Roman Henze

Non-parametric modelling of damper top mounts

This paper details a new non-linear damper top-mount model, and the processes utilized to identify the constituent parameters. The damper top-mount model parameters are extracted from experimental data on commercial damper top mounts. The non-parametric restoring-force-mapping technique is used to construct the damper top-mount model. A damper top-mount model that consists of three elements, which are the non-linear elastic element, the non-linear friction element and the non-linear viscous element, is developed. The amplitude dependence of the top-mount characteristics is modelled by using the friction element and the elastic element, while the frequency dependence of the top mount is modelled by using the restoring-force-mapping technique. In order to obtain and optimize the required model parameters, a new procedure based on a two-stage optimization routine using two different sets of the measurement data for the amplitude-dependent parameters and the frequency-dependent parameters, is proposed. The model is validated by comparing the measured and simulated forces for three different damper top mounts. Good agreement between the measured force and the simulated force is obtained. Furthermore, the proposed model is found to be superior to the existing rubber isolator models.

Optimization of Damper Top Mount Characteristics to Improve Vehicle Ride Comfort and Harshness

A novel optimization technique for optimizing the damper top mount characteristics to improve vehicle ride comfort and harshness is developed. The proposed optimization technique employs a new combined objective function based on ride comfort, harshness, and impact harshness evaluation. A detailed and accurate damper top mount mathematical model is implemented inside a validated quarter vehicle model to provide a realistic simulation environment for the optimization study. The ride comfort and harshness of the quarter vehicle are evaluated by analyzing the body acceleration in different frequency ranges. In addition, the top mount deformation is considered as a penalty factor for the system performance. The influence of the ride comfort and harshness weighting parameters of the proposed objective function on the optimal damper top mount characteristics is studied. The dynamic stiffness of the damper top mount is used to describe the optimum damper top mount characteristics for different optimization case studies. The proposed optimization routine is able to find the optimum characteristics of the damper top mount which improve the ride comfort and the harshness performances together.

Vergleich Unterschiedlicher Systeme zur Aktiven Antriebsmomentenquerverteilung

Dank einer radlastangepassten Ausnutzung des Kraftschlusspotenzials ermoglichen querverteilende Antriebssysteme insbesondere bei frontangetriebenen Fahrzeugen eine deutliche Erhohung der Agilitat und der Fahrleistungen. Das Institut fur Fahrzeugtechnik der Technischen Universitat Braunschweig fuhrte Simulationsstudien fur einen systematischen Konzeptvergleich dieser Systeme durch.

Reproducible transverse dynamics vehicle evaluation in the double lane change

In automotive companies, designing the vehicle dynamics to be customer-oriented with the help of road trials is largely the responsibility of trained professional drivers. A driver model that corresponds to an average — and therefore customer-relevant — driver presents an opportunity to evaluate the vehicle in an objective and reproducible way. This vehicle evaluation was developed at Volkswagen in close cooperation with the Institute for Vehicle Technology at Technical University Braunschweig (Germany).

Effects of damper failure on vehicle stability

The general approach in vehicle dynamics analysis is to use mint state characteristics of the chassis components in vehicle simulation models. However, some of the chassis components are vulnerable to damage which might induce drastic changes in component characteristics. A comprehensive vehicle stability analysis should, therefore, account for the changing characteristics of the components. In the literature, such analyses exist only for slowly-developing damper wear cases. In recent years, there has been an increase in the popularity of controlled dampers. These dampers include an increased number of structural elements and their characteristics depend on the control current supplied by a complex control system. In this study, the effect of sudden shifts in controlled damper characteristics on the stability of the vehicles is examined in detail. Two different types of damper-characteristic shifts are taken into account; the first one is a soft-to-hard transition that takes place due to control current cut-off and the other is a hard-to-soft transition originating from failure of the mechanical components in the damper. A detailed vehicle simulation model is developed, verified and used to simulate different driving manoeuvres where damper failure might affect vehicle stability. The analysis is extended to a vehicle configuration employing a simple ESP structure in order to observe the effects of chassis control systems in minimizing the effects of the damper failure. The results obtained in this study show that the failure of a damper might lead to vehicle instability in some critical driving situations for vehicles lacking advanced chassis control systems.

