Predictive self-adaptive cruise control method for vehicle

Abstract

The invention discloses a predictive self-adaptive cruise control method for a vehicle. The method comprises the following steps of: 1, positioning the position of the vehicle through a GPS (Global Positioning System) or positioning equipment assembled on the vehicle; 2, solving an economic optimal driving speed; step 3, entering a predictive self-adaptive cruise car following mode; fourthly, P-THW is calculated according to the predicted vehicle speeds vp1, vp2... vpn of the vehicle; fifthly, the vehicle is controlled to run with vp1 as the slope entering speed; if vp1lt; vtv, and v1gt; when vtv, enabling v1 to be equal to vtv, and re-planning vp1; 6, driving according to the planned vehicle speed; when vp1lt; vtv, and v1gt; when vtv, taking vtv as a new v1 for re-planning; and 7, calculating the safe turning speed vsafety of the vehicle, wherein the vsafety is the rollover prevention speed. The method has the advantages that vehicle speed is reduced, vehicle safety is guaranteed, and fuel economy is improved; the situation that the vehicle speed is too high in the downhill process after follow-up acceleration is avoided, and fuel consumption is reduced. Unnecessary acceleration behaviors are avoided, the situation that speed reduction is still needed during turning after acceleration is prevented, and energy waste is avoided.

Description

Technical Field

[0001] The present invention relates to a cruise control method, and in particular to a vehicle predictive adaptive cruise control method. Background Art

[0002] Currently, early cruise control systems could only maintain a fixed speed. With the development of sensor technologies such as millimeter-wave radar, lidar, and cameras, as well as intelligent connected technologies, vehicles are now capable of accurately sensing both vehicle information and road conditions. For example, millimeter-wave radar can monitor the distance, speed, and angle of the vehicle ahead in real time, providing critical data support for adaptive cruise control systems. However, traditional adaptive cruise control relies solely on information about the vehicle ahead. This inability to adapt to changing road slopes and curves, such as those on curved roads, makes it difficult to properly adjust the vehicle's speed based on the actual road conditions and the vehicle ahead. The advancement of vehicle-to-vehicle and vehicle-to-infrastructure communication technologies (such as V2X) has further expanded the capabilities of adaptive cruise control systems. Vehicles can not only sense the status of other vehicles but also obtain information about their surroundings and road infrastructure. This allows them to coordinate vehicle and road information, optimally plan their own speed, and avoid unnecessary acceleration and deceleration based on road information. This ensures safety while improving comfort and fuel efficiency.

[0003] Currently, adaptive cruise control systems in vehicles mostly use radar and cameras to sense information such as the distance, speed, and angle of the vehicle ahead. Based on the vehicle's motion, they adjust their driving state, maintaining a reasonable distance and relative speed from the vehicle ahead. They actively follow the vehicle ahead within a set speed range to avoid collision. If there are no vehicles ahead, the system maintains a set desired cruise speed.

[0004] In the above approach, the vehicle's speed is determined solely based on the status information of the vehicle in front, and cannot respond to information such as road slope and curvature. When the speed of the vehicle in front changes, the vehicle can only follow the speed of the vehicle in front. The main phenomena are:

[0005] (1) When there is an uphill slope ahead, the vehicle ahead slows down because of the uphill slope, and the vehicle following it slows down before going uphill;

[0006] (2) When a downhill slope appears ahead, the vehicle ahead speeds up passively due to the downhill slope, and the vehicle follows suit and speeds up before going downhill;

[0007] (3) When a curve appears ahead, the vehicle ahead decelerates to pass the curve, and the vehicle following it decelerates;

[0008] (4) When the leading vehicle turns from an uphill slope to a flat road and accelerates away, the self-vehicle follows and accelerates during the uphill process.

[0009] The above phenomenon will lead to inappropriate acceleration and deceleration of the vehicle, which will consume energy and reduce the vehicle's fuel economy. At the same time, unnecessary acceleration and deceleration will also lead to a decrease in comfort.

[0010] In conventional solutions, the following distance is determined by multiplying the time-to-follow distance THW by the vehicle's speed. The present invention improves the time-to-follow distance calculation method and calculates THW (hereinafter referred to as P-THW) based on the planned vehicle speed.

