KR101026596B1 - trajectory control device and method of mobile robot using omni-wheels - Google Patents

Abstract

An apparatus and method for driving control of a mobile robot using an omni wheel are provided. According to this, the traveling trajectory of the mobile robot using three omni wheels; Setting a base angle of the mobile robot, calculating a rotation angle of the mobile robot, and controlling an angular velocity of the mobile robot; Setting a moving angle of the mobile robot, and calculating a moving angle of the mobile robot; Calculating a rotation speed of each of the three motors corresponding to each of the omni wheels using the controlled angular speed and the calculated moving angle; Controlling the rotation speed of each motor by using the calculated rotation speed of each motor; And driving the mobile robot at the rotational speed of each of the controlled motors, and controlling the rotational speed of each of the motors by sensing each rotational speed of each of the motors by three motor speed sensors. The method may further include controlling the rotation speed of each of the motors by using the calculated rotation speed of each of the motors and the rotation speed of each of the sensed motors, and calculating the rotation angle of the mobile robot. The method further includes sensing the gyro angle of the mobile robot by a gyro sensor, and using the base angle of the set mobile robot and the sensed gyro angle, calculate a rotation angle of the mobile robot.

  Omni Wheel, Mobile Robot, Driving Control Device, Driving Control Method, Base Angle, Rotation Angle, Motor, Rotation Speed

Description

Travel control device and method of mobile robot using omni-wheels}

The present invention relates to a traveling control apparatus and method for a mobile robot using an omni wheel, and more particularly, to travel more efficiently and to travel more agilely and accurately, driving a mobile robot using an omni wheel. A control apparatus and method are provided.

Starting with a robot named ASIMO, developed by Honda, Japan, a so-called humanoid robot in which humans walk with their legs in developed countries including Korea. We have invested a lot in developing. All of the commercialized service robots, such as the conventional cleaning robots, adopt the wheelbase method, which is a movement method used in factory automation and guide robots because of the convenience and mobility. Many experts foresee the use of mobile robotic systems. Therefore, the development of the autonomous mobile robot platform with the basic functions of self-recognition and moving to the desired place will be the component module having the greatest demand in the service robot market in the future.

Service robots are very different from industrial robots in many respects because they operate in the same space as humans. Industrial robots are limited to simple, repetitive tasks and perform only pre-programmed tasks that are independent of humans in a limited and well-organized environment. However, in environments such as offices and homes, where there are no formalized rules, service robots often operate in close proximity to or near humans. In addition, the tasks of service robots are not merely repetitive tasks, but mainly supporting or assisting human beings.

In order to drive the service robot, two wheels and one auxiliary wheel were used. However, this method was limited to more free running indoors.

Recently, in order to improve the shortcomings of the existing mobile robots, autonomous mobile robots using omni wheels, which are a new driving system platform using omni-wheels, have been studied. The autonomous mobile robot was able to realize a holonomic system by using a unique wheel called an omni wheel. The holographic system is defined by the relationship between the degree of freedom that can be controlled and the degree of freedom that can be controlled. When the degree of freedom to control is greater than or equal to the degree of freedom to control, it is called a holographic system. When the degree of freedom to control is less than the degree of freedom to control, it is called a non-holonomic system. The omni wheel consists of a main wheel and auxiliary wheels hanging around it like a satellite. The main wheel rotates about the rotation axis of the motor like a general wheel, and the auxiliary wheel generates slip in the direction of the rotation axis (the direction perpendicular to the main wheel) by external force. Thanks to the omni wheel having such a unique structure, the autonomous mobile robot using a conventional omni wheel could implement a holographic system capable of moving in any direction without a turning radius.

However, in the case of the mobile robot using the omni wheel, despite the many advantages described above, since the position movement and attitude control is very difficult than the conventional general wheels are used, there is a problem that it is not possible to travel quickly and accurately.

Accordingly, an object of the present invention is to enable omniwheels to improve uncertainty in position movement, rotation, and posture, which is the biggest disadvantage of omniwheels, while actively utilizing the advantages of the holographic characteristics of mobile robots using omniwheels. To provide a driving control apparatus and method of a mobile robot using the.

