| Transmission has always been playing an important role in mechanical drive systems since the advent of automobiles. As the briskly and drastic outgrowth of auto industry and the progress of drive control technique, traditional manual transmissions have been replaced by automatic transmissions step by step, in order to ameliorate riding comfort and safety and reduce driver's burdens as well. Nowadays automatic transmission is continuously being enhanced and widely used in various kinds of vehicles at home and abroad under the circumstance among which electronics, computer science, and intelligent control are developed rapidly. Automatic Mechanical Transmission, a brand-new type of automatic transmission, is equipped in vehicle's drive system within recent years, and it can be manufactured by manual transmission product line with low equipment investment because of its high performance and low price. It is AMT that fits the reality of development of automobile industry in China and becomes the focus in the field of auto drive system study. While the AMT is widely used and its relevant research is intensified, the gear decision which is one of the key techniques of AMT is no longer restricted to the control parameters employed frequently by traditional automatic transmissions, and begin to march towards more intelligent data-fusion of diversification.Most existing shift strategies merely rely on a vehicle's own status parameters (throttle opening rate, travelling velocity, speed of engine, etc) and their rates of change to determine whether to shift or not. These kinds of shift strategies whose recognition of road condition is only constrained by the road circumstances of the vehicle's current location or its historical travelling traces within some certain time can't acquire the information of the vehicle's exact position in the road section under such a condition or the road sections in front of the vehicle. Such sorts of shift strategies are not framed and designed based on all the cases of road information, and can't fit the special conditions (long slope ramp, curve, crossing, etc), which might ineluctably lead to cyclic shifts, shift huntings or unnecessary shifts. Hence, it's so necessary to acquire the relevant parameters of the road section where the current vehicle is and the certain range in front of it with an appropriate technique to enhance adaptability of shift strategies to the road.By now, the hybrid location techniques based on satellite positioning and inertial guidance have been matured and widely used in various moving carriers that request high-precision positioning information. In this way, we can get the precise position coordinates and moving directions of the target carriers. On the other hand, with fairly complete and high-precision digital maps and related databases having come into being, they provide us the matching target for positioning information and containers of road parameters. As a result, it is possible to make sure of precise location of current vehicle and the correlated road parameter with the help of combining positioning information with database of road section parameter, which contains the perfect road-net information.The present 2-parameter shift schedule in common use has the deficiency that it lacks accurate identification for road conditions and acquirement of specific road parameters, which must be overcome. In the view of this, road parameter based shift strategy is proposed in this dissertation, which combines the road circumstances with traditional shift schedules to orchestrate the gear decision and the current road condition. By this means shift quality will be improved as well as comfort and safety. The main research contents fall into four primary aspects: Part I: Designing Road Parameter Database (RPD) for shift strategy. On the basis of analysis of the categories and metrics for the road parameters which might have effect on shift strategies, an road parameter database which makes it easy to perform information acquirement and map matching with is self-designed. In the design and establishment, the general space descriptions, such as line, plane and area, are rejected. The involved road nodes are classified in more detail; the various kinds of nodes are taken as the skeleton of road network; connected relation between the each node is used as the specific approach of construction of road section, and the material attributes can be acquired based on the ownership relation between the nodes and road section. In RPD, node and its connected relationship are the only form of expression, while line, as well as area, is not recorded as an independent description.Part II: Method for acquiring positioning information and research on RPD based map matching. It is because satellite positioning and inertial guidance complement each other quite well to obtain precise location coordinates that a integrated positioning method based on GPS/DR is the primary approach to get a vehicle's position. After the road network in RPD is divided into grid matrix as candidate road areas, a novel map matching algorithm which fuses the various factors of distance metric, angle metric, trace metric and road connectivity is proposed based on D-S evidence reasoning in this dissertation. The three working modes of initial positioning, relay positioning and tracing positioning are set, and the switching method and condition are also illustrated.Part III: Real-time acquirement of road parameters. In order to ensure the real-time of data acquirement, a pre-reading mechanism based on list-tree is introduced. This kind of mechanism takes the two crossing street intersections which is closest to the current vehicle as the root and the first level node respectively, then establishes pre-reading tree level by level. According to the correlation between the vehicle's trace, nodes and road section, the pruning and extension will be performed on the tree to refresh the pre-reading tree in time, which can ensure the prompt and efficient acquirement of road parameter information. Based on the correlated node and road section information in the pre-reading data, the geometrical features, such as the gradient of the slope and the radius of curvature near the curvature variation sampling nodes, are calculated with the method of Curve Fitting Algorithm, and the material attributes are also obtained from the RPD directly.Part IV: Application of road parameters to gear decision. After geometrical characteristics parameters and material attributes are achieved and integrated into the traditional 2-parameter shift schedule, a novel road parameter based shift strategy is studied. Four main road conditions are classified, crossing, curve, long gradient (upward) and long gradient (downward), and the shift strategies under different conditions are designed by introducing shifting coefficients. Meanwhile, the constructive suggestions are made aiming at the connections between different conditional road sections.The main research content of this dissertation is an interdisciplinary subject which covers a variety of area including GIS, computer graphics, data fusion and powertrain control, so it will be a technical potential solution to vehicle control. A novel approach to acquiring road parameter and its application to shift strategy are described, which lays a foundation for continuative works. Based upon precise positioning information and digital maps with complete road net, the vehicle's accurate location is obtained to acquire road parameters, then according to road parameters and conditions, appreciate shift strategies are set up to enhance the adaptability of gear decision to road situation, which provides driver and passengers a safer and more comfortable driving environment, improves vehicles' dynamic performance and economical efficiency and is bound to have an even broader prospect for development.
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