[0011] In this invention, the vehicle utilizes intelligent connectivity technology to incorporate road map information, acquiring information such as the slope and curvature of the road ahead. This information, combined with the status of the vehicle ahead, allows the vehicle to optimally plan its cruising speed, avoiding unnecessary acceleration and deceleration. When the speed of the vehicle ahead changes, the vehicle calculates whether there is a collision risk based on the road information. If there is no risk, the vehicle continues at the planned speed, improving fuel economy and comfort. Summary of the Invention

[0012] The main purpose of the present invention is to provide a vehicle predictive adaptive cruise control method to solve the problem that the existing vehicle adaptive cruise process only relies on the status information of the vehicle in front to determine the vehicle speed and cannot respond to information such as road slope and road curvature.

[0013] The vehicle predictive adaptive cruise control method provided by the present invention includes the following steps:

[0014] The first step is to locate the vehicle using GPS or a self-installed positioning device. The vehicle then obtains the road conditions ahead, including road slope, road curvature, and road speed limit, through the ADAS map or the self-installed device. The vehicle also obtains its own status information, including gear position, speed, throttle position, and brake pedal status. The vehicle's motion status and relative position are obtained through cameras and radar.

[0015] The second step is to determine the economically optimal speed based on road information ahead and with the goal of minimizing vehicle driving costs. The vehicle's uphill speed is planned before going uphill, accelerating in advance to accumulate energy. This kinetic energy is released during the uphill climb to overcome gravitational potential energy. The vehicle's entry speed is planned before going downhill, and the speed is reduced or maintained before descending. Gravitational potential energy is used to provide driving power during the downhill climb, and the required downhill torque is calculated to avoid dangerous speeding.

[0016] Step 3: When there is no vehicle ahead, calculate the economically optimal speed sequence v in step 2. p1 ,v p2 …v pn Driving, the corresponding distance is s p1 ,s p2 …s pn, namely the predictive cruise mode; when a vehicle that hinders the self-vehicle's driving appears ahead, calculate the predictive THW, hereinafter referred to as P-THW, and compare P-THW with the set THW threshold THWset. When P-THW >= THWset, it is considered that there is no collision risk, and the self-vehicle drives according to the calculated economically optimal driving speed; when P-THW < THWset, enter the predictive adaptive cruise following mode;

[0017] Let the speed of the vehicle at the current position be v0 and the relative distance be s r , with k sections of roads separated from the vehicle ahead, and the predicted speed for each section of the road is v p1 , v p2 …v pk , the speed when reaching the position of the vehicle ahead is v2, s pk The position is at a distance s1 from the position of the vehicle ahead

[0018]

[0019] Step 4: With the predicted speed v of the self-vehicle p1 , v p2 …v pn Calculate P-THW. When going uphill ahead and the self-vehicle is driving on a flat road, the self-vehicle will accelerate to climb the slope. Kinetic energy is accumulated during the flat-road acceleration, and the kinetic energy is used to overcome the gravitational potential energy during the uphill process to improve the fuel economy of the vehicle, obtain the current speed v0 of the vehicle, the speed v when entering the slope p1 [[ID=二十七]],到达前车位置时车速v1,到达入坡位置距离s p1 ,入坡位置距离前车位置s 1， Specifically as follows:

[0020]

[0021] When P-THW >= THWset, drive according to the planned speed sequence to achieve accelerating up the slope and improve the fuel economy;

[0022] When P-THW < THWset, re-plan the economic speed sequence to make P-THW <= THWset and maximize the improvement of fuel economy;

[0023] When calculating with P-THW, suppress the deceleration behavior of the self-vehicle in a safe situation when the vehicle ahead decelerates, avoid frequent switching of the driving mode of the self-vehicle, reduce the acceleration and deceleration behavior outside the prediction, and improve the comfort;

[0024] Step 5: When the self-vehicle is on a flat road and the vehicle ahead enters a downhill section, if it is in the following cruise working condition, due to potential energy, the vehicle ahead accelerates, and it is necessary to judge the speed v when entering the slope p1 and the speed v of the vehicle ahead tv , if v p1 > v tv, follow the vehicle ahead; if v p1 < v tv , and v p2 < v tv when, control the vehicle's own speed with v p1 as the uphill vehicle speed; if v p1 < v tv , and v1 > v tv when, make v1 = v tv , and re-plan v p1 ;

