Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
  • B62D—MOTOR VEHICLES; TRAILERS
  • B62D15/00—Steering not otherwise provided for
  • B62D15/02—Steering position indicators ; Steering position determination; Steering aids
  • B62D15/027—Parking aids, e.g. instruction means
  • B62D15/0285—Parking performed automatically
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
  • B60T2201/00—Particular use of vehicle brake systems; Special systems using also the brakes; Special software modules within the brake system controller
  • B60T2201/10—Automatic or semi-automatic parking aid systems

Definitions

• the invention relates to a method for supporting the parking of a motor vehicle, which is equipped with a steering actuator and sensors for detecting the vehicle position, the driving state and changing environmental conditions, with a command of a driver to provide regulated support for the parking process by means of the steering actuator and based on predetermined vehicle data and is executed on signals from the sensors, and a device set up to carry out the method.
• an electronically controlled steering splitter attached to the steering gear of the front wheels, based on a driver's steering request detected by a steering wheel sensor, taking into account driving dynamics variables, the modification of the steering angle corresponding to the driver's steering request improved, ie that the vehicle is stabilized in dynamic driving situations.
• the system has a steering servomotor, which corrects the steering angle set by the driver added.
• DE 29 01 504 describes a method and a device for parking motor vehicles, which works with a pure control of the parking process. No feedback signals that change the course of the parking trajectory are taken into account, but instead fixed trajectories are specified.
• the method that solves the above task is characterized by the following steps:
• the path signal recorded in step B is advantageously recorded by a path encoder, preferably by a wheel speed sensor located on each vehicle wheel.
• the yaw angle signal which is also recorded in step, can either be measured by a suitable sensor or can be reconstructed from suitable signals, for example from the yaw rate of a yaw rate sensor and / or from the wheel speeds.
• the ambient conditions are preferably recorded in step C by means of an ultrasonic sensor.
• radar sensors or optical sensors e.g. B. cameras to use.
• the environmental conditions recorded in step C can indicate the shape or dimensions of a parking space.
• the or each target trajectory specified in step D is preferably composed of one or more clothoid arcs and / or one or more circular arcs.
• Radius of curvature s: arc length; a: parameter
• the manipulated variable calculated in step E is subjected to filtering, which smoothes abrupt transitions on the flanks of the manipulated variable.
• a device set up to carry out the method has a control /
• Control unit that receives signals generated by the sensors as a function of the vehicle position, the driving state and the changing environmental conditions and the vehicle data, means for calculating an actual trajectory from the sensor signals and the vehicle data, means for comparing the respectively calculated actual trajectory with one predetermined target trajectory and means for calculating a manipulated variable for a steering actuator from the comparison result.
• the regulating / control unit performing the method can have filter means or can be connected to the steering servomotor via filter means, so that the calculated manipulated variable can be filtered in the manner described above.
• the steering actuator used in the driving dynamics steering system being developed is sufficient because it enables automatic, precise and very fine steering interventions.
• the regulation carried out by the regulating / control unit enables precise maneuvers and temporary deviations from the target trajectory in order to increase driving comfort.
• the filtering increases driving comfort because it can smooth jerky movements of the steering wheel.
• FIG. 1 shows schematically functional blocks of the device according to the invention
• Fig. 2 shows graphically the geometric basis for determining a trajectory over the relationship between the radius of curvature R, the angle ⁇ and the path s;
• Fig. 3 graphically shows a clothoid as a curve, the curvature c (s) of which changes linearly with the path s;
• FIG. 4 illustrates, in a flat representation of a motor vehicle, variables which are used to determine the clothoid arches
• Ultrasonic sensors for recording the ambient conditions
• active wheel speed sensors that provide wheel speed signals until the vehicle stops
• a lateral acceleration sensor (optional) a lateral acceleration sensor.
• Fig. 1 shows functional blocks of the parking assistant.
• Vehicle data are available from block 1.
• block 1 is a memory in which the vehicle data are stored.
• An alternative possibility is a rule / control mechanism, which the
• Block 2 is the sensor block that includes the sensors mentioned above.
• Function block 3 calculates the target trajectory in the manner described below and for this purpose receives the vehicle data from block 1 and the sensor signals from block 2.
• a function block 4 provided for determining the actual trajectory likewise receives the vehicle data from block 1 and the sensor signals from block 2 as input signals.
