Hormoz Marzbani - Academia.edu (original) (raw)
Papers by Hormoz Marzbani
Vehicle System Dynamics, Jan 9, 2023
Springer eBooks, Feb 24, 2012
IEEE Transactions on Intelligent Transportation Systems, Jul 1, 2022
Springer eBooks, 2015
During the project for generating a mathematical algorithm for autonomous vehicles, a sample road... more During the project for generating a mathematical algorithm for autonomous vehicles, a sample road which included different turns and scenarios was required. Studying different types of roads and their line equations Euler spirals, also known as Clothoids were found to be the best solution for designing new roads suitable for autonomous vehicles. During 19th century Arthur Talbot derived the equation of Clothoids to be used as an easement curve for the purpose of avoiding shock and disagreeable lurch of trains, due to instant change of direction. The Euler Spiral is a curve whose degree-of-curve increases directly with the distance along the curve from the start point of the spiral. This provides a linear change in the steering angle required by the driver to go through the turn. In other words for a car traveling on a Clothoid transition road curve there is no need for sudden changes in the steering angle of the wheels. The angle required starts from zero and increases to a maximum value and goes back to zero linearly. This provides a very comfortable ride for the passengers of the vehicle. The use of these curves for road design have been investigated, and a design chart have been proposed to be used for finding the best suitable transition curve for different applications.
IEEE Transactions on Intelligent Transportation Systems, Mar 1, 2022
Autodriver algorithm aims to develop a path-following algorithm for autonomous vehicles using roa... more Autodriver algorithm aims to develop a path-following algorithm for autonomous vehicles using road geometry data and vehicle dynamics. In this study, a novel smart Autodriver algorithm is developed according to practical implications utilizing a more realistic vehicle model and consideration of real-time applicability. A ghost-car path-following approach is introduced to define the desired location of the vehicle at every instance during various maneuvers. Key steady-state characteristics of turning vehicles, namely the curvature, yaw rate, and side-slip responses are discussed and used to construct a path-following controller based on the Autodriver algorithm. A feedback control based on Sliding Mode Control (SMC) is also designed and applied to minimize transient errors between the road and the vehicle positions. Finally, simulations are performed to analyze the path-following performance of the proposed scheme compared to a Model Predictive Controller (MPC) as a widely accepted popular method for autonomous vehicles. Hardware-in-the-loop (HIL) tests are also performed to investigate real-time applicability of the controllers. The results show promising controller performance in terms of error minimization, passenger comfort, and low computational cost for the proposed method.
SAE International Journal of Commercial Vehicles, May 5, 2021
Smart innovation, systems and technologies, 2019
This paper constitutes the second part of the publication series on introducing a new simplified ... more This paper constitutes the second part of the publication series on introducing a new simplified combined-slip tire model for vehicle dynamics. The effectiveness of the proposed model (Elliptic Model) is validated using a comparative dynamic simulation. A five degree of freedom vehicle model is presented and used for simulation. Tire forces are calculated based on both the Elliptic Model and Magic Formula, and simulation results are compared. It has been shown that the simplified tire model shows promising performance and may be used for estimating the tire force capacity, specially up to the saturation point of tire slips.
Vehicle System Dynamics, Apr 5, 2021
Vehicle System Dynamics, Feb 21, 2021
This study deals with drifting as one of the most important nonlinearities in vehicle dynamics. A... more This study deals with drifting as one of the most important nonlinearities in vehicle dynamics. A four-wheel vehicle model is used to calculate the equilibria in planar motion, numerically, by intr...
Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science, Jun 29, 2019
Spot welding is the most common technique used to join sheet metals in the automotive industry du... more Spot welding is the most common technique used to join sheet metals in the automotive industry due to the fast rate of production. Optimising the welding process including the sequence, number and location of the welds would significantly improve the quality of the final product and production cost. This paper presents an overview on the available methods to plan and optimise various aspects of the welding process including welding sequence, weld quantity and location. Firstly, the welding concept in the automotive industry is briefly reviewed. Secondly, the welding process optimisation with emphasis on the welding sequence is discussed. The common gaps and challenges are identified and, lastly, future research to plan and optimise the welding sequence in the automotive body is outlined.
