KR100792908B1 - Method for measuring inclination of vehicle - Google Patents

Abstract

A method for measuring the inclination angle of a vehicle is provided to calculate the inclination angle within the shortest time by using an updated vehicle dynamic characteristic parameter value and two voltage peak values of a voltage signal of an acceleration sensor generated right after the vehicle stops. A method for measuring the inclination angle of a vehicle comprises the steps of: judging whether the vehicle stops or not, by reducing the speed(ST100); judging whether a voltage peak value of an output signal of an acceleration sensor is to be measured or not(ST200); measuring the voltage peak value from the output signal of the acceleration sensor before the voltage peak value reaches a normal state(ST300); estimating a normal voltage value by using the measured voltage peak value and dynamic characteristic parameter of a vehicle(ST400); and converting the calculated normal voltage value into the inclination angle(ST500).

Description

Method for measuring inclination angle of vehicle {Method for measuring inclination of vehicle}

1 is a flow chart showing the configuration of a tilt angle measuring method according to the present invention,

2 is a configuration diagram of a vehicle inclination angle measuring device used in the present invention,

3 is a graph showing the output signal of the acceleration sensor used in the present invention, showing the general response characteristics of free vibration,

4 is a graph showing an output signal of an acceleration sensor obtained by a real vehicle test.

<Explanation of symbols for the main parts of the drawings>

10: vibration sensor 20: control unit

The present invention relates to a method for measuring the inclination angle of a vehicle, and more particularly, it is configured to more quickly measure the inclination angle of the vehicle by using the dynamic characteristic behavior of the vehicle immediately before the sensor value is stabilized immediately after the vehicle stops, The present invention relates to a method of measuring an inclination angle of a vehicle, which can reduce the time required for preventing the vehicle from moving and determining whether to enter / release an idle stop, thereby effectively improving driving performance, oscillation performance, and fuel economy of the vehicle.

BACKGROUND ART Conventional automobiles are vehicles driven by engines using fuel such as gasoline, and development of electric vehicles driven by electric motors has been actively progressed due to the increase of environmental pollution caused by such general engine vehicles.

Gasoline cars have the disadvantage of increasing the environmental pollution by exhausting a lot of exhaust gas, electric vehicles have the advantage of preventing environmental pollution, but there is a disadvantage that can not run for a long time because it is driven by a battery.

In order to solve the disadvantages of the gasoline car and the electric vehicle as described above, a vehicle that combines the functions of the gasoline car and the electric vehicle is a hybrid vehicle.

A hybrid car is a vehicle in which a general gasoline engine driving function and an electric motor driving function are inherent. In other words, a hybrid car is driven by a general gasoline car (driven by an engine driving force) or an electric vehicle (driven by an electric motor driving force) as necessary. Indicates a vehicle that can be.

Since a hybrid vehicle is composed of components different from existing gasoline and electric vehicles such as an engine, a high voltage battery, and an electric motor, various driving methods are required according to battery power conditions when driving a vehicle.

As the driving mode of the hybrid vehicle, the electric vehicle (EV) mode, which is a pure electric vehicle mode using only the rotational force of the electric motor, the engine mode using the rotational force of the engine, and the electricity driven by the power of the battery with the rotational power of the engine as the main power HEV (Hybrid Electric Vehicle) mode, which is an auxiliary mode that uses the rotational power of the motor as an auxiliary power, and a regenerative braking mode that recovers braking and inertia energy from the electric motor and charges the battery when driving by braking or inertia driven by inertia. Can be mentioned.

Meanwhile, even in a hybrid vehicle, the inclination angle of the vehicle (the inclination angle of the driving road) is widely used for controlling the vehicle. For example, inclination angle measurement is required to prevent the vehicle from being pushed on the slope, and the measured inclination angle is prevented from driving the vehicle. It is widely used for idle stop control (determination and control of children stop entry / release point).

In addition, in order for the hybrid vehicle to run in an optimal state, the degree of inclination of the driving path of the vehicle is measured, and according to the measured inclination angle of the inclined road, the main engine of the vehicle is stopped, and the start noise and engine speed control during power generation after starting the engine are controlled. Various control methods have been used.

As is well known, the measurement of the inclination angle of the vehicle (the inclination angle of the driving road) in an automobile generally uses an acceleration sensor.

However, there are many errors in the inclination angle of the vehicle measured using the acceleration sensor.

