315 results about "Adhesion coefficient" patented technology

The invention discloses a control method for avoiding collision during emergent lane changing of a vehicle in a high-speed state and belongs to the technical field of vehicle active safety. A detecting unit obtains a road adhesion coefficient as well as the speeds, distance and accelerated speeds of the vehicle and a vehicle on an adjacent lane through a GPS/INS, millimeter-wave radar, a high-definition camera, a speed sensor and an accelerated speed sensor. A processing unit judges whether an alarm is given or an emergent lane changing collision avoiding intervention measure is taken under the collision risk situation according to the data of the detecting unit. An alarm unit carries out voice prompting and carries out displaying through a vehicle-mounted terminal. An executing unit achieves lane changing collision avoiding intervention through a braking controller and a steering controller. According to the method, risk early warning and lane changing prompting are achieved, under the situation that accidents cannot be avoided through emergent braking, the lane changing direction is judged according to the speed, accelerated speed and distance of the vehicle on the adjacent lane, an emergent lane changing trajectory is planned reasonably, and thus the purpose of avoiding accidents by avoiding collision during emergent lane changing is realized.

The invention discloses an implementation method for a speed feedback sign for bend steering vehicle speed safety state prewarning. The speed feedback sign system which consists of a monitoring camera, a rain sensor and a speed feedback sign device is arranged on the roadbed side of a road in front of a bend entrance in a retrograde vehicle direction, wherein a central control chip, a speed measuring radar, a light emitting diode (LED) display screen and prompting characters are arranged in the speed feedback sign device; a driver is warned to control the vehicle speed within a proper range before a vehicle enters a bend according to the conditions such as types of driven vehicles, weather conditions and road alignment conditions, so that traffic accidents after the vehicle enters the bend are prevented, and bend entrance critical safe vehicle speed corresponding to different vehicle types can be prompted in real time aiming at the change of road adhesion coefficients caused by different weather conditions and different bend road sections, and vehicle speed information and running states are fed back to the driver before the vehicle enters the bend; and therefore, enough time for the driver to adjust the vehicle speed is ensured and the road operation safety is improved.

The invention discloses a hierarchical system used for a four-wheel-hub motor-driven electric automobile, and a control method. First of all, yaw moment is calculated as a yaw moment decision-making layer according to a vehicle speed sensor, a steering wheel rotary angle transmitter, an electronic throttle sensor and an inertia measurement unit; then according to automobile longitudinal force constraints, yaw moment constraints, a maximum adhesion force which can be provided by a pavement and restrictions of motor maximum output moment, target torque of each wheel hub motor is calculated as a target optimization analysis layer; and finally, degrees of similarity to six standard pavements are obtained by inputting two parameters, i.e., an adhesion coefficient and a wheel slip rate into a pavement adhesion coefficient estimation fuzzy controller by means of a current pavement, and an adhesion coefficient estimated value of the current pavement is obtained as a pavement adhesion coefficient monitoring layer after weighted averaging is performed. According to the invention, whole-vehicle stability is taken as a control target, motor torque is reasonably distributed according to operation working conditions, and the controllability, the stability and the economic property of vehicles are improved.

The invention discloses an electric vehicle energy recovery system and a control method thereof. On the basis of the pressure of a brake master cylinder of an electric vehicle, a maximal brake force Fm which is allowed to be applied to a current driving wheel is obtained by calculating according to a brake force distribution curve in an electric vehicle brake system design and a driving wheel locking curve when the electric vehicle travels on a road surface with an ideal synchronous surface adhesion coefficient; and the Fm is converted into a torque, namely a maximal motor brake torque which can be applied currently so that the overall vehicle energy of the electric vehicle can be recovered to the maximum. Simultaneously, the calculated brake torque is corrected according to the requirements on the drivability and the safety of a vehicle, so that brake energy can be recovered to the maximum on the premise of ensuring the drivability and the safety of the electric vehicle.

