JP7161947B2 - Obstacle detection device for construction vehicles - Google Patents

Description

The present invention relates to an obstacle detection device for construction vehicles.

For example, when the rolling roller rolls close to a curb, the driver drives the vehicle while watching the rolling surface around the curb, and thus tends to neglect the direction of travel. As a result, accidents involving contact with surrounding workers are likely to occur, particularly when the vehicle is moving backwards.

To address this problem, there are known alarm devices that use radio waves or ultrasonic waves to issue an alarm when a person or object is detected within a certain distance, or an automatic stop device that automatically stops a vehicle (for example, patent References 1-3). Patent Document 1 discloses a magnetic field generating device mounted on a vehicle, an IC tag attached to a worker, a detecting device for detecting radio waves emitted from the IC tag, and a vehicle when the detecting device detects radio waves. An emergency shutdown system is described that includes an engine shutdown system that shuts down the engine. Patent Document 2 discloses a trigger signal output means mounted on a vehicle, an ID tag attached to a worker, a receiving section for receiving the ID number output by the ID tag, and when the receiving section receives the ID number, is described a stopping system comprising stopping means for stopping a vehicle.

JP 2016-153558 A JP 2017-10483 A

If you try to stop the vehicle immediately after detecting an obstacle, for example, it will stop even if the worker temporarily enters the detection range and then immediately leaves the detection range, resulting in a large number of unnecessary stops. Therefore, the working efficiency of construction vehicles tends to decrease.

SUMMARY OF THE INVENTION The present invention was created to solve such problems, and it is an object of the present invention to provide an obstacle detection device for a construction vehicle that can reduce useless travel stoppages.

The present invention relates to an obstacle detection device mounted on a construction vehicle equipped with a hydraulic travel system circuit, comprising a distance sensor capable of detecting a distance to an obstacle, and temperature or viscosity of hydraulic oil in the travel system circuit. a hydraulic oil sensor that detects the presence of an obstacle based on the detection data of the distance sensor, a control device that outputs a brake signal when it is determined that there is an obstacle, and the brake signal is input and a brake means for braking via a brake that acts on the hydraulic traveling system circuit at the time, and the timing from when the control device determines that there is an obstacle to when the brake signal is output is determined by the hydraulic fluid. Depending on the temperature or viscosity of the hydraulic oil detected by the sensor, if the temperature of the hydraulic oil is below a predetermined threshold value, if the viscosity is above a predetermined threshold value, or if the temperature of the hydraulic oil is higher than a predetermined threshold value Alternatively, the operating timing of the brake means is advanced compared to when the viscosity is lower than a predetermined threshold .

When the temperature of the hydraulic oil in the hydraulic drive system circuit becomes low, the viscosity of the hydraulic oil increases, and the braking distance of the vehicle increases. Therefore, if the braking start timing of the braking means is changed according to the temperature of the hydraulic oil detected by the temperature sensor as the hydraulic oil sensor or the viscosity of the hydraulic oil detected by the viscosity sensor as the hydraulic oil sensor. More specifically, if the start timing of braking is advanced when the temperature is low, the vehicle can be properly stopped regardless of changes in the braking distance caused by the temperature of the hydraulic oil. As a result, it is possible to reduce useless stoppages while avoiding collisions with obstacles.

Further, the present invention is provided with a vehicle speed sensor that detects the traveling speed of the vehicle, and the control device calculates the braking distance E2 from the vehicle speed detected by the vehicle speed sensor and the temperature or viscosity of the hydraulic oil detected by the hydraulic oil sensor. a braking distance calculator that calculates a braking distance; a distance comparator that compares the measured distance E1 to the obstacle detected by the distance sensor with the braking distance E2; and a braking command unit that outputs the brake signal.

According to the present invention, the control program of the control device can be simplified in coping with changes in the braking distance caused by the temperature of the hydraulic fluid in the traveling system circuit.