[0025] Step 6, when the vehicle is going uphill and the vehicle ahead reaches the top of the slope and accelerates away, the vehicle makes a decision based on the planned downhill vehicle speed v p1 , the vehicle speed v of the vehicle ahead tv , and the predicted vehicle speed v2 when reaching the position of the vehicle ahead. When v p1 > v tv when, use v tv as the new downhill vehicle speed; when v p1 < v tv , and v2 < v tv when, drive according to the planned vehicle speed; when v p1 < v tv , and v1 > v tv when, re-plan with v tv as the new v1;

[0026] Step 7, when the curvature of the road ahead changes, calculate the safe cornering vehicle speed v safe of the vehicle, v safe is the anti-rollover vehicle speed, and the target vehicle speed v1 when the vehicle reaches the position of the vehicle ahead. When the vehicle speed v of the vehicle ahead tv < v safe when, follow the vehicle ahead; when the vehicle speed v of the vehicle ahead tv > v[[ID=​​​​​​​​​​​​​​​​In the vehicle predictive adaptive cruise control method provided by the present invention, when the speed of the leading vehicle decreases when entering a road section with a larger slope, the own vehicle does not blindly follow the leading vehicle to decelerate, and the acceleration and deceleration behavior of the own vehicle is determined based on the P-THW calculated by the predicted vehicle speed; in the technical solution provided by the present invention, when the speed of the leading vehicle increases when entering a road section with a smaller slope, the own vehicle does not blindly follow the leading vehicle to accelerate, and the acceleration and deceleration behavior of the own vehicle is determined based on the planned in-slope speed, the speed when reaching the position of the leading vehicle and the speed of the leading vehicle; in the technical solution of the present invention, when the curvature of the road ahead changes, the acceleration and deceleration behavior of the own vehicle is not blindly followed by the leading vehicle, and the acceleration and deceleration behavior of the own vehicle is determined based on the planned safe cornering speed and the speed of the leading vehicle.

[0029] In summary, the beneficial effects of the technical solution provided by the present invention are as follows:

[0030] (1) The vehicle does not follow the preceding vehicle in slowing down. It maintains its speed or accelerates before going uphill. After going uphill, it releases kinetic energy to overcome gravity potential energy, and its speed decreases, ensuring vehicle safety and improving fuel economy.

[0031] (2) The vehicle will actively slow down before going downhill and will not follow the preceding vehicle to accelerate. During the downhill process, the vehicle will use the slope to increase its speed and reach the target speed. This will avoid excessive speed during the downhill process after following the acceleration and reduce fuel consumption.

[0032] (3) It avoids unnecessary acceleration and prevents the need to decelerate again when turning after acceleration, thus avoiding energy waste. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a schematic diagram of the economical vehicle speed planning process described in the present invention.

[0034] Figure 2 This is a flow chart of the cruise mode switching conditions according to the present invention.

[0035] Figure 3 This is a schematic diagram of the preceding vehicle going uphill and the vehicle on a flat road according to the present invention.

[0036] Figure 4 This is a schematic diagram of the vehicle ahead going downhill and the vehicle on a flat road according to the present invention.

[0037] Figure 5 This is a schematic diagram of the vehicle going uphill on a flat road with a vehicle in front according to the present invention. DETAILED DESCRIPTION

[0038] See also Figures 1 to 5 As shown:

[0039] The vehicle predictive adaptive cruise control method provided by the present invention includes the following steps:

[0040] Step 1: The vehicle locates its position through GPS or a positioning device installed on the vehicle itself; obtains the road conditions ahead through an ADAS map or a device installed on the vehicle itself, including information such as road gradient, road curvature, and road speed limit; obtains the vehicle's own status information, including information such as vehicle gear, vehicle speed, throttle opening, and brake pedal status; obtains the moving state and relative position of the vehicle ahead through a camera and radar.

[0041] Step 2: Based on the road information ahead, with the goal of minimizing the vehicle's driving cost, solve for the economically optimal driving speed. Before the vehicle goes uphill, plan the uphill driving speed of the vehicle, accelerate in advance before going uphill to accumulate energy, and release kinetic energy during the uphill process to overcome gravitational potential energy and go uphill. Before the vehicle goes downhill, plan the speed when entering the slope, reduce the speed or maintain the speed before going downhill, and utilize gravitational potential energy to provide driving power for the vehicle during the downhill process. Calculate the required torque for downhill to avoid the risk of the vehicle speeding.

