Estimation of the tire-road interaction forces by using Pacejka’s formulas with combined slips and camber angles. - In: SAE technical papers, ISSN 2688-3627, (2023), SAE technical paper 2023-01-0646, S. 1-14
The growing market demand for highly automated and autonomous vehicles and the need to equip vehicles with ever higher standards of comfort, safety and performance requires knowledge of physical quantities that are often difficult or expensive to measure directly. The absence of direct sensors, the difficulty of implementation, and their cost have led researchers to identify alternative solutions that allow estimating the physical quantity of interest by aggregating other available information. The interaction forces between tire and road are among the most significant. Given that the dynamics of a vehicle are strongly linked to the forces exchanged between the tire and the road, their knowledge is fundamental in the development of control systems aimed at improving performance in terms of handling, road holding or comfort. This paper presents a new technique for the estimation of tire-road interaction forces based on the integration of models and measures. A Central Difference Kalman filter was applied to a Double Track Model. The non-linear Kalman filter allowed us to handle the non-linearity of the system. The tire-road interaction was modelled through Pacejka's magic formulas that into account the combined longitudinal and lateral slips and the camber angle. This version made it possible to carry out complex and realistic manoeuvres. The realized estimator also considers the influence of lateral and longitudinal load transfers and aerodynamic forces in the three spatial directions. The Camber angle used in this observer was estimated through neural networks. The measures used are longitudinal velocity, yaw rate, longitudinal slip and wheel steering angles.
https://doi.org/10.4271/2023-01-0646
Methodologic assessment of brake-by-wire system modelling with regard to accuracy, model complexity and optimization efforts. - In: SAE technical papers, ISSN 2688-3627, (2023), SAE technical paper 2023-01-0666, S. 1-13
Brake-by-wire systems are an innovative and important component of modern high-performance and also electrified vehicles. Due to their decoupled architecture, they enable driver-independent vehicle dynamics control (e.g., brake torque blending) and easy integration of assistance functionalities (e.g. Emergency Brake Assist (EBA)). On the other hand, the development of these functions can cause high costs and development effort, and testing can be critical in case of improper gain tuning. Therefore, already in the concept phase, a large part of the testing is shifted to virtual environments and simulations that allow safe and reproducible experiments without damage. Therefore, suitable and reliable models are needed to represent reality as accurately as possible. This paper deals with the modelling of a purely electrohydraulic brake-by-wire system and a hybrid system with electrohydraulic brakes on the front axle and electromechanical brakes on the rear axle. For comparison, both an experimental approach based on a second-order transfer function and an analytical model are used. These approaches are then evaluated in terms of their accuracy and reliability using real measurements in different dynamic test setups. Finally, it is shown how accurate the approaches are and what advantages can be achieved by using the different methods for system modelling.
https://doi.org/10.4271/2023-01-0666
Road parameter estimation with drone-vehicle communication. - In: SAE technical papers, ISSN 2688-3627, (2023), SAE technical paper 2023-01-0664, S. 1-7
The presented study is dedicated to the technology supporting vehicle state estimation and motion control with a concept drone, which helps the vehicle in sensing the surroundings and driving conditions. This concept allows also extending the functionality of the sensors mounted on the vehicle by replacing or including additional parameter observation channels. The paper discusses the feasibility of such a drone-vehicle interaction as well as demonstrates several design configurations. In this regard, the paper presents a general description of the proposed drone system that assists the vehicle and describes an experiment in measuring the profile of the road with a range sensor. The results obtained in the experiment are described in terms of the accuracy to be achieved using the drone and are compared with other studies, which use the methods of estimation from the sensors mounted on the vehicle. The proposed measurement concept can be applied to a large number of vehicle systems such as adaptive cruise control, active or semi-active suspension, and wheel slip control. The road profile is captured in real-time by a drone, and the telemetry data is processed by the host computer.
https://doi.org/10.4271/2023-01-0664
Fill level measurement of low-permittivity material using an M-sequence UWB radar. - In: International journal of microwave and wireless technologies, ISSN 1759-0795, Bd. 15 (2023), 8, S. 1299-1307
Due to increasingly complex and automated manufacturing processes, the demands on the control parameters of these processes are also increasing. One parameter is the fill quantity of, e.g., liquids in production plants, whose precise determination is of ever-growing importance. Up to now, the exact level of determination under difficult conditions, such as high ambient temperatures, has been a particular challenge. This paper demonstrates a novel method by which an M-sequence UWB radar can determine levels of low-permittivity materials in small metal containers. For this purpose, hot melt is used as an example. Thus, the influence of large temperature differences on the long-term stability of level measurement can also be investigated. The measurements show that the level of hot melt can be measured to be long-term stable with an accuracy of better than 3 mm. Furthermore, the precise determination of the empty state is highly important for many applications. For this reason, this paper shows a method for determining the empty state without complex calibration procedures. For the empty level indication, an accuracy of up to 0.5 mm could be achieved for molten hot glue and 3% of the tank volume, independent of the shape or aggregate state of the medium.
https://doi.org/10.1017/S1759078723000739
Deep learning for the estimation of the longitudinal slip ratio. - In: 2023 IEEE International Workshop on Metrology for Automotive, (2023), S. 193-198
In a road vehicle, the interaction forces between tire and road are strongly influenced by the longitudinal slip ratio. This kinematic quantity, therefore, represents one of the most important in the study of vehicle dynamics. The real-time knowledge of this quantity can allow the estimation of the interaction forces and the development of control systems to improve safety and handling. In particular, Anti-lock Braking Systems (ABS) and Traction Control Systems (TCS). Direct measurements of this quantity would require the insertion of sensors inside the tire, with consequent manufacturing complexity and increased costs. This paper proposes an estimate of the longitudinal slip ratio based on other easily measurable or estimable quantities. This estimator makes use of Neural Networks and is based on preliminary physical considerations.
