Abstract:
The present invention describes a coordination device for nominal values for the brake and/or the engine. The arrangement is based on a system wherein various components contribute to controlling the longitudinal dynamics of a vehicle. According to the present invention, these components generate in parallel to each other intermediate nominal values for the brake and/or the engine. According to the intermediate nominal values prevailing, coordination devices generate engine or brake nominal values which are sent to the corresponding components.

Description:
TECHNICAL FIELD 
     The present invention relates to vehicle control systems and more particularly relates to a method and a device for controlling the longitudinal dynamics of a vehicle. 
     BACKGROUND OF THE INVENTION 
     The present invention relates to the driving dynamics control systems of an automotive vehicle and, therefore, the disclosure of applicant&#39;s application No. 196 54 769.5 of Dec. 28, 1996 is included in its full contents because this application also refers to the longitudinal dynamics control of vehicles. 
     Modern processes and devices for controlling the longitudinal dynamics of a vehicle comprise an engine which is controlled by engine management or a corresponding device, a controlled brake, a controlled transmission as well as a complex vehicle dynamics control which predetermines nominal values for the brake, the transmission and the engine in response to the driver&#39;s demands and internal and external operating conditions of the vehicle. 
     Modern engine management often detects the nominal engine torque as an input quantity, and the brake can be supplied with the nominal brake pressure as an input quantity. These nominal values are generated by an ICC control (Intelligent Cruise Control) to which, in turn, the above-mentioned quantities are sent. Among these are the driver&#39;s speed demand, which is imparted to the vehicle via the accelerator pedal and brake pedal, various quantities sensed by sensors such as speed, longitudinal and transverse acceleration, distance from and relative speed with respect to a vehicle which drives ahead, etc. In longitudinal dynamics control operations, various components influence the nominal engine torque or the nominal brake pressure: On the one hand, the mentioned nominal values are determined according to a predetermined nominal acceleration (which, in turn, results from different components, for example, requirements indicated by the driver, cornering speed control, automatic cruise control, etc.). In addition, there is the traction slip control system TCS by which spinning of the wheels is prevented. TCS control operations reduce the torque requirements to be met by the engine. Engine stall torque control MSR prevents locking of the wheels when shifting down, for example, when shifting from the third into the second gear on a slippery road surface and with rear-wheel drive. Engine stall torque control increases the torque requirements. An automatic stability management system ASMS intervenes especially in the braking of the individual wheels, but can also take effect on the transmission and the engine. For example, individual wheels may be optionally braked with an ASMS control, also known as driving stability control system, in order to prevent a vehicle from skidding. 
     The above-mentioned components thus take effect on the determination of nominal values for the engine, transmission and/or brake. Up to now, however, no satisfying solution has been found regarding the joint processing of all influencing variables to produce nominal values. 
     An object of the present invention is to provide a process and a device for controlling the longitudinal dynamics of a vehicle wherein the specification of nominal values for the engine and/or the brake is achieved easily and in conformity with the individual driving situations. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a first embodiment according to the present invention. 
     FIG. 2 is a second embodiment according to the present invention. 
     FIGS. 3 to  5  are views of individual assignments of the coordinator, or the coordination function, to different systems. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     A first embodiment of the present invention is described with reference to FIG.  1 . Reference numeral  19  designates the engine being controlled, and reference numeral  18  designates the brake system being controlled which is equipped with an ABS control system. Reference numeral  10  designates a device which produces nominal values for the engine and the brake from various quantities. The device  10  produces the nominal values under the assumption that the vehicle has a proper adherence to the road surface, i.e., that the wheels neither lock nor spin. The device  10  can be an ICC longitudinal dynamics control or a cruise control system (CC) (ICC=‘Intelligent Cruise Control’). Reference numeral  17  designates the engine control which controls the engine in accordance with nominal engine values. Reference numeral  16  designates the brake control which controls the brake system  18  in accordance with nominal brake values. 
     According to the present invention, various devices produce further appropriate nominal values for the engine or brake control, and from these nominal values, established functionally in parallel, the nominal values for the brake  18  and/or the engine  19  or its controllers  16  and  17  are determined in a suitable manner in a coordination device  15 . 
     Initially, the production of a nominal brake value is described more precisely. The nominal value generated for the brake is the brake nominal pressure p soll . Various devices produce functionally in parallel intermediate nominal values or intermediate nominal pressures. A first intermediate nominal pressure p bremse  is generated by the device  10 . Another intermediate nominal pressure p ASMS  is generated by the driving stability control system. Another intermediate brake pressure p BA  is generated by a brake assistant. Further intermediate nominal pressures can be determined in a suitable manner by other components. These intermediate nominal values or intermediate nominal pressures, which are determined functionally in parallel, are picked up by a coordination device  14 , and the brake nominal value or brake nominal pressure p soll  is determined from them in a suitable manner. One criterion for the coordination device  14  can be to select the maximum value from the intermediate nominal values or intermediate nominal pressures it picks up, and to send it as a brake nominal value or brake nominal pressure p soll  to the brake system. 
     The generation of nominal engine values will be described in the following. It must be taken into consideration that modern motor control systems in which the so-called ‘E-Gas’(=electronically controlled acceleration) concept (electronic accelerator pedal) is implemented, pick up two nominal engine torques, i.e. M MSR  and M ASR , preferably from the ABS control system. The nominal engine torque M MSR  reflects results of the engine stall torque control, and the nominal engine torque M ASR  reflects results from the engine traction slip control. These nominal engine values are determined from intermediate nominal values. An intermediate nominal value M motor  is generated by the device  10 . Another intermediate nominal value can be generated by the traction slip control  12 , for example, in the form of an intermediate nominal torque. Another intermediate nominal value can be generated by the engine stall torque control  11  in the form of an intermediate nominal torque. These intermediate nominal values or intermediate nominal torques are introduced into a coordination device  15  which determines from them nominal engine values in a suitable fashion. The course of action in this case, too, is that different intermediate nominal values are determined functionally in parallel under different aspects, and nominal engine value(s) is/are determined from the parallel prevailing intermediate nominal values. 
