KR20110032333A - Wheel drive vehicle and wheel contact sensing method of the same - Google Patents

Abstract

PURPOSE: A wheel driving vehicle and a wheel contact sensing method thereof are provided to confirm the position control error of a wheel by sensing the contact of the wheel in various directions. CONSTITUTION: A wheel driving vehicle comprises a wheel(130) and a sensing unit. The wheel is rotatably installed in an arm(120) of a main body(110). The sensing unit senses a non-contact state that the wheel is separated from the ground. The sensing unit comprises a spring(141), first and second sensors, and a controller. When the arm is relatively rotated to the output shaft of an arm drive unit(121), the spring is stretched or compressed. The first and second sensors detect arm drive information and main body posture information. The controller detects the non-contact state of the wheel based on the measured length and reference length of the spring.

Description

WHEEL DRIVE VEHICLE AND WHEEL CONTACT SENSING METHOD OF THE SAME}

The present invention relates to a wheel contact sensing method for sensing the presence or absence of wheel contact and a wheel drive vehicle to which the wheel is applied.

Due to the development and development of advanced science and technology, various technologies have been applied to the military field, and in particular, the development of sensors and computer hardware makes the combat system unmanned.

Developed countries already have great interest in the development of military robots, and the United States, in particular, is conducting research on the unmanned military sector in order to deploy unmanned vehicles in the Future Combat System. Unmanned vehicles are being actively researched in Korea, and various unmanned systems are being developed in the defense sector.

Looking at the direction of technology development in the field of unmanned vehicles, unmanned vehicles will perform mission functions such as surveillance reconnaissance and hitting, command control, and explosive detection / removal. When the wheel driving method is applied to the unmanned vehicle, it is necessary to detect the contact between the wheel and the ground in order to pass the obstacle of the unmanned vehicle.

In general, a contact sensor (or a pressure sensor) is attached between two objects to check whether the two objects are in contact. However, when the friction of the contact portion is severe, such as the unmanned vehicle, it will be difficult to attach the contact sensor.

Therefore, there is a need for a new type of wheel contact sensing structure and method suitable for an unmanned vehicle.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and to provide a new type of wheel contact sensing structure and method for wheel contact sensing of a wheel drive vehicle.

In order to achieve the above object, the present invention provides a main body having a rotatable arm and an arm drive unit for driving the arm, a wheel rotatably mounted to the arm, and a non-contact state in which the wheel is separated from the ground. And a sensing unit, wherein the sensing unit is installed between the arm drive unit and the arm and is tensioned or compressed as the arm moves relative to the output shaft of the arm drive unit, and rotation of the arm relative to the body. A reference length of the spring in the non-contact state from at least one of first and second sensors for detecting driving information and attitude information of the main body with respect to the ground, and rotational drive information of the arm and attitude information of the main body, respectively; Calculating and detecting a non-contact state of the wheel based on the measured length of the spring and the reference length. Disclosed is a wheel driving vehicle and a wheel contact sensing method applied thereto.

In addition, the present invention includes a main body having a rotatable arm and an arm drive for driving the arm, a wheel rotatably mounted to the arm, and a sensing unit for sensing a non-contact state in which the wheel is separated from the ground; The sensing unit is installed between the arm drive unit and the arm, the spring is tensioned or compressed as the arm is rotated relative to the output shaft of the arm drive unit, the rotational drive information of the arm relative to the body and the ground A reference angle of the arm in the non-contact state is calculated from at least one of first and second sensors that detect posture information of the main body, and rotational drive information of the arm and posture information of the main body, respectively; And a controller configured to detect a non-contact state of the wheel based on the rotational movement angle and the reference angle. A wheel drive vehicle wheel and hence the applied detection method as presented.

The inside of the wheel is provided with a wheel driving unit for rotating the wheel, the control unit may operate the wheel driving unit to rotate the wheel in a non-contact state of the wheel. In addition, the controller may be configured to detect a contact state of the wheel in contact with the ground from the speed change of the wheel generated as the wheel is in contact with the ground.

The present invention provides a new type of wheel contact sensing structure and method for detecting a non-contact state of a wheel by using a state of a spring and a touch state of a wheel by using a change in rotational speed of the wheel.

In addition, the present invention is capable of detecting wheel contact in various directions, and has an effect of determining an error in a wheel position control procedure.

