Publications
99 results found
Arif J, Rehman-Shaikh MA, Evangelou S, 2023, Design verification process for subsea oil and gas products, SPE Drilling and Completion, ISSN: 1064-6671
A crucial step in new product development is the Design Verification Process (DVP) which assures thatthe conceptual design of new technology is successfully transformed into a prototype-product. This articleintroduces a novel DVP for subsea electrical and electronic prototype-products. The comprehensive DVPensures that the prototype of the product is designed righteously, is well-documented and is verified accordingto international practices and standards such as The American Petroleum Institute (API), InternationalOrganization for Standardization (ISO), European Norm (EN) and European Union (EU) specifications.Compliance testing (environmental stresses and electromagnetic compatibility) on the product is proposedto achieve the technology readiness level 2 (TRL2) of the first article of a Printed Circuit Board (PCB).Concerning the quality of an electronic circuit board, it is recommended in this paper to follow the guidelinesand specifications of the Institute of printed circuits to certify the robustness of the design. Finally, theproposed DVP is thoroughly exercised on the insulation monitoring PCB under the prescribed test methodsas a case study. The experimental results show that the design is robust, and the product is suitable for usein the intended subsea environment after further raising the technology maturity level of the product.
Chen B, Pan X, Evangelou SA, 2023, Optimal energy management of series hybrid electric vehicles with engine start-stop system, IEEE Transactions on Control Systems Technology, Vol: 31, Pages: 660-675, ISSN: 1063-6536
This paper develops energy management (EM) control for series hybrid electric vehicles (HEVs) that include an engine start-stop system (SSS). The objective of the control is to optimally split the energy between the sources of the powertrain and achieve fuel consumption minimization. In contrast to existing works, a fuel penalty is used to characterize more realistically SSS engine restarts, to enable more realistic design and testing of control algorithms. The paper first derives two important analytic results: a) analytic EM optimal solutions of fundamental and commonly used series HEV frameworks, and b) proof of optimality of charge sustaining operation in series HEVs. It then proposes a novel heuristic control strategy, the hysteresis power threshold strategy (HPTS), by amalgamating simple and effective control rules extracted from the suite of derived analytic EM optimal solutions. The decision parameters of the control strategy are small in number and freely tunable. The overall control performance can be fully optimized for different HEV parameters and driving cycles by a systematic tuning process, while also targeting charge sustaining operation. The performance of HPTS is evaluated and benchmarked against existing methodologies, including dynamic programming (DP) and a recently proposed state-of-the-art heuristic strategy. The results show the effectiveness and robustness of the HPTS and also indicate its potential to be used as the benchmark strategy for high fidelity HEV models, where DP is no longer applicable due to computational complexity.
Yu M, Evangelou S, Dini D, 2023, Advances in active suspension systems for road vehicles, Engineering, ISSN: 2095-8099
Active suspension systems (ASSs) have been proposed and developed for a few decades, and nowadays again become a thriving topic in both academia and industry, due to the high demand in driving comfort and safety, and the compatibility with vehicle electrification and autonomy. Existing review papers on ASSs are mainly about dynamics modelling and robust control, however, the gap between academic research outcomes and industrial application requirements is not yet bridged, hindering most ASS research knowledge from transferring to vehicle companies. This paper comprehensively reviews advances in ASSs for road vehicles, focusing on hardware structures and control strategies. Particularly, state-of-the-art ASSs that have been recently adopted in production cars are detailed, including representative solutions of Mercedes Active Body Control and Audi Predictive Active Suspension; novel concepts that could become alternative candidates are also introduced, including the Series Active Variable Geometry Suspension, and the Active Wheel Alignment System. The ASSs with compact structure, small mass increment, low power consumption, high frequency response, acceptable economic costs and high reliability are more likely to be adopted by car manufacturers. In terms of control strategies, future ASSs not only aim to stabilize the chassis attitude and attenuate the chassis vibration, moreover, but also cooperate with other bodies (e.g., steering and braking) and sensors (e.g., camera) within a car, and even with high-level decision (e.g., reference driving speed) in the overall transportation system – these strategies will be compatible with the rapidly developed electric and autonomous vehicles.