That is, the output signal of the acceleration sensor is transmitted through the electric circuit and the related hardware that receives the signal, and in this process, high frequency noise is involved, and due to an inappropriate signal processing procedure, the correct signal is measured in real time. Difficult to do

As described above, since there are many errors in the inclination angle by the acceleration sensor, there is a problem that reliability of logic in the vehicle using the inclination angle measured by the acceleration sensor in real time is not guaranteed.

In particular, it is difficult to ensure the reliability of the climbing prevention prevention logic using the inclination information, and many limitations are placed on correctly determining the idle stop entry / release timing of the hybrid vehicle.

Because of this characteristic, the conventional inclination angle estimation algorithm is adapted to determine the inclination angle when the output value of the sensor is stabilized after a certain time has elapsed after the vehicle stops (for example, 1.2 seconds to stop the vehicle in order to ensure stable operation of the inclination angle sensor). Determination of tilt angle after elapse; t _ss = 1.2 seconds).

However, this causes a heterogeneity due to the occurrence of jungle and the entry / release of unnecessary idle stops, and in particular, since the output value of the sensor needs to take time to stabilize, there is a problem that rapid vehicle control is impossible.

Therefore, the present invention is invented to solve the above-mentioned conventional problems, and is configured to measure the inclination angle of the vehicle more quickly by using the dynamic characteristic behavior of the vehicle immediately before the sensor value is stabilized immediately after the vehicle stops. It is an object of the present invention to provide a method of measuring an inclination angle of a vehicle that can effectively improve driving performance, oscillation performance, and fuel efficiency of a vehicle by reducing the time required for preventing vehicle slip and determining idle stop entry / release as compared with conventional logic. .

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

In order to achieve the above object, the present invention, the step of determining whether the vehicle is decelerated and stopped (ST100); Determining whether the voltage peak value (amplitude peak value) of the acceleration sensor output signal can be measured (ST200); Measuring a voltage peak value before a steady state from the acceleration sensor output signal (ST300); Estimating and calculating a steady state voltage value using the voltage peak value measured in the step and the vehicle dynamics characteristic parameter (ST400); It provides a method for measuring the inclination angle of the vehicle comprising the step (ST500) converting the steady state voltage value calculated in the above step into the inclination angle.

Here, in the step of estimating and calculating the steady state voltage value (ST400), the steady state voltage using the first voltage peak value and the second voltage peak value measured from the acceleration sensor output signal together with the vehicle dynamic characteristic parameter. It is characterized by estimating the value.

In particular, in the step (ST400) of estimating and calculating the steady-state voltage value, the steady-state voltage value is calculated by the following equation (E1).

Formula (E1):

Where x _{ss is the} steady-state voltage value, x _{1 is the} first voltage peak value, x _{2 is} the second voltage peak value, and δ is the logarithmic characteristic parameter.

The vehicle dynamics parameter is newly calculated, stored and updated using an output signal of the acceleration sensor in a state that satisfies a predetermined condition, and the parameter update is repeated every time the condition is satisfied from starting to starting off. The updated latest parameter value may be used in the step of estimating the steady state voltage value.

The updating of the vehicle dynamic characteristic parameter may include: determining that the vehicle is equal to or higher than a reference vehicle speed after vehicle start (IG ON) (ST10); Determining whether the vehicle is stopped in a state where the reference vehicle speed is equal to or higher than the time when the output voltage value of the acceleration sensor reaches a steady state in the vehicle stop state (ST20); Calculating, storing, and updating vehicle dynamic characteristic parameters by using the voltage peak value measured before the steady state from the output signal of the acceleration sensor (ST30, ST40).

In operation ST40, the vehicle dynamic characteristic parameter is calculated using the first voltage peak value, the second voltage peak value, and the third voltage peak value measured from the acceleration sensor output signal. It is characterized by the calculation.

In particular, in the step ST40 of calculating the vehicle dynamic characteristic parameter, the vehicle dynamic characteristic parameter is calculated by the following equation (E2).

Formula (E2):

Where δ is a logarithmic characteristic parameter, and is a logarithmic attenuation value, x ₁ : first voltage peak value, x ₂ : second voltage peak value, x ₃ : third voltage peak value.

The present invention relates to a method for measuring an inclination angle of a vehicle, and is an improvement of an existing inclination angle estimation algorithm for estimating an inclination angle using an acceleration sensor (vibration sensor).

In particular, the present invention is an improvement on the existing inclination angle estimation algorithm currently applied to the hybrid vehicle, it is possible to more quickly estimate the inclination angle of the vehicle using the dynamic characteristics of the vehicle before the sensor value is stabilized immediately after the vehicle stops. An inclination angle estimation algorithm is provided.

