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The performance of maize picking mechanisms directly affects harvesting quality and working efficiency. Numerous field experiments have been carried out to improving picking performance, but they have been restricted by factors such as high cost, the varieties of maize used and variable harvesting periods. Virtual simulation analysis was proposed as a replacement for field experiments to provide an accurate reference for optimising the picking mechanism. A finite element model of a maize plant and picking mechanism was established based on the experimental results and related data from the research literature. Its accuracy and reasonableness was verified by comparing the simulation results to the data obtained by an experiment using a high-speed camera. The coupling effect of the three main factors (rotational speed of the picking roller, edge angle of the picking board and feed-in speed) were investigated using simulations. The results revealed that the medium rotational speed for the picking roller reduced the damage incurred by maize during the picking process, while ensuring good harvesting efficiency and picking board edge angles in the range 13°–15° were optimal. Although reducing the feed-in speed could reduce damage to the maize, this was not the most prominent factor. Besides, the appropriate rotational speed of the picking roller to guarantee optimal working efficiency was investigated using power consumption experiments. The results of this study should be useful as a reference for the design, development, and optimisation of the maize picking mechanism.

Object recognition based on LIDAR data is crucial in automotive driving and is the subject of extensive research. However, the lack of accuracy and stability in complex environments obstructs the practical application of real-time recognition algorithms. In this study, we proposed a new real-time network for multicategory object recognition. The manually extracted bird’s eye view (BEV) features were adopted to replace the resource-consuming 3D convolutional operation. Besides the subject network, we designed two auxiliary networks to help the network learn the pointwise features and boxwise features, aiming to improve the category and bounding boxes’ accuracy. The KITTI dataset was adopted to train and validate the proposed network. Experimental results showed that, for hard mode, the total average precision (AP) of the category reached 97.4%. For an intersection over a union threshold of 0.5 and 0.7, the total AP of regression reached 93.2% and 85.5%; especially, the AP of car’s regression reached 95.7% and 92.2%. The proposed network also showed consistent performance in the Apollo dataset with a processing duration of 37 ms. The proposed network exhibits stable and robust object recognition performance in complex environments (multiobject, unordered objects, and multicategory). And it shows sensitivity to occlusion of the LIDAR system and insensitivity to close large objects. The proposed multifunction method simultaneously achieves real-time operation, high accuracy, and stable performance, indicating its great potential value in practical application.

To improve the accuracy and actual road equivalence of vehicle performance testing using test benches, a double-drum test bench that meets the test requirements of vehicle control system prototypes and in-use vehicles was designed. Dynamic models of the single-wheel test bench and the vehicle test bench were established, and mechanisms were theoretically analyzed for single-wheel variable adhesion and vehicle load transfer for equivalent testing using the variable placement angle. The mechanism of electromechanical inertia compensation was studied to realize stepless simulation of vehicle inertia and simulate dynamic load while braking. The simulation model of the vehicle test bench system was established based on MATLAB/Simulink. Simulations were carried out to verify the anti-lock braking system (ABS) performance test functionality of the test bench under high adhesion, bisectional, and low adhesion conditions. Referring to the simulation conditions, ABS tests under actual test bench and road conditions were carried out. Results demonstrated that the mechanism of variable load transfer simulation by electromechanical inertia compensation improves the equivalent accuracy compared to that of its road test equivalent, verifying the feasibility of the simulation mechanism. This study could help further improve the accuracy and reduce the cost of vehicle performance testing, thus greatly benefitting the vehicle development and testing industry.

Professor drivers, including racing drivers, can drive cars to achieve drift motions by taking control of the steering angle in high tire slip ratios, which provides a way to improve the driving safety of autonomous vehicles. The existing studies can be divided into two kinds based on analysis methods, and the theory-based is chosen in this study. Because the recent theory based is most applied for planar models with neglect of the rollover accident risk, the nonlinear vehicle model is established by considering longitudinal, lateral, roll, and yaw motions and rolling safety with the nonlinear tire model UniTire. The drift motion mechanism is analyzed in steady and transient states to obtain drift motion conditions, including the velocity limitation and the relationship between sideslip angle and yaw rate, and vehicle main status parameters including the velocity, side-slip angle and yaw rate in drift conditions. The state-feedback controller is designed based on robust theory and LMI (linear matrix inequation) with uncertain disturbances to realize circle motions in drift conditions. The designed controller in simulations realizes drift circle motions aiming at analyzed status target values by matching the front-wheel steering angle with saturated tire forces, which satisfies the Lyapunov stability with robustness. Robust control in drift conditions solves the problem of how to control vehicles to perform drift motions with uncertain disturbances and improves the driving safety of autonomous vehicles.

