REDUNDANT MECHATRONIC SYSTEM

Abstract

A redundant mechatronic system. The redundant mechatronic system is formed with two channels and is or can be connected for the output of a varying mechanical power to a mechanical arrangement, wherein each of the two channels includes an energy supply and an actuation circuit or a common energy supply is connected upstream of both channels, and both channels can be controlled by at least one control unit. The control unit acts on the actuation circuits in such a manner that the actuation circuits in each case switch an electric power specified by the control unit and drawn from the energy supply through to in each case a winding set of at least one electrically operated actuator, in order to generate the mechanical power. The two channels are operated in parallel during normal operation, in such a manner that each channel provides half of the mechanical power to be instantaneously output.

Claims

1. A redundant mechatronic system, comprising: the redundant mechatronic system is formed with two channels and is or can be connected for the output of a varying mechanical power to a mechanical arrangement, each of the two channels comprises an energy supply, or a common energy supply is connected upstream of both channels, each of the two channels contains an actuation circuit and can be controlled by at least one control unit, the control unit acts on the actuation circuits in such a manner that in each case, the actuation circuit switches an electric power specified by the control unit and drawn from the energy supply through to a winding set of at least one electrically operated actuator, in order to generate the mechanical power, the two channels are operated in parallel during normal operation, in such a manner that each channel provides half of the mechanical power to be instantaneously output, each of the two channels is formed such that, when the respective other channel fails, it alone provides the maximum necessary mechanical power for performing a function of the mechanical arrangement, wherein the redundant mechatronic system includes arrangements connected to the control unit, by which overloads in the channels and/or in the components of the channels and/or in the mechanical arrangement can be detected by the control unit, when an overload is detected by means of the control unit, a reduction factor (Rf) counteracting the overload can be established and applied by the control unit, the reduction factor (RI) is calculated such that, in the case of application of the reduction factor (Rf) by the control unit, the maximum available system power of both channels is sufficient for performing the function, the channel power, using the reduction factor (Rf) as control variable, can be controlled by the control unit in such a manner that the respective instantaneous channel power counteracts the overload.

2. The redundant mechatronic system according to claim 1, wherein, by control unit of the redundant mechatronic system, in the case of the occurrence of an overload in one of the two channels and/or on one or more of the components in one of the two channels, the reduction factor (Rf) can be established such that, in the case of its application by the control unit, the channel power in the overloaded channel is reduced by an amount defined by the reduction factor (Rf), and in the non-overloaded channel, it is increased by the same amount.

3. The redundant mechatronic system according to claim 1, wherein, by the control unit of the redundant mechatronic system, in the case of the occurrence of an overload in the mechanical arrangement, the reduction factor (Rf) can be established such that, in the case of its application by the control unit, the power controlled by the control unit is reduced in the one channel and increased in the other channel by the same amount in a temporally alternating manner.

4. The redundant mechatronic system according to claim 1, wherein, in the case of the occurrence of an overload in both channels, a reduction factor (Rf) is determined for each of the channels by the control unit of the redundant mechatronic system, and the reduction factors (Rf) can be established such that, in the case of their application by the control unit, the power, controlled by the control unit, is reduced in both channels by an amount determined by the reduction factor (Rf), and the instantaneously available system power of both channels together is sufficient to perform the function, and in that the power reduction is carried out in a temporally alternating manner by the control unit and is cancelled until an overload is no longer present.

5. The redundant mechatronic system according to claim 1, wherein the channels of the redundant mechatronic system are formed such that, during normal operation, both channels together additionally can provide the power for performing an additional function of the mechanical arrangement, and the control unit is formed such that, in the case of occurrence of an overload, the additional function is deactivated at least when the maximum system power determined by the reduction factor (Rf) is not sufficient for performing the additional function.

6. The redundant mechatronic system according to claim 1, wherein the control unit of the redundant mechatronic system determines the reduction factor (Rf) as a function of the type and/or the degree of the overload that occurred.

7. The redundant mechatronic system according to claim 1, wherein the redundant mechatronic system is part of a servo steering system or of a steer-by-wire system or part of a steering system in an autonomously driving vehicle.

8. A method for operating the redundant mechatronic system according to claim 1, wherein the control unit: cyclically queries the arrangements for the detection of overloads in the channels and/or in the mechanical arrangement, in the case of the occurrence of an overload in one of the channels, it establishes a reduction factor (Rf), with the aid of the reduction factor (Rf), it determines a reduction variable for the instantaneous channel power of the overloaded channel, and, by corresponding actuation of the actuation circuits, it switches the reduced power (P.sub.R1) onto the winding system connected to said actuation circuit of the actuator of the overloaded channel, with the aid of the reduction factor (Rf), it determines an increase variable (Ef) corresponding in terms of amount to the reduction variable, for the instantaneous channel power of the non-overloaded channel, and, by corresponding actuation of the actuation circuits, it switches the power (P.sub.E2) increased by the increase variable onto the winding system connected thereto of the actuator of the non-overloaded channel, it maintains the change of the channel power as long as the overload is detected.