The braking distance calculation unit includes correlation data between vehicle speed and braking distance, and stores a plurality of braking start distances that differ according to the temperature or viscosity of hydraulic oil. Braking to select one braking start distance from among the plurality of braking start distances by referring to temperature or viscosity, and specify braking distance E2 corresponding to the vehicle speed detected by the vehicle speed sensor from the selected braking start distance and a distance specifying unit.
Alternatively, it is preferable that the braking distance calculator calculates the braking distance E2 using a formula using the vehicle speed and the temperature or viscosity of the hydraulic oil as variables.

Further, the present invention is characterized in that the construction vehicle is a compaction roller, and the brake means is an HST brake that acts on a hydraulic traveling system circuit.

According to the present invention, by using the HST brake, it is possible to avoid excessive sudden stops and to reduce flatness defects such as dents on the asphalt paved road surface. In addition, it becomes easy to resume running after the vehicle stops.

ADVANTAGE OF THE INVENTION According to this invention, a useless stop of a driving|running|working stop can be reduced, avoiding the collision of an obstacle.

It is explanatory drawing which shows the detection range of the obstacle detection apparatus with which the tire roller was mounted|worn, (a), (b) is a top view and a side view, respectively. 1 is a configuration block diagram of an obstacle detection device according to the present invention; FIG. 1 is a schematic hydraulic circuit diagram of a travel system including brake means; FIG. It is a graph which shows a braking start distance. FIG. 4 is an output flow diagram of a brake signal; It is correlation data between the inclination angle of the road surface and the braking distance. It is a graph which shows the braking start distance on a level ground and the braking start distance on an incline. FIG. 4 is an output flow diagram of a brake signal corresponding to the inclination angle of a road surface; It is correlation data between hydraulic oil temperature and braking distance. It is a graph which shows the braking start distance at normal time and the braking start distance at low temperature. FIG. 4 is an output flow diagram of a brake signal corresponding to hydraulic oil temperature; 4 is a graph showing a braking start distance corresponding to both the road surface inclination angle and the hydraulic oil temperature;

In FIG. 1, an obstacle detection device 1 of the present invention is mounted on a construction vehicle such as a compaction roller that performs work while traveling at a low speed. FIG. 1 shows a case where the obstacle detection device 1 is mounted on a tire roller 10 that rolls an asphalt road surface or the like with a tire 11 . In FIG. 2, an obstacle detection device 1 includes a distance sensor (distance image sensor 2) capable of detecting the distance to an obstacle G, and determines the presence or absence of an obstacle G based on the detection data of the distance sensor. and a control device 3 that outputs a brake signal R to the brake means 6 when it is determined that there is G. The obstacle detection device 1 also includes a vehicle speed sensor 7 , an inclination sensor 8 and a hydraulic oil sensor 9 .

"distance sensor"
The distance sensor is composed of, for example, a TOF (Time Of Flight) type distance image sensor (3D distance sensor) 2 capable of detecting the distance to the obstacle G from the time difference between the projected light and the reflected light. The distance image sensor 2 includes a light-emitting portion that emits projected light such as infrared rays, and a light-receiving portion that receives reflected light when the projected light hits an object. The distance to the object is measured by measuring the time from when infrared rays are sent from the light emitting part to when the reflected light is received by the light receiving part. The projection angle from the distance image sensor 2 is, for example, 95° in the horizontal direction and 32° in the vertical direction (symbol θ1 shown in FIG. 1(b)), and the projection cross section has a horizontally long rectangular shape. The image resolution is, for example, 64 pixels in the horizontal direction and 16 pixels in the vertical direction, for a total of 1024 pixels. The distance image sensor 2 is attached to the central portion in the vehicle width direction of the rear portion of the tire roller 10 so that the projection light is projected obliquely downward in the backward direction.