Hereinafter, a wheel driving vehicle and a wheel contact sensing method thereof according to the present invention will be described in detail with reference to the accompanying drawings.

1 is a perspective view of a wheel drive vehicle according to an embodiment of the present invention, Figure 2 is a side view of the wheel drive vehicle shown in FIG.

A wheel drive vehicle according to an embodiment of the present invention includes a main body 110 having an arm 120 and a wheel 130 rotatably connected to the arm 120.

A plurality of arms 120 are rotatably connected to both side surfaces of the main body 110. Although the present embodiment illustrates that six arms 120 are connected to each of three sides of the body 110, a total of six arms 120 may have various numbers according to design specifications.

Wheels 130 are rotatably connected to the arms 120. In other words, one end of the arms 120 is rotatably connected to the body 110, and the other end of the arms 120 is rotatably connected to the wheels 130.

The main body 110 is provided with an arm driver 121 for driving the rotation of the arms 120, and the wheel driver 145 (see FIG. 4) for driving the wheels 130 is installed inside the wheels 130. Can be. The arm driver 121 and the wheel driver 145 may be implemented in the form of a drive motor, and they may be individually controlled to be independently driven.

As the arms 120 are rotationally driven relative to the body 110, the position of the body 110 may be raised or lowered, and it may be possible to pass an obstacle.

2 illustrates the body passing through an obstacle as the arms 120 are rotated.

The terrain sensing device mounted on the main body 110 estimates the height of the obstacle, the distance to the obstacle, and the like. As shown in FIG. 2, in order to overcome obstacles vertically protruding forward, rotational driving is performed to lift the arm 120 mounted in front of the main body 110.

Here, in consideration of the sensor error, and lifts the front arm 120 higher than the estimated height of the obstacle derived from the measurement result of the terrain sensing device, and advances the main body 110 by the estimated distance.

Thereafter, the front arm 120 is lowered in the direction in which the obstacle is located in order to contact the front wheel 130 with the obstacle, and when the front wheel 130 is in contact with the obstacle, the arm posture control in the following order for overcoming the obstacle is performed. Will perform.

As such, detecting whether the wheel 130 is in contact with the ground is a very important factor in driving control of the wheel driving vehicle. Hereinafter, a structure of a sensing unit for sensing a wheel contact applied to the present invention and a sensing method applied thereto will be described in detail.

3 is a diagram illustrating a structure of a sensing unit according to an embodiment of the present invention, and FIG. 4 is a block diagram of a sensing unit according to an embodiment of the present invention.

Hereinafter, a description will be given based on any one of the plurality of arms, but the structure of the sensing unit for wheel contact sensing may be implemented in each of the arms, and accordingly, whether the wheels are in contact with each of the arms may be detected.

3 and 4, the sensing unit includes a spring 141 provided between the arm driver 121 and the arm 120 of the main body 110 and a first sensor for detecting rotation information of the arm driver 121. 142, the second sensor 143 detecting posture information of the main body 110, and the non-contact of the wheel 130 based on the information detected from the first and second sensors 142 and 143 and the spring 141. The control unit 144 detects a state.

The arm 120 may be rotated by the driving of the arm driver 121, or may be rotated by a contact force as the wheel 130 contacts the outside (for example, the ground). In the present specification, the rotation of the arm 120 by the driving of the arm driving unit 121 is referred to as 'arm rotation driving', and the rotation of the arm 120 by the wheel contact force is referred to as 'arm rotation movement'.

One end of the spring 141 is fixed to the output shaft of the arm driving unit 121, and the other end of the spring 141 is fixed to the arm 120 so as to be tensioned or compressed according to the rotational motion of the arm 120. The spring 141 may be implemented in the form of a coil spring, a gas spring, a torsion bar, or the like. This embodiment illustrates that the spring 141 is implemented in the form of a coil spring.

In FIG. 3, θ _s denotes an initial mounting angle of the arm 120 with respect to the output shaft of the arm driving unit 121, and the first sensor 142 is an arm 120 from the initial mounting angle during rotation driving of the arm driving unit 121. This rotated angle, that is, the output shaft rotational angle of the arm drive unit 121 is detected. The first sensor 142 may be implemented as an angle sensor (eg, a resolver of the arm driving motor) of the arm driver 121.