9. The method for operating the redundant mechatronic system according to claim 2, wherein the control unit: cyclically queries the arrangements for the detection of overloads in the channels and/or in the mechanical arrangement, in the case of the occurrence of an overload in the mechanical arrangement, it establishes a reduction factor (Rf.sub.2) for both channels, for one of the channels, starting from the power of the channel, which is provided for performing the function, by using the reduction factor (Rf.sub.2), it determines a reduced power (P.sub.R12), and, by corresponding actuation of the actuation circuits, in the first channel, it switches the reduced power (P.sub.R12) onto the winding system of the actuator, which is connected to the actuation circuit, at the same time, for the other channel, starting from the channel power provided for performing the function, using the reduction factor (Rf.sub.2), it determines an increase factor (Ef2), and applying it, it determines an increased power (P.sub.E22), and, by corresponding actuation of the actuation circuits in the one channel, it switches the increased power (P.sub.E22) onto the winding system of the actuator, which is connected to the actuation circuit, within a predetermined time span (T) it cancels the change again, in a time slot provided by the time span (T), it switches the channels and performs the change again. the procedure is repeated as long as the overload is detected.

10. The method according to claim 8, wherein, in the case of the occurrence of an overload, the control unit checks whether, after performed power reduction, both channels together can provide the power for the function and additionally the power for performing an additional function of the mechanical arrangement, and the control unit is formed such that it deactivates the additional function at least when the total system power available due to the power reduction is insufficient for performing the additional function.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Additional embodiments and advantages of the invention are explained in greater detail below in reference to the drawings. In the drawings:

[0027] FIG. 1 shows an autonomous steering system with a redundant mechatronic system as drive in a motor vehicle (simplified partial representation)

[0028] FIG. 2 shows a diagrammatic representation of a first operating principle of the redundant mechatronic system

[0029] FIG. 3 shows a diagrammatic representation of a second operating principle of the redundant mechatronic system

DETAILED DESCRIPTION

[0030] FIG. 1, in a simplified representation, shows an autonomous steering system in a motor vehicle 1 (partial representation). Represented is a redundant mechatronic system 2 which drives a vehicle steering 4 via a drive shaft 3. Said vehicle steering consists of a pinion 7 driven by the drive shaft 3, and acting on a toothed rod 8. The toothed rod 8 in turn acts on the tie rods 5 which are hinged at both ends of the toothed rod 8. The tie rods 5 are rotatably mounted by their second end on steering levers of the wheel suspension 17 and transfer the movements of the toothed rod 8 to the steered wheels 6 attached on the wheel suspension 17.

[0031] The redundant mechatronic system 2 comprises two channels, wherein the first channel consists of a first energy supply 12.1, of a first actuation circuit 11.1 and of a first winding set 10.1 of a double electric motor 9. The second channel analogously consists of a second energy supply 12.2, of a second actuation circuit 11.2 and of a second winding set 10.2 of the double electric motor 9. The double electric motor 9 has only one drive with which it drives the drive shaft 3. The redundant mechatronic system 2 is controlled by a control unit 13 which is connected by control technology to the first actuation circuit 11.1 of the first channel and to the second actuation circuit 11.2 of the second channel. The control unit 13 is moreover connected to an external vehicle computer 16 and has connections to sensors 14 one of which in each case is associated with each of the energy supplies 12.1, 12.2, each of the actuation circuits 11.1, 11.2 and each of the winding sets 10.1, 10.2 of the double electric motor 9 and picks up their temperature, such that a thermal overload can be detected separately in a component-based manner in each of the two channels. The torque sensor 15 picks up a measured value for the torque on the drive shaft 3 and is also connected to the control unit 13. By means of the torque sensor 15, an overload in the steering itself can be detected. As explained above, the redundant mechatronic system 2 is designed such that each of the two channels, in the case of failure of the other channel, can completely take over the performance of the function (in the example, the performance of a steering movement) in each case.

[0032] For the additional explanation of the operating principle of the redundant mechatronic system 2, it is first assumed that a temperature has built up in the first actuation circuit 11.1, which represents a thermal overload. The control unit 13, which during the operation of the arrangement cyclically queries the sensors 14, 15, detects this state as an overload in the first channel.

