Jan Loof

This paper describes the coupling between a three degrees of freedom steering-system model and a multi-body truck model. The steering-system model includes the king-pin geometry to provide the correct feedback torque from the road to the steering-system. The steering-system model is combined with a validated tractor semi-trailer model. An instrumented tractor semi-trailer has been tested on a proving ground and the steering-wheel torque, pitman-arm angle, king-pin angles and drag-link force… Show more

This paper describes the coupling between a three degrees of freedom steering-system model and a multi-body truck model. The steering-system model includes the king-pin geometry to provide the correct feedback torque from the road to the steering-system. The steering-system model is combined with a validated tractor semi-trailer model. An instrumented tractor semi-trailer has been tested on a proving ground and the steering-wheel torque, pitman-arm angle, king-pin angles and drag-link force have been measured during steady-state cornering, a step steer input and a sinusoidal steering input. It is shown that the steering-system model is able to accurately predict the steering-wheel torque for all tests and the vehicle model is accurate for vehicle motions up to a frequency where the lateral acceleration gain is minimum. Even though the vehicle response is not accurate above this frequency, the steering-wheel torque is still represented accurately. Show less

Trucks and in particular tractor semi-trailers are overrepresented in accident statistics. In order to reduce the number of accidents involving trucks on the motor-way, a merging assist for trucks on the highway is developed. This system helps the driver during merging on the motor-way.

Based on the physical components, the steering-system of the truck is modeled. The steering-system is divided in three parts which are connected via spring-dampers elements. A test setup outside of the… Show more

Trucks and in particular tractor semi-trailers are overrepresented in accident statistics. In order to reduce the number of accidents involving trucks on the motor-way, a merging assist for trucks on the highway is developed. This system helps the driver during merging on the motor-way.

Based on the physical components, the steering-system of the truck is modeled. The steering-system is divided in three parts which are connected via spring-dampers elements. A test setup outside of the vehicle is utilized to compare the steering-system model with the real steering-system. These results show that the steering-system model is able to mimic the steering-system for the complete driver input range with an error of less than ten percent. The steering-system model is implemented in a full vehicle model and verified with with an instrumented tractor-semitrailer on a proving ground. These driving tests show that the combination of the vehicle model and the steering-system model is able to mimic the real system with an error of less than five percent.

The modeled conventional steering-system is a passive system in the sense that there is no external input except for the driver to control the steering-angle of the vehicle. A topology is chosen to enable an additional external input to the steering-system apart from the driver. A steering-controller is developed which provides guidance for the driver during a lane-change or during lane-keeping. The steering-system controller is designed in such a way that it ensures manageable driver effort levels while at the same time controlling the steering-system when the driver allows it. Practical experiments with a passenger vehicle show that this method of controlling the steering-system is accepted by drivers. Further expansion to yaw-rate tracking showcases that this method can be used as a lane changing or lane keeping system where the driver is guided but still feels in control. Show less

In this paper a multi-body 44-DOF tractor semi-trailer model is coupled to a 4-DOF steeringsystem
which includes friction and hydraulic power-steering. An extended wheel hub geometry is used to provide the correct feedback torque from the wheels. A tie-rod with stiffness has been included to connect left and right. An instrumented tractor semi-trailer is used to verify the steering-system model predictions during driving. The focus lies on the prediction of the steering-wheel torque and the… Show more

In this paper a multi-body 44-DOF tractor semi-trailer model is coupled to a 4-DOF steeringsystem
which includes friction and hydraulic power-steering. An extended wheel hub geometry is used to provide the correct feedback torque from the wheels. A tie-rod with stiffness has been included to connect left and right. An instrumented tractor semi-trailer is used to verify the steering-system model predictions during driving. The focus lies on the prediction of the steering-wheel torque and the vehicle velocity and steering-wheel angle are prescribed as an input for the simulation. Two tests are discussed in this paper, a J-turn at 80 km/h and sinusoidal steering-wheel input with a frequency of 0.4 Hz at 65 km/h. The comparison of the measured signals and the predicted values shows that the steering-system model is accurate. The non-linearities caused by friction and hydraulic assistance system can clearly be seen in both the measurement and the simulation. Show less

Motion and steering feel contribute to the drivers perception and assessment of vehicle behavior. Steer-by-wire systems offer the freedom to alter the steering feel characteristics. It is unknown whether the mechanical complexity and non-linearity in mechanical steering systems contribute to the performance and awareness of drivers. This study investigates the influence of driving simulator motion and steering-system model complexity on drivers’ performance and subjective assessment of… Show more