[0042] Step 3: When there is no vehicle ahead, drive according to the economically optimal planned speed sequence v p1 , v p2 … v pn corresponding to a distance of s p1 , s p2 … s pn , that is, the predictive cruise mode; when a vehicle that hinders the self-vehicle's driving appears ahead, calculate the predictive THW, hereinafter referred to as P-THW. Compare P-THW with the set THW threshold THWset. When P-THW >= THWset, it is considered that there is no collision risk, and the self-vehicle drives according to the calculated economically optimal driving speed; when P-THW < THWset, enter the predictive adaptive cruise following mode.

[0043] Let the vehicle speed at the current position be v0, the relative distance be s r , separated from the vehicle ahead by k sections of road, and the predicted speed for each section of road is v p1 , v p2 … v pk , and the vehicle speed when reaching the position of the vehicle ahead is v2, s pk The position is at a distance s1 from the position of the vehicle ahead. [[ID=3--5]] [[ID=3--6]]

[0044] [[ID=3--7]] [[ID=3--8]] [[ID=3--9]]

[0045] Step 4: Calculate P-THW based on the self-vehicle's predicted speed v p1 , v p2 … v pn When going uphill ahead and the self-vehicle is driving on a flat road, the self-vehicle will accelerate to climb the slope, accumulate kinetic energy by accelerating on the flat road, and utilize kinetic energy to overcome gravitational potential energy during the uphill process to improve the vehicle's fuel economy. Obtain the current vehicle speed v0, the speed v p1 when entering the slope, the vehicle speed v1 when reaching the position of the vehicle ahead, and the distance s when reaching the slope entry position.p1 The distance of the entry slope position from the position of the vehicle ahead is s 1， Specifically as follows:

[0046]

[0047] When P-THW ≥ THWset, drive according to the planned vehicle speed sequence to achieve an accelerated uphill climb and improve fuel economy;

[0048] When P-THW < THWset, re-plan the economic vehicle speed sequence to make P-THW ≤ THWset and maximize fuel economy;

[0049] When calculating with P-THW, inhibit the deceleration behavior of the vehicle itself in a safe situation when the vehicle ahead decelerates, avoid frequent switching of the driving mode of the vehicle itself, reduce acceleration and deceleration behaviors outside the prediction, and improve comfort;

[0050] Step 5: When the vehicle itself is on a flat road and the vehicle ahead enters a downhill section, if it is in a following cruise condition, due to potential energy, the vehicle ahead accelerates. It is necessary to judge the entry slope speed v p1 and the vehicle speed v tv of the vehicle ahead. If v p1 > v tv , follow the vehicle ahead; if v p1 < v tv , and v[[ID=3,1]] p2 < v tv at this time, control the vehicle itself to drive at the entry slope speed v p1 ; if v p1 < v tv , and v1 > v tv at this time, make v1 = v tv , and re-plan v p1 ;

[0051] Step 6: When the vehicle itself is going uphill and the vehicle ahead reaches the top of the slope and accelerates away, the vehicle itself makes a decision based on the planned exit slope speed v p1 , the vehicle speed v tv of the vehicle ahead, and the predicted vehicle speed v2 when reaching the position of the vehicle ahead. When v p1 > v tv , take v tv as the new exit slope speed; when v p1 < v tv , and v2 < v tv , drive according to the planned vehicle speed; when v p1 < v tv , and v1 > v tv , re-plan with v tv as the new v1;

[0052] Step 7: When the curvature of the road ahead changes, calculate the safe cornering speed v of the host vehicle safe , v safe is the anti-rollover speed, and the target speed v1 when the host vehicle travels to the position of the leading vehicle. When the speed v of the leading vehicle tv < v safe , follow the leading vehicle; when the speed v of the leading vehicle tv > v safe and v tv > v1, travel at the target speed v1; when the speed v of the leading vehicle tv > v safe and v tv < v1, travel at the speed v tv as the target speed.

