Improvement of traction performance and off-road mobility for a vehicle with four individual electric motors: Driving over icy road

To control speed and wheel slip for severe conditions of tire-surface interaction is a challenging task in the design of traction control system for electric vehicles with off-road capability. In this regard, the present paper focuses on a specific traction control for an electric vehicle with four individual in-wheel motors over icy road. The study demonstrates that a proper integration of the speed controller and wheel slip controller can essentially improve the mobility of the vehicle in the cases of acceleration and slope climbing. The paper discusses relevant case studies with particular attention given to the system architecture (sliding mode and PID control methods), extremum-seeking algorithm for maximum tire-road friction and corresponding slip value, and experimental validation of the tire model used in the controller with the help of the Terramechanics Rig in the Advanced Vehicle Dynamics Laboratory (AVDL) at Virginia Polytechnic Institute and State University.     

Development of a vehicle to study the tractive performance of integrated steering-drive systems

This paper describes a test-bed vehicle for studying the integration of the steering system of a wheeled vehicle with the drive system. The vehicle was produced in order to determine whether such an integrated system is practical; to investigate tractive performance compared to other steering-drive systems; and to determine under which conditions such a system has better performance. The integrated steering-drive system of the test-bed vehicle uses a computer to co-ordinate the independently driven wheel speeds of the drive system (which is also the primary steering system) with the steer angles of the non-driven steerable wheels to produce a beneficial secondary steering effect. The secondary steering system assists the primary steering system when side forces act on the vehicle, while producing minimal conflict. This concept can be applied to agricultural vehicles such as tractors, harvesters, mowers, sprayers and self-propelled windrowers. The test-bed vehicle is able to be configured for the following steering-drive systems types: open differential drive with steerable wheels, independent drive wheels with castors, locked differential drive with steerable wheels and a computer integrated steering-drive system. The capacity of the test-bed vehicle to be configured as described is a significant advantage when measuring tractive performance, as the results obtained will be more valid due to the vehicle parameters being the same.     

Development and experimental evaluation of translational semi-active dampers on a high mobility off-road vehicle

This paper describes the further development and experimental evaluation of two-state semi-active translational dampers on a 6×6 high mobility off-road vehicle. As only ride comfort was enhanced during previous work, the low-speed damping characteristics on the semi-active damper was increased in order to improve vehicle handling. The existing passive dampers, as normally fitted to the test vehicle, were modified to the semi-active configuration by adding a bypass assembly and a controllable valve. Experimental work included driving over various repeatable surfaces at different speeds and executing severe lane change manoeuvres. Results indicated that both handling and ride comfort were improved when selecting the semi-active configuration.     

Virtual flight simulation of a dual rotor micro air vehicle

In this paper, a new computational method is developed based on computational fluid dynamics (CFD) coupled with rigid body dynamics (RBD) and flight control law in an in-house programmed source code. The CFD solver is established based on momentum source method, preconditioning method, lower–upper symmetric Gauss–Seidel iteration method, and moving overset grid method. Two-equation shear–stress transport k ? ω turbulence model is employed to close the governing equations. Third-order Adams prediction-correction method is used to couple CFD and RBD in the inner iteration. The wing-rock motion of the delta wing is simulated to validate the capability of the computational method for virtual flight simulation. Finally, the developed computational method is employed to simulate the longitudinal virtual flight of a dual rotor micro air vehicle (MAV). Results show that the computational method can simulate the virtual flight of the dual rotor MAV.     

基于多体动力学递推算法的电动汽车建模与仿真分析

运用多体动力学理论建立整车动力学模型已成为汽车动力学研究的重要手段。以大连理工大学汽车学院研制的某电动汽车为对象,运用多体动力学递推算法建立了包含前后悬架、车身及车轮在内的多体仿真分析模型,将前后悬架视为3个子系统,引入哑体,实现对各子系统的单独处理;同时完成了整车的快速建模与分析;将MATLAB整车仿真程序的结果与ADAMS仿真结果进行比对,二者吻合较好,验证了所建模型及求解算法的正确性。     

A new type of micropump driven by a low electric voltage

In this paper, we propose a new prototype model of a micro pump using ICPF (Ionic Conducting Polymer Film) actuator as the servo actuator. This micro pump consists of two active oneway valves that make use of the same ICPF actuator. The overall size of this micro pump prototype is 12mm in diameter and 20 mm in length. The actuating mechanism is as follows: (1) The ICPF actuator as the diaphragm is bent into anode side by application of electricity. Then the volume of the pump chamber increases, resulting in the inflow of liquid from the inlet to the chamber. (2) By changing the current direction, the volume of the pump chamber decreases, resulting in the liquid flow from the chamber to the outlet. (3) The ICPF actuator is put on a sine voltage, the micro pump provides liquid flow from the inlet to the outlet continuously. Characteristic of the micro pump is measured. The experimental results indicate that the micro pump has the satisfactory responses.     