Springer eBooks, 2016
A variation in the camber of an automotive wheel is desired to compensate a side-slip force reduc... more A variation in the camber of an automotive wheel is desired to compensate a side-slip force reduction owing to transversely normal load shift when the car is cornering. The camber of a steered wheel can be varied by adjusting caster or/and lean angles which are the representations of steering axis orientation. Thus, adjustable camber can be created by variable caster or/and lean angle. Choosing which parameter among the two angles to be the main source of camber generation is a key starting point and dependent on its different effects. Here, homogeneous transformation is employed to establish camber as a function of caster, lean angle, and steering angle in the general case. A comparison between caster and lean angle based on different criteria is made. The comparison shows that a variable caster is more effective than a variable lean angle in generating a smart camber.
Lecture notes in networks and systems, Nov 20, 2018
When steering about the titled kingpin axis, the tyre-road contact point moves along the tyre per... more When steering about the titled kingpin axis, the tyre-road contact point moves along the tyre perimeter. In the literature on the tyre kinematics, this displacement, however, has not been taken into consideration. This results in an inaccuracy in the steering tyre kinematics, especially when the steering angle is large. This paper presents a novel method, utilising homogeneous transformation, to develop the kinematics of a steering tyre with the chance of the tyre-road contact being taken into account. The results show that this novel kinematic model is more accurate than those in the literature. The steering tyre kinematics developed in this investigation is then compared to that one built in ADAMS software for validating purpose.
Procedia Computer Science, 2017
The purpose of this paper is to show the effect of acceleration-variable forward velocity-, on th... more The purpose of this paper is to show the effect of acceleration-variable forward velocity-, on the steady-state and transient responses of turning vehicles and the resulted path of motion of the vehicle. Comparing the responses of the vehicle will be used to prove that there is a negligible difference between the steady-state and transient center of rotation of the vehicle in engineering applications. To show that vehicles are working close to their steady-state conditions even at transient stage, we examine a vehicle in two maneuvers. In the first one, the vehicle is assumed to be moving at a constant forward speed and experiencing a step steer angle change. In the second maneuver, the vehicle experiences a lane change steering input. The transient response of the vehicle, as well as the required time to achieve the steady-state conditions will be analyzed.
SAE International journal of passenger cars, Sep 27, 2016
As long as a tire steers about a titled kingpin pivot, the point coming in contact with the road ... more As long as a tire steers about a titled kingpin pivot, the point coming in contact with the road moves along its perimeter. This movement affects the determination of kingpin moments caused by the tire forces, especially for large steering angles. The movement, however, has been neglected in the literature on the steerable-tire-kinematics-related topics. In this investigation, the homogeneous transformation is employed to develop a kinematic model of a steering tire in which the instantaneous ground-contact point on the tire is considered. The moments about the kingpin axis caused by tire forces are then computed based on the kinematics. A four-wheel-car model is constructed for determining the kingpin moment of steering system during the low-speed cornering maneuver. The result shows that the displacement of the ground-contact point along the tire perimeter is significant for large steering angles. It also indicates that, at the low-speed cornering, the moment about the kingpin axis caused by vertical forces benefits self-centering while those caused by longitudinal forces, lateral forces, and 'aligning' torques facilitate the turn. A parameter study is also conducted to visualize the effects of wheel alignment parameters on the kingpin moment. It appears that an increase in kingpin offset or a decrease in caster angle affects the kingpin moment such that it supports the self-centering. The effects of kingpin inclination and caster trail on the moment, however, depend on the amplitude of steering angle. The result is compared to those derived from a multi-body model for validation.
International journal of nonlinear dynamics and control, 2017
The effect of acceleration-variable forward velocity, have been investigated on the steady-state ... more The effect of acceleration-variable forward velocity, have been investigated on the steady-state and transient responses of turning vehicles and the resulted path of motion of the vehicle. Comparing the two mentioned responses of the vehicle could be used to prove that there is a negligible difference between the steady-state and transient centre of rotation of the vehicle in engineering applications. Dynamics of a vehicle with a constant steer angle and variable forward velocity have been analysed and presented as the proof. It has been shown that it is possible to predict the dynamics of vehicles using their steady state responses within acceptable engineering approximations. More specifically, we determine the dynamic rotation centre of vehicles and compare them with steady-state values. The result would be essential to design autodriver algorithm for autonomous vehicles.
Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering, Oct 17, 2017
When a car is cornering, its wheels usually lean away from the centre of rotation. This phenomeno... more When a car is cornering, its wheels usually lean away from the centre of rotation. This phenomenon decreases lateral force, limits tyre performance and eventually reduces the vehicle lateral grip capacity. This paper proposes a strategy for varying caster in the front suspension, thereby altering the wheel camber to counteract this outward inclination. The homogeneous transformation was utilised to develop the road steering wheel kinematics which includes the wheel camber with respect to the ground during a cornering manoeuvre. A variable caster scheme was proposed based on the kinematic analysis of the camber. A rollable vehicle model, along with a camber-included tyre force model, was constructed. MATLAB/Simulink was used to simulate the dynamic behaviour of the vehicle with and without the variable caster scheme. The results from step steer, ramp steer, and sinusoidal steer inputs simulations show that the outward leaning phenomenon of the steering wheels equipped with the variable caster, is reduced significantly. The corresponding lateral acceleration and yaw rate increase without compromising other handling characteristics. The actively controlled car, therefore, provides better lateral stability compared to the passive car. The tyre kinematic model and the vehicle dynamic model were validated using multibody and experimental data.
Springer eBooks, 2018
Pneumatic tires on motor vehicles have viscoelastic properties, and its friction on the ground is... more Pneumatic tires on motor vehicles have viscoelastic properties, and its friction on the ground is more complicated than metal to metal contact. Research into the friction coefficient of pneumatic tires and road surfaces remains contradictory and elusive as both road surfaces and vehicle design continue to develop. Vehicle safety, road design and collision investigation rely greatly on accurate determination of tire and road surface friction. This study is designed to determine the effect of vehicle velocity, ambient temperature and rainfall on the friction coefficient of pneumatic tires sliding on bitumen road surfaces. To determine these effects, three series of tests were undertaken. Skid resistance tests were performed in a passenger vehicle on bitumen roads at a range of speeds between 30 and 80 km/h, with and without antilock braking, at a range of temperatures between 3 and 43 °C and pre-, during and post-rainfall. The friction coefficient of the pneumatic tires and road surfaces for each variable was determined using an accelerometer.
Vehicle System Dynamics, Jan 9, 2023
Springer eBooks, Feb 24, 2012
IEEE Transactions on Intelligent Transportation Systems, Jul 1, 2022
Springer eBooks, 2015
During the project for generating a mathematical algorithm for autonomous vehicles, a sample road... more During the project for generating a mathematical algorithm for autonomous vehicles, a sample road which included different turns and scenarios was required. Studying different types of roads and their line equations Euler spirals, also known as Clothoids were found to be the best solution for designing new roads suitable for autonomous vehicles. During 19th century Arthur Talbot derived the equation of Clothoids to be used as an easement curve for the purpose of avoiding shock and disagreeable lurch of trains, due to instant change of direction. The Euler Spiral is a curve whose degree-of-curve increases directly with the distance along the curve from the start point of the spiral. This provides a linear change in the steering angle required by the driver to go through the turn. In other words for a car traveling on a Clothoid transition road curve there is no need for sudden changes in the steering angle of the wheels. The angle required starts from zero and increases to a maximum value and goes back to zero linearly. This provides a very comfortable ride for the passengers of the vehicle. The use of these curves for road design have been investigated, and a design chart have been proposed to be used for finding the best suitable transition curve for different applications.
IEEE Transactions on Intelligent Transportation Systems, Mar 1, 2022
Autodriver algorithm aims to develop a path-following algorithm for autonomous vehicles using roa... more Autodriver algorithm aims to develop a path-following algorithm for autonomous vehicles using road geometry data and vehicle dynamics. In this study, a novel smart Autodriver algorithm is developed according to practical implications utilizing a more realistic vehicle model and consideration of real-time applicability. A ghost-car path-following approach is introduced to define the desired location of the vehicle at every instance during various maneuvers. Key steady-state characteristics of turning vehicles, namely the curvature, yaw rate, and side-slip responses are discussed and used to construct a path-following controller based on the Autodriver algorithm. A feedback control based on Sliding Mode Control (SMC) is also designed and applied to minimize transient errors between the road and the vehicle positions. Finally, simulations are performed to analyze the path-following performance of the proposed scheme compared to a Model Predictive Controller (MPC) as a widely accepted popular method for autonomous vehicles. Hardware-in-the-loop (HIL) tests are also performed to investigate real-time applicability of the controllers. The results show promising controller performance in terms of error minimization, passenger comfort, and low computational cost for the proposed method.