In order to achieve the above object, a traveling control method of a mobile robot using an omni wheel according to the present invention comprises the steps of: planning a driving trajectory of a mobile robot using three omni wheels; Setting a base angle of the mobile robot, calculating a rotation angle of the mobile robot, and controlling an angular velocity of the mobile robot; Setting a moving angle of the mobile robot, and calculating a moving angle of the mobile robot; Calculating a rotation speed of each of the three motors corresponding to each of the omni wheels using the controlled angular speed and the calculated moving angle; Controlling the rotation speed of each motor by using the calculated rotation speed of each motor; And driving the mobile robot at the rotational speed of each of the controlled motors, and controlling the rotational speed of each of the motors by sensing each rotational speed of each of the motors by three motor speed sensors. The method may further include controlling the rotation speed of each of the motors by using the calculated rotation speed of each of the motors and the rotation speed of each of the sensed motors, and calculating the rotation angle of the mobile robot. And sensing the gyro angle of the mobile robot by a gyro sensor, and calculating the rotation angle of the mobile robot by using the set base angle of the mobile robot and the sensed gyro angle.

In addition, the traveling control apparatus of the mobile robot using the omni wheel according to the present invention is characterized in that it comprises a control unit for controlling the travel trajectory of the mobile robot using three omni wheels by the above traveling control method.

According to the present invention, the traveling control apparatus and method of the mobile robot using the omni wheel, it is possible to drive the autonomous mobile robot more efficiently, it is possible to drive the autonomous mobile robot more agile and accurate.

Hereinafter, a traveling control apparatus and method for a mobile robot using an omni wheel according to the present invention will be described in detail with reference to the accompanying drawings.

The autonomous mobile robot of the present invention may use an omni wheel having a structure as shown in FIGS. 1A and 1B to implement a holographic system. As shown in FIG. 1B, the omni wheel rotates in the same direction as a general wheel in the A direction by power transmitted to an axis (not shown) of the wheel, and a slip may occur in the B direction by an external force. Is done in groups. By properly placing omni wheels with this unusual structure, a holographic system capable of moving in any direction can be realized by using the speed ratio of each other. The design method using the omni wheel can be divided into a design method using three omni wheels and a design method using four omni wheels.

According to each design scheme, the omniwheel motor driving scheme for straightening is as shown in FIGS. 2A and 2B. The driving kinematics of each of the mobile robots according to the arrangement of the omni wheels as shown in FIGS. 2A and 2B are shown in Equations 1 and 2, respectively.

In the case of the design using three omni wheels, one omni wheel drive motor is energy efficient, while the other two omni wheel drive motors do not transmit all the rotational energy straight ahead. However, in the case of design using four omni wheels, only two omni wheel drive motors can be used to drive like a general wheel base system and energy efficiency is high. However, using four omni wheels requires a separate suspension structure. This is because, if the floor is uneven, all four wheels cannot be grounded, making it difficult to control all the wheels. Therefore, in order to solve this problem, a suspension structure should be used, but it is difficult to design the suspension structure so that the load is applied evenly to all the wheels even when the suspension structure is used. Designing suspension structures is a more difficult task in robots with a non-uniform center of gravity, such as mesclean-up robots, that have to move objects. However, if three omni wheels are used, the three wheels will always be grounded to the floor regardless of the floor condition, and all wheels will always be in control.

Considering these points, the autonomous mobile robot of the present invention will design a traveling system using three omni wheels. If these three omni wheels are used, the holographic system can be realized, and the convenience of movement can be secured in a small space such as a room.

A typical non-holographic system is a car. In order for the car to change direction, it must have some radius of rotation. However, the holographic system can change direction without a separate turning radius, and does not even need to rotate the system to change direction. This is possible to move freely if there is enough space for the robot to move even if the direction is changed in a narrow room, and it is possible to flexibly avoid the obstacle even if a moving obstacle appears suddenly.

Therefore, in the autonomous mobile robot of the present invention, three omni wheels were used, and a special control method for position and direction control of three omni wheels was proposed, and the position and direction control of the autonomous mobile robot as shown in FIG. Use an algorithm.

라고 나타낼 수 있다. 여기서 로봇의 좌표계 [x_l, y_l]를 정의하면, 좌표계의 중심은 로봇의 무게중심점이 되고, 3개의 옴니휠은 α_i(i=1, 2, 3)의 각도로 놓여있다. x_l을 기준으로 하면 α₁=0°, α₂=120°, α₃=240°이다. 하지만 이동 로봇은 α₂=90°로 정의하였으므로, α₁=210°, α₂=90°, α₃=330°이다. 이제 각 바퀴 축의 속도를 v_i라 정의하면, v_i는 수학식 3과 같다.The driving kinematics of an autonomous mobile robot using three omni wheels can use the definition of Rob Van Haendel. First, as illustrated in FIG. 4, if the global coordinate system [x, y] where the robot is located is defined, the position and direction of the robot may be represented by (x, y, θ), and the speed may be represented.

