Browse Topic: Active suspension systems
The transition to software-defined vehicles (SDVs) necessitates a paradigm shift in both control strategies and vehicle architecture. The EU-funded R&D project SmartCorners addresses this challenge by developing integrated, modular, and scalable smart corner systems (SCS) that combine in-wheel motor (IWM)-based propulsion, brake blending, active suspension system, and steer-by-wire functionality in one module. These SCS can be retrofit or smoothly integrated into the highly adaptable skateboard chassis architecture of modern electric vehicles (EVs), enabling scalable deployment across diverse vehicle types. The central approach of this paper is the utilization of artificial intelligence (AI) and machine learning (ML) to implement multi-layer, data-driven control strategies, facilitating real-time actuation, fault mitigation, and user-centric EV architecture. The SmartCorners project strives to demonstrate significant enhancements, including improved real-world driving range due to enhanced energy-efficiency, reduced component and system costs, and a cut-down in development time of EVs, enabled by digital-twin-based design methodologies. Beyond these performance gains, SmartCorners establishes the foundational principles of modularity, adaptability, and software integration that underpin the evolution toward SDVs. The role of thermal and cabin comfort control is completely different for EVs and internal combustion engine vehicles, with the latter using waste heat from the combustion of fossil fuels for cabin heating, ventilation, and cooling (HVAC). In EVs the required energy is directly taken from the traction battery and precise thermal and cabin comfort control affecting essential components of the vehicle but also the user-perceived driving experience. These project achievements highlight a critical bridge between innovation and electrification on component-level, and the holistic software-defined mobility systems of the future.
Performing transportation and exploration tasks on rugged terrain requires both high load-bearing capacity and large suspension stroke. However, the corner module configurations applied to challenging terrain have rarely been explored. This article proposes an integrated framework that combines bionic principles with topology graph–based type synthesis. This framework leads to the creation of a reconfigurable wheel-legged mechanism capable of switching between wheeled locomotion and legged gait modes, which is then implemented as a corner module system. First, inspired by the skeletal–muscular system of the equine leg, a structure–function mapping relationship between the biological system and the mechanical system is established. Second, a multi-loop closed-chain mechanism with biomimetic morphology is represented in the form of graph theory. A configuration atlas of the wheel-legged hybrid mechanism is generated based on the contracted graph and open-loop kinematic chains, and configuration optimization is carried out. Third, on the basis of the optimized configuration, a biomimetic vibration isolation system is integrated. Finally, a corner module system that integrates the reconfigurable wheel-legged mechanism with steering, hub motor is designed, as well as the mechanical structure of modular transporters based on the aforementioned corner modular architecture. The vibration reduction performance and various locomotion modes of the modular transporter are verified by multibody dynamic simulation.
The automotive industry is rapidly evolving with technologies such as vehicle electrification, autonomous driving, Advanced Driver Assistance Systems (ADAS), and active suspension systems. Testing and validating these technologies under India’s diverse and complex road conditions is a major challenge. Physical testing alone is often impractical due to variability in road surfaces, traffic patterns, and environmental conditions, as well as safety constraints. Virtual testing using high-fidelity digital twins of road corridors offers an effective solution for replicating real-world conditions in a controlled environment. This paper highlights the representation of Indian road corridors as digital twins in ASAM OpenDRIVE and OpenCRG formats, emphasizing the critical elements required for realistic simulation of vehicle, tire, and ADAS performance. The digital twin incorporates detailed 3D road profiles (X-Y-Z coordinates), capturing the geometry and surface variations of Indian roads. The process of generating the digital twin of road corridor involves mapping road corridors using high-density and high-precision LiDAR scanning, DGPS, and camera sensors. A framework along with mathematical algorithms is developed and tuned specifically for extracting Indian road corridor elements, enabling the creation of accurate and detailed digital representations of roads and associated infrastructure. Proposed digital twin framework provides a robust foundation for evaluating vehicle and tire performance by capturing the unique characteristics of Indian roads and corridors diverse surface types, complex urban layouts along with varying infrastructure elements. It supports accelerated development cycles, improved safety, and optimized comfort, offering automotive OEMs and suppliers a reliable virtual platform for testing and validating next-generation vehicles tailored to Indian driving conditions.