Claims

1. A vehicle predictive adaptive cruise control method, characterized by: The method includes the following steps: First step: The vehicle locates its position through GPS or the positioning device installed on the vehicle itself; obtains the road conditions ahead through the ADAS map or the device installed on the vehicle itself, including information such as road gradient, road curvature, and road speed limit; obtains the vehicle's own state information, including information such as vehicle gear, vehicle speed, throttle opening, and brake pedal state; obtains the motion state and relative position of the vehicle ahead through the camera and radar. Second step: Based on the road information ahead, with the goal of minimizing the vehicle's driving cost, solve for the economically optimal driving speed. Before the vehicle goes uphill, plan the uphill driving speed of the vehicle, accelerate in advance before going uphill to accumulate energy, and release kinetic energy during the uphill process to overcome gravitational potential energy and go uphill. Before the vehicle goes downhill, plan the speed when entering the slope, reduce the speed or maintain the speed before going downhill, and utilize gravitational potential energy to provide driving power for the vehicle during the downhill process, calculate the required torque for downhill, and avoid danger caused by vehicle speeding. Step 3: When there is no vehicle ahead, drive according to the economically optimal planned vehicle speed sequence v p1 , v p2 … v pn over the corresponding distance s p1 , s p2 … s pn , which is the predictive cruise mode. When a vehicle that obstructs the self-vehicle's driving appears ahead, calculate the predictive THW, hereinafter referred to as P-THW. Compare P-THW with the set THW threshold THWset. When P-THW >= THWset, it is considered that there is no collision risk, and the self-vehicle drives according to the calculated economically optimal driving speed. When P-THW < THWset, enter the predictive adaptive cruise following mode; Assume the current position and speed of the vehicle is v0, and the relative distance is s r , there are k sections of road between the vehicle in front and the vehicle in front. The predicted speed at each section of road is v p1 ,v p2 …v pk , the speed of the vehicle arriving at the front vehicle is v2,s pk The distance between the position and the preceding vehicle is s1 s p1 +s p2 +...+s pk +s1=s r ; Step 4: Use the vehicle to predict the speed v p1 ,v p2 …v pn Calculate P-THW. When the vehicle is on a flat road and the road ahead is uphill, it will accelerate to rush up the slope. Acceleration on a flat road accumulates kinetic energy. The kinetic energy is used to overcome the potential energy of gravity during the uphill process, improving the vehicle's fuel economy. Obtain the vehicle's current speed v0 and the vehicle speed v entering the slope. p1 , the speed when reaching the front vehicle is v1, and the distance to the slope position is s p1 , the distance between the entry position and the front vehicle position is s 1， The details are as follows: s p1 +s1=s r ; When P-THW ≥ THWset, drive according to the planned vehicle speed sequence to achieve accelerating up the slope and improve fuel economy. When P-THW < THWset, re-plan the economic vehicle speed sequence to make P-THW ≤ THWset and maximize the improvement of fuel economy. When calculating with P-THW, suppress the deceleration behavior of the vehicle itself under safe conditions when the vehicle ahead decelerates, avoid frequent switching of the vehicle's driving mode, reduce acceleration and deceleration behaviors outside the prediction, and improve comfort. Step 5: When the vehicle is on a flat road and the vehicle ahead is entering a downhill section, if the vehicle is in a following cruise mode, the vehicle ahead is accelerating due to potential energy. p1 The speed of the vehicle ahead is v tv Size, if v p1 >v tv , follow the car in front; if v p1 <v tv , and v p2 <v tv When v p1 The vehicle speed is used to control the vehicle's driving; if v p1 <v tv , and v1>v tv When v1=v tv , re-plan v p1 ; Step 6: When the vehicle is going uphill and the vehicle ahead reaches the top of the hill and accelerates away, the vehicle will follow the planned speed v p1 , the speed of the preceding vehicle v tv , the predicted speed v2 when arriving at the position of the preceding vehicle is used to make a decision. p1 >v tv When v tv is the new out-slope speed; when v p1 <v tv , and v2 <v tv When v p1 <v tv , and v1>v tv When v tv Re-planned for the new v1; Step 7: When the curvature of the road ahead changes, calculate the safe cornering speed v of the host vehicle safe , v safe is the anti-rollover speed, and the target speed v1 when the host vehicle travels to the position of the leading vehicle. When the speed v tv < v safe , follow the leading vehicle; when the speed v tv > v safe and v tv > v1, travel at the target speed v1; when the speed v tv > v safe and v tv < v1, travel at the speed v tv as the target speed.

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