Regarding the detection range of the obstacle G, if the projection range of the projection light is set as the detection range as it is, that is, if the dimension L1 in the vehicle width direction is set wider than the vehicle width dimension of the tire roller 10, there is no danger of collision. The presence of the obstacle G is first recognized, and the vehicle stops unnecessarily. Therefore, it is preferable to set the dimension L1 of the detection range 4 in the vehicle width direction (indicated by oblique lines in FIG. 1) to substantially the same as the vehicle width dimension of the tire roller 10 . Since the distance image sensor 2 can detect the distance to the obstacle G, the width of the vehicle is set based on the measurement data for each pixel, specifically the distance between the distance image sensor 2 and the obstacle G in the vehicle width direction. The control device 3 can determine whether or not an obstacle G exists in the detected detection range 4 . By using the distance image sensor 2 in this way, the dimension L1 of the detection range 4 can be kept constant over the vehicle front-rear direction. That is, the detection range 4 can be easily set to a substantially rectangular range with one side having the dimension L1 in a plan view as shown in FIG. 1(a). A dimension L2 of the detection range 4 in the longitudinal direction of the vehicle is appropriately set according to the commonly used running speed, and is set to, for example, about 3 meters in the present embodiment. Note that the detection range 4 may be set so as to correspond to the estimated travel route calculated from the turning radius of the vehicle.

In addition, since the projection light from the distance image sensor 2 is projected obliquely downward in the backward direction, the horizontal angle θ2 of the projection light when viewed from above is in a range larger than 95°. Therefore, the distance L3 in the vehicle front-rear direction of the non-detection areas 5, 5 formed between the rear ends of the tire roller 10 and the detection area 4 can be kept small. That is, the undetected blind spots formed on both sides of the rear portion of the vehicle can be reduced.

Data D<b>1 detected by the distance image sensor 2 is output to the control device 3 . The distance sensor used in the present invention is not limited to the TOF sensor as long as it can measure the distance to the obstacle G. A wave type sensor, a stereo camera type sensor, a monocular camera type sensor, or the like may be used.

"Vehicle speed sensor 7"
The vehicle speed sensor 7 is a sensor that detects the traveling speed of the vehicle, and is a rotary encoder or the like that detects the number of revolutions of the tires. Data D2 from the vehicle speed sensor 7 is output to the control device 3 .

"Tilt sensor 8"
The tilt sensor 8 detects the tilt of the vehicle in the traveling direction. Data D3 from the tilt sensor 8 is output to the control device 3 .

"Hydraulic oil sensor 9"
The hydraulic fluid sensor 9 detects the temperature or viscosity of the hydraulic fluid in the hydraulic traveling system circuit. If the hydraulic oil sensor 9 is a temperature sensor, a temperature sensor built in a travel motor M, which will be described later, can be used. Data D4 from the hydraulic oil sensor 9 is output to the control device 3 . Below, the case where the hydraulic oil sensor 9 is used as a temperature sensor will be described.

"Brake Means 6"
An example of the braking means 6 will be described. The tire roller 10 (FIG. 1) is equipped with a hydraulic drive system circuit. In FIG. 3, the hydraulic traveling system circuit includes a hydraulic closed circuit U1 in which a traveling pump P driven by an engine (not shown) and a traveling motor M rotating tires 11 (FIG. 1) are connected in series. ing. The running pump P is a swash plate type pump. The traveling pump P is connected to an oil passage T1 and an oil passage T2 for operating the swash plate. A two-position, three-port electromagnetic valve V1 is interposed in parallel with the traveling pump P between the oil passages T1 and T2.

When the engine is running, the electromagnetic valve V1 is at the right position in FIG. 3, and the oil passages T1 and T2 are not communicated with each other. Therefore, when the forward/reverse lever around the driver's seat is tilted toward the forward position while the engine is running, the swash plate operating oil flows from the oil passage T1 side to the oil passage T2 side and the swash plate tilts to one side. As a result, the pressure oil flows in one direction in the closed circuit U1, the traveling motor M rotates in one direction, and the vehicle moves forward. When the forward/reverse lever is tilted toward the reverse position, the swash plate operating oil flows from the oil passage T2 side to the oil passage T1 side, and the swash plate tilts to the other side. As a result, the pressure oil flows in the other direction in the closed circuit UI, the traveling motor M rotates in the other direction, and the vehicle moves backward.