When the inclination angle measuring method of the present invention is applied to the vehicle's anti-rolling logic, the vehicle can be prevented more quickly and effectively, and in particular, the time required for determining the anti-rolling and the idle stop entry / release in a hybrid vehicle can be reduced. This can contribute to the starting performance and fuel economy of the vehicle.

The inclination angle measurement process according to the present invention is largely performed by a logic module that extracts a dynamic characteristic parameter of a vehicle from an output signal of an acceleration sensor and a logic module that determines an inclination angle by using a response characteristic of a vehicle behavior. The concept of the tilt angle determination logic and the dynamic parameter extraction logic to be performed will be described.

Tilt angle determination logic

Immediately after the vehicle is stopped, the vehicle exhibits a behavior close to free vibration with respect to the center of gravity due to the force of 'ROAD TRANSFER'. The sensor detects each movement of the vehicle and outputs an acceleration signal corresponding thereto.

Therefore, if the information on the characteristics (mass, stiffness, damping rate, etc.) of the vehicle can be known, it is possible to determine the inclination angle by using the response characteristic of the behavior.

With this in mind, the present invention proposes a process of determining the inclination angle using the response characteristics of the vehicle behavior.

Vehicle dynamics parameter extraction logic

As described above, in order to properly analyze the response characteristics, it is necessary to understand the dynamic characteristics parameters of the vehicle (eg, the mass change due to the change of the occupant) which changes frequently.

The behavior of the vehicle varies according to the characteristics of the vehicle body (mass, stiffness, damping rate, etc.). In the present invention, the dynamic characteristics parameter of the vehicle is extracted from the acceleration signal by measuring the output signal of the acceleration sensor, and in particular, in order to calculate a more accurate inclination angle. A method for updating vehicle dynamics parameters is presented.

Hereinafter, the tilt angle measuring method of the present invention will be described in more detail with reference to the accompanying drawings.

1 is a flowchart illustrating a configuration of a method of measuring an inclination angle according to the present invention, and illustrates a process of determining an inclination angle using vehicle dynamic characteristic behavior.

Description of each symbol shown in FIG. 1 is as follows.

2 is a block diagram of the inclination angle measuring device for a vehicle used in the present invention.

Basically, in order to perform the inclination angle measurement process according to the present invention, as shown in FIG. 2, an acceleration sensor (vibration sensor) 10 which detects a vehicle vibration and outputs it as a voltage signal is output from the acceleration sensor 10. A control unit (including a memory in the control unit) 20 for converting the voltage signal into an inclination angle and updating and storing the vehicle dynamic characteristic parameter together with the converted inclination angle should be installed.

In addition, Figure 3 is a graph showing the output signal of the acceleration sensor used in the present invention, a graph showing the general response characteristics of free vibration, in particular the output signal of the acceleration sensor immediately after the vehicle stops (appears before reaching the normal state) A method for calculating the vehicle dynamics parameter δ (a logarithmic attenuation) from the voltage peak values x ₁ , x ₂ , and x ₃ (see Equation 2 below), and the output signal of the acceleration sensor (x ₁ , which is the sensor voltage peak value). , x ₂ ) and a method of calculating a steady state voltage value corresponding to an inclination angle using the calculated vehicle dynamics parameter (see Equation 1 below).

In FIG. 3, x ₁ , x ₂ , x ₃ , x ₄ , and x ₅ (= x _i ) are voltage peak values (amplitude peak values) of the acceleration sensor output signal, and in the acceleration sensor output signal according to the vehicle vibration immediately after the vehicle stops. It is the voltage peak value that appears until the sensor signal reaches steady state.

In the present invention, the voltage peak value is measured after the vehicle is stopped, and the inclination angle is converted therefrom after calculating the estimated voltage value using the voltage peak value and the vehicle dynamics parameter.

Here, the vehicle dynamics parameter is newly calculated using the voltage peak value of the acceleration sensor output signal measured at each vehicle stop, stored in the memory, and updated, and the newly updated vehicle dynamics parameter is used at the next vehicle stop. The steady state voltage value is calculated and the inclination angle is converted.

The tilt angle measuring method according to the present invention includes the steps of determining whether the vehicle decelerates and stops (ST100), and determining whether the voltage peak value (amplitude peak value) of the acceleration sensor output signal can be measured (ST200); Measuring a voltage peak value from the acceleration sensor output signal (ST300), estimating and calculating a steady state voltage value using the voltage peak value measured in the step and the vehicle dynamics parameter (ST400), and the step Comprising a step of converting the steady-state voltage value calculated in the inclination angle (ST500), and storing the converted inclination angle (600).

