FRINK Linked Data Fragments server

Matches in SemOpenAlex for { <https://semopenalex.org/work/W820781247> ?p ?o ?g. }

• W820781247 abstract "Vehicle behaviour near limit of adhesion is studied using linear optimal .control techniques and relatively simple vehicle models. Both time-invariant andtime-varying approaches are used. Controllability is applied as a post-processingtool to analyse resultant vehicle behaviour.First, a 4WS controller is developed using a linear time-invariant method, with areference model control structure. Two handling objectives are defined, which arethought to provide predictable dynamics. Advantages of using a reference modelcontrol are clearly shown. With a developed control structure, it is shown that theprescribed target dynamics is achieved, provided tyre forces are available. It isalso found that controller is robust to small changes in various vehicleparameter values.As a next step, time-varying modelling approach was used in order to betterrepresent vehicle operating conditions through various dynamic range,including limit of adhesion. An iterative vehicle path optimisation problem isformulated using a linear time-varying control approach. The validity of theoptimisation method is studied against steady-state simulation result at thelimit of adhesion. It is shown that method is capable of finding a trajectory inthe vicinity of friction limit, where front tyres are used fully whilstretaining some margin at rears. However, a couple of Issues are discovered.First, due to quadratic nature of road geometry cost function, trajectorycould get locked if vehicle runs very close to edge of road. Hence, the. optimisation needs to be formulated such that level of optimality on thetrajectory remains consistent throughout manoeuvre at each iteration.Secondly, it is found that inappropriate control demands are produced if thesystem matrix becomes poorly conditioned near limit. This results inoptimisation failure.In order to understand mechanism of this failure, controllability of linear timevaryingsystem was analysed and its properties were discussed in detail. First, thecalculation methods of controllability gramian matrix are investigated andsome practical limitations are found. The gramian matrix is then used to define anopen loop control sequence. It is found that damping of system has asignificant influence on control strategy. Subsequently, the movingcontrollability window of a fixed time period is found to provide mostrelevant information of changing dynamics through time. The study showedthat failure of optimisation in vicinity of friction limit was indeeddue to lack of controllability and optimisation method itself was functioningcorrectly.The vehicle path optimisation problem is then extended to include longitudinaldynamics, enabling simulation of more general manoeuvres. The single cornersimulation showed that optimisation converges to an out-in-out path, with iterative solution improving continuously in a first order manner. Simulations withvarious controller settings showed that strategy is reasonably robust providedthat changes in parameter settings are kept within a reasonable magnitude. It isalso confirmed that optimisation is able to drive a vehicle close to limitunder different types of operations required, i.e. braking, cornering andacceleration. The study was then performed with slightly more complex roadgeometry in order to investigate if the· optimisation is capable of prioritisingcertain· part of manoeuvre in order to achieve better overall result.Unfortunately, this problem could not be solved successfully. The optimisationconcentrated on latter part of manoeuvre as it had higher sensitivity to thefinal cost. This resulted in clearly sub-optimal overall performance.Finally, relatively simple study is conducted to investigate correlation betweenvarious vehicle settings and optimisation results. Using path optimisationproblem formulation, iris found that more oversteer vehicles are able toachieve better· result with more margin left in rear tyre force capacity. Thehandling objective functions used for 4 WS controller is also calculated for theresultant trajectories. It is found that neutral steer cost had a strong correlation,whereas linearity cost showed no noticeable correlation.The controllability analysis was applied on various vehicle settings using stepsteer simulation. It showed that more understeering vehicle retains highercontrollability throughout dynamics range. It is also found that higher inertiagives better controllability near limit, however, it gives less controllability atmore moderate operating conditions." @default.
• W820781247 created "2016-06-24" @default.
• W820781247 creator A5043670312 @default.
• W820781247 date "2010-01-01" @default.
• W820781247 modified "2023-09-27" @default.
• W820781247 title "Vehicle path optimisation and controllability on the limit using optimal control techniques" @default.
• W820781247 hasPublicationYear "2010" @default.
