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A type of automated manual transmission gearshift system that uses two linear actuators to perform gearshift events is presented. The shifting mechanism can be made simpler by using linear actuator to drive the shift fork directly. The mathematical model of the actuator is built and analyzed. Coordinated control of the engagement and disengagement processes is created based on a detailed analysis of the gearshift process in order to shorten the shift time. The force characteristics test reveals the nonlinear output characteristics. The precise displacement control need for coordinated control and stable control requirement for the shifting operation are satisfied by a linear extended state observer based controller. To verify the novel gearshift system and the control method, a test bench and control system are constructed. The results of the simulations indicate that the displacement control's accuracy is enhanced. As the speed difference reaches 500 r/min, the testing results demonstrate a noticeably reduced of shift force fluctuation and jerk generated during the gearshift process, from 20 m/s3 to 3.1 m/s3. With the improved gearshift system and control method, the gearshift coordinated control can also save 25 ms of shift time.

A detailed system dynamics model is essential for the design and calibration of the system controller. This paper introduces a control-oriented full dynamic model for the dog clutch engagement process that can be integrated with other system dynamic models found in ground vehicle transmission systems, such as the shifting mechanism system. This integrated model can be used later to design a position controller of the shifting mechanism's linkages to achieve a successful gearshift process. The engagement process is divided into four main stages, each of which has distinct dynamic behavior. The dynamics of each discrete stage are analyzed and modeled, and then, the discrete stages are integrated into one model using the hybrid automata modeling technique. Hybrid automata enables us to describe the continuous states within the discrete stages, which is better than continuous time techniques. The possible interactions between the sliding sleeve and the gear are analyzed and based on these interactions, the transition paths' conditions between these stages are established. The hybrid automata model comprises four discrete stages and ten guards that govern the transition between these stages. This model was simulated using Simulink State flow. Three cases are considered to verify the model, and the results showed that it could accurately capture the continuous system dynamics despite four discrete states. Furthermore, the transitions between the discrete states match the possible transition paths and guards. [ABSTRACT FROM AUTHOR]

Due to the more demanding quality requirements for the vehicle manipulating comfort imposed by the market in recent years, the driver's feeling during gear shifting has become very important in the design stage of the shifting systems. This paper combines the ergonomics theory with the vehicle shifting device, and expounds the application and practice of the ergonomics in the innovative design of the vehicle shifting device. Firstly, GSA analysis system is used to pre-evaluate the static and dynamic shifting performance of the whole vehicle, and analyzes the shifting device of the vehicle transmission according to ergonomics theory. And then the corresponding improvement measures are put forward for the existing defects in the shifting device. Finally, the post-test analysis is carried out to verify the effectiveness in improving the driving experience of the whole vehicle, and ultimately enhance the competitiveness of the studied shifting device in the vehicle industry.

Problem. The article is devoted to improvement of operational parameters of electromechanical automated drive of gear shift of heavy trucks and buses, improvement of the design of the actuator of the gearbox drive gear control, optimizing operation of the algorithm of controlling the automated electromechanical drive of gear shift. Goal. By analyzing information sources, requirements are set for the automated gearbox drive. On the basis of the analysis of existing designs of the gearshift drives in the mechanical transmission boxes, it was concluded that it is expedient to further improve the electromechanical drive of the gear shift with the actuators on the basis of DC motors, as the most current for use in transmission of heavy trucks and buses. Methodology. The main disadvantage of such structures at the moment is seen in the lack of universality of the analogues considered, concerning their use in gearboxes of different production. This, in turn, negatively affects the cost and reliability of the drive. Results. The dynamical processes taking place in the automated switching mechanism are considered, the mathematical model of the electric motor is investigated and the parameters are determined which influence the work process, the types of electric motors used in the technique, the equations used in mathematical modeling are described, the prospects of rational gearbox control are considered. According to the results of the analysis of the obtained results for further improvement, the design of the actuating mechanism of gear shift with two electric motors of direct current of own design is proposed. It is determined that the proposed new interconnections between the structural elements of the gearshift mechanism allow simultaneously obtaining the required speed of the drive, high accuracy of the adjustment, and provide the necessary effort on the synchronizer. A mathematical description of the working process of transmission switching on by automated electromechanical drive of gear shift is executed. Practical value. The mathematical model of the executive mechanism of the electromechanical drive gearbox transmission includes: differential equations that describe the operation of the electric motor of the direct current, as well as the equation of connection.