Active suspensions can alter the dynamic behavior of a vehicle in real time to respond optimally to any given operating scenario. Today’s active suspension technologies such as hydraulics, rotary electromagnetics, and linear electromagnetics do offer performance gains but these gains are outweighed by important disadvantages including high power consumption, low quality of force, and high costs and weights. Controlled slippage magnetorheological (MR) actuators are an emerging alternative actuation technology that is light, compact, power dense, and produces a high-quality force, making it ideal for active suspension applications. This article conducts an in-depth experimental assessment of the potential of MR actuators to increase vehicle ride comfort quality when used as active suspensions. Four high power MR actuators are installed on a BMW 330Ci and tests are performed on a closed road. Results show that with an impedance controller, comfort is increased by 67% at 65 km/h and by 61% at 80 km/h. These results compare favorably with the best-in-class electromagnetic active suspension technologies reported to date and suggest that MR actuators are promising for automotive active suspensions.
The objective of the present article is to design a nonlinear passive suspension system for an automobile subjected to random road excitation which generates a performance as close to a fully active suspension system as possible. Linear Quadratic Regulator (LQR) control is used to synthesize an active suspension system. The control forces corresponding to the nonlinear passive suspension and the active suspension are equated, and the parameters are optimized as the performance error between the two systems is reduced. The nonlinear equations of motion are reduced to equivalent linear equations, where the system states are a function of the vehicle response statistics, by using the equivalent linearization method. The performance of the optimized nonlinear model and the linear model are compared with the performance of the LQR control active suspension system. The nonlinear model performs better than the linear system with chosen parameters. The optimized system achieves almost an equal response to the active suspension system for ride comfort and road holding over the specified velocity range. The optimum response of a passive suspension system with nonlinear suspension elements is achieved using a novel optimization method. This method provides design flexibility, and it has great engineering importance for application in the design of various vibration control devices.
The vehicle performance is examined based on its specific performance indices. These specific performance indices include stability, ride comfort, steering ability, etc. The vehicle ride comfort is an important factor of vehicle quality and receiving large attention. The majority of previous investigations are focused on vertical vibration analysis of the sprung mass of the vehicle subjected to vertical excitations from the road surface. This study evaluates the ride characteristics of a coupled vertical-lateral 13 degrees of freedom (DoF) full-car model of a light passenger four-wheel vehicle developed with the Lagrangian method. The random vertical and lateral undulations of the road surface have been accounted for in the analysis and represented by the Power Spectral Density (PSD) function. The vehicle ride is assessed based on the International Organization for Standardization (ISO) 2631-1 annexure and the vehicle overall ride index is determined. The vehicle’s vertical-lateral dynamics are evaluated based on a 1-8 hr comfort boundary laid in ISO specifications. In a further study, the vehicle inertial, suspension, and geometric parameters, which critically influence the vertical and lateral ride, have been identified. The vehicle’s vertical ride covers a relatively wide band of frequencies under the discomfort level of ISO comfort boundaries and is found to be more crucial as compared with the lateral ride; the recommendations are made to improve the vertical ride in preference. The total value of weighted Root Mean Square (RMS) acceleration of the vehicle determined from the present analysis is 2.47 m/s2, and the ride comfort index was found to be in the range “very uncomfortable” specified in ISO 2631-1 annexure. The present study provides a basis for the vehicle designer for the modification in the vehicle parameter values to obtain optimum ride comfort.
Ride comfort assessment is undoubtedly related to the interaction between the vehicle tires and the road surface. Indeed, the road profile represents the typical input for tire vertical load estimation in durability analysis and for active/semi-active suspension controller design. However, the road profile evaluation through direct experimental measurements involves long test time and excessive cost required by professional instrumentations to detect the road irregularities with sufficient accuracy. An alternative is shifting attention towards efficient and robust algorithms for indirect road profile evaluation. The object of this work aims at providing road profile estimation starting from vehicle dynamics measurements, through accessible and traditional sensors, with the application of a linear Kalman filter algorithm. The filter is designed and tuned by considering the pitch/bounce half-car models for the prediction phase and by measuring vertical accelerations and angular speeds for the correction phase. The estimator is then tested on experimental data, acquired driving a passenger car over a road bump at different vehicle speeds. The vehicle used in the experimental campaign is a two-passenger electric quadricycle involved in the demonstration phase of the European project STEVE.
The article examines quarter-car dynamics with the possible separation of its tire from the road. A set of nondimensionalized differential equations has been proposed to minimize the involved parameters. Time and frequency response investigation of the system has been analyzed insightfully considering tire-road separation. To measure the separation of the tire, a time fraction index is defined, indicating the fraction of separation time in a cycle at steady-state conditions. Minimizing the index is assumed as the objective of the optimized system. An actuator is applied to the vehicle suspension in parallel with the mainspring and damper of the suspension. Particle Swarm Optimization (PSO) is used to properly tune a Proportional-Integral-Derivative (PID) controller for the active suspension system excited by a harmonic excitation. To verify the effectiveness of the control proposed, the controlled result compared with a passive suspension system illustrates the design, achieving a more comfortable ride with a significant decrease of the separation time.
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