Three-dimensional measuring arm with automatic positioning function

Abstract

The invention discloses a three-dimensional measuring arm with an automatic positioning function, which comprises a measuring arm body, the measuring arm body comprises a base, a plurality of rigid arm rods hinged in sequence, precise angle encoders and an end effector interface, the precise angle encoders and the end effector interface are arranged at the hinged positions and the connecting positions of the rigid arm rods and the base and used for measuring the joint rotation angle, and the rigid arm rods are rotationally connected with the base; one measuring arm body is provided with an automatic positioning structure; the automatic positioning structure comprises a multi-axis inertial measurement unit, a plurality of visual positioning sensors and a plurality of positioning mark points. By means of the mode, the three-dimensional measuring arm with the automatic positioning function is provided with an automatic positioning structure, the position of the measuring arm in a measuring space can be automatically, rapidly and precisely determined without manual intervention, and the measuring efficiency and convenience are greatly improved.

Description

Technical Field

[0001] This invention belongs to the field of precision measuring equipment technology, and specifically relates to a three-dimensional measuring arm with automatic positioning function. Background Technology

[0002] Traditional articulated 3D measuring arms are high-precision portable measuring devices. They consist of multiple rotary joints and rigid arms connected in series, with a contact probe or non-contact scanning head integrated at the end. Before measurement, strict "zeroing" or "positioning" operations must be performed to establish the transformation relationship between the measuring arm coordinate system and the workpiece coordinate system.

[0003] In the existing technology, the positioning of the measuring arm usually requires the operator to manually use the measuring arm's probe to contact three or more predefined reference points on the workpiece or fixture. This process is cumbersome, time-consuming, and requires high operator skills. This process must be repeated every time the measuring arm moves or is accidentally bumped, which seriously affects the measurement efficiency. Summary of the Invention

[0004] The main technical problem solved by this invention is to provide a three-dimensional measuring arm with automatic positioning function, which can improve measurement efficiency and convenience.

[0005] To solve the above-mentioned technical problems, one technical solution adopted by the present invention is: to provide a three-dimensional measuring arm with automatic positioning function, including a measuring arm body, the measuring arm body including a base, a plurality of rigid arms that are hinged in sequence, a precision angle encoder and an end effector interface for measuring the joint rotation angle disposed at each hinge and at the connection between the rigid arms and the base, the rigid arms being rotatably connected to the base, and an automatic positioning structure being installed on the measuring arm body; The automatic positioning structure includes a multi-axis inertial measurement unit, several visual positioning sensors, and several positioning markers; The multi-axis inertial measurement unit is fixedly installed on the base. The multi-axis inertial measurement unit includes a three-axis gyroscope and a three-axis accelerometer. The three-axis gyroscope and the three-axis accelerometer are installed in a housing with electromagnetic shielding and vibration reduction functions on the base. Several visual positioning sensors are fixedly installed on the base with their fields of view facing the working area. The visual positioning sensors are industrial cameras, and the industrial cameras are installed in a non-parallel optical axis manner. Several positioning markers are fixedly arranged in the measurement environment and have known three-dimensional coordinates. The types of positioning markers include passive optical feature points and active light-emitting markers, and the number of them is not less than four. They are fixedly arranged in the measurement environment in a non-coplanar manner.

[0006] In a preferred embodiment of the present invention, the bottom of the base is provided with a quick clamping structure, the quick clamping structure including a magnetic base, a vacuum suction cup and a mechanical clamp.

[0007] In a preferred embodiment of the present invention, the end effector interface is a standardized electrical and mechanical interface, and the end effector interface is equipped with a trigger probe, the types of which include a contact trigger probe, an optical scanning probe, and a laser line scanning probe.

[0008] In a preferred embodiment of the present invention, an ambient light suppression component is installed on the industrial camera, and the ambient light suppression component is a narrow bandpass filter installed in front of the lens of the industrial camera.

[0009] In a preferred embodiment of the present invention, a control box is fixed to the side of the base, and a calibration module is installed inside the control box. The calibration module is electrically connected to the automatic positioning structure and the precision angle encoder. The calibration module includes a data processing unit and an automatic calibration algorithm unit embedded therein. The calibration module is connected to a data interface module, which is one or a combination of a wired network interface and a wireless communication module.

[0010] In a preferred embodiment of the present invention, the data processing unit employs an embedded processor, and the automatic calibration algorithm unit employs a multi-sensor fusion algorithm based on Kalman filtering.

[0011] The beneficial effects of the present invention are: the present invention provides a three-dimensional measuring arm with automatic positioning function. The measuring arm has an automatic positioning structure, which can automatically, quickly and accurately determine its position in the measurement space without manual intervention, greatly improving measurement efficiency and convenience. Attached Figure Description

[0012] Figure 1 This is a front view of a three-dimensional measuring arm with automatic positioning function.