The invention discloses a method for estimating the longitudinal adhesion coefficient of a road. The method comprises the following steps: preliminarily estimating a longitudinal road adhesion coefficient in real time on the road surface of a flat expressway by using a recursive least squares (RLS) method with a forgetting factor specific to a front-wheel steering four-wheel automobile on the basis of an overall longitudinal dynamics model and a simplified magic formula tire model; further filtering signal noise by using an extended Kalman filter (EKF) algorithm by taking the estimated longitudinal road adhesion coefficient and a tire model parameter as expansion states, and realizing self-adaptive adjustment of a tire model coefficient; finally, acquiring accurate and robust longitudinal road adhesion coefficient estimation in real time. The method can adapt to working conditions of high slip rate and low slip rate of flat expressways at the same time.

The invention discloses a vehicle ABS test bed with changeable attachment coefficient and comprises a front and a back shaft frames, a front and a back fly wheel shafts, a transmission box and a telescopic transmission shaft; the front and the back shaft frames are respectively and symmetrically provided with a front left wheel, a front right wheel, a back left wheel and a back right wheel roller group and the front left wheel, the front right wheel, the back left wheel and the back right wheel roller group are totally uniform; each roller group is respectively connected with the output end of a torque controller through a transmission belt in correspondence and the input end of the torque controller is respectively and rigidly connected with the front and the back fly wheel shafts; the front and the back fly wheel shafts are connected with the telescopic transmission shaft through the transmission box to realize mutual synchronization; each fly wheel shaft is rigidly and symmetrically provided with two fly wheels with same turning inertia; the braking force of the wheel of the measured vehicle can be changed by controlling magnetizing current of the torque controller when the wheel is in lock braking and then the attachment coefficient of the road can be simulated. The invention can be widely applied in vehicle examination, ABS research and development, vehicle maintenance and service industry.

The invention discloses an automobile active anti-collision early warning system based on millimeter-wave radars. The automobile active anti-collision early warning system mainly comprises a signal acquiring and processing module I, an automobile information acquiring module II, a judgment recognition module III, a man-machine interaction module IV and an execution system module V. The signal acquiring and processing module I utilizes the millimeter-wave radars I-1 to obtain the speed, a distance and an azimuth angle of a target X relative to an automobile Z and outputs the information processed by a processor I-2. The automobile information acquiring module II utilizes an ABS wheel speed sensor II-1 to obtain the automobile speed and road adhesion coefficient of the automobile Z and outputs the information processed by an auxiliary II-2. The judgment recognition module III judges the type of the target X, transmits the target type to the man-machine interaction module IV and transmits a control strategy to the execution system module V. By taking corresponding avoidance control measures, the automobile active anti-collision early warning system can remind a drive to take the measures so as to ensure safe and comfortable driving in advance of enough time, effectively recognize a dangerous target, remind the driver and improve the system safety.

The invention provides an automatic emergency braking method and an automatic emergency braking device. The method comprises the steps that a corresponding relationship of road adhesion coefficient and target deceleration is set, and the target deceleration obtained through the corresponding relationship can avoid the intervention of a deadlock prevention braking system under the condition of the road adhesion coefficient; the current road adhesion coefficient is obtained via the deadlock prevention braking system; the corresponding relationship is searched according to the current road adhesion coefficient, so that the current target deceleration is obtained; the collision time is calculated according to the speed of the vehicle, the speed of a front vehicle, the distance between the two vehicles and the current target deceleration; when the collision time is less than a threshold value, the automatic emergency braking is carried out according to the current target deceleration. The automatic emergency braking method and the automatic emergency braking device aim to ensure the performance of the automatic emergency braking system and prevent the occurrence of collision accidents when the vehicle runs under lower road adhesion coefficient.

The invention provides an automobile service braking efficiency dynamic monitoring and alarming system, and belongs to the fields of automobile electronics and safety technologies. The system is characterized in that an output end of an original automobile card reader, an output end of an original automobile CAN bus, an output end of a gyroscope and an output end of a brake pedal sensor are connected with an input end of an information collection and control unit respectively; firstly, the information collection and control unit collects automobile pitch angles through the gyroscope, and the gradient of a monitored road is not more than 1%; secondly, the information collection and control unit detects the maximum deceleration of an automobile in the ABS working process, and the adhesion coefficient of the monitored road is not less than 0.7; thirdly, the information collection and control unit eliminates working conditions like pits, deceleration strips and road steps according to the maximum braking deceleration of the automobile; fourthly, the information collection and control unit monitors brake pedal strokes through the brake pedal displacement sensor so as to distinguish emergent brake working conditions. The CAN bus is used for collecting ABS wheel speed signals, the initial speed of braking is estimated in a maximum wheel speed method, MFDD is computed in real time combined with braking deceleration signals and is compared with a pre-stored standard value, and the compared result is sent to the alarming device to give an alarm to a driver. The automobile service braking efficiency dynamic monitoring and alarming system can carry out on-line monitoring and estimation on service braking efficiency and can be a great help for preventing traffic accidents caused by service braking efficiency abnormity, and is simple in structure, easy to realize and low in cost.