The second sensor 143 detects attitude information of the main body 110, specifically, a pitch angle of the main body 110 with respect to the ground. This pitch angle is generated as the main body 110 is tilted with respect to the ground during the rotational driving of the arms 120. The second sensor 143 may be implemented as an attitude sensor mounted on the main body 110.

The control unit 144 detects the reference length L of the spring 141 in the non-contact state from at least one of the rotation information and the attitude information of the arm drive unit 121, and the measured length and the detected reference length of the spring 141. The non-contact state of the wheel 130 is detected based on (L).

On the other hand, in addition to this method, the control unit 140 detects the reference angle φ of the spring 141 in a non-contact state from at least one of the rotation information and the attitude information of the arm drive unit 121, and the arm 120 It is also possible to detect the non-contact state of the wheel 130 based on the rotational movement angle and the reference angle φ.

That is, the controller 140 detects the non-contact state of the wheel 130 or the reference angle of the arm 120 based on the reference length L of the spring 141 and the measured length measured when the spring 141 is deformed. And the non-contact state of the wheel 130 is detected based on the rotation angle measured during the rotational movement of the arm 120.

The control unit 140 may adopt one of the above two methods, or may be implemented as a mixed method of the two methods.

The following is a formula showing a method of detecting the reference angle φ and the reference length L based on the illustration of FIG. 3.

In FIG. 3 and the above equations, W denotes the load of the arm 120 and the wheel 130, and l _S denotes the distance between the center of rotation of the arm 120 and the center of gravity of the arm 120 and the wheel 130. .

θ _S represents the initial mounting angle of the arm 120 with respect to the output shaft of the arm drive 121, θ _P is the rotation of the mounting surface (D) of the arm drive 121 output shaft relative to the horizontal plane (S) horizontal to the ground Indicates the angle. Here, θ _P may occur due to the pitch angle of the main body 110 as the main body 110 is tilted, or may occur as the arm 120 is driven and rotated with respect to the main body 110.

K _r represents the rotational spring constant and W _l represents the load acting on the mounting point of the linear spring by W _r . And K ₁ represents a linear spring constant.

Referring to the above equations, the reference angle (φ) and the reference length (L) is determined based on the weight of the arm 120 and the wheel 130, the physical properties of the spring 141 and the like. In addition, it can be seen that the load (W _r ) for determining the reference angle (φ) and the reference length (L) is changed by θ _P , which is dependent on the pitch angle of the main body 110 and the rotation angle of the arm drive unit 121. Is determined by.

The first sensor 142 and the second sensor 143 of the sensing unit sense them, respectively, so that the controller 144 can detect the reference angle φ or the reference length L.

5 is a flowchart illustrating a wheel contact sensing method according to an exemplary embodiment of the present invention.

First, rotation information of the arm driver 121 and posture information of the main body 110 are detected through the first sensor 142 and the second sensor 143 (S10). In addition, the controller 144 calculates the reference length L of the spring 141 or the reference angle φ of the arm 120 in the same manner as in the above equations (S20).

The above processes are performed in real time when the wheel driving vehicle is driven, and the controller 144 compares the measurement length of the spring 141 deformed during the rotational movement of the arm 120 with the reference length L, or the arm 120. Compare the measured angle and the reference angle (φ) for the rotational movement of (S30).

When the measured value falls within the error range of the reference length L or the reference angle φ, the controller 144 recognizes that the wheel 140 is in a non-contact state (S40).

On the other hand, in order to detect that the wheel is switched to the contact state in contact with the ground in such a non-contact state, the control unit 144 operates the wheel drive unit 145 so that the wheel 130 rotates (S50). At this time, the wheel driver 145 rotates the wheel 130 with the minimum power that the wheel 130 can rotate.

When the wheel 130 during rotation in contact with the ground in a non-contact state, a change occurs in the rotational speed of the wheel 130, the control unit 144 is a change occurs in the rotational speed of the wheel (S60) It is recognized that 130 is in the contact state (S70).

The wheel touch sensing structure and method related to the present invention as described above have the following effects.

In general, as a wheel contact detection method, a method of confirming wheel contact using a slip ratio which is a relationship between a wheel rotation speed and a vehicle speed may be used. In this case, there is a problem that this method is difficult to use. This is because, if the speed is generated on the wheel while the vehicle is stopped, the positional change of the vehicle occurs.