When the engine is not running, the solenoid valve V1 is in the left position as shown in FIG. 3, and the oil passages T1 and T2 are in communication. A closed hydraulic circuit U2 is formed between the solenoid valve V1 and the traveling pump P, and no differential pressure is generated between the oil passages T1 and T2, so that the swash plate is positioned at the neutral position. . As a result, an HST (Hydro Static Transmission) brake acts in the closed circuit U1.

The brake means 6 of this embodiment utilizes this electromagnetic valve V1. The controller 3 outputs a brake signal R and switches the electromagnetic valve V1 from the right position to the left position when the obstacle determination unit 21, which will be described later, determines that there is an obstacle G. FIG. As a result, even when the engine is running and the forward/reverse lever is tilted toward the reverse position, the swash plate is positioned at the neutral position, the HST brake is applied in the closed circuit U1, and the driving motor M is operated. Stop. Between the charge pump P1 built in the running pump P and the negative brake M1 built in the running motor M, an electromagnetic valve V2 is interposed for operating the negative brake M1 during parking. .

Here, if the brake signal R is output immediately after it is determined that there is an obstacle G, for example, even if the obstacle G is a worker and immediately goes out of the detection range 4, the vehicle stops uselessly. It will happen. Focusing on the braking distance of the vehicle by the braking means 6, the present inventor changed the timing at which the braking of the braking means 6 starts, that is, the timing from when it is determined that there is an obstacle G to when the brake signal R is output. By doing so, both avoidance of collision with the obstacle G and reduction of useless travel stops are achieved. A specific example will be described below.

"control device 3"
As shown in FIG. 2 , the control device 3 includes an obstacle determination section 21 , a braking distance calculation section 22 , a distance comparison section 23 and a braking command section 24 . The obstacle determination unit 21 determines whether or not there is an obstacle G based on the data D1 from the distance image sensor 2 .

First, a case in which only the running speed of the vehicle (hereinafter also referred to as vehicle speed) is considered will be described. The braking distance of a vehicle varies depending on the vehicle speed, and the higher the vehicle speed, the longer the braking distance. For example, as shown in FIG. 4, the storage unit 25 of the braking distance calculation unit 22 stores preset braking start distance data S (hereinafter simply referred to as braking start distance S). The braking start distance S is correlation data between the vehicle speed and the braking distance, and the higher the vehicle speed, the longer the braking distance. In FIG. 2, when the obstacle determination unit 21 determines that there is an obstacle G, the distance comparison unit 23 compares the measured distance E1 to the obstacle G obtained from the data D1 of the distance image sensor 2 and the braking start distance S Among them, the braking distance E2 corresponding to the vehicle speed obtained from the data D2 of the vehicle speed sensor 7 is compared. When "measured distance E1≤braking distance E2", the braking command unit 24 outputs a brake signal R to the electromagnetic valve V1.

An output flow of the brake signal R is shown in FIG. The control device 3 acquires data D1 in step ST1, and determines whether or not there is an obstacle G in step ST2. If NO in step ST2, the process returns to step ST1. If YES in step ST2, the measured distance E1 is calculated from the data D1 in step ST3, and the braking distance E2 is specified from the braking start distance S based on the data D2. At step ST4, it is determined whether or not the measured distance E1 is equal to or less than the braking distance E2. If NO, the process returns to step ST1, and if YES, a brake signal R is output at step ST5.

The braking start distance S is longer as the vehicle speed is higher. Therefore, when the vehicle speed is high, the timing (time) from when the obstacle determination unit 21 determines that there is an obstacle G to when the brake signal R is output is shortened. Conversely, if the vehicle speed is low, there is still time to contact the obstacle G, so even if the timing is delayed, the collision can be avoided. As a result, regardless of the magnitude of the vehicle speed, it is possible to achieve both avoidance of collision with the obstacle G and reduction of useless stops.

