Vehicle centre of mass, roll-centre and pitch-centre height estimation

Sep 18, 2026

The vehicle centre of mass is a critical parameter that strongly affects vehicle dynamics. The vertical position of the centre of mass relative to the roll and pitch centres influences load transfer during braking and cornering, and these values can change substantially, particularly on off-road vehicles with large differences between laden and unladen weight. The paper presents a real-time algorithm that estimates suspension forces and inertial parameters from low-cost sensor measurements using an unscented Kalman filter. Experimental validation is performed on an off-road vehicle across multiple manoeuvres and terrains, supporting improved vehicle safety and control.

LanguageEnglish

CategoryResearch & Report

FormatPDF

Pages21

Reading Time53 min

AccessFree to download

1 Introduction

Vehicle inertia properties and control relevance

Centre of mass height and load transfer

Estimation approaches using vehicle dynamics and sensing

Vehicle centre of mass, roll-centre and pitch-centre height estimation Theunis R. Botha* and P. Schalk Els Department of Mechanical and Aeronautical Engineering, University of Pretoria, Private Bag x20 Hatfield, 0028, South Africa Email: [theunis.botha@up.ac.za](theunis.botha@up.ac.za) Email: [schalk.els@up.ac.za](schalk.els@up.ac.za) *Corresponding author Abstract: The location of a vehicle’s centre of mass is an important parameter as it has a determining effect on the dynamics of a vehicle. The height of the vehicle centre of mass from the roll and pitch centres has a large influence on the load transfer which occurs between wheels during braking and cornering manoeuvres. These vehicle parameters can vary significantly especially on off-road vehicles due to the large differences in laden and unladen weight. This paper proposes an algorithm where suspension forces and inertial parameters are estimated in real time using inexpensive sensor measurements and an unscented Kalman filter. The algorithm is experimentally validated on an offroad vehicle performing various manoeuvres and driving over different terrains. The real time estimation of these parameters could contribute significantly to improving vehicle safety and control. Keywords: centre of gravity estimation; suspension force estimation; roll centre height; pitch centre height. Reference to this paper should be made as follows: Botha, T.R. and Els, P.S.(2019) ‘Vehicle centre of mass, roll-centre and pitch-centre height estimation’, Int. J. Vehicle Systems Modelling and Testing, Vol. 13, No. 4, pp.319–339 . Biographical notes: Theunis R. Botha received his PhD in Mechanical Engineering from the University of Pretoria, South Africa in 2015. His PhD work focused on using digital image correlations to perform vehicle measurement such as tyre slip angle and slip ratio using digital cameras. Currently, he is employed as a Senior Lecturer at the University of Pretoria, South Africa. His research interests are dynamics, integrated vehicle safety systems, autonomous vehicle control, mechatronics, parameter estimation and digital image correlation P. Schalk Els worked in industry, developing and testing military wheeled vehicles for five years, where he was actively involved in new technology projects and applied research. Highlights include semi-active dampers for heavy vehicles, including the world’s first semi-active hydraulic rotary damper (with Horstman Defence) . In 1999, he joined the Department of Mechanical and Aeronautical Engineering at the University of Pretoria as a permanent staff member and obtained a PhD in 2006. His current research interests include semi-active dampers, semi-active springs and height adjustment to improve ride comfort, handling, rollover propensity and life of heavy off-road vehicles. Copyright © 2019 Inderscience Enterprises Ltd. 320 T.R. Botha andP.S. Els 1 Introduction Accurate real-time information on vehicle inertia properties, specifically the vehicle mass, centre of mass (CoM) location and the distance of the centre of mass to the roll and pitch centres, can greatly improve control algorithms related to braking, handling and vehicle safety. The vehicle mass and its lateral and longitudinal location have a significant effect on vehicle handling as it directly affects the handling characteristics of the vehicle (Gillespie, 1992; Jazar, 2017) . While most stability controllers assume prior knowledge of the location of the centre of mass (Di Cairano et al., 2013; Rubin and Arogeti, 2015; Tchamna and Youn, 2013) the centre of mass position is not always constant and changes based on loading conditions. The loading conditions on passenger vehicles may not vary greatly between unladen and fully laden. However, on SUV, off-road as well as mining and agricultural vehicles the change is mass can be substantial and will have a significant effect on the handling of the vehicle. The height of the centre of mass above the r

FAQs

Why is the vehicle centre of mass location important?

It determines key aspects of vehicle dynamics and significantly influences control-related behaviour such as braking and handling. Its position affects how the vehicle transfers load between wheels under acceleration.

How does centre-of-mass height relative to roll and pitch centres affect vehicle performance?

The height largely determines the load transfer generated by vehicle body acceleration. This information can help evaluate roll-over propensity and support stability control and safety systems.

What method does the paper propose to estimate these parameters in real time?

It proposes an algorithm that estimates suspension forces and inertial parameters using inexpensive sensor measurements combined with an unscented Kalman filter. The approach is validated experimentally on an off-road vehicle over various manoeuvres and terrains.

Sep 18, 2026

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