74 results about "Transportation planning" patented technology

The invention relates to the technical field of AGV path planning, in particular to an intelligent obstacle avoidance and path optimization method and system for an AGV. The method comprises the following steps: obtaining an omnibearing image of an AGV activity area; performing static obstacle recognition on the omnibearing image to construct each static obstacle model; performing scene three-dimensional structure perception on the omni-directional image, and performing three-dimensional mapping based on each static obstacle model so as to obtain a global perception scene model; obtaining a cargo transportation planning log; performing cargo global available path planning on the global perception scene model according to a cargo transportation planning log, and constructing a global available planning path; and carrying out dynamic path optimization based on the global available planning path, and carrying out dynamic obstacle potential collision point mining according to the dynamically optimized transportation path so as to generate a collision time point and a collision position point. According to the invention, through dynamic and efficient path obstacle avoidance planning, the accuracy and stability of AGV driving are improved.

The invention discloses a multimodal transport organization mode dynamic optimization method based on big data processing, which relates to the technical field of multimodal transport data optimization, and comprises the steps of collecting various data in a transport process in real time, and carrying out data optimization based on transport network nodes of a target area. A multimodal transport grid model is constructed, first site information and second site information in a multimodal transport planning path are collected, first weather prediction data and second weather prediction data are collected in real time, and the multimodal transport grid model based on weather changes is formed. An optimization algorithm is adopted to solve the multimodal transport path optimization model with constraint conditions and based on weather changes; according to the method, the influence of the weather factors on the transportation mode can be fully considered when the multimodal transportation organization mode is dynamically optimized, the situation that the established transportation mode cannot be safely and successfully executed on schedule due to the weather influence is avoided, the transportation mode can be flexibly adjusted by introducing the first weather prediction data and the second weather prediction data, and the transportation efficiency is improved. Therefore, the smooth operation of multimodal transport is ensured.

The invention discloses a non-power-grid sporadic material emergency purchase response system considering risk priority. The system comprises a sporadic material demand trend pre-judgment module, a risk perception purchase adaptation module, a risk income balance optimization module, an emergency purchase scheduling module, a non-power-grid material response module and a module cooperative control module. According to the system, data such as historical purchase and consumption rate are integrated through a demand trend pre-judgment module to output a demand prediction result, risk and performance parameters are coupled through a risk perception purchase adaptation module to generate an adaptation scheme, and an optimal purchase strategy is calculated through a risk income balance optimization module. A scheduling instruction is generated through an emergency purchase scheduling module according to the risk priority, a non-power-grid material response module executes inventory checking, transportation planning and other operations, and a module cooperation control module achieves whole-process data synchronization and parameter dynamic adjustment. According to the system, the decision-making scientificity and response efficiency of non-power-grid sporadic material emergency purchase are improved, and emergency purchase burstiness and complexity requirements are met.

The invention provides a supply chain optimization method and system for cargo import and export, and relates to the technical field of supply chain optimization, and the method comprises the steps: building a distributed account book based on block chain nodes; determining a trigger condition and execution logic, and generating a smart contract; installing an Internet of Things sensor, obtaining cargo environment parameters generated based on a monitored cargo environment, and carrying out information synchronous updating with the distributed account book to obtain whole-process monitoring data; carrying out transportation analysis according to the cargo demand prediction model to obtain predicted logistics data; carrying out transportation planning, and generating a supply chain strategy; and executing the supply chain strategy based on the intelligent contract, generating supply chain data, and performing visual display of the supply chain data. Through the method and the device, the technical problems of serious information island phenomenon and incapability of efficiently sharing data in the prior art can be solved, the technical targets of supply chain data transparency and automatic management are realized, and the technical effect of improving the overall efficiency and the strain capacity of the supply chain is achieved.

The invention provides a storage network planning method and a logistics simulation system for energy enterprise materials, and relates to the field of energy enterprise material planning, user data is received through an interactive interface, and the user data is pre-processed and stored in a database; after a user triggers a solving instruction, a back end calls a solver to construct a mixed integer programming model, a warehouse network layout scheme is iteratively optimized based on a constraint satisfaction algorithm, and a result is stored back to a database; the support visualization module generates a multi-dimensional chart to display data before and after optimization, provides a data export function to output a portable document according to a preset format, integrates business rules, algorithm solution and visual interaction, supports dynamic optimization and rapid verification of an energy storage network, realizes dynamic collaborative optimization of storage site selection, inventory decision and transportation planning, and improves the efficiency of the energy storage network. And through introduction of multi-scene and multi-dimensional simulation analysis capability, an integrated optimization and simulation platform and a human-computer interaction friendly visual decision-making interface are constructed.

