TWI895835B - Mobile robot precision measurement and orientation assistance module - Google Patents

Abstract

A mobile robot precision measurement and orientation assistance module is mounted on a robot and used in conjunction with a laser tracker capable of setting coordinate points. The module comprises a drive assembly; a reflector assembly, rotated by the drive assembly, having a mirror for reflecting laser light emitted by the laser tracker; a sensor unit capable of sequentially sensing three-axis acceleration and a Z-axis angle over multiple time periods; and a control unit capable of calculating the acceleration over each time period to obtain a horizontal rotation angle. The horizontal rotation angle and the Z-axis angle are summed to obtain a corrected rotation angle. The corrected rotation angle is used to control the rotation angle of the drive assembly, ensuring that the reflector of the reflector assembly accurately faces the laser tracker. This allows for simple, fast, and accurate control, solving problems where known orientations are complex and inaccurate.

Description

Mobile robot precision measurement and orientation assistance module

This invention relates to orientation technology, particularly an auxiliary module for mobile robot precision measurement of moving objects. Specifically, the module combines a three-dimensional measurement device with the auxiliary module to form a four-dimensional auxiliary module. This module is suitable for mobile robot orientation precision measurement and can also be used to measure the positioning accuracy of mobile robotic arms.

With technological advancements, industry is moving towards intelligent automation. To improve manufacturing efficiency and quality, the logistics industry and factories are widely using automated equipment to manufacture products and move objects, saving manpower and improving timeliness. Mobile robots are a key component of automated equipment for object handling. Because they are automatically controlled by pre-programmed functions to perform repetitive tasks, they offer greater stability and timeliness than manual labor. However, mobile robots are composed of transmission mechanisms and wheels. During movement, wheel speed differences or slippage often lead to cumulative errors. Therefore, mobile robot products must undergo precision testing before leaving the factory.

Three-dimensional laser trackers are commonly used for measuring robot accuracy, offering rapid detection and high accuracy. However, there is currently no commercially available auxiliary equipment for measuring the orientation accuracy of mobile robots. Furthermore, the measurable range of laser trackers is limited by the reflector's ±30° measurement angle, making them inapplicable for measuring the orientation accuracy of mobile robots undergoing large rotation angles and movements.

As shown in Figure 1, current robotic arm precision measurement typically uses a fixed standard reflector assembly 50A. This fixed standard reflector assembly 50A lacks a self-rotating structure and function. Due to the limited ±30° measurement angle of its reflector 51A, the maximum measurable range is relatively small. Therefore, the existing laser tracker 30 paired with the fixed reflector 51A faces a limited measurable range issue that needs to be improved.

In view of this, the purpose of the present invention is to provide a mobile robot precision measurement and orientation assistance module, which provides a mobile robot precision measurement and orientation assistance module with an additional dimension of active rotation angle, capable of performing orientation precision measurement over a large rotation angle and a wide range of movement.

To achieve the above-mentioned object, the present invention provides a mobile robot precision measurement and orientation assistance module, which is installed on a robot and used in conjunction with a laser tracker. The laser tracker can set coordinate points. The mobile robot precision measurement and orientation assistance module includes a drive group; a reflector group, which is rotated by the drive group and has a reflector for reflecting the laser tracker. Laser light is emitted from the drive assembly; a sensor unit can sequentially sense a three-axis acceleration and a Z-axis angle at multiple time intervals; a control unit can calculate the acceleration at each time interval to obtain a horizontal rotation angle, sum the horizontal rotation angle and the Z-axis angle to obtain a corrected rotation angle, and use the corrected rotation angle to control the rotation angle of the drive assembly so that the reflector of the reflector assembly accurately faces the laser tracker.

With the aforementioned technical features, the mobile robot precision measurement and orientation assistance module of the present invention utilizes an auxiliary measurement device that not only provides X-, Y-, and Z-axis measurement, but also features a yaw detection function installed on the mobile robot that automatically detects rotation about the Z axis. This makes it a four-dimensional auxiliary measurement device. This allows the laser tracker's three-dimensional measurement to simultaneously perform large-angle rotation and wide-range orientation precision measurement, acquiring data for mobile spatial working points. This solves the problem of limited fixed reflectors, maximizes the measurable range, significantly reduces measurement time, and reduces manufacturing costs.

Preferably, the control unit obtains the three-axis velocity using the three-axis acceleration.

Preferably, the control unit calculates the three-axis displacement using the three-axis velocities.

