KR0176540B1 - Position correction device of mobile robot - Google Patents

Abstract

The present invention relates to a position correction device for a mobile robot, and more particularly to a position correction device for a mobile robot using a vision system.

In the position correcting apparatus of a mobile robot for the purpose of the present invention, a landmark portion which is position image data of an object to be worked by the robot, a camera portion located on the landmark and inputting the landmark data to the camera; Vision controller connected to read the position of the landmark data from the camera, a robot controller for comparing the landmark data position input from the vision controller and the data position to work to correct the position of the robot according to the position error .

As described above, according to the present invention, the robot can work even on a moving body having a large stop error.

Description

Position correction device of mobile robot

Figure 1a shows a plan view of a robot in a wheel drive driverless vehicle according to the present invention.

Figure 1b shows a front view of the robot in a wheel drive driverless vehicle according to the present invention.

2 shows a block diagram of a position correction apparatus using the vision system of FIGS. 1A and 1B.

3 shows a robot and a camera coordinate system for a position correction method of a mobile robot.

4 is a flow chart for the position correction method of the mobile robot of the present invention.

The present invention relates to a position correction device for a mobile robot, and more particularly to a position correction device for a mobile robot using a vision system. In general, most robots used in the industrial field perform assembly, welding, and relocation work along a taught position coordinate system at a fixed position. With the development of robot application technology, a system is being developed in which a robot does not work only in a fixed position but is mounted on a moving device such as a rail or an unmanned vehicle, and performs work in various workspaces. In the application of such a mobile robot, the positional accuracy of the moving body is extremely poorer than the repeating accuracy of the robot, so that position correction is sometimes required.

In the conventional mobile robot, a robot is mounted on a linear moving device such as a rail. These moving devices are mechanically constrained in addition to the moving direction and maintain a high positional accuracy since the stop position is determined using a sensor in the moving direction.

The conventional mobile robot travels along a mobile device such as a rail, and attaches a sensor or a sensor detecting device for stopping the mobile robot to a working position where the robot is to work. Therefore, the robot moves along the work command and works. In addition, since the moving device maintains high stopping accuracy, there is no need to compensate for the stopping position error, and the robot teaches and uses the position coordinate system at each workbench like a robot operating at a fixed position.

However, the prior art has the following problems. In other words, construction is required on the site to install a mobile device, and therefore it is difficult to apply it according to the change of the site. In addition, the work efficiency is lowered because only linear movement along the moving device.

To overcome these shortcomings, wheeled driverless cars were used. In other words, the wheel drive driverless vehicle does not need an external device such as a rail, so it is easy to apply to the field and can run in all directions, and thus the work efficiency is high. However, this system has a disadvantage in that the position error is large because the positioning is performed only by a sensor such as an ultrasonic wave or a gyro.

Accordingly, an object of the present invention is to provide a device that enables the operation by mounting the robot on the wheel-driven driverless vehicle by correcting the stop position error of the wheel-driven driverless vehicle using a vision system.

A position correcting apparatus of a mobile robot for achieving the above object, the apparatus comprising: a landmark unit which is position image data of an object to be worked by a robot; A camera unit located on the landmark and inputting landmark data; A vision controller coupled to the camera for reading the position of landmark data from the camera; And a robot controller for comparing the landmark data position input from the vision controller with the data positions to be worked and correcting the position of the robot according to the position error.

A method for correcting a stationary position error occurring in a mobile robot for achieving the above another object, the method comprising: an initialization step of storing work position coordinate point data to be worked by the robot; A data reading step of moving the robot to read landmark data, which is position data of a work object, using a camera; A position error measuring step of measuring a position error by comparing the position coordinate data stored in the initialization step with the landmark data which is the position data of the work object; And a movement amount calculation step of calculating a home movement amount of the robot by using the position error in the position error measurement step.

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

Figure 1a shows a plan view of a robot in a wheelless driverless vehicle according to the present invention, the six-axis robot 110, the working table 120, the landmark 130 with position coordinates X _V and Y _V , position It is composed of a driverless vehicle 140 having coordinates X ₀ and Y ₀ .

FIG. 1B is a front view of the robot in the wheelless driverless vehicle according to the present invention, and includes a six-axis robot 152, a driverless vehicle 154, a gripper 156, a vision camera 158, and a landmark 160. ), The work table 170 is configured.