https://doi.org/10.1109/MetroAutomotive57488.2023.10219139
Data augmentation for design of concentric tube continuum robots by generative adversarial networks. - In: Proceedings in applied mathematics and mechanics, ISSN 1617-7061, Bd. 23 (2023), 4, e202300278, S. 1-7
Concentric tube continuum robots are a promising type of robot for various medical applications. Their application in neurosurgery poses challenging requirements for design and control that can be addressed by physics-informed data-based approaches. A prerequisite to data-based modeling is an informative, rich data set. However, limited access to experimental data raises interest in partially or entirely synthetic data sets. In this contribution, we study the application of generative adversarial networks (GANs) for data augmentation in a data-based design process of such robots. We propose a GAN framework suitable for curve-fitting to generate synthetic trajectories of robots along with their corresponding control parameters. Our evaluation shows that the GANs can efficiently produce meaningful synthetic trajectories and control parameter pairs that show a good agreement with simulated trajectories.
https://doi.org/10.1002/pamm.202300278
Double-pass modulated differential confocal microscopy for closed-loop axial control of direct laser writing. - In: Optical Measurement Systems for Industrial Inspection XIII, (2023), 126180R, S. 126180R-1-126180R-11
Direct laser writing is a popular method for mask-less lithography that already achieved commercial grade. However, it is still challenging to realize homogeneously exposed structures on 3D-shaped substrates. A common source of the variation in exposure is a changing distance of the substrate surface with the photoresist towards the plane of the narrowest waist of the exposure beam. To tackle this issue, we propose a differential confocal probe that employs a spatially modulated pinhole. This phase-modulated lock-in principle enables highly resolved depth sensing without ambiguity about the direction of the deviation from the focal plane. However, the modulation contrast must be high enough to achieve this, which is why the measuring beam passes the pinhole twice. This probe is integrated into the nanopositioning and nanomeasuring machine via a position-based controller. We demonstrate the capability to follow 10◦ inclined substrates.
https://doi.org/10.1117/12.2673874
Long-term wavelength stabilisation of widely modulated lasers. - In: Optical Measurement Systems for Industrial Inspection XIII, (2023), 1261816, S. 1261816-1-1261816-8
In this paper, we present a novel technique for stabilisation of widely wavelength modulated lasers (>100pm) over long time scales, where modulation depths exceed the spectral width of standard reference features, such as gas absorption lines, by over an order of magnitude. The technique operates by controlling the temporal separation between successive appearances of a gas absorption line on the up and down sweeps of a sinusoidal laser wavelength modulation waveform. The influence of the signal distortions introduced by the laser intensity modulation that are associated with laser diode injection current modulation are also addressed. The technique is applied to a range-resolved interferometric system interrogating a Mach-Zehnder interferometer operating in thermally stable conditions, using an absorption feature from a fibre-coupled gas cell as a reference. Proof-of-principle measurement results achieved using this technique are presented, demonstrating a notional fractional stability of 3.9×10−7 without further correction.
https://doi.org/10.1117/12.2673684
A fibre optic angle sensing tape for applications in robotics and automation. - In: Optical Measurement Systems for Industrial Inspection XIII, (2023), 126180D, S. 126180D-1-126180D-6
A dual-fibre single-plane angle-sensing tape that utilizes optical Fibre Segment Interferometry and Range- Resolved Interferometry (RRI) for angle sensing is presented. The sensing tape facilitates the multiplexing of an array of angle sensors along its length and can be retrofitted into small robots and construction equipment. We demonstrate its application on three non-rotational joints of a small five-axis robot, describing the design, construction, measurement principle, and presenting measurement results. Preliminary data shows that the angles measured by the sensing tape exhibited agreement within a range of ±0.005˚ with the manufacturer-installed angle encoder of the robot.
https://doi.org/10.1117/12.2673185
Development of microinterferometers based with fiber coupling :
Entwicklung von Mikrointerferometern mit Faserkopplung. - In: Technisches Messen, ISSN 2196-7113, Bd. 90 (2023), S. S108-S113
Die Einsatzmöglichkeiten von konventionellen Interferometersystemen sind oft aufgrund ihrer Baugröße eingeschränkt. Weiterhin stellen sie noch immer preisintensive, manuell gefertigte Präzisionsbaugruppen dar. Ihr Einsatz ist daher ökonomisch nur für Nischenanwendungen in der Hochtechnologie gerechtfertigt. Aus diesem Grund wird ein neues kompaktes Mikrointerferometer entwickelt, welches auf dem Michelson-Prinzip basiert. Die gesamte Baugröße dieses Mikrointerferometer beträgt 40 mm x 20 mm x 15 mm. Als Strahlteiler wird eine Strahlteilerplatte verwendet, der nicht auf beiden Seiten parallel ist, sondern einen Keilwinkel hat. Dadurch wird der Interferenzwinkel erzeugt. Außerdem sind beide Seiten mit Polarisationsbeschichtung und Entspiegelungsbeschichtung versehen. Zukünftig können die Beschichtungen auf eine große Platte vorbereitet werden und dann ist eine Massenfertigung für die Strahlteilerplatten möglich, sodass die Herstellungskosten dieser Strahlteilerplatten reduziert werden.
https://doi.org/10.1515/teme-2023-0073