Pan X, Chen B, Timotheou S, et al., 2023, A convex optimal control framework for autonomous vehicle intersection crossing, IEEE Transactions on Intelligent Transportation Systems, Vol: 24, Pages: 163-177, ISSN: 1524-9050
Cooperative vehicle management emerges as a promising solution to improve road traffic safety and efficiency. This paper addresses the speed planning problem for connected and autonomous vehicles (CAVs) at an unsignalized intersection with consideration of turning maneuvers. The problem is approached by a hierarchical centralized coordination scheme that successively optimizes the crossing order and velocity trajectories of a group of vehicles so as to minimize their total energy consumption and travel time required to pass the intersection. For an accurate estimate of the energy consumption of each CAV, the vehicle modeling framework in this paper captures 1) friction losses that affect longitudinal vehicle dynamics, and 2) the powertrain of each CAV in line with a battery-electric architecture. It is shown that the underlying optimization problem subject to safety constraints for powertrain operation, cornering and collision avoidance, after convexification and relaxation in some aspects can be formulated as two second-order cone programs, which ensures a rapid solution search and a unique global optimum. Simulation case studies are provided showing the tightness of the convex relaxation bounds, the overall effectiveness of the proposed approach, and its advantages over a benchmark solution invoking the widely used first-in-first-out policy. The investigation of Pareto optimal solutions for the two objectives (travel time and energy consumption) highlights the importance of optimizing their trade-off, as small compromises in travel time could produce significant energy savings.
Feng Z, Yu M, Evangelou SA, et al., 2023, Mu-synthesis PID control of full-car with parallel active link suspension under variable payload, IEEE Transactions on Vehicular Technology, Vol: 72, Pages: 176-189, ISSN: 0018-9545
This paper presents a combined μ -synthesis PID control scheme, employing a frequency separation paradigm, for a recently proposed novel active suspension, the Parallel Active Link Suspension (PALS). The developed μ -synthesis control scheme is superior to the conventional H∞ control, previously designed for the PALS, in terms of ride comfort and road holding (higher frequency dynamics), with important realistic uncertainties, such as in vehicle payload, taken into account. The developed PID control method is applied to guarantee good chassis attitude control capabilities and minimization of pitch and roll motions (low frequency dynamics). A multi-objective control method, which merges the aforementioned PID and μ -synthesis-based controls is further introduced to achieve simultaneously the low frequency mitigation of attitude motions and the high frequency vibration suppression of the vehicle. A seven-degree-of-freedom Sport Utility Vehicle (SUV) full car model with PALS, is employed in this work to test the synthesized controller by nonlinear simulations with different ISO-defined road events and variable vehicle payload. The results demonstrate the control scheme's significant robustness and performance, as compared to the conventional passive suspension as well as the actively controlled PALS by conventional H∞ control, achieved for a wide range of vehicle payload considered in the investigation.
Yu M, Evangelou S, Dini D, 2022, Parallel active link suspension: full car application with frequency-dependent multi-objective control strategies, IEEE Transactions on Control Systems Technology, Vol: 30, Pages: 2046-2061, ISSN: 1063-6536
In this article, a recently proposed at basic level novel suspension for road vehicles, the parallel active link suspension (PALS), is investigated in the realistic scenario of a sport utility vehicle (SUV) full car. The involved rocker-pushrod assembly is generally optimized to maximize the PALS capability in improving the suspension performance. To fully release the PALS functions of dealing with both low- and high-frequency road cases, a PID control scheme is first employed for the chassis attitude stabilization, focusing on the minimization of both the roll and pitch angles; based on a derived linear equivalent model of the PALS-retrofitted full car, an H∞ control scheme is designed to enhance the ride comfort and road holding; moreover, a frequency-dependent multiobjective control strategy that combines the developed PID and H∞ control is proposed to enable: 1) chassis attitude stabilization at 0-1 Hz; 2) vehicle vibration attenuation at 1-8 Hz; and 3) control effort penalization (for energy saving) above 10 Hz. With a group of ISO-defined road events tested, numerical simulation results demonstrate that, compared to the conventional passive suspension, the PALS has a promising potential in full-car application, with up to 70% reduction of the chassis vertical acceleration in speed bumps and chassis leveling capability of dealing with up to 4.3-m/s² lateral acceleration.