SAE International Journal of Commercial Vehicles, May 5, 2021
Smart innovation, systems and technologies, 2019
This paper constitutes the second part of the publication series on introducing a new simplified ... more This paper constitutes the second part of the publication series on introducing a new simplified combined-slip tire model for vehicle dynamics. The effectiveness of the proposed model (Elliptic Model) is validated using a comparative dynamic simulation. A five degree of freedom vehicle model is presented and used for simulation. Tire forces are calculated based on both the Elliptic Model and Magic Formula, and simulation results are compared. It has been shown that the simplified tire model shows promising performance and may be used for estimating the tire force capacity, specially up to the saturation point of tire slips.
Vehicle System Dynamics, Apr 5, 2021
Vehicle System Dynamics, Feb 21, 2021
This study deals with drifting as one of the most important nonlinearities in vehicle dynamics. A... more This study deals with drifting as one of the most important nonlinearities in vehicle dynamics. A four-wheel vehicle model is used to calculate the equilibria in planar motion, numerically, by intr...
Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science, Jun 29, 2019
Spot welding is the most common technique used to join sheet metals in the automotive industry du... more Spot welding is the most common technique used to join sheet metals in the automotive industry due to the fast rate of production. Optimising the welding process including the sequence, number and location of the welds would significantly improve the quality of the final product and production cost. This paper presents an overview on the available methods to plan and optimise various aspects of the welding process including welding sequence, weld quantity and location. Firstly, the welding concept in the automotive industry is briefly reviewed. Secondly, the welding process optimisation with emphasis on the welding sequence is discussed. The common gaps and challenges are identified and, lastly, future research to plan and optimise the welding sequence in the automotive body is outlined.
Springer eBooks, 2016
A variation in the camber of an automotive wheel is desired to compensate a side-slip force reduc... more A variation in the camber of an automotive wheel is desired to compensate a side-slip force reduction owing to transversely normal load shift when the car is cornering. The camber of a steered wheel can be varied by adjusting caster or/and lean angles which are the representations of steering axis orientation. Thus, adjustable camber can be created by variable caster or/and lean angle. Choosing which parameter among the two angles to be the main source of camber generation is a key starting point and dependent on its different effects. Here, homogeneous transformation is employed to establish camber as a function of caster, lean angle, and steering angle in the general case. A comparison between caster and lean angle based on different criteria is made. The comparison shows that a variable caster is more effective than a variable lean angle in generating a smart camber.
Lecture notes in networks and systems, Nov 20, 2018
When steering about the titled kingpin axis, the tyre-road contact point moves along the tyre per... more When steering about the titled kingpin axis, the tyre-road contact point moves along the tyre perimeter. In the literature on the tyre kinematics, this displacement, however, has not been taken into consideration. This results in an inaccuracy in the steering tyre kinematics, especially when the steering angle is large. This paper presents a novel method, utilising homogeneous transformation, to develop the kinematics of a steering tyre with the chance of the tyre-road contact being taken into account. The results show that this novel kinematic model is more accurate than those in the literature. The steering tyre kinematics developed in this investigation is then compared to that one built in ADAMS software for validating purpose.
Procedia Computer Science, 2017
The purpose of this paper is to show the effect of acceleration-variable forward velocity-, on th... more The purpose of this paper is to show the effect of acceleration-variable forward velocity-, on the steady-state and transient responses of turning vehicles and the resulted path of motion of the vehicle. Comparing the responses of the vehicle will be used to prove that there is a negligible difference between the steady-state and transient center of rotation of the vehicle in engineering applications. To show that vehicles are working close to their steady-state conditions even at transient stage, we examine a vehicle in two maneuvers. In the first one, the vehicle is assumed to be moving at a constant forward speed and experiencing a step steer angle change. In the second maneuver, the vehicle experiences a lane change steering input. The transient response of the vehicle, as well as the required time to achieve the steady-state conditions will be analyzed.