Current regenerative braking systems in electric vehicles have several problems, such as complex structures, too many control parameters, and inconsistent braking responses. To solve these problems, a control algorithm with multidisciplinary design optimization (MDO) is proposed based on the novel regenerative&ndash, mechanical coupled brake-by-wire system. A dynamic model of the novel regenerative braking system was established to analyze the mechanism of coupled braking and propose a braking torque distribution strategy. To realize a better balance between the optimum braking stability and the maximum regenerative energy recovery based on the braking torque distribution strategy and sample points, the MDO mathematical model was developed to optimize the control parameters with the collaborative optimization algorithm. The finite sample points comprising the vehicle speed, battery state-of-charge, and braking severity were obtained through an optimal Latin hypercube design and represent the overall design space. A network was established based on the sample points and the optimization results. Using this network, the in-depth characteristics of the sample points and the optimization results were obtained through supervised learning to develop the control algorithm for vehicle braking. A simulation was performed using the normal braking condition, and the simulation results demonstrated that the control algorithm has higher control precision than conventional methods and better real-time performance than online optimization.

For the disadvantages of current electric vehicles regenerative braking, a new design of regenerative brake-by-wire system based on mechanical-electron-magnetism integration is proposed. The new system has electromagnetic braking mode and hybrid braking mode, the former uses electromagnetic braking and the latter combines electromagnetic braking with friction braking. In the hybrid braking mode, the new system can realize friction braking without extra actuator energy. To research the braking characteristics and braking principle of the regenerative brake-by-wire system, the vehicle dynamic model is established. The braking performance and energy recovery efficiency of the system are studied under emergency braking condition. The results show the regenerative brake-by-wire system based on mechanical-electron-magnetism integration not only meets brake comfort under low braking strength and stability under high braking strength, and brake efficiency, but also has better braking response and robustness. With the feature of variable pedal ratio, it conforms to driver's pedal feeling. The control parameters are reduced and the performance of control system is improved. The new braking system can maintain a high recovery efficiency in a wide range of brake strength and increase the driving range of electric vehicles effectively.

Project the structure of horizontal pendulum restriction vehicle system, and set up the system dynamic model. Based on the Matlab/Simulink, establish the dynamic simulation system of the horizontal pendulum restriction vehicle system for the Chery A3 car. Using the brake/drive integrated ESP control principle, based on the simulation model, we respectively simulate and analyze the ESP control performances of the vehicle system and the horizontal pendulum restriction vehicle system in different simulation conditions. The study results indicate that the ESP control performances of the vehicle system and the horizontal pendulum restriction vehicle system have remarkable consistency. The theory of the horizontal pendulum restriction vehicle system for the ESP control performances test is not only feasible but also safe, reliable, high efficiency and low cost.

Project the braking feedback lockup braking-driving integrated system for electric vehicles. Design and optimize the integrated system based on the motor and the disc brake. Set up the integrated system dynamic model. Based on the Matlab/Simulink, establish the simulation system of regenerative braking dynamic and ABS control for the electric vehicles with the braking-driving integrated system. Based on the simulation system, respectively simulate and analyse the regenerative braking performances with or without ABS control on three conditions: driving straightly on high adhesion condition ground, low adhesion condition ground and steering driving on a curve path. The study results indicate that the electric vehicle with the braking-driving integrated system has better ABS performances than the electric vehicle with the general brake system, and has more the regenerative braking efficiency than other regenerative braking systems. DOI: http://dx.doi.org/10.5755/j01.mech.18.3.1871

Set up the vehicle stability control dynamics system based on the unsteady constraints. Establish the vehicle stability control dynamics equivalent system based on the unsteady constraints using the artificial neural network and the ESP control principle based on the integrated control of brake and drive. Based on the Matlab/Simulink establish the stability performances simulation test system of the vehicle dynamics equivalent system for the Chery A3 car. Using the simulation model, respectively simulate the stability performances of the vehicle dynamics equivalent system and the independent vehicle system on steadystate conditions of neutral steering, under steering and over steering. The study results indicate that the stability performances of the vehicle dynamics equivalent system based on the unsteady constraints and the independent vehicle system show remarkable consistency, it will provide a theoretical basis and technical support for establishing the safe and efficient test platform for vehicle stability control based on the unsteady constraints vehicle stability control dynamics equivalent system to research the vehicle stability control performances.http://dx.doi.org/10.5755/j01.mech.17.5.729

Project the structure of the low slip test system on vehicle ABS control performance, prove the principle of the test system. Set up the dynamic model of experimental system. Based on the Matlab/Simulink, establish the simulation system of the low slip test system on vehicle ABS control performance for the Chery A3 car. In the basic of this simulation system, this paper simulate and analyses the vehicle ABS control performance on the different road with the high, medium and low adhesive coefficients respectively. The study results show that the ABS control performance on the condition of the different adhesive coefficients can be evaluated based on the low slip test system on vehicle ABS control performance, and can obviously decrease the slip rate between the wheel and the rolling drum, especially on the road with lower adhesive coefficient, the effect is more significant. It can overcome many disadvantages such as serious slip between the wheel and the rolling drum, rapid tire wear, loud noises, the severe pollution and so on that usually occur in the previous experiment of ABS control performance.