, if all trailer wheels are steerable, then the off-tracking problem can also be solved. The previous work devised an algorithm for a B-double in forward motion, whereby an on-board computer would be used to calculate the correct wheel and hitch angles and a control system would implement these angles. The purpose of the present technical note is to complete the study of a numerical algorithm for navigating a B-double truck–trailer vehicle by considering travel in the reverse direction. In this case the angle of the front wheels of the truck must also be controlled by the on-board computer. The algorithm for determining the effective angle of the truck’s steerable wheels is derived using an innovative combination of vector geometry and calculus and completes the total control system for these B-double vehicles. The paper concludes with a simulation study of the control algorithm demonstrating its versatility for reversing along twisting paths and effectiveness in reducing off-tracking.
Description:
This paper presents a new algorithm for the control of a snake-like robot with passive joints and active wheels. Each segment has four autonomously driven and steered wheels. The algorithm approximates the ideal solution in which all wheels on a segment have the same centre of curvature with wheel speeds, providing cooperative redundancy. Each hitch point joining segments traverses the same path, which is determined by an operator, prescribing the path curvature and front hitch speed. The numerical algorithm developed in this paper is simulation tested against a previously derived analytical solution for a predetermined path. Further simulations are carried out to show the effects of changing curvature and front hitch speed on hitch path, wheel angles and wheel speeds for a one, two and three segment robot.
Description:
This paper presents a new algorithm for the control of a snake-like robot with passive joints and active wheels. Each segment has four autonomously driven and steered wheels. The algorithm approximates the ideal solution in which all wheels on a segment have the same centre of curvature with wheel speeds, providing cooperative redundancy. Each hitch point joining segments traverses the same path, which is determined by an operator, prescribing the path curvature and front hitch speed. The numerical algorithm developed in this paper is simulation tested against a previously derived analytical solution for a predetermined path. Further simulations are carried out to show the effects of changing curvature and front hitch speed on hitch path, wheel angles and wheel speeds for a one, two and three segment robot.
Description:
Mathematical modelling of CO2 capture from industrial flue gas by absorption into amine solutions such as monoethanolamine (MEA) has been undertaken for decades and steady state, rate-based and dynamic models have been constructed to predict the changes in the process. Recently, dynamic models have been used to predict the effect that physical operational changes have on the absorption process. As more is learnt about the chemistry of MEA and CO2 it becomes evident that the absorption system is losing available MEA, by degradation and by vaporization into the gaseous phase. This paper describes a dynamic model of the absorber column that can be used to predict the reduction of available MEA, the loss of MEA to the atmosphere, and the build-up of heat stable salts. The proposed mathematical model consists of a system of partial differential equations to represent the change of each component with height of the column and with time. It has been validated with data from a pilot capture plant located at the brown coal fired Loy Yang power station in Australia.
Description:
Summary "'Integral cohomology algebras' explores the algebraic objects consisting of cohomology groups with integer coefficients and the primary cohomology operations acting on them. These cohomology algebras are contrasted with their Eckmann-Hilton dual of homotopy groups and primary homotopy operations. They are also shown to generalize the Steenrod algebra structures for cohomology over finite fields. Several examples are given using the cohomology algebra structure to distinguish between topological spaces. The earlier chapters provide a comprehensive summary of the Eckmann-Hilton duality of integral cohomology and homotopy groups and the natural primary operations on them. A final chapter discusses directions for future research."--Back cover.
Description:
This paper presents two new algorithms for real-time calculation of the wheel angles and speeds of gantry tractor modules. In transport mode, the gantry tractor is, in a sense, a snakelike robot with passive joints and active wheels, with each module having autonomous four-wheel drive and four-wheel steering. The algorithms determine the wheel angles and speeds of each module with the prescription that the four wheels will have the same center of curvature, wheel speeds provide cooperative redundancy, and all hitching points follow the same path, thereby eliminating scuffing and minimizing off-tracking. Details of the analytical algorithm for a predetermined path were presented at the 2009 IEEE International Conference on Industrial Technology, together with a simulation for a single module. In this paper, we also present the results of a newly developed numerical algorithm which enables the gantry tractor to be steered online by an operator. We also show, by simulation, that this new numerical algorithm gives a good approximation to analytical solutions. The numerical algorithm is then used to calculate wheel angles and speeds for a three-module tractor with the results depicted graphically as functions of time.
Description:
A new method of automatically maneuvering a gantry tractor through right-angle turns, U-turns, and narrow gates is described in this paper. In order to maximize traction and maneuverability, both the wheel-angle steering effect and the drive-wheel-speed steering effect are integrated. This technique produces identical and cooperative redundant steering systems. The necessary wheel angles and drive wheel speed have been simulated. The advantage of cooperative redundancy is that when any steering system begins to fail, it is reinforced by the other steering system
Description:
This paper presents a new algorithm for online, real-time calculation of the wheel angles and speeds of gantry tractor modules. In dasiaworkingpsila mode the modules are latched together to form a rigid truss, whereas in dasiatransportpsila mode, the modules are unlatched so that they are only connected at their hitch points allowing the module to maneuver along curved paths.