The present invention detects the non-contact state of the wheel 130 by using the change in the length or angle of the spring 141 in consideration of the attitude of the vehicle and the rotation angle of the arm, by applying a minimum driving force only to the detected wheel 130 When the contact with the ground again occurs by using a change in the rotational speed of the wheel 130 to determine the occurrence of contact, the above problems are solved.

FIG. 6 is a graph measuring an arm resolver angle and a wheel angular velocity of the arm during the driving process of FIG. 2.

When the front arm 120 is lifted away from the ground for overcoming the obstacle, the spring 141 (rotational spring) installed on the front arm 120 is in a down state in the ground direction (-direction). This is due to the influence of the weight of the main body 110 and the weight of the arm 120, and in the above process, the controller 144 detects that the wheel 130 is in a non-contact state. For reference, in the present experimental example, the spring 141 is implemented in a rotatable form such as a torsion bar and a torsion spring.

When the non-contact state of the wheel 130 is detected, the controller 144 applies a command for rotating the wheel 130 to the wheel driver 145, and the wheel 130 rotates with the minimum power.

Then, when the front of the arm 120 is lowered and the contact of the wheel 130 and the ground occurs, a change in the rotational speed of the wheel 130 occurs. The graph according to the present embodiment illustrates a state in which the wheel 130 is stopped while rotating. At this time, the rotation spring 141 has a rotation angle in a direction opposite to the ground (+ direction).

Again, when the arm 120 is rotated in the opposite direction to the ground to change the attitude of the vehicle, the rotation spring 141 has a rotation angle in the − direction. When the rotation angle of the rotation spring 141 comes within the range of the reference angle φ, the controller 144 detects the non-contact state of the wheel 130 and operates the wheel driver 145 again.

As described above, the angle of the rotation spring 141 and the rotation speed change of the wheel 130 when the wheel 130 is sequentially changed from the non-contact to the non-contact state to the ground are shown in FIG. 6.

7 is a view showing a wheel contact detection method according to another embodiment of the present invention.

This embodiment shows the operation of the sensing unit in a situation that may occur due to sensor measurement error, etc. when driving the obstacle of the wheel drive vehicle.

Incorrect estimates of the height of obstacles can occur due to sensor measurement errors or ground irregularities. In this case, the front wheel 130 is in contact with the obstacle in the step of traveling by the estimated distance while the front arm 120 is lifted.

In this case, since the force generated by the contact between the wheel 130 and the obstacle acts in the longitudinal direction of the arm 120, the change in the length of the spring 141 hardly appears. However, a speed change occurs in the rotating wheel 130.

Using this point, the controller 144 may detect the sensing accuracy of the height of the obstacle, that is, whether the height of the obstacle is accurately estimated. That is, if it is detected that the front wheel 130 is in contact with the obstacle before reaching the estimated distance, the controller determines that there is a problem in lifting the front arm, that is, estimating the height of the obstacle. Accordingly, the present invention is capable of detecting wheel contact in various directions as well as the ground, thereby determining an error in a wheel position control procedure.

In the above described with reference to the accompanying drawings, a wheel driving vehicle and a wheel contact detection method according to the present invention, the present invention is not limited by the embodiments and drawings disclosed herein, the scope of the technical idea of the present invention Various modifications can be made by those skilled in the art.

1 is a perspective view of a wheel drive vehicle according to an embodiment of the present invention.

FIG. 2 is a side view of the wheel drive vehicle shown in FIG. 1. FIG.

3 is a diagram illustrating a structure of a sensing unit related to an embodiment of the present invention.

Figure 4 is a block diagram of a sensing unit related to an embodiment of the present invention.

5 is a flow chart showing a wheel contact detection method associated with an embodiment of the present invention.

Figure 6 is a graph measuring the rotation angle of the arm and the rotation speed of the wheel during the driving process of the vehicle described in FIG.

7 is a view showing a wheel contact detection method associated with another embodiment of the present invention.

