Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
  • B62D—MOTOR VEHICLES; TRAILERS
  • B62D5/00—Power-assisted or power-driven steering
  • B62D5/04—Power-assisted or power-driven steering electrical, e.g. using an electric servo-motor connected to, or forming part of, the steering gear
  • B62D5/0457—Power-assisted or power-driven steering electrical, e.g. using an electric servo-motor connected to, or forming part of, the steering gear characterised by control features of the drive means as such
  • B62D5/046—Controlling the motor
  • B62D5/0463—Controlling the motor calculating assisting torque from the motor based on driver input
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
  • B62D—MOTOR VEHICLES; TRAILERS
  • B62D5/00—Power-assisted or power-driven steering
  • B62D5/04—Power-assisted or power-driven steering electrical, e.g. using an electric servo-motor connected to, or forming part of, the steering gear
  • B62D5/0457—Power-assisted or power-driven steering electrical, e.g. using an electric servo-motor connected to, or forming part of, the steering gear characterised by control features of the drive means as such
  • B62D5/0481—Power-assisted or power-driven steering electrical, e.g. using an electric servo-motor connected to, or forming part of, the steering gear characterised by control features of the drive means as such monitoring the steering system, e.g. failures
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
  • B62D—MOTOR VEHICLES; TRAILERS
  • B62D5/00—Power-assisted or power-driven steering
  • B62D5/04—Power-assisted or power-driven steering electrical, e.g. using an electric servo-motor connected to, or forming part of, the steering gear
  • B62D5/0457—Power-assisted or power-driven steering electrical, e.g. using an electric servo-motor connected to, or forming part of, the steering gear characterised by control features of the drive means as such
  • B62D5/0481—Power-assisted or power-driven steering electrical, e.g. using an electric servo-motor connected to, or forming part of, the steering gear characterised by control features of the drive means as such monitoring the steering system, e.g. failures
  • B62D5/0493—Power-assisted or power-driven steering electrical, e.g. using an electric servo-motor connected to, or forming part of, the steering gear characterised by control features of the drive means as such monitoring the steering system, e.g. failures detecting processor errors, e.g. plausibility of steering direction
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
  • B62D—MOTOR VEHICLES; TRAILERS
  • B62D6/00—Arrangements for automatically controlling steering depending on driving conditions sensed and responded to, e.g. control circuits
  • B62D6/008—Control of feed-back to the steering input member, e.g. simulating road feel in steer-by-wire applications