Georgiou A, Furqan T, Jaimoukha I, et al., 2022, Computationally efficient robust model predictive control for uncertain system using causal state-feedback parameterization, IEEE Transactions on Automatic Control, ISSN: 0018-9286
This paper investigates the problem of robustmodel predictive control (RMPC) of linear-time-invariant (LTI)discrete-time systems subject to structured uncertainty andbounded disturbances. Typically, the constrained RMPCproblem with state-feedback parameterizations is nonlinear(and nonconvex) with a prohibitively high computationalburden for online implementation. To remedy this, a novelapproach is proposed to linearize the state-feedback RMPCproblem, with minimal conservatism, through the use ofsemidefinite relaxation techniques. The proposed algorithmcomputes the state-feedback gain and perturbation onlineby solving a linear matrix inequality (LMI) optimization that,in comparison to other schemes in the literature is shownto have a substantially reduced computational burdenwithout adversely affecting the tracking performance of thecontroller. Additionally, an offline strategy that providesinitial feasibility on the RMPC problem is presented. Theeffectiveness of the proposed scheme is demonstratedthrough numerical examples from the literature.
Feng Z, Yu M, Evangelou S, et al., 2022, Feedforward PID control of full-car with parallel active link suspension for improved chassis attitude stabilization, IEEE Conference on Control Technology and Applications (CCTA 2022), Publisher: IEEE
PID control is commonly utilized in an active suspension system to achieve desirable chassis attitude, where, due to delays, feedback information has much difficulty regulating the roll and pitch behavior, and stabilizing the chassis attitude, which may result in roll over when the vehicle steersat a large longitudinal velocity. To address the problem of the feedback delays in chassis attitude stabilization, in this paper, a feedforward control strategy is proposed to combine with a previously developed PID control scheme in the recently introduced Parallel Active Link Suspension (PALS). Numerical simulations with a nonlinear multi-body vehicle model areperformed, where a set of ISO driving maneuvers are tested. Results demonstrate the feedforward-based control scheme has improved suspension performance as compared to the conventional PID control, with faster speed of response in brakein a turn and step steer maneuvers, and surviving the fishhook maneuver (although displaying two-wheel lift-off) with 50 mph maneuver entrance speed at which conventional PID control rolls over.
Yu S, Pan X, Georgiou A, et al., 2022, Robust Model Predictive Control Framework for Energy-Optimal Adaptive Cruise Control of Battery Electric Vehicles, European Control Conference (ECC), Publisher: IEEE, Pages: 1728-1733
Arif J, Rehman-Shaikh MA, Evangelou SA, 2022, Novel evaluation and testing of technology qualification process of subsea oil and gas products, Journal of Petroleum Science and Engineering, Vol: 208, Pages: 1-11, ISSN: 0920-4105
Use of robust products is of utmost importance in the subsea production systems to ensure the maximum utilization of the energy resources available under the seabed. To achieve highly reliable products, a comprehensive technology qualification program is proposed in this paper for the subsea electrical and electronics-based products. The recommended qualification program is specifically focused on a novel technology readiness level 4 (TRL4) process of the product used in an intended environment condition, which guarantees the product availability on the seabed without any operational failures. The analytical assessment on the products’ design, operating conditions and compliance stress tests are proposed following the internationally recognized standards, e.g. The American Petroleum Institute (API) , International Electrotechnical Commission (IEC), Institute of Electrical and Electronics Engineers (IEEE), International Organization for Standardization (ISO), European Standards (EN) and European Union (EU-directives). Modified environmental tests methods and novel product safety procedures are introduced for the first time to ensure that products meet the acceptance criteria set in the proposed TRL4 process. Finally, the proposed TRL4 process and its recommended test methods are exercised on the various functional units of the subsea electronic module. The experimental results show that the product is fit for use in the subsea environment after going through the proposed extensive qualification test program.