2 is a block diagram of a position correction apparatus using the vision system of FIGS. 1A and 1B and includes a vision camera 210, a landmark 220, a vision controller 230, and a robot controller 240. do.

Specific embodiments of the present invention will be described in detail with reference to FIGS. 1A, 1B, and 2.

As shown in FIGS. 1A and 1B, six-axis robots 110 and 152 are mounted on wheel-driven driverless vehicles 140 and 154, and a gripper for picking up an object to be worked on the six-axis ends of the six-axis robots 110 and 152. Gripper 156 is attached.

A vision CCD (Charge Coupled Device) camera 158 (FIG. 2, 210) is attached to the gripper 156, and the vision CCD camera 158 is the vision controller 230 of FIG. 2 in the driverless vehicle 140,154. ) The vision controller (FIG. 230) may exchange information while communicating with the six-axis robot controller (FIG. 240). The work benches 120 and 170 on which the six-axis robots 110 and 152 will work are attached with landmarks 130 and 160 (FIG. 2, 220) for recognizing image data.

3 shows a robot and a camera coordinate system for a position correction method of a mobile robot, and a rotation angle of θ ₁ : 1 axis and θ ₆ : 6 axis on the planes of the X _r and Y _r axes recognized by the robot and the camera. Rotation angle, X _LM , Y _LM : landmark coordinate, d _c : camera center and 6 axis center angle distance.

Figure 4 is a flow chart for the position correction method of the mobile robot of the present invention, the initialization step 400, the data reading step 410 of the landmark, the position error measuring step 420, the home position movement amount calculation step 430 )

In FIGS. 1A and 1B, the 6-axis robots 110 and 152 perform a teaching operation to store work position coordinate points on the work benches 120 and 170 (FIG. 4 400). In addition, the vision CCD camera 158 (FIG. 2, 210) is placed on the landmarks 130, 160, and FIG. 220, and the landmark data is input at this time, and the coordinate points of the robot that recognizes the landmark are also stored. Let's do it.

The driverless cars 140 and 154 then move to stop at the working position. The robot is then moved to a specific position coordinate system (landmark coordinate point) that stores the image data of the landmark. In step 410 of FIG. 4, image data of a landmark is read.

In operation 430 of FIG. 4, the position error is measured by comparing the position coordinate data stored in the teaching operation with the landmark data which is the position data of the target object. Since the position error always occurs only on a plane, image data is required only for plane information. The position errors (ΔX _V , ΔY _V , Δθ _V ) are measured using the vision system of FIGS. 1A and 1B and FIG. 2.

In operation 440 of FIG. 4, the home robot's home position movement amount ΔX ₀ , ΔY ₀ , Δθ ₀ is calculated based on the positional error of the driverless vehicle from the measured image data of the landmark. Since Δθ ₀ and Δθ _V are the same, the equation is derived by transforming coordinates with the coordinate system of FIG. 3 as follows.

Where X _LM , Y _LM : landmark coordinate, d _c : distance between camera center and 6 axis center, θ ₁ : 1 axis rotation angle, θ ₆ : 6 axis rotation angle, S △ ₁₆ = Sin (△ θ _V + θ ₁ + θ ₆ ), C △ ₁₆ = Cin (Δθ _V + θ ₁ + θ ₆ ), SΔ = Sin (Δθ _V ), S ₁₆ = Sin (θ ₁ + θ ₆ ), CΔ = Cos (Δθ _V ), C ₁₆ = Cos (θ ₁ + θ ₆ ).

Finally, the robot moves by the robot's origin moving amount (ΔX ₀ , ΔY ₀ , Δθ ₀ ) with respect to the position coordinate point, and performs the robot operation.

As described above, according to the present invention, the robot can work even on a moving body having a large stop error.

In addition, the present invention can be applied when the robot is mounted on all moving bodies having a position correction error in addition to the wheel drive driverless vehicle.

In addition, the present invention can be applied to other robots other than the 6-axis robot.

Claims (1)

A position correcting apparatus for a mobile robot, comprising: a landmark unit which is position image data of an object to be worked by a robot; A camera unit located on the landmark and inputting landmark data; A vision controller coupled to the camera for reading the position of landmark data from the camera; And a robot controller for comparing the landmark data position input from the vision controller with the data positions to be worked and correcting the position of the robot according to the position error.