Preferably, the three-axis speed is obtained as follows:

Where v is the velocity of the three axes, t is time, τ is the data entry, a is the acceleration, and d is the displacement of the three axes. The displacement of the three axes is obtained as follows:

The three-axis displacement obtained from the previous equation is combined with the three-axis position of the first pen to obtain the three-axis position of the second pen, which is the following equation: ( x',y',z' )=( x,y,z )+( dx,dy,dz )

Where ( x', y', z' ) is the relative position of the three axes of the back pen, (x , y, z ) is the relative position of the three axes of the front pen, dx is the X-axis displacement, dy is the Y-axis displacement, and dz is the Z-axis displacement. After obtaining the three-axis position of the back pen, the distance between each axis is obtained by comparing it with the coordinate point of the laser tracker. The horizontal rotation angle is calculated based on the arc tangent of the trigonometric function, which is the following formula:

Where θ ₁ is the horizontal rotation angle, (△ x ,△ y ,△ z ) is the distance between each axis; the Z-axis angle output by the sensor unit is integrated with the horizontal rotation angle ( θ ₁ ) to obtain the corrected rotation angle ( ), that is, the following formula: θ' ₁ = θ ₁ + θ _Z

in, is the correction rotation angle, θ1 is _the horizontal rotation angle, _and θZ is the Z-axis angle.

Preferably, the sensor unit has an accelerometer for sensing the three-axis acceleration.

Preferably, the sensor unit has a gyroscope for sensing the Z-axis angle.

The detailed structure, features, and usage of the mobile robot precision measurement and orientation assistance module provided by this invention will be described in the detailed description of the embodiments that follow. However, those skilled in the art will understand that these detailed descriptions and the specific embodiments listed for implementing the invention are intended solely to illustrate the invention and are not intended to limit the scope of the patent application for the invention.

10: Directional Assistance Module

20: Robot

30: Laser Tracker

40: Drive Group

50: Reflection Group

51: Reflector

60: Sensor unit

61: Accelerometer

62: Gyroscope

70: Control unit

The following is a further explanation of the mobile robot precision measurement and orientation assistance module provided by the present invention, using an embodiment and accompanying figures. FIG1 is a diagram illustrating the movement of a conventional orientation assistance module.

Figure 2 is a control schematic diagram of a more specific embodiment of the present invention.

Figure 3 is a diagram illustrating the movement state of a more specific embodiment of the present invention.

First, it should be noted that the technical features provided by this invention are not limited to the specific structures, uses, and applications described in the embodiments. The terms used in this description are illustrative and readily understood by those skilled in the art. Directional terms such as "front, top, bottom, back, left, right, top, bottom, inside, and outside" mentioned in this specification are merely illustrative and based on normal usage directions, and are not intended to limit the scope of the claims.

Please refer to Figures 2 and 3. The present invention provides a mobile robot precision measurement and orientation assistance module 10, which is mounted on a robot 20 and used in conjunction with a laser tracker 30.

The laser tracker 30 can set coordinate points on the X-axis, Y-axis, and Z-axis, for example (0.0, 0.0, 1.0).

The present invention provides a mobile robot precision measurement and orientation assistance module 10, which mainly includes a drive unit 40, a reflection unit 50, a sensor unit 60, and a control unit 70.

The orientation assistance module 10 is installed on the robot 20 and can set the starting X-axis, Y-axis, and Z-axis coordinate points of the mobile robot 20, for example (0.0, 3.0, 1.0).

The drive assembly 40 has a servo motor.

The reflector assembly 50 is driven to rotate by the drive assembly 40 and includes a reflector 51 for reflecting the laser light emitted by the laser tracker 30.

The sensor unit 60 includes an accelerometer 61 and a gyroscope 62. The accelerometer 61 can sense and calculate acceleration changes, while the gyroscope 62 can sense and calculate angular deviation. In this embodiment, the sensor unit 60 uses the MPU-6050 model. The sensor unit 60 sequentially senses three-axis acceleration and a Z-axis angle over multiple time periods. The three-axis acceleration is obtained using the accelerometer 61, and the Z-axis angle is obtained using the gyroscope 62.

The control unit 70 is electrically connected to the sensor unit 60 and includes a microprocessor and an IMU (Inertial Measurement Unit) circuit system. The microprocessor is electrically connected to the IMU circuit system. The control unit 70 calculates the acceleration to obtain a horizontal rotation angle. This horizontal rotation angle is summed with the Z-axis angle to obtain a corrected rotation angle, which is used to control the rotation angle output of the drive unit 40, enabling precise control of relative rotation speed and angle. In this embodiment, the microprocessor uses a single chip (ESP-32).

In this example, sensor unit 60 acquires the three-axis acceleration and the Z-axis angle at a rate of 1,000 data points per second, averaging every 10 data points to ensure data accuracy. The horizontal rotation angle is calculated using quadratic integration to determine the angular displacement.

First, the three-axis speed is calculated according to the following integral formula, namely formula (1):

Where v is the velocity of the three axes, t is time, τ is the data entry number, a is the acceleration, and d is the displacement of the three axes. Preferably, t is 10 milliseconds.