The invention discloses an electronic parking braking method. The method comprises the following steps of: first, parking braking, namely transferring prestored air pressure in an air reservoir to brake chambers of each wheel by controlling an active air supply electromagnetic valve to realize the parking braking; and second, releasing braking, namely when a road section is a straight road surface, simultaneously releasing a drive wheel and a driven wheel of a controlled vehicle once; and when the road section is a downhill road section or an uphill road section, adopting a corresponding control strategy according to the rotating situations of each wheel of the vehicle, and releasing the air pressure in the brake chambers of each wheel of the controlled vehicle separately by utilizing a pressure maintaining effect of an antilock brake system (ABS) electromagnetic regulating valve. The electronic parking braking method has a reasonable design, low investment cost, high intelligence degree and good use effect, is convenient to operate, and solves the practical problems of high technical requirements on drivers, brake force transfer gap of mechanical system, great difficulties in starting operation on low-adhesion coefficient road surface and ramp, poor use effect and the like in a conventional mechanical parking braking system.

The invention relates to a road surface self-adaptive driving anti-skid control method and system of a distributed driving electric automobile and belongs to the technical field of vehicle control. According to the road surface self-adaptive driving anti-skid control method of the distributed driving electric automobile, by estimating a current road surface peak adhesion coefficient in real time,a current road surface optimal slip rate is obtained according to a corresponding linear relation between the current road surface peak adhesion coefficient and the current road surface optimal slip rate; by combining a current wheel center speed, a current wheel reference wheel speed is determined; a difference between an actual wheel speed and the reference wheel speed is calculated; according to the wheel speed difference, the moment of a wheel, which slips in a driving state, is controlled by using a sliding mode variable structure controller; and therefore, it is guaranteed that the wheelslip rate is controlled to the current road surface optimal slip rate. According to the road surface self-adaptive driving anti-skid control method of the distributed driving electric automobile, thewheel slip rate is controlled to the current road surface optimal slip rate to realize self-adaptive control of anti-skid driving of the wheel.

The invention discloses a convolutional neural network-based road adhesion coefficient identification method in the field of image identification. In most of the existing technologies, dynamic modeling is adopted to indirectly estimate the road adhesion coefficients, and according to the method disclosed by the invention, an image processing method is adopted to directly identify the road adhesion coefficients, so that defects in the prior art can be overcome. The method comprises the following steps of: acquiring different road condition pictures; calibrating a road adhesion coefficient; establishing a road condition picture database; judging a position calibrated by a feature area of each road condition picture in the database by utilizing an image segmentation algorithm; extracting sensitive areas with different pixel sizes; inputting the sensitive areas which serve as training samples into a convolutional neural network to carry out training; and finally identifying road conditions by utilizing the trained convolutional neural network so as to obtain the road adhesion coefficient. Compared with the prior art, the method has the advantage that road adhesion coefficients (the road adhesion coefficients are assumed to be known in most conditions during trajectory tracking) are identified by adoption of images, so that the safety and comfort of drivers in the driving process are strengthened.