SAE International journal of passenger cars, Sep 27, 2016
As long as a tire steers about a titled kingpin pivot, the point coming in contact with the road ... more As long as a tire steers about a titled kingpin pivot, the point coming in contact with the road moves along its perimeter. This movement affects the determination of kingpin moments caused by the tire forces, especially for large steering angles. The movement, however, has been neglected in the literature on the steerable-tire-kinematics-related topics. In this investigation, the homogeneous transformation is employed to develop a kinematic model of a steering tire in which the instantaneous ground-contact point on the tire is considered. The moments about the kingpin axis caused by tire forces are then computed based on the kinematics. A four-wheel-car model is constructed for determining the kingpin moment of steering system during the low-speed cornering maneuver. The result shows that the displacement of the ground-contact point along the tire perimeter is significant for large steering angles. It also indicates that, at the low-speed cornering, the moment about the kingpin axis caused by vertical forces benefits self-centering while those caused by longitudinal forces, lateral forces, and 'aligning' torques facilitate the turn. A parameter study is also conducted to visualize the effects of wheel alignment parameters on the kingpin moment. It appears that an increase in kingpin offset or a decrease in caster angle affects the kingpin moment such that it supports the self-centering. The effects of kingpin inclination and caster trail on the moment, however, depend on the amplitude of steering angle. The result is compared to those derived from a multi-body model for validation.
International journal of nonlinear dynamics and control, 2017
The effect of acceleration-variable forward velocity, have been investigated on the steady-state ... more The effect of acceleration-variable forward velocity, have been investigated on the steady-state and transient responses of turning vehicles and the resulted path of motion of the vehicle. Comparing the two mentioned responses of the vehicle could be used to prove that there is a negligible difference between the steady-state and transient centre of rotation of the vehicle in engineering applications. Dynamics of a vehicle with a constant steer angle and variable forward velocity have been analysed and presented as the proof. It has been shown that it is possible to predict the dynamics of vehicles using their steady state responses within acceptable engineering approximations. More specifically, we determine the dynamic rotation centre of vehicles and compare them with steady-state values. The result would be essential to design autodriver algorithm for autonomous vehicles.
Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering, Oct 17, 2017
When a car is cornering, its wheels usually lean away from the centre of rotation. This phenomeno... more When a car is cornering, its wheels usually lean away from the centre of rotation. This phenomenon decreases lateral force, limits tyre performance and eventually reduces the vehicle lateral grip capacity. This paper proposes a strategy for varying caster in the front suspension, thereby altering the wheel camber to counteract this outward inclination. The homogeneous transformation was utilised to develop the road steering wheel kinematics which includes the wheel camber with respect to the ground during a cornering manoeuvre. A variable caster scheme was proposed based on the kinematic analysis of the camber. A rollable vehicle model, along with a camber-included tyre force model, was constructed. MATLAB/Simulink was used to simulate the dynamic behaviour of the vehicle with and without the variable caster scheme. The results from step steer, ramp steer, and sinusoidal steer inputs simulations show that the outward leaning phenomenon of the steering wheels equipped with the variable caster, is reduced significantly. The corresponding lateral acceleration and yaw rate increase without compromising other handling characteristics. The actively controlled car, therefore, provides better lateral stability compared to the passive car. The tyre kinematic model and the vehicle dynamic model were validated using multibody and experimental data.
Springer eBooks, 2018
Pneumatic tires on motor vehicles have viscoelastic properties, and its friction on the ground is... more Pneumatic tires on motor vehicles have viscoelastic properties, and its friction on the ground is more complicated than metal to metal contact. Research into the friction coefficient of pneumatic tires and road surfaces remains contradictory and elusive as both road surfaces and vehicle design continue to develop. Vehicle safety, road design and collision investigation rely greatly on accurate determination of tire and road surface friction. This study is designed to determine the effect of vehicle velocity, ambient temperature and rainfall on the friction coefficient of pneumatic tires sliding on bitumen road surfaces. To determine these effects, three series of tests were undertaken. Skid resistance tests were performed in a passenger vehicle on bitumen roads at a range of speeds between 30 and 80 km/h, with and without antilock braking, at a range of temperatures between 3 and 43 °C and pre-, during and post-rainfall. The friction coefficient of the pneumatic tires and road surfaces for each variable was determined using an accelerometer.