• the rotation rate sensor is particularly important for the reconstruction of the yaw angle.
• the yaw angle can also be measured by a corresponding yaw angle sensor.
• the target trajectory specified in block 3 and the actual trajectory determined in block 4 are combined in one
• Comparator 8 compared.
• Function block 5 calculates the manipulated variable from the comparison result and from signals from blocks 1 and 2.
• the comparison between the target and actual trajectories enables precise control of the steering angle by means of the manipulated variable calculated in block 5. This regulation is possible because the steering interventions are carried out by a regulating / control unit.
• the manipulated variable calculated in function block 5 is filtered in function block 6. This filtering smoothes the flank of the manipulated variable and thus ensures that the steering acceleration and the jerk on the steering wheel do not become too high.
• the function block 6 is also supplied with vehicle data from the block 1 and filtered there or included in the filtering of the manipulated variable.
• driving state signals for example the orientation of the motor vehicle
• driving state signals for example the orientation of the motor vehicle
• Function block 7 represents an actuator which is designed as a steering actuator.
• the sensors and the steering actuator can Be part of a vehicle dynamics steering system. The additional costs for a device according to the invention in a motor vehicle can thus be reduced to a minimum.
• a control unit e.g. a vehicle computer that is present in the vehicle anyway.
• FIG. 2 shows how the angle ⁇ behaves with the change in the path s as a function of the radius of curvature R.
• the curvature c (s) is given by equation 1.1:
• the angle ⁇ is calculated from the path s using the following equation:
• Equation (1.11) can be transformed as follows:
• Equation 1.13 is used to quickly calculate important points of the trajectory.
• the following section uses the procedure to calculate a parking trajectory.
• the parking trajectory is calculated using an algorithm which is based on equation 1.13 explained above. Intuitive steering
• the vehicle to be parked is parallel to the parking space.
• the trajectory in the longitudinal direction is assumed to match the existing parking space.
• the parking trajectory should intuitively include the following phases:
• phases 2, 4 and 7 are assumed to be clothoid trajectories.
• phases 2 and 6, 3 and 5 are symmetrical.
• phase 2 is derived from FIG. 4.
• the clothoids are determined by a parameter k, which is based on the limitation of the steering angle and the driving and steering speeds.
• phase 3 is calculated so that the vehicle drives deep enough into the parking space.
• the influence of this Length on the trajectory is shown using FIGS. 6 and 7.
• FIG. 6 shows the trajectory of the vehicle when phase 4 does not exist.
• Coordinate system illustrates an exemplary parking trajectory and the underlying target steering angle.
• the route traveled is required to program the control system in the vehicle. In the vehicle, this path is measured with active wheel speed sensors or in a simplified form with the help of a position sensor.
• the wheel speed sensors can precisely measure the wheel speed down to zero speed.
• the driver is allowed to perform steering interventions during the parking process. However, these steering interventions have no influence on the maneuver. If there is an obstacle in the way of parking, the driver should brake and stop the parking process. Since the
• the yaw angle is calculated on the basis of the signals supplied by the yaw rate sensor. In highly dynamic driving maneuvers, this calculation can U. be time problematic. On the other hand, there are usually no steps when parking
• the parking assistant enables the steering angle to be properly controlled by calculating the yaw angle so that the vehicle orientation corresponds to the expected behavior.
• errors that can lead to a deviation between the driven and the calculated trajectory such as errors in the steering system or different friction, can be corrected.
• the manipulated variable is shown in the 1 shown function block 6 filtered by smoothing the abrupt jumps in the manipulated variable.
• the manipulated variable can be filtered so that the steering acceleration is limited. Since the target trajectory remains unchanged, deviations from the target trajectory can occur. Temporary deviations from the target trajectory are thus tolerated in order to enable a uniform driving maneuver and thereby increase driving comfort.
• the deviations between the target trajectory and the actual trajectory are corrected in the course of the parking process by the regulating / control unit using the method according to the invention.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Transportation (AREA)
• Mechanical Engineering (AREA)
• Steering Control In Accordance With Driving Conditions (AREA)

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• 1999
  • 1999-08-24 DE DE1999140007 patent/DE19940007A1/de not_active Withdrawn
• 2000
  • 2000-08-18 EP EP00969185A patent/EP1218808A1/de not_active Withdrawn
  • 2000-08-18 JP JP2001519240A patent/JP2003507263A/ja active Pending
  • 2000-08-18 WO PCT/DE2000/002818 patent/WO2001014941A1/de active Application Filing

Non-Patent Citations (1)

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