Yu M, Cheng C, Evangelou S, et al., 2021, Series active variable geometry suspension: full-car prototyping and road testing, IEEE-ASME Transactions on Mechatronics, Vol: 27, ISSN: 1083-4435
In this paper, afull-car prototype of the recently proposed mechatronic suspension, Series Active Variable Geometry Suspension (SAVGS), is developed for on-road driving experimental proof of concept, aiming to be adopted by suspension OEMs (original equipment manufacturers) as an alternative solution to fully active suspensions. Particularly, mechanical modifications are performed to both corners of the front double-wishbone suspensionof a production car, with active single-links attached to the upper-ends of the spring-damper units, while both corners of the rear suspension remain inthe original (passive) configurations.The mechanical modifications involve innovatively designed parts to enable the desired suspension performance improvements, while maintaining ride harshness at conventional levels.Areal-time embedded system is further developed to primarily implement:1) power supply, data acquisition and measurementsof the vehicle dynamics related variables, and 2) robust control application for the ride comfort and road holding enhancement, which is based on a derived linearized model of the full-car dynamics and a newly synthesizedH-infinity control scheme. Results obtained from on-road driving experiments are inessential agreement with numerical simulation results also produced. Overall, the full-car prototypeof SAVGS demonstrates promising suspension performance,with anaverage 3 dB attenuation (or equivalently 30% reduction) of the chassis vertical acceleration at aroundthe human-sensitive frequencies (2-5Hz),as compared to the original vehicle with the passive suspension system. More importantly, the prototype also indicatesthe practicality of the solution, as the SAVGS retrofit to a real car is achieved by simple mechanical modifications, compact actuator packaging, smallmass increment(21.5kg increase with respect to the original vehicle), limited power usage
Arif J, Rehman-Shaikh MA, Evangelou S, 2021, Comprehensive technology qualification process for subsea electronics assemblies, IEEE Transactions on Industrial Electronics, Vol: 68, Pages: 6358-6368, ISSN: 0278-0046
Subsea production systems technologies are being developed steadily to address the technological issues associated with the deep-sea environment, primarily pressure and temperature. To ensure the reliable operation of electrical/electronic systems for at least 25-years on theseabed, a comprehensive technology qualification program is proposed in this paper. In relation to this, Technology Readiness Level of the Subsea electrical/electronics assembly is achieved after conducting devised environmental stress tests compliant to the internationally recognizedstandards, e.g. API, ISO, IEC and IEEE. The comprehensive tests methods of the qualification program are explained to achieve the technology readiness level 3 of the Subsea printed circuit board and sub-assemblies. Finally, experimental test results of a standalone Subsea Ethernet Switchand also functional verification with 100 meters of electrical flying lead undergoing the prescribed test methods show that the Subsea electronics comply with the international standards and is fit for use in the Subsea environment.
Georgiou A, Evangelou S, Jaimoukha I, et al., 2021, Tracking control for directional drilling systems using robust feedback model predictive control, 1st Virtual IFAC World Congress, Publisher: Elsevier, Pages: 11974-11981, ISSN: 2405-8963
A rotary steerable system (RSS) is a drilling technology which has been extensively studied and used for over the last 20 years in hydrocarbon exploration and it is expected to drill complex curved borehole trajectories. RSSs are commonly treated as dynamic robotic actuator systems, driven by a reference signal and typically controlled by using a feedback loop control law. However, due to spatial delays, parametric uncertainties and the presence of disturbances in such an unpredictable working environment, designing such control laws is not a straightforward process. Furthermore, due to their inherent delayed feedback, described by delay differential equations (DDE), directional drilling systems have the potential to become unstable given the requisite conditions. This paper proposes a Robust Model Predictive Control (RMPC) scheme for industrial directional drilling, which incorporates a simplified model described by ordinary differential equations (ODE), taking into account disturbances and system uncertainties which arise from design approximations within the formulation of RMPC. The stability and computational efficiency of the scheme are improved by a state feedback strategy computed offline using Robust Positive Invariant (RPI) sets control approach and model reduction techniques. A crucial advantage of the proposed control scheme is that it computes an optimal control input considering physical and designer constraints. The control strategy is applied in an industrial directional drilling configuration represented by a DDE model and its performance is illustrated by simulations.
Pan X, Chen B, Evangelou SA, et al., 2021, Optimal motion control for connected and automated electric vehicles at signal-free intersections, 59th IEEE Conference on Decision and Control (CDC), Publisher: IEEE, Pages: 2831-2836, ISSN: 0743-1546
Traffic congestion is one of the major issues for urban traffic networks. The connected and autonomous vehicles (CAV) is an emerging technology that has the potential to address this issue by improving safety, efficiency, and capacity of the transportation system. In this paper, the problem of optimal trajectory planning of battery-electric CAVs in the context of cooperative crossing of an unsignalized intersection is addressed. An optimization-based centralized intersection controller is proposed to find the optimal velocity trajectory of each vehicle so as to minimize electric energy consumption and traffic throughput. Solving the underlying optimization problem for a group of CAVs is not straightforward because of the nonlinear and nonconvex dynamics, especially when the powertrain model is explicitly modelled. In order to ensure a rapid solution search and a unique global optimum, the optimal control problem (OCP) is reformulated via convex modeling techniques. Several simulation case studies show the effectiveness of the proposed approach and the trade-off between energy consumption and traffic throughput is illustrated.