The invention discloses a path planning method and system for power grid engineering construction machinery transportation, and a medium. The method comprises the following steps: constructing a construction environment model and a grid adjacency list according to path planning data; processing the construction environment model and the grid adjacency list based on a path connectivity algorithm to obtain a weighted grid connectivity graph; analyzing the weighted grid connected graph based on a path analysis algorithm to obtain a transportation route combination graph; on the basis of a path selection algorithm, selecting a route communicating all construction nodes of the construction area in the transportation route combination diagram as a temporary transportation route; and detecting all the temporary transportation routes based on a route detection algorithm to obtain a target transportation route. Therefore, the shortest and most economical transportation planning path is found through the adaptive path algorithm and the deep reinforcement learning technology.

The invention provides an air-railway connection OD acquisition method and device based on mobile phone signaling data, and relates to the technical field of comprehensive transportation planning and management, and the method comprises the steps: obtaining the mobile phone signaling data of a plurality of users; obtaining a plurality of pieces of target signaling data; determining a plurality of first signaling data; performing secondary screening based on the base station identifiers and the timestamps in the multiple pieces of first signaling data, and determining multiple pieces of second signaling data; generating a plurality of corresponding travel data based on the plurality of second signaling data; and obtaining a plurality of target travel data. According to the invention, based on the mobile phone signaling data of the users, part of the users not passing through the railway station and the civil aviation station are eliminated, then the users not adopting the sky-railway connection are eliminated, and finally the travel data of the multi-card users are merged, so that detailed and accurate sky-railway connection OD information is obtained. A research sample can be provided for route recommendation and transfer city optimization of the air-railway linkage, and the network efficiency of a traffic system is further improved.

The invention relates to the technical field of public transport planning, and discloses a calculation method for quantitative evaluation of a bus track connection relationship, and the method comprises the following steps: 1, collecting data: collecting travel time, travel cost data and track travel time data between any stations of a bus line; according to the calculation method for the quantitative evaluation of the bus track connection relationship, a comprehensive quantitative evaluation model is provided by comprehensively evaluating the travel time, the cost and the competition coefficient between the bus line and the track line; the comprehensive evaluation method can more accurately identify and quantify the advantages and disadvantages in the bus track connection relationship, thereby helping a planner to optimize the layout of bus lines and track lines, reducing resource waste, improving the overall transportation efficiency, and improving the transportation efficiency by optimizing connection points and adjusting operation strategies. The transfer time and waiting time of passengers can be reduced, the travel experience of the passengers is improved, and the operation cost is reduced.

The invention discloses a global and neighborhood feature fused railway network node importance degree evaluation method. The method comprises the following steps: obtaining railway transportation network node evaluation data; constructing a railway transportation facility topology network and railway transportation service complex network model; analyzing the global importance of the railway network nodes; outputting neighborhood attributes of the railway network nodes; setting a global and neighborhood feature fusion factor, and calculating a network node comprehensive importance index; and evaluating the importance of the railway network nodes. According to the method, the node importance of the railway transportation complex network is rapidly and accurately evaluated, the node importance evaluation result is more objective and accurate by fusing the global and neighborhood characteristics of the railway network nodes, and technical service support is provided for scientific and efficient railway transportation planning and complex network node importance analysis.

The invention discloses a traffic planning method, which realizes real-time monitoring, regulation and optimization of a traffic system by collecting, analyzing and processing real-time traffic data and combining an advanced traffic management algorithm. According to the invention, by using a data processing algorithm, the real-time data of the traffic system can be analyzed according to the timely acquired data, and the real-time monitoring and response to the traffic condition can be realized; through deep analysis and mining of big data, traffic demands and road condition changes can be accurately evaluated, and accurate decision support is provided for traffic planning and management. Flexible traffic management strategies and regulation and control means are adopted, and targeted traffic management and adjustment can be realized according to traffic characteristics of different time periods and regions; multiple factors such as traffic flow, road conditions, traffic facilities and the like are comprehensively considered, and the operation efficiency and safety of the traffic system are comprehensively optimized.