The braking start distance S is set, for example, as a distance value slightly larger than the limit braking distance T actually measured for the vehicle. In FIG. 4, the braking start distance S is set to about 0.5 m at 2 km/h, about 1 m at 4 km/h, about 1.6 m at 6 km/h, and about 2.4 m at 8 km/h.

In addition to the vehicle speed, another factor that changes the braking distance of the vehicle is the inclination angle of the road surface. Since construction vehicles are particularly heavy, there is a strong tendency for the braking distance to increase as the inclination angle increases due to the effects of gravity on downhills. FIG. 6 shows an example of correlation data between the road surface inclination angle (in percent) and the braking distance when the vehicle speed is 8 km/h and 12 km/h. It can be seen that, at any vehicle speed, the braking distance increases as the inclination angle of the road surface increases. In particular, the higher the vehicle speed, the greater the rate of increase in the braking distance. At 12 km/h, the braking distance increases from 3 m on a flat surface, that is, when the slope is zero, to 5.6 m on a 14% road surface. .

To address this problem, the control device 3 includes a braking distance calculator 22 that calculates the braking distance E2 from the vehicle speed detected by the vehicle speed sensor 7 and the tilt angle detected by the tilt sensor 8, as shown in FIG. . Two examples in which the braking distance calculator 22 calculates the braking distance E2 will be described below.

"First embodiment (corresponding example of inclination angle)"
The braking distance calculator 22 includes a memory 25 and a braking distance identifier 26 . The storage unit 25 stores a plurality of braking start distances S and Sa that are composed of correlation data between vehicle speed and braking distance and that differ according to the inclination angle of the traveling direction of the vehicle. As an example, as shown in FIG. 7, a braking start distance S for flat ground and a braking start distance Sa for slope ground are stored. The braking start distances S and Sa are longer as the vehicle speed increases. The braking start distance Sa is set longer than the braking start distance S at all vehicle speeds, and increases as the vehicle speed increases. The braking start distance S is set, for example, as a distance value that is slightly larger than the limit braking distance T actually measured on flat ground. The braking start distance Sa is also set as a distance value slightly larger than the limit braking distance Ta actually measured on a slope (12% road surface).

The braking distance specifying unit 26 refers to the tilt angle detected by the tilt sensor 8, selects one braking start distance from among the plurality of braking start distances S and Sa, and detects the vehicle speed sensor 7 from the selected braking start distance. A braking distance E2 corresponding to the detected vehicle speed is specified.

In FIG. 7, only one braking start distance Sa is set assuming a descending gradient of about 12% for sloped terrain. It corresponds to the braking start distance S, and for descending gradients beyond that, it is finely divided for each inclination angle, such as for descending gradients of 2 to 4 percent, for descending gradients of 4 to 8 percent, and for descending gradients of 8 percent or more. , a plurality of braking start distances Sa for slopes may be set and stored in the storage unit 25 .

"Second embodiment (example of corresponding tilt angle)"
In the first embodiment, the braking distance E2 is calculated from the preset braking start distances S and Sa. In the second embodiment, however, the formula (1) "E2 =fa(v,α)” to calculate the braking distance E2. Calculation formula (1) is an expression of the relationship that the braking distance E2 increases as the vehicle speed and the inclination angle increase.
E2: braking distance fa: function v: speed α: inclination angle

FIG. 8 is an output flow chart of the brake signal R when considering the tilt angle. The control device 3 acquires data D1 in step ST11, and determines whether or not there is an obstacle G in step ST12. If NO in step ST12, the process returns to step ST11. If YES in step ST12, the measured distance E1 is calculated from the data D1 in step ST13.