[0033] The reaction to the detection of the overload is subsequently explained in greater detail with the aid of FIG. 2. For this purpose, in the representation, the power course in the two channels is shown. The upper representation in FIG. 2 shows the power course P.sub.K1 in the first channel and the lower representation in the drawing shows the power course P.sub.K2 in the second channel, in each case with respect to time t.

[0034] In reaction to the detection of the above-discussed overload at time TA, the control unit 13 establishes a reduction factor Rf, which is 40% in the example, based on the type (excess temperature in the first actuation circuit 11.1) and optionally on the level of the excess temperature, when a corresponding temperature measurement is provided. Starting from the power P.sub.N1 necessary at this time for performing the function, the control unit 13 reduces this power P.sub.N1, with the assistance of the reduction factor Rf, by the power P to the reduced power P.sub.R1, in that it correspondingly reduces the current intensity flowing via the actuation circuit 11.1. At the same time, the control unit, applying the reduction factor Rf with opposite mathematical sign, determines an increase factor Ef for the second channel and increases the power P.sub.N2 necessary at this time for performing the function by the power P to the increased power P.sub.E2, in that it correspondingly increases the current intensity which the actuation circuit 11.2 applies to the second winding system 10.2. The above described state is maintained until the control unit, at time T.sub.E, by querying the sensor 14, no longer detects an elevated temperature in the actuation circuit 11.1.

[0035] As can be seen from FIG. 2, the necessary power reduction in the first channel due to the thermal overload of the first actuation circuit 11.1 is completely compensated by the power increase in the second channel. The first actuation circuit as a result receives the opportunity to cool, while the components in the second channel are only insignificantly heated, since the second channel is operated within its specification.

[0036] FIG. 3 shows an additional example of the operating principle of the redundant mechatronic system. For this purpose, in this case as well, the power course in the two channels is shown in the representation. In FIG. 3, the upper representation shows the power course P.sub.K12 in the first channel and the lower representation in the drawing shows the power course P.sub.K22 in the second channel, in each case with respect to time t.

[0037] In this example, it is assumed that the control unit 13 detects an excessively high torque at time T.sub.A2 via the torque sensor 15. An excessively high torque can be caused, for example, when the steered wheels are on a supporting surface which strongly impedes a steering movement and a steering movement is carried out when the vehicle is standing still.

[0038] In reaction to the detection of the above-discussed overload at time T.sub.A2, the control unit 13 establishes a reduction factor Rf.sub.2, which is 50% in the example, based on the type of overload (overshooting of torque in the steering). Starting from the power P.sub.N12 necessary at this time for performing the function, the control unit 13 reduces this power P.sub.N12, with the assistance of the reduction factor Rf.sub.2, by the power P.sub.2 to the reduced power P.sub.R12, in that it correspondingly reduces the current intensity flowing via the actuation circuit 11.1. At the same time, applying the reduction factor Rf.sub.2 with opposite mathematical sign, the control unit determines an increase factor Ef.sub.2 for the second channel and it increases the power P.sub.N22 necessary at this time for performing the function by the power P.sub.2 to the increased power P.sub.E22 in that it correspondingly increases the current intensity which the actuation circuit 11.2 applies to the second winding system 10.2. After the elapse of the time t, the control unit 13 reverses the change performed, and, after the elapse of a time t, the control unit again performs the changes with switching of the channels, such that now the power P.sub.N12 in the first channel is increased by the power P.sub.2 to the increased power P.sub.E22, and the power P.sub.N22 in the second channel is reduced by the power P to the reduced power P.sub.R22. The above-described procedure is repeated until the control unit 13, by querying the torque sensor 15, at time T.sub.E2, does not detect an increased torque.

[0039] In contrast to the example described in connection with FIG. 3, one can also proceed in such a manner that the control unit 13 establishes the increase factor Ef.sub.2 to be higher than the reduction factor Rf.sub.2. Thereby, the system power is increased in a pulsed manner, such that a possible obstacle impeding the steering movement can be overcome. The increase factor Ef.sub.2 can here be increased at most until the maximum channel power is reached.

[0040] In conclusion, it should be pointed out that, in the examples according to FIG. 2 and FIG. 3, for reasons having to do with the representation, the power P.sub.N1 necessary for performing the function was assumed to be constant; however, this does not have to be the case. Instead, it is likely that the power P.sub.N1, P.sub.N12 necessary for performing the function varies, since, depending on the situation, the steering movements predetermined by the vehicle computer 16 also vary. In this case, the power reductions P, P.sub.2 or power increases +P, +P.sub.2 naturally also vary.