The paper shows results of an experimental and theoretical study of dynamic processes in the vehicle transmission after kinematic alignment of elements during gearshifts. The purpose of the research is increasing the quality of transient processes in the vehicle transmission. Applying an analysis of experimental results obtained through looking into dynamics of a 3-ton vehicle transmission and studying literature sources it was established that dynamic loading of the transmission after the kinematic stage of shifting (i. e. synchronizing speeds of driving and driven elements in the gearbox) is influenced by oscillations which are in the single-node mode. Solving the task of increasing transient processes is achieved by applying a method of control power redistribution. By employing simulation models a number of methods were used to regulate power redistribution. Results of computations made it possible to determine that the efficiency of power redistribution are closely related to initial conditions of the process under the study. In the progress of the research a method for identifying the initial conditions was developed. This method is based determining signatures of the torque and its derivatives. In accordance with the research results it turned out that it is appropriate to apply the ZVD (zero vibration derivation) algorithm of power redistribution for low gears (below 4th) from point of view achieving better overshoot and robustness characteristics and a satisfactory response rate level. For higher gears it is recommended that the Ramp algorithm (linear increase in the control input) be used for the cases when the response rate is not longer than period of the single-node mode of oscillations occurring in the dynamic system during a gear shift. Application of the proposed algorithms allows to bring down dynamic loading of the transmission and also to improve the comfort in vehicles.

Abstract This study proposes a modeling method for optimal real-time control of a continuously variable transmission (CVT)-based plug-in hybrid electric vehicle (PHEV), which is designed to solve a highly coupled nonlinear optimization problem namely the control of the transmission ratio (TR) and the power split ratio (PSR). Power transmission and power consumption models were first established by carefully introducing convex approximations and relaxations of the powertrain components. Then, the minimum equivalent fuel consumption problem was formulated and converted to a standard convex quadratic programming (QP) problem. Based on the QP modeling method, the equivalent consumption minimization strategy (ECMS) was proposed and verified by hardware-in-the-loop tests, computational efficiency simulations, and performance simulations. The results obtained indicated that the computational efficiency and effectiveness of the QP-based modeling method are high enough to be applied to real-world vehicle controllers, and the fuel economy can be improved significantly as compared to an ECMS without integrated optimization. It was concluded that the QP-based modeling method has high practical value and broad prospects for application to real-time optimal control. [ABSTRACT FROM AUTHOR]

Micro-slip control of multi-disc clutches is effective for attenuation of vibration and smooth gearshifts in dual clutch transmission. This paper proposes a method to apply micro-slips on the clutches for gearshift process, which differs from the conventional lockup control. The vehicle powertrain is modelled as a six degrees of freedom dynamic system, including a hydraulic actuator model. Micro-slips of dual clutches are realised by a closed-loop feedback controller according to the control-oriented model. The controller is used to evaluate demands of the clutch torques and transform them to input currents for the hydraulic solenoid valves. Numerical analysis and experiment are preformed, and the results show that the effect of clutch micro-slips is significant in improving the shift smoothness and the drive comfort of the dual clutch transmission during gearshifts. [ABSTRACT FROM AUTHOR]

The target torque of engaging clutches during gearshift is a key factor that affects the dynamic response of powertrains equipped with the dual clutch transmissions (DCT). This paper investigates a method to estimate the target torque of engaging clutches under conditions where engine torque and measurement signals contain white noise and some vehicle parameters (the radius of wheel and rolling friction coefficient) are uncertain. To compute the target torque accurately, the state of system should be estimated when the uncertain parameters exist. The vehicle powertrain is modeled as the 3DOF system when one clutch is closed and the 4DOF system when two clutches are open, while the measured signals include speeds of the engine, transmission, and vehicle (rotational speed of wheels). In addition to traditional extended Kalman filter (EKF), both the joint extended Kalman filter (JEKF) and dual extended Kalman filter (DEKF) are used to estimate the target torque. The simulation results show that DEKF and JEKF provide much higher accuracy in the estimation of target torque than EKF when some parameters of the model are uncertain, so as to produce a better ride performance of the transmission during gearshift, i.e. reduction of power interruption and compressed shifting time. Furthermore, the DEKF provides higher accuracy than the JEKF in estimating uncertain parameters. [ABSTRACT FROM AUTHOR]

The paper recommended sequence of possible safe combinations of virtual and real nodes for testing automatic transmissions at different stages. It describes a mathematical model for automatic hydromechanical transmission designed to work together with a single programmed controller. Examples of the simulation are shown. The main components of the complex are designed to operate with MatLab/Simulink. Loading modes of transmission and the most mobile machines combines the task of technological and transport resistances backgrounds. The operating cycle consists of moving off, acceleration, gear, performance of technological and transport operations. The virtual model is used for testing aims for programmed controllers to check them and to improve gear - shifting algorithm.