Also, in step ST13, the braking distance E2 is specified from the data D2 and D3. In the case of the first embodiment, one of the braking start distance S and the braking start distance Sa is selected by referring to the tilt angle obtained from the data D3. As for the selection method, for example, an appropriately set threshold is compared with the data D3, and if the data D3 is equal to or less than the threshold, the braking start distance S for flat ground is selected, and if it is greater than the threshold, the braking start distance Sa for slope ground is selected. to select. Then, based on the data D2, the braking distance E2 is specified from either the selected braking start distance S or Sa. In the case of the second embodiment, the braking distance E2 is specified from the formula (1).

Next, in step ST14, it is determined whether or not the measured distance E1 is equal to or less than the braking distance E2. If NO, the process returns to step ST11, and if YES, a brake signal R is output in step ST15.

The braking start distance Sa for slope ground is set longer than the braking start distance S for flat ground. Therefore, on a slope, the timing (time) from when the obstacle determination unit 21 determines that there is an obstacle G to when the brake signal R is output is shortened. Conversely, on flat ground, the required braking distance is shorter than on sloping ground, and there is time to contact the obstacle G, so collision can be avoided even if the timing is delayed. As a result, regardless of changes in the braking distance due to slopes, it is possible to achieve both avoidance of collisions with obstacles G and reduction of useless stoppages. The same applies to the braking distance E2 calculated in the second embodiment.

Next, as another factor that changes the braking distance of the vehicle, when the HST brake is used as in the present embodiment in a construction vehicle having a hydraulic travel system circuit, the hydraulic oil temperature (or hydraulic oil viscosity) of the travel system circuit is mentioned. FIG. 9 shows an example of correlation data between hydraulic oil temperature and braking distance when the vehicle speed is 8 km/h and 12 km/h. At a speed of 8 km/h, the braking distance is almost constant when the hydraulic oil temperature is about 20° C. or higher, but when the temperature is lower than that, the braking distance becomes longer as the temperature drops. At a speed of 12 km/h, the braking distance does not change much at 30°C or higher, but below that, the lower the temperature, the longer the braking distance. Thus, the lower the hydraulic oil temperature, the higher the viscosity of the hydraulic oil and the longer the braking distance.

To address this problem, the control device 3 in FIG. ing. Two examples in which the braking distance calculator 22 calculates the braking distance E2 will be described in the same manner as in the case of the inclination angle.

"First embodiment (Example of response to hydraulic oil temperature)"
The braking distance calculator 22 includes a storage unit 25 and a braking distance specifying unit 26 . The storage unit 25 stores a plurality of braking start distances S, Sb which are composed of correlation data between vehicle speed and braking distance and which differ according to the operating oil temperature of the traveling system circuit. As an example, as shown in FIG. 10, a braking start distance S at normal time and a braking start distance Sb at low temperature are stored. The braking start distances S and Sb are longer as the vehicle speed is higher. The braking start distance Sb is set longer than the braking start distance S at all vehicle speeds, and increases as the vehicle speed increases. The braking start distance S is set, for example, as a distance value slightly larger than the limit braking distance T actually measured under normal conditions (when the hydraulic oil temperature is about 30° C.). The braking start distance Sb is also set as a value with a margin that is slightly greater than the limit braking distance Tb actually measured at a low temperature (operating oil temperature of about 3° C.).

The braking distance specifying unit 26 refers to the hydraulic oil temperature detected by the hydraulic oil sensor 9, selects one braking start distance from among the plurality of braking start distances S and Sb, and determines the vehicle speed from the selected braking start distance. A braking distance E2 corresponding to the vehicle speed detected by the sensor 7 is specified.

In FIG. 10, only one braking start distance Sb is set assuming a case where the hydraulic oil temperature is about 3° C. for low temperature use, but for example, when the temperature is 30° C. or higher, the braking start distance S at the normal time is set. Correspondingly, if the temperature is lower than that, the low temperature range is finely divided into multiple ranges, such as for low temperatures of 3 to 10°C, for low temperatures of 10 to 20°C, and for low temperatures of 20 to 30°C. A braking start distance Sb for low temperature may be set and stored in the storage unit 25 .