That is, when the vehicle is stopped after the vehicle starts to be driven in the ignition key ON state, that is, when the vehicle speed becomes 0, the controller determines whether the voltage peak value can be measured from the output signal of the acceleration sensor, where the acceleration sensor is If it is possible to measure the voltage peak value from the output signal of, the steady-state voltage corresponding to the inclination angle is determined by using the measured first voltage peak value x ₁ and the second voltage peak value x ₂ , the logarithmic attenuation value δ, which is a stored vehicle dynamics parameter. Compute the value x _ss .

Here, the steady state voltage value x _ss may be calculated by Equation 1 below.

Thereafter, the inclination angle is converted from the estimated calculated steady state voltage value x _ss , the converted inclination angle is stored, and the converted inclination angle is used for vehicle control.

If the vehicle speed is not zero or if the first voltage peak value x ₁ and the second voltage peak value x ₂ cannot be measured, the previously stored tilt angle is used.

Thus, in the present invention, the inclination angle is estimated before the steady state of the sensor signal is reached using only two voltage peak values of the acceleration sensor output signal, and the vehicle control can be performed more quickly than the conventional method using the estimated inclination angle. It becomes possible.

That is, according to the inclination angle measuring method of the present invention, even when the inclination angle is required for vehicle control, the inclination angle estimated using two voltage peak values as described above, even before the sensor signal reaches a steady state (normal state) Estimated by the inclination angle of the vehicle).

On the other hand, in order to correctly analyze the response characteristics in the process of calculating the steady state voltage value, it is necessary to accurately identify and apply vehicle dynamic characteristics parameters that are frequently changed due to occupant weight, cargo weight, vehicle weight, stiffness, and damping. The property parameters should be updated with the most recent data.

Therefore, the controller continuously performs the process of updating the vehicle dynamics characteristic parameter in a state that satisfies a predetermined condition, and in the present invention, the updated vehicle dynamics characteristic parameter is used for calculating the inclination angle.

That is, the controller calculates the vehicle dynamics parameter based on the output signal of the acceleration sensor whenever the vehicle stops after driving at a certain speed or more after IG ON, and stores and updates the calculated vehicle dynamics parameter at this time. Therefore, the newly updated dynamic characteristic parameter is used in the process of calculating the inclination angle at the next stop of the vehicle (exactly in calculating the steady state voltage value estimation).

As described above, a process of calculating and updating the vehicle dynamic characteristic parameter is shown on the right side of FIG. 1, which is performed separately from the process of calculating the inclination angle on the left side.

First, in a state ST10 in which the vehicle speed v _t0 becomes _equal to or more than the preset reference vehicle speed v ₀ after the vehicle is started, the vehicle speed v _t is 0 after that, that is, the vehicle is stopped after the vehicle stops. If the time t _stop has passed the time t _ss at which the sensor voltage reaches a steady state (ST20), the logarithmic attenuation value, which is a vehicle dynamics parameter, is measured using the voltage peak value measured before reaching the steady state (ST30). δ is calculated, stored and updated (ST40).

At this time, the logarithmic attenuation value δ is calculated using the first voltage peak value x ₁ , the second voltage peak value x ₂ , and the third voltage peak value x ₃ measured from the output signal of the acceleration sensor. It is as shown in Formula 2.

The logarithmic attenuation value δ calculated as described above is newly stored and updated in the controller, and the updated logarithmic attenuation value δ is used for calculating the steady state voltage value of the tilt angle determination process described above.

The dynamic characteristic parameter update process is continuously performed until the vehicle is turned off (IG OFF), and the newly updated dynamic characteristic parameter is used immediately after the inclination angle determination process.

Of course, when the vehicle speed v _t0 does not become higher than the preset reference vehicle speed v ₀ after starting the vehicle, the parameter update is not newly performed, and the most recently updated and stored dynamic characteristic parameter δ is used during the inclination angle determination process. Done.

4 is a graph showing the output signal of the acceleration sensor obtained by the actual vehicle test, which shows the output signal of the acceleration sensor obtained by the inventor of the present invention on a 16% slope (corresponding to an acceleration sensor voltage of 2.7107 volts). When the dynamic characteristic parameter δ was calculated, a value of δ = 0.4624 was calculated.

Table 1 shows the inclination angles measured by applying the method of the present invention to various types of slopes, and after estimating the voltage value in the steady state and converting the inclination angle therefrom, there was a slight error. In view of the fact that the inclination recognition was not possible, the inclination angle measuring method of the present invention can be very usefully applied to vehicle control.