The invention relates to a real-time road adhesion coefficient detection method and detection system, belongs to the technical field of intelligent automobile detection and monitoring, and is used for real-time accurate detection of road adhesion coefficient. The method comprises the following steps of: establishing a real time road adhesion coefficient detection model and testing system under automobile damped condition; under the condition that the automobile is travelling on a flat road, depressing by a driver a clutch pedal while depressing a brake pedal, so that engine braking is isolated; acquiring the rotation speed of front and back wheels, the longitudinal acceleration of an automobile centroid, the speed of the automobile and the vertical load on the front and back vehicle through an information acquisition system; obtaining the road adhesion coefficient through a road adhesion coefficient computation model; and displaying thee adhesion coefficient on a display unit in real time. The system comprises the information acquisition unit for acquiring automobile information in real time, a data processing unit for processing information input by the information acquisition unit, a singchip system for controlling data acquisition and realizing data computational analysis and controlling result output, and an LED (Light-Emitting Diode) output display unit.

The invention belongs to the technical field of automobile brakes, in particular to a method for estimating the brake pressure of an automobile and the peak value of the road adhesion coefficient, more particularly, the invention intends to provide a method for estimating the brake pressure of an automobile and the peak value of the road adhesion coefficient on the basis of the conditions of the wheel speed and pressure control under the condition that no component for measuring the brake pressure is introduced. The method comprises the following steps: grading the peak value of the road adhesion coefficient and the brake pressure; and estimating the peak value of the road adhesion coefficient and the initial brake pressure of a wheel cylinder. By estimating the peak value of the road adhesion coefficient and the initial brake pressure of the wheel cylinder, the invention is capable of estimating the brake pressure of the automobile and the peak value of the road adhesion coefficient under the condition that no component for measuring the brake pressure is introduced, thus improving the breaking efficiency of an ABS (anti-lock braking system) and providing strong support for the fail-safe function. According to the tests, the maximum relative error between the estimated value and the measured value of the pressure of the wheel cylinder of the brake is lower than 10%, thus meeting the requirements for ABS control, reducing the cost and facilitating the popularization of the ABS in the field of braking and being beneficial to the improvement on the traffic safety.

The invention discloses a self-adaptive autonomous emergency brake (AEB) control algorithm based on road adhesion. The self-adaptive autonomous emergency brake control algorithm based on the road adhesion predicates collision risk between a vehicle and a forward obstacle though obtaining forward obstacle information, information of the vehicle and a road adhesion coefficient and makes a final pre-warning and autonomous braking decision by taking control input of a driver into consideration so as to remind the driver of adopting forward collision avoidance control or avoid collision between the vehicle and the forward obstacle or reduce collision degree between the vehicle and the forward obstacle by using autonomous braking interference if necessary. According to the self-adaptive autonomous emergency brake control algorithm based on the road adhesion, on the premise of not changing the configuration of the existing vehicle-mounted sensor, the road adhesion coefficient is estimated in real time; the pre-warning and autonomous braking opportunity can be automatically adjusted in a safe distance model according to the road adhesion coefficient so that the forward collision avoidance safety on road surfaces with various road adhesion coefficients is ensured and false alarm or false brake interference is avoided; driving safety and good driving experience are both achieved; and during driver brake interference, the self-adaptive autonomous emergency brake control algorithm based on the road adhesion can apply necessary brake assistance according to the calculated collision risk.

Provided is a four-wheel steering control method for maintaining the lateral stability of an automobile under an extreme working condition. The method is characterized by involving a reference model,a tire lateral force and cornering stiffness processor, an MPC controller and an automobile model. The reference model is used for determining the desired automobile yaw rate; the tire lateral force and cornering stiffness processor is used for determining side slip angle, lateral force and cornering stiffness of tires; the automobile model is used for outputting the actual motion state information of the automobile, and the actual motion state information includes automobile longitudinal velocity, yaw rate, centroid side slip angle and road adhesion coefficient; the MPC controller combines the desired automobile yaw rate and the actual motion state information of the automobile for optimization solution to obtain rotation angle of rear wheels of the automobile and outputting to the automobile model to control the lateral stability of the automobile under the extreme working condition.