Development of a dynamometric vehicle to assess the drawbar performance of high-powered agricultural tractors

Agricultural tractors are machines originally designed to mechanize agricultural tasks, especially tillage and pulling. A large part of research activities have been interested in optimizing tractor efficiency, in particular in terms of emissions and energy. In this frame, the OECD Tractor Code 2 sets out a drawbar test in specific controlled conditions with the aim of evaluating the power of the tractor available at the drawbar. The principal measurement chain relies on dynamometric vehicles (DV) that are instrumented vehicles specifically engineered to develop horizontal force at the drawbar of agricultural tractors. The CREA Laboratory of Treviglio, Italy, engineered a new dynamometric vehicle to test tractors with up to 200 kW at the drawbar (245 kW at the engine flywheel) and a maximum of 118 kN drawbar force. The chosen basis is a FIAT 6605 N truck (TM 69 6 × 6) which has been transformed into a hydrostatic vehicle driven by a hydraulic system and an auxiliary gearbox. The maximum drawbar force was verified up to 122 kN. The drawbar power verification (200 kW) was successfully carried. The final verification confirmed that the project is valid for the investigation and optimization of the parameters regarding the traction efficiency of agricultural tractors.     

一种新型后装式垃圾车结构优化设计

首先对后装式压缩垃圾车的车厢截面形状进行优化,设计出一种具有椭圆截面车厢的新型后装式垃圾车.给出椭圆截面车厢的自重、惯性、压缩、挤入、推出等压缩垃圾载荷的数学表达.而后对车厢与填科器结构进行多种危险工况的有限元分析,采用导重法对结构构件尺寸进行优化设计,在保证结构应力小于许用应力的前提下,本新型椭圆截面后装武垃圾车结构质量比原来的矩形截面压缩垃圾车减少了33.5%,是同类后装武压缩垃圾车中的最轻者.     

Experimental demonstration of a new concept of drag reduction and thermal protection for hypersonic vehicles

A new idea of drag reduction and thermal protection for hypersonic vehicles is proposed based on the combination of a physical spike and lateral jets for shockreconstruction. The spike recasts the bow shock in front of a blunt body into a conical shock, and the lateral jets work to protect the spike tip from overheating and to push the conical shock away from the blunt body when a pitching angle exists during flight. Experiments are conducted in a hypersonic wind tunnel at a nominal Mach number of 6. It is demonstrated that the shock/shock interaction on the blunt body is avoided due to injection and the peak pressure at the reattachment point is reduced by 70% under a 4° attack angle.     

Initiation and stabilization of combustion at low pressure and temperature by means of a nonequilibrium electric discharge

The pattern of supersonic (M = 2) flow near the surface of a plate at points on which propane jets are injected normal to the air flow direction is investigated. For the initiation and intensification of the chemical reactions a nonequilibrium discharge is used. This is created between an anode oriented along the flow, the plate surface, and a metal interceptor mounted on the plate. The results of a schlieren visualization of the flows developed are presented. Spectroscopic studies show that the distribution of plasmochemical reaction products has a number of fundamental differences as compared with the case of propane injection along the plate surface. A comparative analysis of these distributions for identical gasdynamical experimental conditions is important for testing calculation models of reactive-mixture supersonic flows in which electric discharges are used for ignition and the stabilization of combustion.     

Investigation of flows past a plate in the presence of exoergic processes driven by the interaction between a nonequilibrium electric discharge and a propane-air mixture

Supersonic flow (M = 2) past a plate along which propane is injected is investigated within the framework of the solution of problems of combustion initiation and stabilization at low static temperatures and pressures in the presence of a nonequilibrium discharge and metal and dielectric interceptors mounted on the plate surface. The experiments show that two zones with exoergic reactions develop when a metal interceptor is mounted on the plate. One zone is located ahead of the leading separation zone and the other above and behind the interceptor edge, its boundary partially penetrating into the supersonic flow region. Using modern spectroscopic methods, the radiation intensity distributions of a series of plasmochemical reaction products are obtained in the neighborhood of the plate ahead of the interceptor, behind it, and above its edge. It is found that the fuel is intensively converted under the action of the discharge with the occurrence of a series of free radicals, atomic hydrogen and oxygen which are themselves chemically active.