O sistema de transmissão de um trator agrícola tem por principal finalidade transmitir a potência gerada no motor ao sistema hidráulico, à tomada de potência e às rodas motrizes. A caixa de câmbio é formada por uma série de engrenagens que permitem a correta seleção da velocidade e do torque mais adequados a uma determinada operação. Assim, as transmissões podem ser classificadas, basicamente, em três categorias: mecânicas, hidrostáticas e hidrodinâmicas, sendo as transmissões mecânicas subdivididas em engrenagens deslizantes e sincronizadas. Este trabalho objetivou analisar os diferentes tipos de transmissões disponibilizados em 169 modelos de tratores fabricados no Brasil, com a finalidade de avaliar a real distribuição nas diferentes faixas de potência e estabelecer possíveis relações entre esses parâmetros. Como resultado, evidencia-se uma forte tendência de tratores agrícolas com potência menor que 111,8kW possuírem transmissão do tipo mecânica, e tratores acima de 111,8kW, do tipo hidrostática.The transmission system of an agricultural tractor has a main purpose to transmit the power generated in the hydraulic motor, the power take off and the drive wheels. The gearshift consists of a series of gears that allows the correct selection of speed and torque more appropriate to a particular operation. Then, the transmissions can be classified, basically, in three categories: mechanical, hydrostatic and hydrodynamic, being the mechanical transmissions subdivided in sliding gear and synchronized. Then, the objective of this research was to analyze the different types of transmissions available in 169 models of tractors made in Brazil in order to evaluate the real distribution of them in different power ranges and establish possible correlations. As a result, it was shown a strong tendency for agricultural tractors with power less than 111.8kW possessing mechanical transmission and tractors above 111.8kW possessing the hydrostatic type.

The existing electrically automated manual transmission employs DC motors to carry out gearshift events. It is relatively complicated and has potential to be improved both in structure and transmission efficiency. A novel gearshift system that utilizes a 2-DOF electromagnetic actuator to realize the automation of gearshift is proposed. The structure and working principle are introduced, and the coupling system model of the actuator is developed to investigate its characteristics. The results show that the utilization of the electromagnetic actuator in automated manual transmission gearshift system is appropriate. Multi-stage control strategy including PID algorithm and optimal control is introduced to improve the gearshift quality. A look-up table is developed to adjust the peak force of synchronization process according to the working condition. Finally, the conceptual gearshift system and the control strategy are verified on a test bench. The results show that the controller can adjust the peak force of the synchronization process timely and the designed control strategy achieves the compromise of indexes of gearshift quality. The novel gearshift system is technically feasible. [ABSTRACT FROM AUTHOR]

In this paper, a model-based nonlinear gearshift controller is designed by the backstepping method to improve the shift quality of vehicles with a dual-clutch transmission (DCT). Considering easy-implementation, the controller is rearranged into a concise structure which contains a feedforward control and a feedback control. Then, robustness of the closed-loop error system is discussed in the framework of the input to state stability (ISS) theory, where model uncertainties are considered as the additive disturbance inputs. Furthermore, due to the application of the backstepping method, the closed-loop error system is ordered as a linear system. Using the linear system theory, a guideline for selecting the controller parameters is deduced which could reduce the workload of parameters tuning. Finally, simulation results and Hardware in the Loop (HiL) simulation are presented to validate the effectiveness of the designed controller. [ABSTRACT FROM AUTHOR]

