Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication
Reexamination Certificate
2001-02-20
2002-08-13
Zanelli, Michael J. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Reexamination Certificate
active
06434451
ABSTRACT:
TECHNICAL FIELD
The present invention generally relates to vehicle control systems and more particularly relates to a system, preferably for influencing the performance of a motor vehicle.
BACKGROUND OF THE INVENTION
Systems for controlling or regulating many different variables regarding the vehicle dynamics of a motor vehicle are becoming increasingly complex, since more and more new functions are being implemented in motor vehicles. Brake-control systems (ALS), traction control systems (TCS), steering control systems, chassis control systems, vehicle-dynamics control systems and motor management systems are well-known examples of such systems.
What these systems have in common is that they require information regarding the movement of the vehicle in relation to the road. For this purpose, appropriate sensors are employed to measure the vehicle's longitudinal and transversal movements as well as the yawing motion of the vehicle.
Rate of rotation or rate of yaw sensors using the coriolis force are used for determining the movement about the vertical axis of the vehicle. In general such sensors have a movable mechanical structure comprising an electric-mechanical transducer excited for periodic oscillations. When the sensor detects a rotation about an axis vertical to the excited oscillation, the movement of the oscillation leads to a coriolis force that is proportional to the measured variable, i.e. the angular velocity. Through the coriolis force a second oscillation, orthogonal relative to the excited oscillation, is excited in a mechanical-electric transducer. This second oscillation can be detected by various measuring procedures, with the detected variable serving as the measure for the rate of rotation acting on the rate of rotation sensor.
A known rate of rotation sensor
100
is shown in FIG.
1
. The rate of rotation sensor shown here exhibits an electric-mechanical transducer
101
and a mechanical-electric transducer
102
, whose mechanical structure is designed as a quartz tuning fork. An excitation amplifier
103
(oscillator) excites a fundamental oscillation of the quartz in the electric-mechanical transducer. The current flowing through the electric-mechanical transducer is measured by a current-voltage converter
104
and returned to the input of the excitation amplifier
103
, which always switches at the zero passage transition with an hysteresis.
The sensitivity of the electric-mechanical transducer
101
depends on the mechanical amplitude of oscillation of the tuning fork. In order to obtain a defined sensitivity of the rate of rotation sensor, the amplitude of oscillation is stabilized with respect to the effects of temperature and aging. For this purpose, it is necessary to measure the amplitude of oscillation. This can be done by means of additional components or the current-voltage converter
104
, whose output signal, following a full-wave rectification
105
with subsequent filtering, provides a d.c. voltage signal that is proportional to the amplitude of the electric-mechanical transducer
101
. The control deviation is determined by integrating a subtractor in the full-wave rectifier
105
.
The actual control element is a PI controller
106
in order to achieve as low control deviations of the amplitude of oscillation as possible.
The electric-mechanical transducer
101
is firmly and mechanically connected to mechanical-electric transducer
102
which is designed in the same way as the electric-mechanical transducer and also consists of quartz. The mechanical-electric transducer
102
provides a signal having the same oscillation frequency as the excited electric-mechanical transducer
101
; however, its amplitude is proportionally dependent on the rate of rotation. This concerns the oscillation that was amplitude-modulated through the rate of rotation, with two side bands and suppressed carrier. Parasitic signals are superimposed by unbalances between the electric-mechanical transducer and the mechanical-electric transducer and capacitive overcoupling between the lines and electrodes. The tuning-fork-shaped mechanical-electric transducer provides a charge as signal that is preamplified in a signal recording amplifier
107
as the first input step. The signal is further amplified in a multistage amplifier
108
due to the low signal amplitude. In a synchronous rectifier
109
, which is activated by the excitation signal, the modulated signal is transformed into a rectified rate of rotation signal. This is necessary because the amplitude of the modulated signal contains the amount of the rate of rotation, the phase contains the sign. The synchronous rectifier is an effective filter for interference signals with shifted phases. The desired rate of rotation signal is available following the synchronous rectification. In a last amplifier stage
110
, undesired higher frequency residual signals are dampened by means of a low pass and the scaling is set to the desired output voltage range of about 5 Volt by means of amplification.
These types of rate of rotation or rate of yaw sensors are well known. Cylinders, prisms, tuning forks, micromechanically produced elements of silicon or quartz are used as transducer bodies (vibration bodies). Just as there are many different designs for transducer bodies, so there are various designs for the analog switching elements related to the transducer bodies in the sensor housing
111
, which are designed according to the transducer body, its material, the excitation frequency, etc.
Thus, the rate of rotation sensor described in more detail as an example of sensors comprises analog subassemblies with firmly defined scopes of function: e.g. excitation, rectification, amplification, filtering, etc. The result of the sensors is then provided for further processing to a common interface, to which an evaluation unit that controls the driving dynamics of the motor vehicle can be connected.
In the past these hardware functions required a relatively large constructional volume and resulted in high costs. Furthermore, they had the disadvantage that the user could not, or only with great difficulty, make any changes in the analog hardware functions of the sensor and thus strongly limited the flexibility for the user. It is not necessary to integrate additional functions such as, for example, suppression of resonance characteristics of the transient response characteristics. In addition, the stability of the analog hardware functions can be attained only at high costs.
It is well known that at least two sensors for detecting the movements of the motor vehicle are related to an evaluation unit for evaluating the signals of the sensor units, with this evaluation unit being combined with the sensors to form a sensor module. The sensors are well-known longitudinal and/or transversal acceleration sensors and/or commercially available rate of rotation sensors. In the evaluation unit interference induced by the motor vehicle is filtered, temperature effects are compensated and the sensor signals are transformed to any point of the motor vehicle.
It is the object of the present invention to provide a system that allows significantly more flexible signal processing and ensures higher long-term stability.
Due to the fact that the system consists of an electric-mechanical transducer and a mechanical-electric transducer with a sensor unit comprising a signal recording amplifier, which is connected to an A/D signal converter by way of an output and to a D/A signal converter of a digital signal processing unit by way of an input, the interface and the consistent distribution of the functions into a purely sensor-related sensor unit and a purely evaluation-related signal processing unit are achieved. A significant feature of the system according to the present invention is the low number of electronic operating switching operations or analog switching elements required for the transducers. The fine-mechanically or micromechanically formed transducer bodies used for rate of rotation sensors, which make use of electric-physical effects
Burgdorf Jochen
Burghardt Roland
Lohberg Peter
Loreck Heinz
Continental Teves AG & Co. oHG
Rader & Fishman & Grauer, PLLC
Zanelli Michael J.
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