The invention relates to the technical field of urban and rural traffic planning, in particular to a rail transit connection shared bicycle use influence analysis method based on built environment and interpretable machine learning, which comprises the following steps: S1, identifying traffic behaviors of taking shared bicycles as rail transit connection trips, obtaining shared bicycle order data in a target area, and determining the order data of the shared bicycles in the target area; constructing a shared bicycle connection use database; s2, determining a research area of a built environment around each subway station, and delimiting an annular buffer area around the subway station as a research range; s3, fusing multi-source built-up environment data, including objective built-up environment indexes and perceptual built-up environment indexes; s4, on the basis of the data in S1 and S3, establishing an influence factor data set of the environment on the use of the shared bicycle; the method comprises the following steps: identifying a traffic behavior of taking a shared bicycle as a rail traffic connection trip, obtaining shared bicycle order data in a target area, extracting riding OD point, distance and time information, and constructing a shared bicycle connection use database;

The present application belongs to the field of underground space development and application and transportation planning, and particularly relates to a development suitability evaluation method for urban subway freight system, which comprises the following steps: step (1), establishing an analysis framework for development suitability of urban subway freight system; step (2), evaluation indexes and quantitative calculation for development suitability of urban subway freight system; step (3), multi-source data collection; and step (4), establishment of index processing process and evaluation criteria. The present application proposes a method combining qualitative and quantitative methods to evaluate the suitability of comprehensive logistics solutions based on urban subway freight, and the evaluation content is comprehensive and operable, thereby providing reliable decision support for sustainable transition of urban freight transportation from highway dominant mode to railway collaborative transportation.

The present invention provides a method and device for obtaining air-rail intermodal OD based on mobile phone signaling data, relating to the field of integrated transportation planning and management technology. The method comprises obtaining mobile phone signaling data of multiple users; obtaining multiple target signaling data; determining multiple first signaling data; performing secondary screening based on base station identifiers and timestamps in the multiple first signaling data to determine multiple second signaling data; generating corresponding multiple trip data based on the multiple second signaling data; and obtaining multiple target trip data. Based on the user's mobile phone signaling data, the present invention first eliminates some users who have not passed through railway stations and civil aviation stations, then eliminates users who have not used air-rail intermodal, and finally merges the trip data of users with multiple cards to obtain detailed and accurate air-rail intermodal OD information. This method can provide research samples for air-rail intermodal route recommendations and transit city optimization, thereby improving the network efficiency of the transportation system.

The application provides a kind of storage-conveying combined planning method, device and equipment considering weak link identification of regulation capacity and storage medium. It relates to the technical field of new energy storage and transportation planning. The method accurately identifies weak nodes and bottleneck lines for peak regulation by constructing adjustment capacity supply and demand imbalance tracing and weak link evaluation index. And it analyzes the dynamic relationship between energy storage configuration and line expansion, and constructs a combined planning model considering the trade-off between economy and flexibility. The effectiveness and rationality of the method are verified by matching the Garver-6 system example with actual operation data. The example shows that: on the one hand, the evaluation index can accurately identify weak nodes and bottleneck lines for peak regulation, providing guidance for subsequent planning. On the other hand, the proposed planning method avoids waste of energy storage investment and redundancy of line expansion, and significantly improves the weak links of the power grid.

The invention provides a storage-transmission joint planning method, device and equipment considering weak link identification of adjustment capability, and a storage medium. Relates to the technical field of new energy storage and transmission planning. According to the method, peak regulation weak nodes and bottleneck lines are accurately identified by constructing regulation capability supply and demand imbalance traceability and weak link evaluation indexes; and the dynamic relationship between energy storage configuration and line extension is analyzed, and a joint planning model considering the balance of economy and flexibility is constructed. The effectiveness and rationality of the method are verified by matching actual measurement operation data with Garver-6 system example analysis. Examples show that on one hand, the evaluation indexes can accurately recognize peak regulation weak nodes and bottleneck lines, and guidance is provided for follow-up planning; and on the other hand, the planning method avoids energy storage investment waste and line extension redundancy, and significantly improves weak links of the power grid.