Georgiou A, Tahir F, Evangelou S, et al., 2021, Robust moving horizon state estimation for uncertain linear systems using linear matrix inequalities, 59th IEEE Conference on Decision and Control - CDC 2020, Publisher: IEEE, Pages: 2900-2905
This paper investigates the problem of state estimation for linear-time-invariant (LTI) discrete-time systems subject to structured feedback uncertainty and bounded disturbances. The proposed Robust Moving Horizon Estimation (RMHE) scheme computes at each sample time tight bounds on the uncertain states by solving a linear matrix inequality (LMI) optimization problem based on the available noisy input and output data. In comparison with conventional approaches that use offline calculation for the estimation, the suggested scheme achieves an acceptable level of performance with reduced conservativeness, while the online computational time is maintained relatively low. The effectiveness of the proposed estimation method is assessed via a numerical example.
Pan X, Chen B, Dai L, et al., 2021, Decentralized Model Predictive Control for Automated and Connected Electric Vehicles at Signal-free Intersections, 60th IEEE Conference on Decision and Control (CDC), Publisher: IEEE, Pages: 2659-2664, ISSN: 0743-1546
Hu R, Pan X, Chen B, et al., 2021, Optimal Energy Management for Fuel and Emissions Minimization of Series Hybrid Electric Vehicles with Consideration of Engine Preheating, European Control Conference (ECC), Publisher: IEEE, Pages: 1347-1352
Evangelou S, Rehman-Shaikh MA, 2020, Comprehensive energy efficiency analysis of series hybrid electric vehicles with dual-phase-shift-controlled DC-DC converter, Journal of the Franklin Institute, Vol: 357, Pages: 8761-8799, ISSN: 0016-0032
By considering converter fundamental operating principles, the paper first derives a complete set of analytic expressions of theoverall power losses of a conventional Dual Active Bridge (DAB) bi-directional DC-DC converter under Dual Phase Shift (DPS)control. Expressions for conduction and switching losses in the electronic devices acting as the converter switches, and copperand core losses in the isolation transformer, are derived and accounted for in the DC-DC converter model. DPS control involvesmany more converter operating conditions, in comparison tothe more common single-phase-shift (SPS) control, which makes theanalytic power loss characterization of a DPS-controlled converter an arduous task. Subsequently and by employing thederivedanalytic converter power loss model with exemplary parameter values, the paper analyzes the efficiency of a high-fidelity fullhybrid electric vehicle (HEV) model that includes a DAB DC-DC converter, under a wide range of realistic driving conditions andconverter operation, including low- to high-speed driving, and converter DPS operation. Two popular hybrid powertrain energymanagement schemes, the Thermostat and Power Follower control strategies, are used to simulate the vehicle model to reinforcethe range of realistic vehicle operating conditions. The results show that in series HEV applications more accurate modeling ofDC-DC converter models than conventional constant efficiency models is required to predict converter losses, and also the fidelityin the characterization of converter losses can have a significant impact on the vehicle fuel consumption prediction.
Chen B, Li X, Evangelou S, et al., 2020, Joint propulsion and cooling energy management of hybrid electric vehicles by optimal control, IEEE Transactions on Vehicular Technology, Vol: 69, Pages: 4894-4906, ISSN: 0018-9545
This paper develops an optimal control methodology for the energy management (EM) of a series hybrid electric vehicle (HEV) with consideration of ancillary cooling losses, to minimize fuel consumption. Both engine and battery thermal management (TM) models are integrated into the HEV powertrain model as they interact with each other during operation. By collecting all components for propulsion and cooling, a control-oriented model is established, which enables the joint EM and TM optimization problem to be solved simultaneously. Experimental driving cycles are utilized to reveal the impact of the cooling losses on the fuel economy under different driving circumstances. The case study shows the effectiveness of the proposed strategy in finding the optimal power sharing of the hybrid powertrain with consideration of both propulsion and overall cooling requirements. Moreover, a benchmark method based on separately optimized EM and conventional thermostat and PI controlled cooling systems is introduced to verify the solution quality of the proposed approach. It is demonstrated that the proposed method outperforms the benchmark by 0.7%-2.49% in terms of fuel economy, depending on the driving scenarios.