Can be represented. If the coordinate system [x _l , y _l ] of the robot is defined, the center of the coordinate system becomes the center of gravity of the robot, and the three omni wheels lie at an angle of α _i (i = 1, 2, 3). Based on x ₁ , α ₁ = 0 °, α ₂ = 120 °, and α ₃ = 240 °. However, since the mobile robot is defined as α ₂ = 90 °, α ₁ = 210 °, α ₂ = 90 °, and α ₃ = 330 °. Now define the speed of each wheel axis as v _i , v _i is

v _i = v _{trans, i} + v _rot

Where v _{trans, i} is the velocity for movement of axis i and v _rot is the velocity for rotation.

First, only the velocity component for purely moving can be defined as in Equation 4.

Using this, the remaining v _{trans, i} may be defined as in Equation 5.

Now only the speed component for pure rotation can be defined as in Equation 6.

Where R is the distance from the center of gravity of the robot to the wheels.

When Equation 5 and Equation 6 are combined, the result is shown in Equation 7.

에 대한

로 행렬식으로 나타내면 그 결과는 수학식 8과 같다. This

For

When expressed as a determinant, the result is shown in Equation 8.

를 수학식 9와 같이, 로봇 좌표계

로 변환할 수 있다.Back to global coordinate system

As shown in equation (9), the robot coordinate system

Can be converted to

Using Equation 9, Equation 8 may be arranged as in Equation 10.

Using this, v _i can be defined as Equation 11 again.

v _i is the speed of each axis. The relationship between v _i and the motor speed can be expressed as in Equation 12.

를 수학식 13과 같이 정의할 수 있다.Where r is the radius of the wheel. Using this

May be defined as in Equation 13.

For autonomous mobile robots, α ₁ = 210 °, α ₂ = 90 °, α ₃ = 330 °. Therefore, by using Equation 13, the rotational speed V _x (x = 1, 2, 3) of each motor may be defined as in Equations 14 to 16.

The above equations are used to control the speed of the omni wheel driving motor corresponding to each omni wheel, and to drive by modifying the attitude of the mobile robot using a gyro sensor.

The mobile robot 100 of the present invention traveling in such a manner includes a control unit 10 applied to the traveling control apparatus of the mobile robot using the omni wheel, as shown in FIG. 5. In addition, the omni wheel unit 20, the omni wheel motor unit 30, the omni wheel motor speed sensing unit 40, the gyro sensor 50, and may be configured to include a power supply (60).

Here, the control unit 10 is a part for controlling the overall operation of the mobile robot 100 according to the present invention, the mobile robot 100 using three omni wheels according to the driving control method described below with reference to FIG. It may be provided with a microprocessor for controlling the driving trajectory, such as the movement and rotation of the position and each controller for controlling the operation of the above-described components. In addition, the microprocessor controls a driving trajectory such as position movement and rotation of the mobile robot 100 by feeding back a signal sensed from the omni wheel motor speed sensing unit 40 and the gyro sensor 50. As the controller, a motor speed controller such as a motor driver, a PID angular speed controller, or the like may be used.

The omni wheel part 20 and the omni wheel motor part 30 constitute a traveling part of the mobile robot 100. The omni wheel unit 20 includes three omni wheels 21, 23, 25, and three axes (not shown) fastened corresponding to each of the omni wheels 21, 23, 25.

The omni wheel motor unit 30 includes three motors 31, 33, and 35 for rotating each of the omni wheels 21, 23, and 25 so as to rotate each of the omni wheels 21, 23, and 25. Equipped. As the motors 31, 33, 35, for example, a DC motor is used.

The omni wheel motor speed sensing unit 40 includes three motor speed sensors 41, 43, 45 for sensing the rotational speeds of the motors 31, 33, 35, respectively. As the motor speed sensors 41, 43 and 45, for example, an encoder sensor is used.

The gyro sensor 50 is a sensor that senses a direction or angle indicating the posture of the mobile robot 100.

The power supply unit 60 may be configured to include a rechargeable battery as a power supply unit for supplying operation power required for each component of the mobile robot 100.

On the other hand, the mobile robot 100, although not shown in the drawings, the software for controlling the driving trajectory, such as the position movement and rotation of the mobile robot 100 is stored in advance to recognize the object outside the storage unit, the mobile robot 100 The object recognition unit may further include an RFID reader for reading a signal from the RFID tag. In an environment in which the mobile robot 100 autonomously runs, a plurality of environmental sensors such as RFID tags are generally disposed in advance.

A method of driving the mobile robot 100 configured as described above will be described with reference to FIGS. 6 and 7.