Claims (16)

A main body having a rotatable arm and an arm driving unit for driving the arm, a wheel rotatably mounted to the arm, and a sensing unit sensing a non-contact state in which the wheel is separated from the ground, The sensing unit, A spring installed between the arm drive unit and the arm, the spring being tensioned or compressed as the arm moves relative to the output shaft of the arm drive unit; First and second sensors for detecting rotational drive information of the arm with respect to the main body and attitude information of the main body with respect to the ground, respectively; And Calculating a reference length of the spring in the non-contact state from at least one of rotational drive information of the arm and attitude information of the main body, and detecting a non-contact state of the wheel based on the measured length of the spring and the reference length Wheel drive vehicle comprising a control unit. A main body having a rotatable arm and an arm driving unit for driving the arm, a wheel rotatably mounted to the arm, and a sensing unit sensing a non-contact state in which the wheel is separated from the ground, The sensing unit, A spring installed between the arm drive unit and the arm, the spring being tensioned or compressed as the arm moves relative to the output shaft of the arm drive unit; First and second sensors for detecting rotational drive information of the arm with respect to the main body and attitude information of the main body with respect to the ground, respectively; And The reference angle of the arm in the non-contact state is calculated from at least one of the rotation driving information of the arm and the posture information of the main body, and the non-contact state of the wheel is based on the rotational movement angle and the reference angle of the arm. Wheel drive vehicle comprising a control unit for detecting. The method according to claim 1 or 2, The arm is provided in plurality in the main body is driven individually, The sensing unit is a wheel drive vehicle, characterized in that each provided in the plurality of arms. The method according to claim 1 or 2, And the spring is any one of a coil spring, a gas spring, and a torsion bar. The method according to claim 1 or 2, Wheel drive vehicle, characterized in that the rotational drive information of the arm includes an output shaft rotational angle of the arm drive unit. The method according to claim 1 or 2, The first sensor is an angle sensor of the arm drive unit, the second sensor is a wheel drive vehicle, characterized in that the attitude sensor mounted on the main body. The method according to claim 1 or 2, Inside the wheel is provided with a wheel drive for rotating the wheel, The control unit is a wheel drive vehicle, characterized in that for operating the wheel driving unit to rotate the wheel in a non-contact state of the wheel. The method of claim 7, wherein The control unit is a wheel drive vehicle, characterized in that for detecting the contact state that the wheel is in contact with the ground from the speed change of the wheel generated as the wheel is in contact with the ground. The method of claim 7, wherein The wheel driving unit is a wheel driving vehicle, characterized in that for driving the wheel rotation with the minimum power that the wheel is rotatable. A spring connected between the arm drive unit and the arm and the first and the first vehicle when the wheel drive vehicle includes a main body having a rotatable arm and an arm drive unit for driving the arm, and a wheel rotatably mounted to the arm. In the wheel contact detection method of a wheel drive vehicle for detecting a non-contact state in which the wheel is separated from the ground using a sensor, Detecting rotational driving information of the arm and posture information of the main body with respect to the ground through the first and second sensors, respectively; Calculating a reference length of the spring in the non-contact state based on at least one of rotational drive information of the arm and attitude information of the main body; And Measuring the length of the spring and detecting a non-contact state of the wheel based on the measured length of the spring and the reference length of the spring. A spring connected between the arm drive unit and the arm and the first and the first vehicle when the wheel drive vehicle includes a main body having a rotatable arm and an arm drive unit for driving the arm, and a wheel rotatably mounted to the arm. In the wheel contact detection method of a wheel drive vehicle for detecting a non-contact state in which the wheel is separated from the ground using a sensor, Detecting rotational driving information of the arm and posture information of the main body with respect to the ground through the first and second sensors, respectively; Calculating a reference angle of the arm in the non-contact state based on at least one of rotation information of the arm and posture information of the main body; And Measuring a rotational movement angle of the arm and detecting a non-contact state of the wheel based on the measurement angle of the arm and the reference angle. The method according to claim 10 or 11, wherein Wheel drive detection method of the wheel drive vehicle, characterized in that the rotational drive information of the arm comprises an output shaft rotation angle of the arm drive unit. The method of claim 10, And the reference length is detected based on the weights of the arms and the wheels and the physical properties of the springs. The method of claim 11, And the reference angle is detected based on the weight of the arm and the wheel and the physical properties of the spring. The method according to claim 10 or 11, wherein Driving the wheel to rotate in a non-contact state of the wheel; And And detecting a contact state of the wheel in contact with the ground from a change in speed of the wheel generated when the wheel is in contact with the ground. The method according to claim 10 or 11, wherein Sensing a height of an obstacle located in front of the main body; Driving the wheel to rotate in a non-contact state of the wheel; And And detecting the accuracy of the sensing result from a change in speed of the wheel generated when the wheel contacts the obstacle.

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