The invention relates to a technology for preparing a mineral composite solid lubricant for well drilling on the basis of by-products in chemical industry. The solid lubricant is prepared by taking by-product residue (or residual liquid) of sodium dithionite powder distillation as a main ingredient, adopting graphite and/or expanded graphite mineraloid as a loading material, taking animal oil or vegetable oil or oil based surfactants derived from the animal oil or the vegetable oil as a lubricating property regulator, and adding a certain amount of a combined drilling-fluid property regulator prepared by matching special fluid loss additive for drilling fluid, a collapse preventing agent and an emulsifying agent according to a specific proportion through processes such as mixing, extrusion, kneading, and the like. The preparation method comprises a cross blending method, a kneading method, a twin-screw-rod extrusion method, a single-screw-rod extrusion method, and the like. Compared with the prior art, the invention has the advantages of simultaneously enhancing two lubricating properties of the adhesion coefficient reducing rate and the friction resistance coefficient reducing rate of the drilling fluid lubricant, and the collapse preventing property, and has the characteristics of low price, simplicity for production process, convenience for field transport and storage of petroleum drilling and geological prospecting drilling, and the like.

The invention discloses a torque vector control system of a hub four-wheel drive purely-electric vehicle. The torque vector control system comprises a vehicle state monitor, a friction coefficient estimator, a differential torque yawing moment decision making module, a torque control distributor module and a torque coordination control module. The differential torque yawing moment decision makingmodule is used for acquiring vehicle differential torque yawing moment by establishing a kinematics parameter relationship according to the driver input steering wheel rotating angle, vehicle motion information, the road surface adhesion coefficient, lateral tire force and longitudinal tire force. The torque control distributor module is used for acquiring ideal torque distributed values of all wheels according to four-wheel hub motor brake and drive torque requirements, the vehicle motion information, the road surface adhesion coefficient, tire parameter information, the battery SOC value anddifferential torque yawing moment. The control stability of the vehicle can be improved, and the steering sensitivity of the vehicle can be improved.

The invention relates to a high-friction coefficient composition brake shoe. The high-friction coefficient composition brake shoe comprises a steel backing and a friction material, the friction material comprises the following raw materials including, by weight, 1-5 parts of aramid fiber, 8-12 parts of butadiene-acrylonitrile rubber, 0.5-1 part of stearic acid, 0.3-1 part of an accelerant, 0.6-1 part of sulphur, 0.5-1 part of zinc oxide, 4-7 parts of phenolic resin, 10-20 parts of inorganic composite fiber, 8-15 parts of iron powder, 10-20 parts of barium sulfate, 7-15 parts of kibdelophane powder, 5-10 parts of steel wool fiber, 1-3 parts of bauxite, 8-15 parts of potassium feldspar powder, 2-5 parts of mica, 2-5 parts of flake graphite, 5-10 parts of sepiolite fiber and 2-5 parts of molybdenum disulfide. By means of the high-friction coefficient composition brake shoe, the change of the speed of the wear rate of the high-friction coefficient composition brake shoe can be basically identical to the change of the adhesion coefficient of a wheel track, the abrasion loss when a vehicle is braked is less, failure can not occur in braking, and the traffic safety is guaranteed. The invention provides a production method of the high-friction coefficient composition brake shoe at the same time.

The invention provides a drive anti-skid control method and a vehicle. The drive anti-skid control method includes the steps that the current control stage of a vehicle in a drive anti-skid state is determined; the current road adhesion coefficient of the vehicle is determined; according to the current control stage and the current road adhesion coefficient, the maximum torque permitted by the road surface is determined; and according to the maximum torque permitted by the road surface, the drive anti-skid required torque is output, wherein the drive anti-skid required torque is used for conducting drive anti-skid on the vehicle. By the adoption of the provided drive anti-skid control method, the response speed can be increased, robustness is enhanced, and control accuracy can be improved.

The invention provides a torque distribution method and system of a four-wheel drive vehicle and a vehicle. The torque distribution method of the four-wheel drive vehicle includes the following stepsthat a vehicle speed, a front wheel speed and a rear wheel speed are detected; a front axle slip ratio is obtained according to the road surface adhesion coefficient, the vehicle speed and the front wheel speed, and a rear axle slip ratio is obtained according to the road surface adhesion coefficient, the vehicle speed and the rear wheel speed; and an initial front and rear axle torque distribution ratio is adjusted according to the demand torque, the front axle slip ratio and the rear axle slip ratio to avoid vehicle slipping. The torque distribution method of the four-wheel drive vehicle caneffectively avoid wheel slipping and improve the dynamic property of the vehicle, thereby improving the stability and safety of the vehicle.