Yu M, Cheng C, Evangelou S, et al., 2020, Robust control for a full-car prototype of series active variable geometry suspension, 2019 IEEE 58th Conference on Decision and Control, Publisher: IEEE
The Series Active Variable Geometry Suspension (SAVGS) which has been recently proposed shows promising potential in terms of suspension performance enhancement, limited power consumption and so on. In this paper, the control aspects of a full-car prototype with the front axle retrofitted by the SAVGS, which is developed to validate the practical feasibility of the novel mechatronic suspension, are addressed. Two 12 Vdc batteries and one DC/AC inverter constitute an independent power source that supplies the overall embedded mechatronic system, with two AC rotary servo motors driving the single links (in the SAVGS) at two front corners, respectively.A robust control scheme, with an outer-loop H-infinity control and an inner-loop actuator velocity tracking control, is synthesized to enhance the vehicle ride comfort and road holding performance. Numerical simulations of the full-car prototype, withthetypical road events of a 2 Hz harmonic road, and a speed humptested, are performed. Nonlinear simulation results provide the potential suspension performance improvement contributed by the SAVGS and the power usage in the batteries, which will be compared in the future with the upcoming experimental testing results of the prototype on-road driving.
Feng Z, Yu M, Cheng C, et al., 2020, Uncertainties Investigation and mu-Synthesis Control Design for a Full Car with Series Active Variable Geometry Suspension, International Federation of Automatic Control
Pan X, Chen B, Evangelou SA, 2020, Optimal Vehicle Following Strategy for Joint Velocity and Energy Management Control of Series Hybrid Electric Vehicles, 21st IFAC World Congress on Automatic Control - Meeting Societal Challenges, Publisher: ELSEVIER, Pages: 14161-14166, ISSN: 2405-8963
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Li X, Chen B, Evangelou SA, 2020, Optimized Design of Multi-Speed Transmissions for Parallel Hybrid Electric Vehicles, 21st IFAC World Congress on Automatic Control - Meeting Societal Challenges, Publisher: ELSEVIER, Pages: 14147-14153, ISSN: 2405-8963
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Chen B, Pan X, Evangelou SA, et al., 2020, Optimal Control for Connected and Autonomous Vehicles at Signal-Free Intersections, 21st IFAC World Congress on Automatic Control - Meeting Societal Challenges, Publisher: ELSEVIER, Pages: 15306-15311, ISSN: 2405-8963
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Frezza G, Evangelou SA, 2020, Ecological Adaptive Cruise Controller for a Parallel Hybrid Electric Vehicle, 18th European Control Conference (ECC), Publisher: IEEE, Pages: 491-498
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Chen B, Evangelou SA, Lot R, 2019, Series hybrid electric vehicle simultaneous energy management and driving speed optimization, IEEE/ASME Transactions on Mechatronics, Vol: 24, Pages: 2756-2767, ISSN: 1083-4435
The energy management (EM) and driving speed co-optimization of a series hybrid electric vehicle (S-HEV) for minimizing fuel consumption is addressed in this article on the basis of a suitably modeled series powertrain architecture. The paper proposes a novel strategy that finds the optimal driving speed simultaneously with the energy source power split for the drive mission specified in terms of the road geometry and travel time. Such a combined optimization task is formulated as an optimal control problem that is solved by an indirect optimal control method, based on Pontryagin's minimum principle. The optimization scheme is tested under a rural drive mission by extensive comparisons with conventional methods that deal with either speed optimization only or EM strategies with given driving cycles. The comparative results show the superior performance of the proposed method and provide further insight into efficient driving.