The present invention discloses a joint prediction method for urban tourism traffic demand based on attraction intensity, including: (1) obtaining target area data; (2) dividing the target area into tourism-type, transportation-type and comprehensive-type communities; (3) defining tourism traffic and subdividing it into occurrence-type tourism traffic and attraction-type tourism traffic; (4) using the GM (1,1) grey prediction model to predict the total tourism demand in the target area; (5) using the factor analysis method to calculate the attraction intensity of scenic spots in the target area. (6) predicting the occurrence and attraction traffic volume of tourism in scenic spots. (7) predicting the tourism distribution traffic volume in communities. The present invention takes into account the differences in characteristics between tourism traffic and commuting traffic, and the impact of the location distribution of transportation, commerce, hotels, etc. on tourism traffic demand, introduces factor analysis to quantify the attraction intensity of scenic spots, proposes a joint prediction method for tourism traffic, and obtains the OD matrix of tourism traffic distribution, which provides a theoretical basis for tourism traffic planning.

This invention discloses a method for assessing the accessibility level of public transportation based on work-residence integration, belonging to the field of urban public transportation planning and assessment technology. The method includes: acquiring multi-source data on the public transportation system of the target area, including static geographic information, departure timetables, and historical operation data; dividing the area into spatial analysis units based on planning boundaries and linear geographic elements; calculating and standardizing three indicators—spatial coverage, service frequency intensity, and operational reliability—for each unit; employing an objective weighting method based on information entropy to automatically determine the weight of each indicator according to its dispersion across all units; weighting and aggregating the standardized indicator values ​​of each unit with their corresponding weights to generate a comprehensive public transportation network service capacity index; and finally generating and outputting a service capacity visualization map based on this index. This invention, through multi-dimensional quantification and objective weighting, achieves a scientific and comprehensive assessment of public transportation service capacity, providing intuitive decision support for planning and management.

This invention relates to the field of airport integrated transportation, specifically to a method for assessing the competitive status of airport landside transportation niches. Based on niche theory, this invention uses the breadth, overlap, and competitive dynamics of transportation niches as core dimensions for evaluating airport landside transportation competitiveness. By constructing a quantitative model of transportation niches, it analyzes the competitive and cooperative relationships among different modes of transportation and the mechanism of imbalance in carrying capacity ratios, thereby characterizing the comprehensive competitiveness of airport landside transportation and providing a scientific basis for optimizing airport landside transportation planning and improving transportation efficiency. This invention can be used to reveal the competitive and cooperative mechanisms and evolutionary patterns of airport landside transportation niches, in order to solve the key problems currently facing the development of airport landside transportation.

The invention belongs to the technical field of intelligent traffic, particularly relates to an intelligent traffic prediction control method and system based on dynamic functional cell body coupling, and aims to solve the problems that an existing traffic planning method is low in prediction accuracy and poor in adaptability in a dynamic network. According to the method, high-order structure features of a traffic network are extracted based on directed motif and a graph neural network (GNN), and urban functional cell bodies are dynamically divided; continuous evolution of the urban functional cell body structure is ensured through a time smoothing mechanism; the mutual feedback intensity between the urban functional cell bodies is predicted by utilizing an urban functional cell body embedding and time sequence model (such as LSTM); and a prediction result is adaptively adjusted in combination with dynamic states (birth, expansion, shrinkage and death) of urban functional cell bodies. On the basis of dynamically adapting to a time-varying traffic environment, regional traffic flow prediction is realized, and when the method is applied to traffic planning, regional flow management, congestion early warning and infrastructure planning can be optimized, and intelligent traffic and green city development are promoted.

The invention discloses a construction method, a control method and a system for a hierarchical control model of a plug-in hybrid power truck, and the construction method comprises the steps: constructing an energy control model of a plug-in hybrid power vehicle based on an improved DDPG; determining a state set S and an action set action based on an improved DDPG plug-in hybrid electric vehicle energy control model, and a reward function J and a constraint function based on adaptive change of truck driving data; step 2, collecting a standard working condition and a gradient, taking the standard working condition and the gradient as a sample set, inputting the sample set into the energy control model of the plug-in hybrid electric vehicle based on the improved DDPG constructed in the step 1 for training, and obtaining a trained energy control model of the plug-in hybrid electric vehicle based on the improved DDPG; coordination processing is carried out on a surveying and mapping map of a mining platform, a mixed integer nonlinear programming model Ttotal is established, a driving path of a main queue and a driving path of a single vehicle are obtained through solving, and the transportation planning requirement can be met. Therefore, the problems of mining area intersection congestion, electric shovel transportation waiting, low information island decision-making efficiency and the like are effectively solved.