First, when a power switch (not shown) of the mobile robot 100 is turned on, the power supply unit 60 of the mobile robot 100 supplies operating power to each component that requires operating power. In this state, in step S10, the controller 10 grasps the current position of the mobile robot 100 through a magnetic position recognition process using, for example, an RFID reader and an RFID tag in the present given environment. Then, the controller 10 plans a driving trajectory for moving the mobile robot 100 to the destination using the location information in order to control the driving of the mobile robot 100.

After planning the driving trajectory of the mobile robot 100, in step S20, the controller 10 sets the base angle of the mobile robot 100 by proceeding from step S21 to step S25, By calculating the rotation angle of the (100) to control the angular velocity of the mobile robot 100, in parallel with the control unit 10 proceeds to step S27 and step S29 to set the moving angle of the mobile robot 100 And, the moving angle of the mobile robot 100 is calculated.

In more detail, in step S21, the controller 10 sets the base angle Base_Angle of the mobile robot 100. Base angle Base_Angle represents the head direction of the mobile robot (100).

After setting the base angle Base_Angle, in step S23, the controller 10 calculates the rotation angle of the mobile robot 100. That is, the controller 10 receives the gyro angle Gyro_Angle θgyro sensed at step S60 described later every sampling. The gyro angle (Gyro_Angle) (θgyro) represents the rotation angle (Rotation_Angle) of the current mobile robot 100. Thereafter, the controller 10 may increase the rotation angle to a constant value by adding the rotation angle to the base angle.

After calculating the rotation angle of the mobile robot 100, in step S25, the controller 10 obtains a difference value between the base angle and the gyro angle (Gyro_Angle) (θgyro), and the PID angular velocity in the controller 10. The controller uses the difference as an error value to control the angular velocity (Vw).

In parallel with steps S21 to S25, in step S27, the controller 10 sets the moving angle Move_Angle of the mobile robot 100. The moving angle Move_Angle represents the absolute direction in which the mobile robot 100 is to be moved. On the other hand, when the mobile robot 100 rotates, if the moving angle (Move_Angle) of the mobile robot 100 is not corrected, the mobile robot 100 cannot move in the original desired direction and moves in a circle or swirl pattern. Will be done.

After setting the moving angle (Move_Angle) of the mobile robot 100, in step S29, in order to move the mobile robot 100 in the desired direction even during rotation, the controller 10 of the mobile robot 100 In the moving angle Move_Angle, the moving angle Move_Angle of each moment is recalculated by subtracting the gyro angle Gyro_Angle θgyro of the mobile robot 100 sensed in step S60 described later.

Subsequently, in step S30, the control unit 10 moves by applying the moving angle Move_Angle and the speed of the desired motor Desired_Velocity calculated in step S23 to the above-described equations (14) to (16). The rotational speeds V _x (x = 1, 2, 3) of the motors 31, 33, 35 are respectively calculated to move the robot 100 in the desired direction.

Then, in step S40, the controller 10 calculates the final rotational speed of the motors 31, 33, 35 by adding up the calculated rotational speed V _x and the controlled angular velocity Vw. Thereafter, a motor speed controller, for example, a motor driver in the controller 10 controls the rotation speeds of the motors 31, 33, and 35 in accordance with the calculated final rotation speed. Accordingly, in step S70, since the omni wheels 21, 23, and 25 rotate in correspondence with the controlled rotation speeds of the motors 31, 33, and 35, the mobile robot 100 continues to travel.

On the other hand, in step S50, the motor speed sensor (41, 43, 45), for example, the encoder sensor of the omni wheel motor speed sensing unit 40 is the rotational speed of the controlled motor (31, 33, 35) The sensing is fed back to the controller 10. Therefore, in step S40, the motor drivers 31, 33, and 35 so that the motor driver in the controller 10 corresponds to the calculated final rotation speed using the rotation speeds of the sensed motors 31, 33, 35. Control the speed of rotation.

In step S60, when the mobile robot 100 rotates according to the rotation of the motors 31, 33, and 35, the gyro sensor 50 senses the information and feeds it back to the controller 10. Accordingly, in step S23, the controller 10 further applies the information from the gyro sensor 50 to calculate the rotation angle of the mobile robot 100. In addition, in step S29, the controller 10 further applies the information from the gyro sensor 50 to calculate the moving angle of the mobile robot 100.

The current rotational speeds of the motors 31, 33, and 35 are the sum of the angular speeds for moving at the moving angle Move_Angle and the angular speeds for correcting the attitude. In order to determine the exact position of the mobile robot 100, first the angular velocity component Should be removed. Since the angular velocity component is the rotational speed V _rot , the angular velocity of the mobile robot 100 may be known using the gyro sensor 50, and the rotational speed V _rot may be obtained using Equation 6 described above.