[0013] The components in the attached diagram are labeled as follows: 1. Base; 2. Rigid boom; 3. Precision angle encoder; 4. End effector interface; 5. Multi-axis inertial measurement unit; 6. Visual positioning sensor; 7. Housing; 8. Quick clamping structure; 9. Control box; 10. Calibration module. Detailed Implementation

[0014] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby providing a clearer and more explicit definition of the scope of protection of the present invention.

[0015] Please see Figure 1 The embodiments of the present invention include: A three-dimensional measuring arm with automatic positioning function includes a measuring arm body, which includes a base 1, a plurality of rigid arm rods 2 that are hinged sequentially, a precision angle encoder 3 for measuring the joint rotation angle and an end effector interface 4 disposed at each hinge point and at the connection between the rigid arm rods 2 and the base 1. The rigid arm rods 2 are rotatably connected to the base 1. The measuring arm body is equipped with an automatic positioning structure, which can automatically, quickly and accurately determine its position in the measurement space without manual intervention, greatly improving measurement efficiency and convenience.

[0016] The rigid arm 2 is made of carbon fiber composite material.

[0017] The precision angle encoder 3 is an absolute grating encoder used to measure the rotation angle of each joint in real time.

[0018] The automatic positioning structure includes a multi-axis inertial measurement unit 5, several visual positioning sensors 6, and several positioning markers. The automatic positioning structure is used to determine the absolute pose of the measuring arm body in space.

[0019] The multi-axis inertial measurement unit 5 is fixedly installed on the base 1. The multi-axis inertial measurement unit 5 includes a three-axis gyroscope and a three-axis accelerometer. The three-axis gyroscope and the three-axis accelerometer are installed in a housing 7 with electromagnetic shielding and vibration reduction functions on the base 1. Its function is to continuously sense the angular velocity and acceleration changes of the base 1 part when the measuring arm is stationary or moving, and provide an initial estimate of attitude and displacement changes.

[0020] Several visual positioning sensors 6 are fixedly installed on the base 1 with their fields of view facing the working area. The visual positioning sensors 6 are industrial cameras. Several industrial cameras are installed in a non-parallel optical axis manner to expand or overlap their joint field of view. Their function is to capture images of the positioning markers arranged in advance in the working area and calculate the three-dimensional position and three-dimensional orientation of the base 1 relative to the group of positioning markers through the built-in visual algorithm.

[0021] Several positioning markers are fixedly arranged in the measurement environment and have known three-dimensional coordinates. The types of positioning markers include passive optical feature points and active light-emitting markers, and there are no fewer than four of them. They are fixedly arranged in the measurement environment in a non-coplanar manner, and their function is to provide an absolute spatial reference for the visual positioning sensor 6.

[0022] By identifying the positioning markers using the visual positioning sensor 6, the global coordinate system of the measuring arm can be automatically established or restored within seconds, greatly shortening the equipment preparation time.

[0023] The base 1 is provided with a quick-clamping structure 8 at its bottom, which is used for temporary fixed installation.

[0024] The types of quick clamping structures 8 include magnetic bases, vacuum chucks, and mechanical clamps.

[0025] The end effector interface 4 is a standardized electrical and mechanical interface. The end effector interface 4 is equipped with a trigger probe, which can be a contact trigger probe, an optical scanning probe, or a laser line scanning probe.

[0026] An ambient light suppression component is installed on the industrial camera. The ambient light suppression component is a narrow bandpass filter installed in front of the lens of the industrial camera.

[0027] A control box 9 is fixed to the side of the base 1. A calibration module 10 is installed inside the control box 9. The calibration module 10 is electrically connected to the automatic positioning structure and the precision angle encoder 3.

[0028] The calibration module 10 is used to receive and fuse inertial data, visual pose data and joint angle data, and output the calibrated global coordinate system parameters of the measuring arm through the fusion algorithm.

[0029] The calibration module 10 includes a data processing unit and an automatic calibration algorithm unit embedded therein. The calibration module 10 is connected to a data interface module, which is one or a combination of a wired network interface and a wireless communication module. The data interface module is used to output the real-time and accurate global coordinate system parameters of the measuring arm calculated by the calibration module 10, as well as the coordinates of the measurement points collected by the probe installed on the end effector interface 4, to an external control device.

[0030] The data processing unit employs an embedded processor to receive and fuse inertial data from the multi-axis inertial measurement unit 5, visual pose data from the visual positioning sensor 6, and joint angle data from the precision angle encoder 3.