• W820781247 type Work @default.
• W820781247 sameAs 820781247 @default.
• W820781247 citedByCount "0" @default.
• W820781247 crossrefType "dissertation" @default.
• W820781247 hasAuthorship W820781247A5043670312 @default.
• W820781247 hasConcept C121332964 @default.
• W820781247 hasConcept C126255220 @default.
• W820781247 hasConcept C1276947 @default.
• W820781247 hasConcept C129844170 @default.
• W820781247 hasConcept C134306372 @default.
• W820781247 hasConcept C13662910 @default.
• W820781247 hasConcept C151201525 @default.
• W820781247 hasConcept C154945302 @default.
• W820781247 hasConcept C203479927 @default.
• W820781247 hasConcept C2524010 @default.
• W820781247 hasConcept C2775924081 @default.
• W820781247 hasConcept C28826006 @default.
• W820781247 hasConcept C33923547 @default.
• W820781247 hasConcept C41008148 @default.
• W820781247 hasConcept C47446073 @default.
• W820781247 hasConcept C48209547 @default.
• W820781247 hasConcept C6557445 @default.
• W820781247 hasConcept C86803240 @default.
• W820781247 hasConcept C91575142 @default.
• W820781247 hasConceptScore W820781247C121332964 @default.
• W820781247 hasConceptScore W820781247C126255220 @default.
• W820781247 hasConceptScore W820781247C1276947 @default.
• W820781247 hasConceptScore W820781247C129844170 @default.
• W820781247 hasConceptScore W820781247C134306372 @default.
• W820781247 hasConceptScore W820781247C13662910 @default.
• W820781247 hasConceptScore W820781247C151201525 @default.
• W820781247 hasConceptScore W820781247C154945302 @default.
• W820781247 hasConceptScore W820781247C203479927 @default.
• W820781247 hasConceptScore W820781247C2524010 @default.
• W820781247 hasConceptScore W820781247C2775924081 @default.
• W820781247 hasConceptScore W820781247C28826006 @default.
• W820781247 hasConceptScore W820781247C33923547 @default.
• W820781247 hasConceptScore W820781247C41008148 @default.
• W820781247 hasConceptScore W820781247C47446073 @default.
• W820781247 hasConceptScore W820781247C48209547 @default.
• W820781247 hasConceptScore W820781247C6557445 @default.
• W820781247 hasConceptScore W820781247C86803240 @default.
• W820781247 hasConceptScore W820781247C91575142 @default.
• W820781247 hasLocation W8207812471 @default.
• W820781247 hasOpenAccess W820781247 @default.
• W820781247 hasPrimaryLocation W8207812471 @default.
• W820781247 hasRelatedWork W1530348526 @default.
• W820781247 hasRelatedWork W1550318033 @default.
• W820781247 hasRelatedWork W1911843934 @default.
• W820781247 hasRelatedWork W1922999941 @default.
• W820781247 hasRelatedWork W1989040639 @default.
• W820781247 hasRelatedWork W2036040289 @default.
• W820781247 hasRelatedWork W2100658816 @default.
• W820781247 hasRelatedWork W2141133832 @default.
• W820781247 hasRelatedWork W2201042969 @default.
• W820781247 hasRelatedWork W2733738428 @default.
• W820781247 hasRelatedWork W2788472701 @default.
• W820781247 hasRelatedWork W2801306839 @default.
• W820781247 hasRelatedWork W2887128059 @default.
• W820781247 hasRelatedWork W2971232659 @default.
• W820781247 hasRelatedWork W2981926071 @default.
• W820781247 hasRelatedWork W30105802 @default.
• W820781247 hasRelatedWork W3110143542 @default.
• W820781247 hasRelatedWork W82545020 @default.
• W820781247 hasRelatedWork W2182253485 @default.
• W820781247 hasRelatedWork W2183142109 @default.
• W820781247 isParatext "false" @default.
• W820781247 isRetracted "false" @default.
• W820781247 magId "820781247" @default.
• W820781247 workType "dissertation" @default.