Motion and steering feel contribute to the drivers perception and assessment of vehicle behavior. Steer-by-wire systems offer the freedom to alter the steering feel characteristics. It is unknown whether the mechanical complexity and non-linearity in mechanical steering systems contribute to the performance and awareness of drivers. This study investigates the influence of driving simulator motion and steering-system model complexity on drivers’ performance and subjective assessment of on-centre handling in a heavy goods vehicle. 32 subjects (12 professional truck drivers and 20 university participants) completed a total of eight short experimental highway rides including merging, while the simulator’s motion system was either turned on or off and the steering system model either resembled a linear or a realistic nonlinear behavior. The results show that a linear steering system is preferred by the drivers and no performance degradation occurs with the linear system, indicating that for future truck steering systems, a linear haptic feedback may be considered. The presence of motion did not significantly alter this result. Show less

The prediction of steering wheel torque in a truck is a challenging subject due to
the number of components connecting the driver to the front wheels. In previous work, a steering-system model has been created which relates the power steering assistance torque to the input
torque supplied by the driver via a look-up table. In this work the model will be extended with
a more detailed hydraulic model which makes use of a Wheatstone bridge with hydraulic resistances.
This makes the… Show more

The prediction of steering wheel torque in a truck is a challenging subject due to
the number of components connecting the driver to the front wheels. In previous work, a steering-system model has been created which relates the power steering assistance torque to the input
torque supplied by the driver via a look-up table. In this work the model will be extended with
a more detailed hydraulic model which makes use of a Wheatstone bridge with hydraulic resistances.
This makes the model valid for different flow-rates and provides more insight. To find the
parameters for the model, a test setup is used to monitor the relevant pressures as well as the flow
through the system. The model will be used to reproduce the measurements. It is shown that the
model is suitable for the calculation of the steering wheel torque and pressures in the system with
a high precision. Show less

The steering behaviour in a driving simulator has a significant influence on a driving realism. This study investigates the influence of the complexity of a steering-system model on the subjective assessment of truck steering feel in on-centre handling. Ten subjects drove a highway task with and without lateral wind disturbance with 4 steering-system model variants. The results show that detailed modelling of the steering system plays a significant role in the subjective assessment of truck… Show more

The steering behaviour in a driving simulator has a significant influence on a driving realism. This study investigates the influence of the complexity of a steering-system model on the subjective assessment of truck steering feel in on-centre handling. Ten subjects drove a highway task with and without lateral wind disturbance with 4 steering-system model variants. The results show that detailed modelling of the steering system plays a significant role in the subjective assessment of truck steering feel, and has a corresponding effect on objective steering performance.
The steering behaviour in a driving simulator has a significant influence on a driving realism. This study investigates the influence of the complexity of a steering-system model on the subjective assessment of truck steering feel in on-centre handling. Ten subjects drove a highway task with and without lateral wind disturbance with 4 steering-system model variants. The results show that detailed modelling of the steering system plays a significant role in the subjective assessment of truck steering feel, and has a corresponding effect on objective steering performance. Show less

This article describes the design of a traction control system in an electric Formula Student vehicle. In many race applications the accelerator pedal is difficult to control for an in-experienced driver, especially in the case of electric vehicles, where a large torque is available from standstill. A 3-DOF driveline model is used in combination with a 7-DOF vehicle model and a non-linear tyre model based on 10 parameters. The driveline and tyre model are validated by measurements. These models… Show more

This article describes the design of a traction control system in an electric Formula Student vehicle. In many race applications the accelerator pedal is difficult to control for an in-experienced driver, especially in the case of electric vehicles, where a large torque is available from standstill. A 3-DOF driveline model is used in combination with a 7-DOF vehicle model and a non-linear tyre model based on 10 parameters. The driveline and tyre model are validated by measurements. These models are used to design a suitable traction control system. This system consists of an open-loop part, which uses the longitudinal and lateral acceleration to calculate a torque limit via a driver provided friction estimation. The feed-back part of the controller regulates the slip-ratio of the rear-wheels. The traction control system is first implemented in the vehicle model and later in an electric Formula Student vehicle. A comparison is made between the vehicle with and without traction control. The vehicle with traction control performs significantly better in terms of longitudinal acceleration and shows a better driveability in terms of lateral acceleration. Show less