Then, the three-axis displacement is obtained according to the following integral formula, namely formula (2):

Next, use the three-axis displacement obtained from the previous formula and combine it with the three-axis position of the first pen to obtain the three-axis position of the second pen, that is, formula (3): (x',y',z' ) = ( x,y,z ) + ( dx,dy,dz ) ... Formula (3)

Where ( x',y',z' ) is the three-axis position relative to the back pen, ( x,y,z ) is the three-axis position relative to the front pen, dx is the X-axis displacement, dy is the Y-axis displacement, and dz is the Z-axis displacement.

After obtaining the three-axis position of the back pen, the distance between each axis is obtained by comparing it with the 30-coordinate point of the laser tracker. The horizontal rotation angle is calculated based on the arctangent of the trigonometric function, which is formula (4):

Where θ1 _is the horizontal rotation angle, and (△ x , △ y , △ z ) is the distance between the axes.

The Z-axis angle output by the sensor unit 60 is combined with the horizontal rotation angle ( θ ₁ ) to obtain the corrected rotation angle ( ), that is, formula (5): θ' ₁ = θ ₁ + θ _Z ...Formula (5)

in, is the correction rotation angle, θ1 is _the horizontal rotation angle, _and θZ is the Z-axis angle.

A single chip (ESP-32) uses this corrected rotation angle to control the servo motor and records and stores the three-axis acceleration values and angles.

The sensor unit 60's accelerometer 61 and gyroscope 62 accurately track the robot's 20 movements, both fast and slow. It receives position signals and transmits the resulting position back to the control unit 70, which calculates the current position and issues commands to the drive unit 40 to automatically rotate the robot 20 to the corresponding angle.

The reflector assembly 50 is equipped with a reflector 51. The drive assembly 40 drives the reflector assembly 50 to rotate. The light emitted by the laser tracker 30 is reflected back to the laser tracker 30, which then receives the robot's 20-point position information.

In comparison, current robotic arm precision measurement uses fixed standard reflectors, which have a smaller maximum measurable range. The mobile robotic precision measurement and orientation assistance module 10 of the present invention can at least double the maximum measurable range, offering the novelty of autonomous relative rotation and compatibility with various laser trackers.

Furthermore, when the end-of-arm or mobile robot moves, the precision measurement module 10 of the present invention can autonomously and timely adjust the corresponding rotation angle as the robot moves and rotates, eliminating the impact of the reflection angle limit of the reflector 51 on the robot's measurement. This increases the robot's measurement range. Compared to foreign products that are only suitable for dedicated laser trackers, the present invention can be used with various laser trackers and can be universally installed on mobile robots to perform precision measurement.

In summary, the mobile robot precision measurement and orientation assistance module 10 of the present invention has achieved its objectives through the above-described implementation.

40: Drive Group

60: Sensor unit

61: Accelerometer

62: Gyroscope

70: Control unit

Claims (3)

A mobile robot precision measurement and orientation assistance module is mounted on a robot and used in conjunction with a laser tracker that can set coordinate points. The module includes: a drive assembly; a reflector assembly rotated by the drive assembly, the reflector assembly having a reflector for reflecting laser light emitted by the laser tracker; and a sensor unit capable of sequentially sensing three-axis acceleration and a Z-axis angle over multiple time periods. A control unit calculates the acceleration at each time period to obtain a horizontal rotation angle, sums the horizontal rotation angle with the Z-axis angle to obtain a corrected rotation angle, and uses the corrected rotation angle to control the rotation angle of the drive assembly so that the reflector of the reflector assembly accurately faces the laser tracker. The control unit calculates the three-axis velocity using the three-axis acceleration. The control unit calculates the three-axis displacement using the three-axis velocity. The control unit calculates the three-axis velocity using the following formula: in, is the three-axis speed, For time, is the data record, is the acceleration, is the displacement of the three axes; the control unit obtains the displacement of the three axes as follows: The three-axis displacement obtained by the previous formula is combined with the three-axis position of the front pen to obtain the three-axis position of the back pen, which is the following formula: in, is the position of the three axes relative to the back pen. is the position of the three axes relative to the front pen. is the X-axis displacement, is the Y-axis displacement, is the Z-axis displacement. After obtaining the three-axis position of the back pen, the distance between each axis is obtained by comparing it with the coordinate point of the laser tracker. The horizontal rotation angle is obtained based on the arc tangent of the trigonometric function, which is the following formula: in, is the horizontal rotation angle, The Z-axis angle output by the sensor unit is integrated with the horizontal rotation angle ( ), add up to get the corrected rotation angle ( ), that is, the following formula: θ' ₁ = θ ₁ + θ _Z , where, To correct the rotation angle, is the horizontal rotation angle, and θ _Z is the Z-axis angle. The mobile robot precision measurement and orientation assistance module as described in claim 1, wherein the sensor unit has an accelerometer for sensing and obtaining the three-axis acceleration. The mobile robot precision measurement and orientation assistance module as described in claim 1, wherein the sensor unit has a gyroscope for sensing and obtaining the Z-axis angle.