Description:
The authors explain why the geometrical coincidences in the windmill diagram of mathematician Euclid did not occur by chance. One of them is the intersection of segments —AL, —FC and —KB at a point. To determine the orthocentre which is the point of intersection of the altitudes of triangle, they had to construct parallelograms and look for the perpendicular bisectors. For triangle PBC, they found that its orthocentre will give coincidence of the altitude spread from A.
Description:
Fossil fuels are used widely for energy production and are likely to continue to play a major role world wide for many years to come. Much work has been done on the technology for capturing CO2 from gaseous industrial effluent. For large-scale applications like coal or natural gas-fired power plants, using amine solvents to capture post-combustion CO2 is the most mature CO2 capture technology. This technique can be used to retrofit existing plants by treating the flue gas after combustion. This paper details a dynamic mathematical model for the absorber column constructed from first principles. The loss of MEA through oxidative degradation has been quantified here for the first time and this is currently not possible using commercial packages. Reaction rate kinetics have been employed to predict the accumulation of oxidation products which is limited by the incomplete knowledge of the dominant reactions between O2 and MEA. When research has produced more detailed information about the products formed during this oxidation, it can be inserted easily into the model. Validation has been performed using data from the CSIRO PCC pilot plant at AGL Loy Yang. A limited parametric study of the impact of operating conditions on oxidation was performed.
Description:
The algebraic structure of the natural integral cohomology operations is explored by means of examples. We decompose the generators of the groups with and into the operations of cup products, cross-cap products and compositions. Examination of these decompositions and comparison with other possible generators demonstrates the existence of relations between integral operations that have withheld formulation. The calculated groups and generators are collected in a table for practical reference.
Description:
This paper presents the results of calculations of the wheel angles and the drive wheel speeds to ensure that the steering effect of the wheel angles and the steering effect of the speeds of the drive wheels are identical. These calculations are general insofar as the centre of curvature of the path of the centre of the vehicle can lie anywhere in the 'horizontal' plane, including within the plan view of the vehicle. These minimal turning circles at times require large wheel angles and large differences in the drive wheel speeds. When the driver selects a centre of curvature inside the rectangle defined by the wheelbase and the track, problems arise owing to the multiple solutions of the arctan function. This problem is solved so that flipping of the wheels through 180° is avoided. Similar problems can arise in the calculation of the correct wheel speed because of the ambiguity of the square root function, which has both positive and negative roots. This problem is also solved. Alternative driver interfaces are described in detail. Vehicles with cooperative redundant multiple steering systems promise safety benefits relative to vehicles with a single non-redundant steering system and environmental benefits relative to vehicles with conflicting redundant multiple steering systems. The safety benefits result from increased traction, stability and manoeuvrability (especially on hills). The environmental benefits include reduced ground damage, tyre wear and fuel wastage on turning. These vehicles would be used to best advantage as extreme off-road vehicles. The general case of vehicles described is capable of both pure rotation and pure translation in any direction, and all motion in between. This maximized manoeuvrability also makes the system ideal for vehicles operating in confined spaces, such as forklift trucks.
Description:
This paper presents the results of calculations of the wheel angles and the drive wheel speeds to ensure that the steering effect of the wheel angles and the steering effect of the speeds of the drive wheels are identical. These calculations are general insofar as the centre of curvature of the path of the centre of the vehicle can lie anywhere in the 'horizontal' plane, including within the plan view of the vehicle. These minimal turning circles at times require large wheel angles and large differences in the drive wheel speeds. When the driver selects a centre of curvature inside the rectangle defined by the wheelbase and the track, problems arise owing to the multiple solutions of the arctan function. This problem is solved so that flipping of the wheels through 180° is avoided. Similar problems can arise in the calculation of the correct wheel speed because of the ambiguity of the square root function, which has both positive and negative roots. This problem is also solved. Alternative driver interfaces are described in detail. Vehicles with cooperative redundant multiple steering systems promise safety benefits relative to vehicles with a single non-redundant steering system and environmental benefits relative to vehicles with conflicting redundant multiple steering systems. The safety benefits result from increased traction, stability and manoeuvrability (especially on hills). The environmental benefits include reduced ground damage, tyre wear and fuel wastage on turning. These vehicles would be used to best advantage as extreme off-road vehicles. The general case of vehicles described is capable of both pure rotation and pure translation in any direction, and all motion in between. This maximized manoeuvrability also makes the system ideal for vehicles operating in confined spaces, such as forklift trucks.