Definitions

• the invention relates to a method for operating a power steering system, such a power steering system, a control device and a computer program and a computer program product for carrying out the method.
• Power steering systems also referred to as power steering systems, serve to achieve a reduction in the force that must be applied by the driver to steer.
• a motor torque is calculated as a function of various input variables, which is superimposed on the manual torque applied by the driver as an additional torque.
• safety measures In order to limit possible error effects in EPS systems, additional measures are known, which are referred to below as safety measures. For this purpose, operating points can be prevented by observing the combination of manual and motor torque relevant to safety by limiting to permissible combinations in the function path.
• the publication DE 10 2009 000 165 A1 describes a method for operating a power steering system, in which an engine computation unit calculates an engine torque and adjusts it by a suitable motor drive.
• a plausibility check of the calculated engine torque is carried out within the framework of the safety concept, which is represented by a 3-level concept, for example.
• An integration of a component above an engine torque limit curve and a decrementation of an integrator with a component below the engine torque limit curve are performed.
• the desired engine torque in level 1 is limited at a first integration threshold.
• level 2 the limitation is monitored.
• an intrinsically safe motor torque limit curve is used as a function of an actual torque.
• the presented method is used to operate a power steering system, wherein an engine computation unit calculates an engine torque and adjusts it by a suitable engine control, with a plausibility check of the calculated engine torque taking into account a measured manual torque. In addition, an amount of the additional moments of at least one special function is taken into account.
• the measured manual torque is increased.
• the manual torque is reduced.
• the plausibility check is carried out within the scope of e.g. a 3-level concept.
• the manual torque which is usually detected by a manual torque sensor, is regulated by specifying a desired manual torque.
• a power steering system of a motor vehicle which is particularly suitable for carrying out a method of the type described above.
• This power steering system comprises an electronic computing unit for calculating an engine torque, an electric motor for initiating a usually specified additional torque or engine torque, and a device for detecting a current hand torque.
• a manual torque sensor for example a torsion bar torque sensor, is usually used.
• the power steering system is characterized in that a plausibility of the calculated engine torque is performed taking into account the measured manual torque and that in the plausibility of an additional amount of additional moments of at least one special function is taken into account.
• control unit which is provided in particular for use in a power steering system of the type described.
• This control unit has an electronic computing unit, with which an engine torque is calculated, which is subjected to a plausibility check. In this case, an additional amount of additional moments of a special function is taken into account.
• the behavior of the safety function can basically be distinguished in cases where the special function increases the manual torque and cases in which the special functions reduce the manual torque.
• Increasing the hand moment means reducing the assist power, i.
• the EPS motor has to bring less moment into the system.
• the engine torque always remains within the limits, because a reduction of the support performance is safety-related, the transition to safe state (no support).
• a functional limitation does not occur.
• the moment overlay should make it easy for the driver if he steers in the right direction. "To make easy” means reducing the manual torque in this case, which means increasing the EPS motor torque.
• Advantages of the invention include, inter alia, that a moment-based EPS special function can be operated without functional restriction, without requiring a deactivation of the safety function and a change of the accepted released parameters of the safety function. In doing so, potentially possible error effects are improved.
• the procedure can be justified in the context of the proof of security.
• the method described is particularly suitable for use in EPS systems with means for introducing an additional torque to achieve a free steering moment influencing means for detecting the current hand moments, means for detecting electrical quantities of the electric motor and means for detecting the rotor position or the rotor speed of the electric motor.
• the presented control is typically done with a control system that is suitable for controlling a given additional torque.
• the following process steps are typically carried out:
• control is thus carried out with a control system for generating additional moments, wherein expediently a microprocessor is provided which communicates with an intelligent security computer (watchdog).
• an intelligent security computer watchdog
• the 3-level concept is used to secure the computer core.
• the method discussed is based, at least in some of the embodiments, on the following requirements for the EPS special functions:
• the superimposition moments must either be restricted in terms of magnitude and gradient to intrinsically safe values or must ensure ASILD integrity through plausibility measures.
• the overlay moments may only be requested in special situations and must be monitored and limited in time.
• the superposition moments must make the switch-on direction plausible and rule out unwanted, possibly oscillating sign changes.
• the computer program described comprises program code means for performing all the steps of a method as described above when the computer program is executed on a computer or a computing unit.
• a computer program is also presented with program code means to perform all the steps of a method described above when the computer program is executed on a computer or a corresponding computing unit.
• the computer program product comprises these program code means which are stored on a computer readable medium.
• This computer program can be stored on a computer-readable data carrier, such as a floppy disk, CD, DVD, hard disk, a USB memory stick or the like or an Internet server as a computer program product. From there, the computer program can be transferred to a memory element of the control unit.
• a computer-readable data carrier such as a floppy disk, CD, DVD, hard disk, a USB memory stick or the like or an Internet server as a computer program product. From there, the computer program can be transferred to a memory element of the control unit.
• Figure 1 shows an embodiment of the power steering system according to the invention.
• Figure 2 shows a graph of the course of the engine torque limit curve to illustrate the safety function for special functions that increase the manual torque.
• FIG. 3 shows in a graph the progression of the engine torque limit curve to clarify the safety function for special functions which reduce the manual torque.
• Figure 1 shows in the figures Figure 1 a and Figure 1 b shows an embodiment of the power steering system, which is generally designated by the reference numeral 10. Furthermore, a steering handle 12, a front axle 14 with two hinged wheels 16, an electric motor or EPS motor 18, a control unit 20 with an electronic computing unit 21 and a manual torque sensor 22 are shown in FIG. By the control unit 20 with arithmetic unit 21, a motor drive for driving the motor 18 is realized.
• FIG. 1 b which describes a software which is executed in the arithmetic unit 21 from FIG. 1 a
• a control 23 and a block 24 are provided, which specify default values for the control 23.
• a driver assistance section 25 and a steering feel command area 26 are provided.
• the steering feeling is introduced via the path M Le nkgeti (arrow 27) into the system, the overlay moments on the path M driver assistance (arrow 28).
• the manual torque sensor signal is input from the manual torque sensor 22 of Figure 1 a.
• the specification of the engine torque for the motor 18 of Figure 1 a is introduced via the path M Le nkgeti (arrow 27) into the system, the overlay moments on the path M driver assistance (arrow 28).
• the solution is based on the correction of the manual torque to compensate for the additional torque caused by the change of the special function and thus leaves the tuned and freewheeling parameters unchanged. This calculates a manual torque without special function for the identical steering movement would be required. This corrected signal is supplied to the safety function. There are no functional limitations associated with the special functions.
• FIG. 2 shows a curve 30 of the engine torque limit curve in a graph.
• the actual moment of hand is plotted on an abscissa 32 and the engine torque is plotted on an ordinate 34.
• the illustration serves to clarify the correction of the safety function for special functions that increase the manual torque.
• the replacement manual torque corresponds to the manual torque that is required when the curve is passed through without special function.
• the permissible engine torque is shifted from the first region 50 into a second region 52 (arrow 54), with the result that the possible error effects are significantly lower.
• the engine torque limit curve 30 is plotted in accordance with FIG.
• the illustration serves to clarify the correction of the safety function for special functions that reduce the manual torque.
• the proportion of the electric motor increases because he has to give more support.
• At low torques due to the plausibility measure however, only low EPS engine torques are permitted, ie the requirement of the special function is only possible to a very limited extent and is limited (first range 60).
• the replacement manual torque corresponds to the manual torque that is required when the curve is passed through without special function.
• the permissible engine torque is shifted from the first area 60 into a second area 62 (arrow 64) and the torque request of the special function is permitted.

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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)
• Power Steering Mechanism (AREA)

Priority Applications (3)

Applications Claiming Priority (2)

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ID=44947107

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Country Status (5)

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Citations (3)

Family Cites Families (16)

• 2010
  • 2010-11-15 DE DE102010043915.0A patent/DE102010043915B4/de active Active
• 2011
  • 2011-11-15 CN CN201180054853.8A patent/CN103209880B/zh active Active
  • 2011-11-15 WO PCT/EP2011/070087 patent/WO2012065961A1/de not_active Ceased
  • 2011-11-15 JP JP2013539221A patent/JP5926274B2/ja active Active
• 2013
  • 2013-05-09 US US13/890,641 patent/US9555829B2/en active Active

Patent Citations (3)

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