[0031] The automatic calibration algorithm unit adopts a multi-sensor fusion algorithm based on Kalman filtering. Its function is to use the absolute pose provided by the visual positioning sensor 6 as a reference, combined with the short-time accuracy of the multi-axis inertial measurement unit 5 and the internal geometric model of the precision angle encoder 3, to compensate and calibrate the coordinate system drift caused by the overall movement of the measuring arm or the accumulation of joint errors in real time through the fusion algorithm, thereby outputting a high-precision, unified global coordinate system of the measuring arm.

[0032] Working principle: When the measuring arm is placed near the workbench, the visual positioning sensor 6 automatically captures and identifies the positioning markers within the field of view. The data processing unit in the calibration module 10 runs the computer vision program in the automatic calibration algorithm unit to calculate the precise three-dimensional position and three-dimensional attitude of the base 1 relative to the global coordinate system. At the same time, the data from the multi-axis inertial measurement unit 5 is used to stabilize the image processing and compensate for the instantaneous jitter of the visual positioning sensor 6. This absolute pose information is fused with the data read from the precision angle encoder 3 at each joint. The fusion algorithm determines in real time the precise position of the trigger probe installed on the end effector interface 4 in the global coordinate system. All data is transmitted to the external control device through the data interface module.

[0033] Once the measuring arm is moved, the above-mentioned automatic positioning process will be quickly re-executed, and the measurement can be resumed without manual intervention. It can automatically, quickly and accurately determine its position in the measurement space without manual intervention, which greatly improves the measurement efficiency and convenience.

[0034] Unlike existing technologies, this invention provides a three-dimensional measuring arm with automatic positioning function. This measuring arm has an automatic positioning structure, which can automatically, quickly and accurately determine its position in the measurement space without manual intervention, greatly improving measurement efficiency and convenience.

[0035] In the description of this invention, it should be noted that all components are general standard parts or components known to those skilled in the art. Their structures and principles can be learned by those skilled in the art through technical manuals or conventional test methods. The terms "upper," "lower," "left," "right," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship that the product of this invention is usually placed in during use. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0036] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A three-dimensional measuring arm with automatic positioning function, comprising a measuring arm body, the measuring arm body including a base, a plurality of rigid arms hinged sequentially, a precision angle encoder and an end effector interface for measuring joint rotation angle disposed at each hinge and at the connection between the rigid arms and the base, wherein the rigid arms are rotatably connected to the base, characterized in that, An automatic positioning structure is installed on the body of the measuring arm; The automatic positioning structure includes a multi-axis inertial measurement unit, several visual positioning sensors, and several positioning markers; The multi-axis inertial measurement unit is fixedly installed on the base. The multi-axis inertial measurement unit includes a three-axis gyroscope and a three-axis accelerometer. The three-axis gyroscope and the three-axis accelerometer are installed in a housing with electromagnetic shielding and vibration reduction functions on the base. Several visual positioning sensors are fixedly installed on the base with their fields of view facing the working area. The visual positioning sensors are industrial cameras, and the industrial cameras are installed in a non-parallel optical axis manner. Several positioning markers are fixedly arranged in the measurement environment and have known three-dimensional coordinates. The types of positioning markers include passive optical feature points and active light-emitting markers, and the number of them is not less than four. They are fixedly arranged in the measurement environment in a non-coplanar manner.

2. The three-dimensional measuring arm with automatic positioning function according to claim 1, characterized in that, The base is provided with a quick-clamping structure, which includes magnetic bases, vacuum suction cups and mechanical clamps.

3. A three-dimensional measuring arm with automatic positioning function according to claim 1, characterized in that, The end effector interface is a standardized electrical and mechanical interface, and the end effector interface is equipped with a trigger probe. The types of trigger probes include contact trigger probes, optical scanning probes, and laser line scanning probes.

4. A three-dimensional measuring arm with automatic positioning function according to claim 1, characterized in that, An ambient light suppression component is installed on the industrial camera. The ambient light suppression component is a narrow bandpass filter installed in front of the lens of the industrial camera.

5. A three-dimensional measuring arm with automatic positioning function according to claim 1, characterized in that, A control box is fixed to the side of the base. A calibration module is installed inside the control box. The calibration module is electrically connected to the automatic positioning structure and the precision angle encoder. The calibration module includes a data processing unit and an automatic calibration algorithm unit embedded therein. The calibration module is connected to a data interface module, which is one or a combination of a wired network interface and a wireless communication module.

6. A three-dimensional measuring arm with automatic positioning function according to claim 5, characterized in that, The data processing unit employs an embedded processor, and the automatic calibration algorithm unit employs a multi-sensor fusion algorithm based on Kalman filtering.

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