Chen B, Evangelou S, Lot R, 2019, Hybrid electric vehicle two-step fuel efficiency optimization with decoupled energy management and speed control, IEEE Transactions on Vehicular Technology, Vol: 68, Pages: 11492-11504, ISSN: 0018-9545
Hybrid electric vehicles (HEVs) offer an effective solution for emissions reduction and fuel energy savings. The pursuit of further improvements in their energy efficiency has led to the two fundamental optimization challenges of vehicle speed and powertrain energy management (EM), which are inherently coupled. This paper examines the vehicle speed and powertrain EM co-optimization problem for fuel economy for a series HEV following a prescribed route with expected traveling time. In order to overcome the computational burden of a large scale optimal control problem (OCP), this work presents a novel two-step optimal control strategy that suitably separates the co-optimization problem on the basis of involving the characteristics of the HEV powertrain power split and losses in the speed optimization step without an explicit use of a powertrain model. A benchmark method that simultaneously solves the optimal driving speed and the energy source power split is introduced, which is used to show the solution quality of the proposed approach. It is illustrated that the proposed method yields a driving speed solution close to the benchmark method, and additionally it outperforms the benchmark fuel economy, with much higher computational efficiency. The simplicity and effectiveness of the proposed two-step approach make it a practical and implementable EM control strategy.
Moreno-Ramirez C, Tomas-Rodriguez M, Evangelou S, 2019, Effects of interconnected suspension systems on the in-plane dynamics of sport motorcycles, Symposium on the Dynamics and Control of Single Track Vehicles
The effects of interconnected front and rear suspension systems on the in-plane dynamics of sportmotorcycle is investigated. The interconnected suspension mathematical description is presentedand included in a high-fidelity motorcycle model. The suspension behaviour under road step bumpinputs is studied for different values of stiffness and damping interconnection coefficients. Optimalvalues of interconnection coefficients are proposed for the current motorcycle model. Finally, theoscillating dynamics of the motorcycle at straight running conditions is studied through its normalmodes.
Yu M, Evangelou S, Dini D, 2019, Position control of parallel active link suspension with backlash, IEEE Transactions on Industrial Electronics, Vol: 67, Pages: 4741-4751, ISSN: 0278-0046
In this paper, a position control scheme for the novel Parallel Active Link Suspension (PALS) with backlash is developed to enhance the vehicle ride comfort and road holding. A PALS-retrofitted quarter car test rig is adopted, with the torque flow and backlash effect on the suspension performance analyzed. An elastic linear equivalent model of the PALS-retrofitted quarter car, which bridges the actuator position and the equivalent force between the sprung and unsprung masses, is proposed and mathematically derived, with both the geometry and backlash nonlinearities compensated. A position control scheme is then synthesized, with an outer-loop H∞ control for ride comfort and road holding enhancement and an inner-loop cascaded proportional-integral control for the reference position tracking. Experiments with the PALS-retrofitted quarter car test rig are performed over road cases of a harmonic road, a smoothed bump and frequency swept road excitation. As compared to a conventional torque control scheme, the newly proposed position control maintains the performance enhancement by the PALS, while it notably attenuates the overshoot in the actuator’s speed variation, and thereby it benefits the PALS with less power demand and less suspension deflection increment.
Li X, Evangelou S, 2019, Torque-leveling threshold-changing rule-based control for parallel hybrid electric vehicles, IEEE Transactions on Vehicular Technology, Vol: 68, Pages: 6509-6523, ISSN: 0018-9545
A novel rule-based control strategy is proposed for the energy management of parallel hybrid electric vehicles (HEVs): the torque-leveling threshold-changing strategy (TTS). In contrast to the most commonly used heuristic electric assist control strategy (EACS) that is designed based on the load following approach, the TTS proposes and applies the new fundamental concept of torque leveling. This mechanism operates the engine with a constant torque when the engine is active, thus ensuring the engine works at an efficient operating point. The TTS additionally extends and uses a design concept that has previously been proposed in the context of series HEVs, thethreshold-changing mechanism, to operate the HEV in a chargesustaining manner. By exploiting this new set of design principles for parallel HEVs, the TTS realizes energy source control sharing behavior that is reminiscent to optimization-based methods. To show its effectiveness, the TTS is implemented to a through-theroad (TTR) HEV and benchmarked against two conventional control strategies: Dynamic Programming (DP) and the EACS. The results show that the TTS, despite its simplicity, is able to deliver comparable fuel economy as the global optimization approach DP and thus achieve significant improvement compared to the EACS. In addition, to facilitate real-time application, a simplified version of the TTS (STTS) is also developed, which is able to deliver similar performance as the TTS but is more simple to implement in practice.
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