The invention discloses a bulk commodity transportation management method and platform based on a block chain, and relates to the field of bulk commodity transportation management. The logistics transportation planning route in the block chain is acquired, the basic type of each logistics physical node in the planning route is extracted, the logistics operation performed at the logistics physical nodes is summarized, and the logistics information integration model based on the planning route is constructed. Whole-course logistics information of bulk commodity materials is described by using a formalized expression mode, real-time logistics information when the commodity materials arrive at each logistics physical node is collected and synchronized to a block chain, the synchronized real-time logistics information in the block chain is dynamically matched to a logistics information integration model, and the logistics information integration model carries out logistics information integration. And calculating and acquiring the accuracy and integrity of the real-time logistics information at the current logistics physical node, respectively setting early warning thresholds of the accuracy and integrity of the logistics information, and judging the real-time logistics information at the current logistics physical node according to the early warning thresholds.

The invention relates to the field of airport comprehensive traffic, in particular to an airport landside traffic ecological niche competition state assessment method, which is based on an ecological niche theory, takes the traffic ecological niche width, the overlapping degree and the competition situation as core dimensions for assessing airport landside traffic competitiveness, and establishes a traffic ecological niche quantification model to assess the airport landside traffic competitiveness. Analyzing a competitive cooperation relationship and a carrying ratio imbalance mechanism of different transportation modes to describe comprehensive competitiveness of airport landside traffic, and providing a scientific decision basis for airport landside traffic planning optimization and transportation efficiency improvement; the method can be used for revealing the competitive cooperation mechanism and the evolution law of the airport landside traffic ecological niche so as to solve the key problem faced by the current airport landside traffic development.

The present invention discloses a method for calculating the optimal public transportation motorization share rate in small and medium-sized cities, which relates to the technical field of motorized travel structure optimization and is applied to public transportation planning in small and medium-sized cities. The method comprises: determining the composition of the motorized transportation system in the small and medium-sized cities, and determining traffic allocation parameters according to motorized transportation allocation characteristics; determining motorized travel time characteristics according to traffic supply and demand characteristics and traffic allocation parameters; determining an optimization index for the public transportation motorization share rate, and constructing an optimization objective function and constraint conditions based on traffic supply and demand characteristics, motorized travel time characteristics, and motorized mode characteristics; establishing a system optimal public transportation motorization share rate model based on the optimization objective function and constraint conditions; solving the optimal public transportation motorization share rate model based on the CRITIC-ideal point method, and determining the optimal share rate value. The method can be used to calculate the optimal public transportation motorization share rate in small and medium-sized cities, providing a basis for formulating public transportation development goals in small and medium-sized cities.

The invention belongs to the technical field of traffic transportation planning, and particularly relates to a signal timing method for lane grouping control at a roundabout. The signal timing method comprises the following steps: step 1, collecting and analyzing road geometric condition data and traffic operation data of a current roundabout; 2, determining traffic channelization and traffic organization modes of the roundabout based on a lane grouping control strategy; 3, determining a signal phase scheme of the roundabout; and step 4, determining a roundabout signal timing scheme. The method solves the technical problems of congestion and delay in the roundabout, and has the advantages of dynamically adjusting signal timing, improving traffic efficiency and safety, and reducing system complexity and cost.

The invention relates to the technical field of storage intelligent management systems, in particular to a cold chain storage intelligent management system based on the internet of things, which comprises an internet of things network constructed by a plurality of cold chain warehouses, and is characterized in that each cold chain warehouse is internally provided with a temperature adjusting device, an image acquisition device, a temperature acquisition device and a storage and transportation planning module; determining a circulation coefficient according to the space utilization rate of the corresponding cold chain warehouse, determining a to-be-circulated storage object list based on the circulation coefficient and the historical warehouse-out data, and responding to the to-be-circulated storage object list or the to-be-stored object list to obtain the to-be-delivered storage object list so as to match the cold chain warehouse. And a warehousing strategy is determined according to the number of the cold chain warehouses which can be matched. According to the invention, the technical problem that the storage environment of the stored objects is not matched with the actual demand due to the change of the storage environment of the stored objects and the space proportion caused by the fact that the warehouse-in and warehouse-out link of the goods is not comprehensively considered in the prior art is solved.