     When the engine  19  picks up only one single nominal engine value or one signal nominal engine torque, the intermediate nominal values or intermediate nominal torques can be produced, for example, by a selection of maximum values. 
     FIG. 1 shows an embodiment which includes an intermediate nominal torque that is determined according to a nominal acceleration and each one intermediate nominal torque determined from the engine stall torque control  11  or the traction slip control  12 . Also, an engine equipped with electronically controlled acceleration management is assumed. In this case, the maximum value is selected from the intermediate nominal torque M motor  which is established according to the nominal acceleration in the device  10  and the intermediate nominal torque generated by the engine stall torque control  11 , and is issued as a nominal engine torque M MSR  to the engine. The intermediate nominal torque determined by the traction slip control  12  is issued as nominal engine torque M ASR  to the engine. 
     The torque requirements requested by the driver of the vehicle can be processed in various ways: one possibility is to consider these torque requirements by the driver as another intermediate nominal torque or another intermediate nominal value and to introduce it into the coordination device  15  where it is processed in an appropriate manner. FIG. 1, however, shows an embodiment where the processing of the direct driver&#39;s wish does not take place in the coordinator  15  but in the engine electronic unit  17 . Initially, the maximum value is determined therein from the driver&#39;s torque requirements M fahrer  and the engine nominal torque M MSR . Further, the minimum value is selected from this maximum value and the engine nominal torque M ASR , and the so produced nominal torque M mot  is used to control the engine. 
     The fact that the intermediate nominal values are determined in parallel when the nominal values for the brake and/or the engine are determined, they may be tested simultaneously and checked for defined relations between them. According to these checking operations, the nominal engine value may influence the nominal brake value and vice-versa, or reactions to the nominal acceleration being adjusted may be performed. For example, if the intermediate nominal torque M motor  which originates from the ICC control or device  10  is smaller than the intermediate nominal torque generated by the engine stall control, a reaction to the nominal acceleration generated by the acceleration controller may be effected by an appropriate device. 
     In the embodiment shown, the coordination device  14  picks up, beside the intermediate nominal pressure p bremse  from the ICC control  10 , the intermediate nominal pressure p ASMS  from the driving stability control system  13 , an intermediate nominal pressure p BA  from a brake assistant, and the intermediate nominal pressure according to the driver&#39;s wish p fahrer  for determining the nominal brake value. When any one of the values p ASMS , p BA  or p fahrer  prevails in the maximum value generation, shown as an example, this may e.g. cause deactivation of the ICC function or the ICC controller  10 . 
     FIG. 1 shows a coordination device  14  for the nominal brake pressure and a coordination device  15  for the nominal engine torque(s). These coordination devices  14  and  15  can be provided individually or in combination. 
     At reference numeral  25 , FIG. 2 shows a variation of the coordination device  15  of FIG.  1 . Exactly as the coordination device  15  of FIG. 1, device  25  picks up intermediate nominal torques from ICC control  10 , traction slip control  12 , and engine stall torque control  11 . The coordination device  25  cooperates, however, with an engine management in which the inputs of the nominal values are processed as is shown in FIG.  2 . The maximum value is then determined in the coordination device  25  from the intermediate nominal torque of the ICC control  10  and the intermediate nominal torque of the engine stall torque control  11 . The minimum is determined from the so established value and the intermediate nominal torque of the traction slip control, and the so determined value is sent to the engine management as nominal engine torque M MSR . The nominal engine torques M MSR  and M ASR  are processed in the engine electronic unit  27  so that, initially, the minimum value is selected in the engine electronic unit  27  from the nominal engine torque M ASR  and the driver&#39;s requirements M fahrer , and the maximum value is selected from this minimum value and the nominal engine torque M MSR , and this maximum value is then used as an engine torque M mot  to control the motor. 
     FIGS. 3 to  5  show individual functional assignments of the ICC control  10 , the coordinators  14  and  15  and the control electronic units  16  and  17  for the brake and the engine. 
     In the embodiment of FIG. 3, the ICC control  10 , the coordination device  34  for the brake and the coordination device  35  for the motor are separate functional blocks. This separation can be effected, for example, so that the individual objects are carried out by different processors, if necessary, different printed circuit boards, and also, if necessary, at different locations in the vehicle. 
     In the embodiment of FIG. 4, the two coordination devices  44  and  45  are integrated in one function or a functional block. This integration can be effected in the way that the function is performed, for example, by the same processor or at least on the same printed circuit board. When the coordination objectives are executed by the same processor, the advantage is that fewer serial interfaces have to be drafted and operated. 
     FIG. 5 shows an embodiment in which parts of the ICC control  10  form a function group, and the actual acceleration controller in conjunction with the coordinators form another function group. These function groups can be configured in the way that they are designed or realized by processors of their own, possibly on own printed circuit boards and, further, at different locations in the vehicle. Parts of the ICC control are integrated in a functional block so that the latter furnishes a nominal acceleration as an output which is picked up and further processed by the other functional block. The advantage of this embodiment is that the reactive effect to the required nominal acceleration can be performed in certain operating conditions in a simple fashion. Further advantages are achieved with respect to the number and the configuration of serial interfaces. The fact that the number of serial interfaces is reduced permits linking different signals more easily, for example, for plausibility checks, for reactions and transverse effects, and further polls.