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Control allocation strategies for an electric vehicle with a wheel hub motor failure
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Vehicle Dynamics.ORCID iD: 0000-0001-7427-2584
KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.ORCID iD: 0000-0002-6283-7661
Volvo Cars AB.
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Vehicle Dynamics.ORCID iD: 0000-0001-8928-0368
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2015 (English)In: International Journal of Vehicle Systems Modelling and Testing, Vol. 10, no 3, 263-287 p.Article in journal (Refereed) Published
Abstract [en]

Three fault-tolerant control strategies for electric vehicles with wheel hub motors are presented and compared, which are all based on the control allocation principle. The main objective is to maintain the directional stability of the vehicle in case of a component failure during high speed manoeuvres. Two simplified strategies that are suited for on-board implementation are derived and compared to an optimal control allocation strategy and a reference vehicle with a basic electronic stability control system. The occurring faults are considered to be in the electric high-voltage system that can arise in wheel hub motors. All three control allocation strategies show improved re-allocation of traction forces after a severe fault, and hence an improved directional stability. However, the performance of both simplified algorithms shows limitations in case of force demands outside the capabilities of the respective actuator. This work shows that vehicle safety is increased by the proposed fault-tolerant control strategies.

Place, publisher, year, edition, pages
2015. Vol. 10, no 3, 263-287 p.
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
URN: urn:nbn:se:kth:diva-166463DOI: 10.1504/IJVSMT.2015.070164OAI: diva2:811134

Updated from Accepted to Published. QC 20150701

Available from: 2015-05-11 Created: 2015-05-11 Last updated: 2016-04-01Bibliographically approved
In thesis
1. Controlling over-actuated road vehicles during failure conditions
Open this publication in new window or tab >>Controlling over-actuated road vehicles during failure conditions
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The aim of electrification of chassis and driveline systems in road vehicles is to reduce the global emissions and their impact on the environment. The electrification of such systems in vehicles is enabling a whole new set of functionalities improving safety, handling and comfort for the user. This trend is leading to an increased number of elements in road vehicles such as additional sensors, actuators and software codes. As a result, the complexity of vehicle components and subsystems is rising and has to be handled during operation. Hence, the probability of potential faults that can lead to component or subsystem failures deteriorating the dynamic behaviour of road vehicles is becoming higher. Mechanical, electric, electronic or software faults can cause these failures independently or by mutually influencing each other, thereby leading to potentially critical traffic situations or even accidents. There is a need to analyse faults regarding their influence on the dynamic behaviour of road vehicles and to investigate their effect on the driver-vehicle interaction and to find new control strategies for fault handling.

A structured method for the classification of faults regarding their influence on the longitudinal, lateral and yaw motion of a road vehicle is proposed. To evaluate this method, a broad failure mode and effect analysis was performed to identify and model relevant faults that have an effect on the vehicle dynamic behaviour. This fault classification method identifies the level of controllability, i.e. how easy or difficult it is for the driver and the vehicle control system to correct the disturbance on the vehicle behaviour caused by the fault.

Fault-tolerant control strategies are suggested which can handle faults with a critical controllability level in order to maintain the directional stability of the vehicle. Based on the principle of control allocation, three fault-tolerant control strategies are proposed and have been evaluated in an electric vehicle with typical faults. It is shown that the control allocation strategies give a less critical trajectory deviation compared to an uncontrolled vehicle and a regular electronic stability control algorithm. An experimental validation confirmed the potential of this type of fault handling using one of the proposed control allocation strategies.

Driver-vehicle interaction has been experimentally analysed during various failure conditions with typical faults of an electric driveline both at urban and motorway speeds. The driver reactions to the failure conditions were analysed and the extent to which the drivers could handle a fault were investigated. The drivers as such proved to be capable controllers by compensating for the occurring failures in time when they were prepared for the eventuality of a failure. Based on the experimental data, a failure-sensitive driver model has been developed and evaluated for different failure conditions. The suggested fault classification method was further verified with the conducted experimental studies.

The interaction between drivers and a fault-tolerant control system with the occurrence of a fault that affects the vehicle dynamic stability was investigated further. The control allocation strategy has a positive influence on maintaining the intended path and the vehicle stability, and supports the driver by reducing the necessary corrective steering effort. This fault-tolerant control strategy has shown promising results and its potential for improving traffic safety.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2015. xii, 84 p.
TRITA-AVE, ISSN 1651-7660 ; 2015:23
vehicle dynamics, vehicle safety, driver-vehicle interaction, failure analysis, wheel hub motor failure, over-actuation, fault-tolerant control
National Category
Vehicle Engineering
Research subject
Vehicle and Maritime Engineering
urn:nbn:se:kth:diva-166819 (URN)978-91-7595-597-1 (ISBN)
Public defence
2015-06-05, Kollegiesalen, Brinellvägen 8, KTH, Stockholm, 09:30 (English)

QC 20150520

Available from: 2015-05-20 Created: 2015-05-19 Last updated: 2015-05-20Bibliographically approved

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