The invention discloses an unmanned aerial vehicle transportation network planning method based on LoRA enhanced strategy gradient, and belongs to the technical field of traffic transportation planning and management, and the method comprises the steps: firstly constructing a directed graph taking a central station as a root; nodes are classified, feasible paths are selected, construction cost and transportation cost are calculated, and a weighted LA-OVRP model is constructed; mDP and LoRA strategy tables are used for modeling path selection, and a directed root tree is generated; optimizing the strategy table through discount return and gradient descent; and finally, selecting a parent station path with the maximum probability for each demand station, and only distributing and outputting a feasible solution taking a central station as a root for a flow hub, thereby solving the problem of constructing an unmanned aerial vehicle transportation network taking a central node as a root in a low-altitude economic area environment, enabling node site selection and a flow transportation path to be collaboratively optimized, and improving the transportation efficiency of the unmanned aerial vehicle. Therefore, the weighted sum of the construction cost and the transportation cost is minimized, and the site selection effect and the transportation efficiency of the low-altitude economic area are improved.

The present invention discloses a comprehensive transportation mode OD acquisition method considering connecting travel, which includes four steps of data collection, utility calculation, proportion analysis and OD acquisition. By collecting and analyzing travel OD matrix data within a region, the travel utility of all feasible travel mode combinations between two places is calculated according to a formula, and on this basis, the travel proportion of all feasible travel mode combinations between the two places is calculated, and finally the mode OD matrix of the travel mode between the two places is obtained by calculation. The method is supported by actual data, takes into account the possibility of connecting travel between cities, has strong practicality and operability, is of great significance for comprehensive transportation travel mode classification prediction and transportation planning, and also provides a practical and scientific basis for the planning and transformation of passenger transport hubs between urban agglomerations and the dispatch optimization of transport capacity between hubs, so as to more scientifically and reasonably improve the supply capacity and quality of transportation services and improve the travel experience of passengers.

The invention discloses a general cargo transportation three-dimensional simulation method and system and electronic equipment. The method comprises the following steps: step 1, obtaining basic information of general cargos and space parameters of a cargo ship; 2, constructing a three-dimensional model of the cargo ship based on the cargo size, weight and shape parameters obtained in the step 1 and the space parameters of the cargo ship; 3, dynamically simulating the layout of the grocery in the three-dimensional model based on the three-dimensional model constructed in the step 2 by using a genetic algorithm or an ant colony algorithm; step 4, outputting a cargo arrangement scheme based on a dynamic simulation result in the step 3; step 5; applying a deep learning model; step 6; a virtual reality technology is utilized. According to the method, the three-dimensional model is established by acquiring cargo information and cargo ship parameters, a layout and an output scheme are dynamically simulated by using genetic algorithms and the like, accurate recognition is realized through deep learning, interaction is enhanced through virtual reality, and the transportation planning accuracy and efficiency are improved.

The invention relates to the technical field of transportation planning of an intelligent port, in particular to a port coal transfer planning optimization method based on artificial intelligence, which comprises the following steps: S1, acquiring a coal loading image and a coal loading weight; s2, inputting a coal loading image of a transport vehicle into the coal type identification model to obtain a coal type prediction result; s3, inputting a coal loading image of the transport vehicle into the loading volume prediction model to obtain a coal loading volume prediction result; s4, selecting an optimal unloading area based on the coal loading weight, the coal type prediction result and the coal loading volume prediction result in combination with the coal stacking real-time state of the coal storage yard; and S5, generating transfer planning information based on the position information of the optimal unloading area. According to the invention, the uniformity and safety of stacking of the coal in the storage yard are obviously enhanced, the space utilization rate of the port coal storage yard is greatly improved, and intelligent, efficient and safe management of the whole process of port coal transfer is realized.

A route guiding device for transportation planning is provided and includes: a base; a standing post, fixedly connected to a top of the base; a lifting rod, movably arranged inside and connected to the standing post; a fixation rod, where a side of the fixation rod near the lifting rod is fixedly connected to the lifting rod. By setting up the stabilizing mechanism, after the device is moved to the in-use position, the positioning pin is taken out to release positioning of the movable rod. The movable rod is moved out of the fixation case and is positioned again by the positioning pin. The movable rod is prevented from moving randomly. The first electric extendable-retractable rod moves the support plate downwards to contact the contact surface and stops operating until the base is lifted up to a certain height.