In this way, in the present invention, the acceleration sensor is stabilized by real-time grasping (updating) information on the characteristics (mass, stiffness, attenuation) of the vehicle body, and using the body characteristics and the output signal of the acceleration sensor obtained in real time. By estimating the inclination angle of the steady state in the previous transient section, it is possible to significantly reduce the inclination recognition time compared with the prior art.

As described above, according to the method for measuring the inclination angle of the vehicle according to the present invention, the shortest time is obtained by using only two voltage peak values among the voltage signals of the acceleration sensor that occur immediately after the vehicle stops together with the updated latest vehicle dynamic characteristic parameter values. The vehicle is configured to be able to calculate the inclination angle within the vehicle, thereby enabling rapid vehicle control.

Conventionally, after the vehicle is stopped and the acceleration sensor is stabilized (about 1.2 seconds), the inclination is recognized to determine whether to release the idle stop or to determine the delay time of the anti-roller release.

On the other hand, according to the present invention, it is possible to shorten the inclination recognition time by estimating the inclination angle of the steady state in the transient section immediately after the vehicle stop, and greatly improve the performance of the vehicle control logic by using the inclination angle information which is quickly determined. Will be.

Compared to the conventional logic, it is possible to effectively improve driving performance, starting performance and fuel economy of the vehicle by reducing the time required for preventing the vehicle from moving and determining the idle stop entry / release.

Expected expected time can be shortened to about 60% of the current 1.2 seconds to about 0.5 seconds as shown in FIG.

In addition, it is possible to reduce the error of the estimated inclination angle and the true value by calculating the dynamic characteristics parameters of the vehicle in real time.

Claims (7)

Determining whether the vehicle is decelerated and stopped (ST100); Determining whether the voltage peak value (amplitude peak value) of the acceleration sensor output signal can be measured (ST200); Measuring a voltage peak value before a steady state from the acceleration sensor output signal (ST300); Estimating and calculating a steady state voltage value using the voltage peak value measured in the step and the vehicle dynamics characteristic parameter (ST400); Converting the steady state voltage value calculated in the above step into an inclination angle (ST500); Inclination angle measurement method of a vehicle comprising a. The method according to claim 1, In estimating and calculating the steady state voltage value (ST400), the steady state voltage value is obtained by using the first voltage peak value and the second voltage peak value measured from the acceleration sensor output signal together with the vehicle dynamic characteristic parameter. Method for measuring the inclination angle of the vehicle, characterized in that the estimated calculation. The method according to claim 2, And estimating and calculating the steady state voltage value (ST400), wherein the steady state voltage value is calculated by the following equation (E1). Formula (E1):

Where x _{ss is the} steady-state voltage value, x _{1 is the} first voltage peak value, x _{2 is} the second voltage peak value, and δ is the logarithmic characteristic parameter. The method according to claim 1, The vehicle dynamics parameter is newly calculated, stored and updated by using the output signal of the acceleration sensor in a state of satisfying a predetermined condition, and the parameter update is repeated whenever the condition is satisfied from starting to starting off, and the steady state is performed. And using the updated latest parameter value in the step of estimating the voltage value. The method according to claim 4, The updating of the vehicle dynamics parameter may include: Determining that the vehicle is equal to or higher than the reference vehicle speed after the vehicle start (IG ON) (ST10); Determining whether the vehicle is stopped in a state where the reference vehicle speed is equal to or higher than the time when the output voltage value of the acceleration sensor reaches a steady state in the vehicle stop state (ST20); Calculating, storing, and updating vehicle dynamic characteristic parameters by using the voltage peak value measured before the steady state from the output signal of the acceleration sensor (ST30, ST40); Inclination angle measurement method of a vehicle comprising a. The method according to claim 5, In the calculating of the vehicle dynamic characteristic parameter (ST40), the vehicle dynamic characteristic parameter is calculated using the first voltage peak value, the second voltage peak value, and the third voltage peak value measured from the acceleration sensor output signal. Method of measuring the inclination angle of the vehicle, characterized in that. The method according to claim 6, In the calculating of the vehicle dynamic characteristic parameter (ST40), the vehicle dynamic characteristic parameter is calculated by the following equation (E2). Formula (E2):

Where δ is a logarithmic characteristic parameter, and is a logarithmic attenuation value, x ₁ : first voltage peak value, x ₂ : second voltage peak value, x ₃ : third voltage peak value.

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