를 알 수 있으며, 자이로센서(50)를 이용하여 이동로봇(100)의 현재 자세(θ)를 알 수 있으므로 수학식 14 내지 수학식 16을 이용한 연립방정식으로 x, y축의 속도를 구할 수 있다. 먼저 수학식 12을 이용하여 V_i를 구하고 회전속도(V_rot)를 제거하면 수학식 14 내지 수학식 16은 수학식17 내지 수학식 19와 같이 나타낼 수 있다.In this way, the rotational speed (V _rot ) is known, and the motor speed sensors (41, 43, 45), for example, using an encoder

Since the current position (θ) of the mobile robot 100 can be known using the gyro sensor 50, the velocity of the x and y axes can be obtained by using a system of equations using Equations 14 to 16. First, when V _i is obtained using Equation 12 and the rotation speed V _rot is removed, Equations 14 to 16 may be expressed as Equations 17 to 19.

Here, since θ is known, -sin (θ + α _i ) cos (θ) is replaced with s _i and cos (θ + α _i ) cos (θ) c _i , It can be simply expressed as in Equation 22.

을 제외하고 나머지 값들은 모두 알고 있는 값이기 때문에 이를 상수로 생각하여 수학식 20 내지 수학식 22을 이용한 연립방정식으로 풀면 수학식 23 및

Except for the rest of the values are all known values, so consider them as constants and solve the system of equations using equations (20) to (22).

It may be expressed as in Equation 24.

을 구하고, 이를 수학식 23에 대입하여

을 구한다.

을 이용하여 현재 좌표 x, y를 구하고 나면, 기존의 방법을 이용하여 이동로봇(100)의 주행을 상기 계획된 주행궤적을 따라가도록 제어할 수 있다.Since there are three equations and two variables, the solution is easy. In equation (24)

, And substitute this into Equation 23

.

After the current coordinates x and y are obtained, the driving of the mobile robot 100 can be controlled to follow the planned driving trajectory using an existing method.

Therefore, in the present invention, by using a new driving method using the omni wheel for the traveling system of the mobile robot, the holographic system using the omni wheel enables more efficient navigation in a narrow room, and also uses the holonomic system using the omni wheel. It can be moved quickly and accurately.

On the other hand, the present invention has been described in connection with the above-mentioned preferred embodiment, it is possible to make various modifications or variations without departing from the spirit and scope of the present invention. Accordingly, the appended claims are intended to cover such modifications or changes as fall within the scope of the invention.

1A and 1B are physical photographs and graphic views showing omni wheels of a mobile robot, respectively.

2A and 2B are diagrams for explaining a motor driving method using three omni wheels and four omni wheels of a mobile robot, respectively.

3 is a diagram illustrating an algorithm for controlling a position and a direction of a mobile robot.

4 shows the kinematics of a mobile robot.

Figure 5 is a block diagram schematically showing a mobile robot applied to the traveling control method of a mobile robot using an omni wheel according to the present invention.

6 is a block diagram showing a traveling control system of a mobile robot applied to a traveling control method of a mobile robot using an omni wheel according to the present invention;

7 is a flowchart illustrating a traveling control method of a mobile robot using an omni wheel according to the present invention.

Claims (2)

Planning driving trajectory of the mobile robot using three omni wheels; Setting a base angle of the mobile robot, calculating a rotation angle of the mobile robot, and controlling an angular velocity of the mobile robot; Setting a moving angle of the mobile robot, and calculating a moving angle of the mobile robot; Calculating a rotation speed of each of the three motors corresponding to each of the omni wheels using the controlled angular speed and the calculated moving angle; Controlling the rotation speed of each motor by using the calculated rotation speed of each motor; And Driving the mobile robot at a rotational speed of each of the controlled motors, The controlling of the rotation speed of each motor further includes sensing the rotation speed of each motor by each of three motor speed sensors, wherein the calculated rotation speed of each of the motors and each of the sensed motors are sensed. The rotational speed of each of the motor to control the rotational speed, The calculating of the rotation angle of the mobile robot further includes sensing the gyro angle of the mobile robot by a gyro sensor, and using the base angle of the set mobile robot and the sensed gyro angle. Traveling control method of the mobile robot using the omni wheel, characterized in that for calculating the rotation angle of. A traveling control apparatus for a mobile robot using an omni wheel, characterized in that it comprises a control unit for controlling the traveling trajectory of the mobile robot using three omni wheels according to the traveling control method of claim 1.

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