Abstract: This paper focuses on the shift control strategy and the related experiments for dry dual clutch transmissions (DCT). The gearshift processes, upshifts and downshifts, have been analyzed by model simulation. The control strategies for both the torque phase and the inertia phase of both clutches are proposed during the shift process respectively. The throttle controller for engine torque and clutch torque controllers have been designed for both torque phase and inertia phase. The system model has been established on Matlab/Simulink platform. The simulation results show that the proposed control strategies satisfy the shifting requirement in terms of shift response and smoothness. Furthermore, the experiment on the prototype vehicle equipped with DCT has been conducted to analyze the shifting process with the control strategy proposed in this paper. The test data is highly agreeable to the simulation data and the effectiveness of shift control strategies is validated by the comparison between simulation results and the test data. [Copyright &y& Elsevier]

In general, gearshift is related to change of acceleration due to the changing gear ratio. Modern double-clutch transmissions allow for shaping the acceleration transition by controlling the torques transmitted by the clutches. Thus, the question arises about an optimal transition law for the acceleration. The paper demonstrates that jerk and change of jerk may be considered as major sources of discomfort. Thus, a bi-criterion optimization problem is formulated for finding an optimal acceleration transition and an associated shift control. The problem is solved by analytical and polynomial approaches, and a theoretically optimal solution is shown. The latter is applied to a simple simulation model of a double-clutch transmission to demonstrate its applicability. [ABSTRACT FROM AUTHOR]

For the purpose of engineering development for a new 8-step speed automatic transmission, a simplified dynamic model for this gearbox was established and key parameters which affected the shift quality were analyzed. Aiming at four different shift types, the ideal characteristics of shift clutch and engine control were set up. By using torque estimation method, PI slip control algorithm and engine coordinated control principle, the control model and transmission controller were well developed for three shift phases which included rapid-fill phase, torque phase and inertia phase. The testing environment on the rig and prototype vehicle level was built and the testing results obtained in ultimate condition could verify the accuracy and feasibility of this shift control strategy. The peak jerk during shift process was controlled within ±2 g/s where the smooth gearshift was obtained. The development proposal and algorithm have a high value for engineering application. [ABSTRACT FROM AUTHOR]

This paper proposes a design method for the energy management strategy to explore the potential fuel saving of a hybrid electric vehicle (HEV) equipped with an automated manual transmission. The control algorithm is developed based on the combination of dynamic programming (DP) and Pontryagin's minimum principle (PMP) to optimally control the discrete gearshift command, in addition to the continuous power split between the internal combustion engine and the electric machine. The proposed method outperforms DP in terms of computational efficiency, being 171 times faster, without loss of accuracy. Simulation results for a middle-sized HEV on the New European Drive Cycle show that, to further optimize the gearshift strategy, an additional fuel saving of 20.3% can be reached. Furthermore, with the start–stop functionality available, it is shown that the two-point boundary-value problem following from PMP cannot be solved with sufficient accuracy without loss of optimality. This means that the finding of a constant value for the Lagrange multiplier while satisfying the battery state-of-energy (SOE) at the terminal time is not always guaranteed. Therefore, an alternative approach of SOE feedback control to adapt the Lagrange multiplier is adopted. The obtained results are very close to the globally optimal solution from DP. Simulation results, including the start–stop functionality, show that the relative fuel saving can be up to 26.8% compared with the case of a standard gearshift strategy. [ABSTRACT FROM PUBLISHER]

The transmission system of an agricultural tractor has a main purpose to transmit the power generated in the hydraulic motor, the power take off and the drive wheels. The gearshift consists of a series of gears that allows the correct selection of speed and torque more appropriate to a particular operation. Then, the transmissions can be classified, basically, in three categories: mechanical, hydrostatic and hydrodynamic, being the mechanical transmissions subdivided in sliding gear and synchronized. Then, the objective of this research was to analyze the different types of transmissions available in 169 models of tractors made in Brazil in order to evaluate the real distribution of them in different power ranges and establish possible correlations. As a result, it was shown a strong tendency for agricultural tractors with power less than 111.8kW possessing mechanical transmission and tractors above 111.8kW possessing the hydrostatic type. [ABSTRACT FROM AUTHOR]