"Second embodiment (example of response to hydraulic oil temperature)"
In the first embodiment, the braking distance E2 is calculated from the preset braking start distances S and Sb, whereas in the second embodiment, the calculation formula (2) " E2=fb ₁ (v, T)” to calculate the braking distance E2. Calculation formula (2) is an expression of the relationship that the higher the vehicle speed, the longer the braking distance E2, and the lower the operating oil temperature, the longer the braking distance E2.
E2: braking distance _fb1 : function v: speed T: hydraulic oil temperature

In the case of the hydraulic oil viscosity, the braking distance E2 is calculated by the formula (3) "E2=fb ₂ (v, μ)" using the vehicle speed and the hydraulic oil viscosity as variables. Calculation formula (3) is an expression of the relationship that the higher the vehicle speed, the longer the braking distance E2, and the higher the hydraulic oil viscosity, the longer the braking distance E2.
E2: Braking distance fb ₂ : Function v: Velocity μ: Hydraulic oil viscosity

FIG. 11 is an output flow chart of the brake signal R in consideration of the low temperature. The control device 3 acquires data D1 in step ST21, and determines whether or not there is an obstacle G in step ST22. If NO in step ST22, the process returns to step ST21. If YES in step ST22, the measured distance E1 is calculated from the data D1 in step ST23.

Also, in step ST23, the braking distance E2 is specified from the data D2 and D4. In the case of the first embodiment, one of the braking start distance S and the braking start distance Sa is selected with reference to the hydraulic oil temperature obtained from the data D4. As for the selection method, for example, an appropriately set threshold value is compared with the data D4. to select. Then, based on the data D2, the braking distance E2 is specified from either the selected braking start distance S or Sb. In the case of the second embodiment, the braking distance E2 is specified from the formula (2) or (3).

Next, in step ST24, it is determined whether or not the measured distance E1 is equal to or less than the braking distance E2. If NO, the process returns to step ST21, and if YES, a brake signal R is output in step ST25.

The braking start distance Sb at low temperatures is set longer than the braking start distance S at normal times. Therefore, when the temperature is low, the timing (time) from when the obstacle determination unit 21 determines that there is an obstacle G to when the brake signal R is output is shortened. Conversely, under normal conditions, the required braking distance is shorter than when the temperature is low, and there is time to contact the obstacle G, so collision can be avoided even if the timing is delayed. As a result, regardless of changes in the braking distance caused by the hydraulic oil temperature, it is possible to achieve both avoidance of collision with the obstacle G and reduction of useless stoppages. The same applies to the braking distance E2 calculated in the second embodiment.

The preferred embodiments of the present invention have been described above. If the construction vehicle is a compaction roller such as the tire roller 10, if the brake means 6 is an HST brake acting on the closed circuit U1 of the running pump P and the running motor M, the engine will be stopped. As a result, excessive sudden stops can be avoided, and flatness defects such as dents on the asphalt paved road surface can be reduced. In addition, the operation of resuming traveling is facilitated.

Further, the hydraulic oil sensor 9 may be a viscosity sensor that detects the viscosity of the hydraulic oil. Further, although the distance image sensor 2 is attached to the rear portion of the vehicle in this embodiment, it may be attached to the front portion of the vehicle to detect the forward direction of the vehicle. Also, the brake means 6 may be a parking brake device, a drum brake device, or the like.

In the case of dealing with both the inclination angle of the slope and the hydraulic oil temperature, for example, as shown in FIG. is multiplied by the above and added to the braking start distance Sa for the slope to calculate the braking start distance Sc. That is, the braking start distance Sc is calculated by the formula "Sc=Sa+k(Sb-S)". From this braking start distance Sc, a braking distance E3 corresponding to the vehicle speed detected by the vehicle speed sensor 7 is specified. Then, it is sufficient to determine whether or not the measured distance E1 is equal to or less than the braking distance E3 and output the brake signal R.