Practicability study on the suitability of artificial, neural networks for the approximation of unknown steering torques

ABSTRACT For steer-by-wire systems, the steering feedback must be generated artificially due to the system characteristics. Classical control concepts require operating-point driven optimisations as well as increased calibration efforts in order to adequately simulate the steering torque in all driving states. Artificial neural networks (ANNs) are an innovative control concept; they are capable of learning arbitrary non-linear correlations without complex knowledge of physical dependencies. The present study investigates the suitability of neural networks for approximating unknown steering torques. To ensure robust processing of arbitrary data, network training with a sufficient volume of training data is required, that represents the relation between the input and target values in a wide range. The data were recorded in the course of various test drives. In this research, a variety of network topologies were trained, analysed and evaluated. Though the fundamental suitability of ANNs for the present control task was demonstrated.

High Resolution Radar-based Occupancy Grid Mapping and Free Space Detection.

The high-resolution radar sensors have the ability to detect thousands of reflection points per cycle, which promotes the perception capability on a pixel level similar to video systems. In this paper, an occupancy grid map is created to model the static environment. The reflection amplitudes of all detection points are compensated, normalized, and then converted to the detection probability based on a radar sensor model. According to the movement of the ego vehicle, the a posteriori occupancy probability is computed to build the occupancy grid map. Thereafter the occupancy grid map is converted to the binary grid map, where the grids in the obstacle areas are defined as occupied. In order to eliminate the outliers, the connected occupied grids are clustered using the Connected-Component Labelling algorithm. Through the Moore-Neighbour Tracing algorithm the boundaries of the clustered occupied grids are recognized. Based on the boundaries, the interval-based free space detection is performed using the Bresenhams line algorithm. As mentioned, the occupancy grid map and the free space detection results obtained from radar road measurements match with the real scenarios.

To whom does the driver's seat belong in the future?: a case of negotiation between gender studies and automotive engineering

This article provides an experience report on an interdisciplinary cooperation between two gender researchers and two automotive engineers at a German technical university. It focuses on the negotiation processes around a joint research proposal, dealing with the question of how to create concepts for a trustworthy human-machine interaction in automated driving systems that satisfy the requirements of different user groups. These systems aim to offer the choice of automobility to groups of users who have so far had rather limited access, or have had reasons to refuse usage. Discussions in the interdisciplinary team are still ongoing. Their substantial shifts and their expected methodological and epistemological effects are analyzed from a feminist science and technology studies (STS) perspective. The general objective of this paper is to provide insights about the contributions and challenges of integrating approaches from gender studies into the field of automotive engineering in order to support interdisciplinary dialogues that foster a socially fair and inclusive digital transformation.

Advanced parameter analysis for damper influence on ride dynamics

The conflicting objectives related to damping characteristics of vehicle suspensions promote further development of new damper concepts. The effort is no longer limited to finding the optimal damper velocity–force characteristics for a vehicle suspension system. Besides this basic design parameter, the amplitude- and frequency-dependent characteristics of dampers are also taken into consideration. The first step in adjustment of the velocity, displacement, and frequency-dependent damper characteristics is to understand the effect of these characteristics on the dynamics of the vehicle. Therefore, in this study, the interaction between the damper characteristics and vehicle ride response is analyzed by using a detailed mathematical damper model together with a verified full vehicle simulation model. A semi-parametric detailed damper model is first verified through physical testing of different dampers and then it is fully parameterized and implemented inside the full vehicle simulation model. A parameter variation analysis is performed to show the effect of the different damper characteristics on vehicle ride comfort.

Robust vehicle handling dynamics of light-weight vehicles against variation in loading conditions

This paper proposes a vehicle dynamics control system to compensate the change in vehicle handling dynamics of light-weight vehicles due to variation in loading conditions. Considering the electrification of future mobility, a light-weight vehicle equipped with in-wheel-motors is a target vehicle of this research and it can generate additional direct yaw moment control input, so-called “DYC input”, by transverse distribution of driving/braking forces to control vehicle yawing as well as side slip motions. First, the change in vehicle handling dynamics against variation in loading conditions is analyzed by using linear two-wheel vehicle model in planar motions. Next, the control law of DYC system is proposed as a feedforward of steering angular velocity and a feedback of vehicle yaw rate. Finally, the effectiveness of the proposed DYC system is verified by simulation of nonlinear vehicle model with a nonlinear tire force model.