Doubts have been raised on whether the car industry will manage to reach the goal set by the Voluntary Agreement with the European Commission, unless tougher measures are taken to reduce CO2 emissions. Taking a stance from the concept of downsizing, we study the historical development of two strategies: first, shifting the market toward smaller cars, market downsizing; second, a technical downsizing, i.e., technical improvements that have enabled a reduction of engine size. We focus on the Swedish new car market from 1975 to 2002. Analysis is done by combining sales statistics with databases over car model parameters. The development of the top and bottom 10% and 20% of the car market of various parameters points to an increased differentiation of the market; still, the market share of small models remains low. We identify the potential for downsizing created by increase of maximum specific torque and power and conclude that these have enabled the cylinder volume to stabilize around 2 l. Increase in engine size has also partly been dampened by the utilization of supercharging. The potential savings of fuel use presented by the introduction of a sixth gear in manual gearboxes have not materialized since gearshifts have not systematically been used to lower engine speed. We conclude that there are few signs of a downsizing in the Swedish new car fleet. From a market perspective, larger cars are still dominant and the technical potentials to reduce engine size have not been harnessed. [ABSTRACT FROM AUTHOR]

A gearshift control strategy for modern automated manual transmissions (AMTs) with dry clutches is proposed. The controller is designed through a hierarchical approach by discriminating among five different AMT operating phases: engaged, slipping-opening, synchronization, go-to-slipping, and slipping-closing. The control schemes consist of decoupled and cascaded feedback loops based on measurements of engine speed, clutch speed, and throwout bearing position, and on estimation of the transmitted torque. Models of driveline, dry clutch, and controlled actuator are estimated on experimental data of a medium size gasoline car and used to check through simulations the effectiveness of the proposed controller. [ABSTRACT FROM PUBLISHER]

• New framework for multiobjective gearshift optimization as Pareto solution set. • Mutual influence on optimization result investigated and revealed, in depth. • Multiobjective gearshift optimization problem transformed into nonlinear programming problem by Legendre pseudospectral method. • Solution set gives optimal gearshift trajectories for various performance orientations. • Application of Pareto solution set in transmission control unit. Most researches on transmission gearshift optimization have converted multiobjective problems into single-objective problems using the linear weighted method. A new framework for the multiobjective optimization of the gearshift, in the form of a Pareto solution set, is proposed in this study. Shift duration, friction work, and continuous jerk are selected as the gearshift optimization objectives for a seamless two-speed transmission, utilized in electric vehicles. For this multiobjective optimization, numerous iterations were performed using the Legendre pseudospectral method, which includes advantages such as faster convergence and larger radius of convergence. The numerical results presented as a Pareto solution set provide the optimal gearshift trajectories for different performance orientations. By comparing the selected samples, the inherent relationships among the gearshift objectives were investigated in detail and revealed. This framework for solving multiobjective problems can also be applied to other optimization problems with different complex constraints and objective functions. [ABSTRACT FROM AUTHOR]

Background: Various techniques have been described for pedicle screw placement with established clinical and radiological success. Suboptimal screw trajectories can compromise bony purchase and, worse yet, cause neurological and vascular injuries. Thus, it is of paramount importance to achieve maximum accuracy of screw placement. Our objective is to evaluate the accuracy of pedicle screw placement in the thoracolumbar spine by resident surgeons. Two popular techniques, gearshift versus drill, were compared., Methods: This is a a cadaveric surgical technique comparison study. Six resident surgeons instrumented the spine from T1 to S1 using both gearshift and drill techniques. Each pedicle was randomly assigned to either of the techniques. Pedicle screws were placed freehand without radiographic guidance. Violations (medial, lateral, anterior, superior and inferior) were recorded by studying the computerized tomographic scans of instrumented cadavers by blinded observers. Critical perforations were defined as greater than 2mm breach of the pedicle wall., Results: A total of 100 vertebrae (200 pedicles) were instrumented in the six cadavers. 103 pedicles were breached (51.5% of total pedicles). Lateral violations were the most encountered (65% of violations, 67 total, 48 critical, 19 noncritical) followed by medial (24%, 25 total, 13 critical, 12 noncritical), and the rest were anterior (3%), superior (4%) and inferior (4%). There was no overall difference in violations comparing the gearshift technique (49.5%, 51 total, 37 critical, 14 noncritical) with drill technique (50.5%, 52 total, 33 critical, 19 noncritical). Analyzing the breaches at individual vertebra indicated most violations at T6 (11), T5 (10), followed by T3 (9) and T4 (9), decreasing towards the lumbosacral vertebrae., Conclusion: The results of this study suggest that the gearshift and drill techniques for placement of pedicle screws in the thoracolumbar spine fare similarly with regards to risk of breach when applied by resident surgeons.