In addition, an arbitrary coefficient is set, and the braking distance E3 is calculated by the formula ( ₄ ) "E3=fc1(v, α, T)" using the three variables of vehicle speed, inclination angle, and hydraulic oil temperature. good too. Calculation formula (4) is an expression of the relationship that the higher the vehicle speed, the longer the braking distance E3, the higher the inclination angle, the longer the braking distance E3, and the lower the hydraulic oil temperature, the longer the braking distance E3.
E3: Braking distance fc ₁ : Function v: Velocity α: Inclination angle T: Hydraulic oil temperature

In the case of the hydraulic oil viscosity, the braking distance E3 is calculated by the formula (5) "E3=fc ₂ (v, α, μ)" using the three variables of the vehicle speed, the inclination angle, and the hydraulic oil viscosity. Calculation formula (5) is an expression of the relationship that the higher the vehicle speed, the longer the braking distance E3, the higher the inclination angle, the longer the braking distance E3, and the higher the hydraulic oil viscosity, the longer the braking distance E3.
E3: Braking distance fc ₂ : Function v: Velocity α: Inclination angle μ: Hydraulic oil viscosity

1 obstacle detection device 2 distance image sensor (distance sensor)
3 control device 6 braking means 7 vehicle speed sensor 8 tilt sensor 9 hydraulic oil sensor 10 tire roller (construction vehicle)

Claims (5)

An obstacle detection device mounted on a construction vehicle equipped with a hydraulic traveling system circuit,
a distance sensor capable of detecting the distance to an obstacle;
a hydraulic oil sensor that detects the temperature or viscosity of the hydraulic oil in the traveling system circuit;
a control device that determines the presence or absence of an obstacle based on the detection data of the distance sensor and outputs a brake signal when it is determined that there is an obstacle;
braking means for braking via a brake that acts on the hydraulic travel system circuit when the brake signal is input;
with
the timing from when the control device determines that there is an obstacle to when the brake signal is output varies according to the temperature or viscosity of the hydraulic oil detected by the hydraulic oil sensor;
When the hydraulic oil temperature is below a predetermined threshold value or when the viscosity is above a predetermined threshold value, the braking means is more effective than when the hydraulic oil temperature is above the predetermined threshold value or when the viscosity is below the predetermined threshold value. An obstacle detection device for a construction vehicle, characterized in that the operation timing of the construction vehicle is advanced. Equipped with a vehicle speed sensor that detects the running speed of the vehicle,
The control device is
a braking distance calculation unit that calculates a braking distance E2 from the vehicle speed detected by the vehicle speed sensor and the temperature or viscosity of hydraulic oil detected by the hydraulic oil sensor;
a distance comparison unit that compares the measured distance E1 to the obstacle detected by the distance sensor and the braking distance E2;
a braking command unit that outputs the brake signal when the measured distance E1 becomes equal to or less than the braking distance E2;
The obstacle detection device for a construction vehicle according to claim 1 , characterized by comprising: The braking distance calculator,
a storage unit that includes correlation data between vehicle speed and braking distance and stores a plurality of braking start distances that differ according to the temperature or viscosity of hydraulic oil;
One braking start distance is selected from the plurality of braking start distances by referring to the temperature or viscosity of the hydraulic oil detected by the hydraulic oil sensor, and the vehicle speed detected by the vehicle speed sensor from the selected braking start distance. A braking distance identification unit that identifies a braking distance E2 corresponding to
The obstacle detection device for a construction vehicle according to claim 2 , characterized by comprising: The braking distance calculator,
3. The obstacle detection device for a construction vehicle according to claim 2 , wherein the braking distance E2 is calculated by a formula using the vehicle speed and the temperature or viscosity of the hydraulic oil as variables. The construction vehicle is a compaction roller,
5. The obstacle detection device for a construction vehicle according to claim 1 , wherein said braking means is an HST brake acting on a hydraulic travel system circuit.

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