MONITORING FUNCTION AND LASER RADAR

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to Chinese Patent Application No. 202111447010.6, filed December 1 , 2021 , entitled “A LIDAR OUTER ROTOR MOTOR WITH ROTATIONAL SPEED MONITORING AND LIDAR,” the content of which is hereby incorporated by reference in its entirety.

TECHNICAL FIELD

The present invention relates to the technical field of laser radars, and in particular to an outer-rotor motor for a laser radar with a rotational speed monitoring function, and a laser radar having the outer-rotor motor.

BACKGROUND

Laser Radars are radar systems that emit a laser beam to measure values of features, such as position and speed, of a target. In the working principle thereof, a detection signal (a laser beam) is transmitted to the target, and then a received signal (a target echo) reflected from the target is compared with the transmitted signal and appropriately processed to obtain relevant information of the target, such as distance, orientation, height, speed, attitude, even shape, and other parameters of the target, so as to detect, track and identify the target.

A laser radar mainly includes a housing, a motor and an optical reflecting mirror. In the prior art, an inner-rotor motor is usually used to separate two key components in the manner of transmission members connection. The more the transmission chains, the greater the optical cumulative error, i.e., the structural optical measurement accuracy of the inner- rotor motor is greatly reduced, which affects the use of experience. Moreover, the inner-rotor motor has the form of a prism between bearings, the volume is large, and it is not easy to control the reflected laser to be in a driving direction of a vehicle.

An optical reflecting mirror of an outer-rotor motor is fixed to a rotor and rotates with the rotor, so the stability of the rotational speed of the motor has a great influence on the stability of point cloud imaging of the laser radar. In the prior art, a double closed-loop control system for speed and current is usually used to adjust and control the rotational speed of the motor. However, due to the compact structure of the motor of the laser radar, how to design the double closed-loop control system becomes difficult.

SUMMARY

In view of the above existing technical problems, objectives of the present invention are to provide an outer-rotor motor for a laser radar with a rotational speed monitoring function and a laser radar. Through the rational structural design, rotational speed data of the motor is collected once to obtain the rotational speed of the motor in real time, and the rotational speed of the motor is adjusted to facilitate the control of the motor so as to improve the stability of the rotational speed of the motor and ensure the stability of point cloud imaging of the laser radar.

Technical solutions of the present invention are as follows.

One of the objectives of the present invention is to provide an outer- rotor motor for a laser radar with a rotational speed monitoring function, the outer-rotor motor comprising: a motor shaft over which a bearing is fitted; a housing comprising a top housing and a bottom housing respectively arranged at two ends of the motor shaft; a rotor assembly comprising a rotor yoke fixedly arranged at an outer ring of the bearing, an optical reflecting mirror fixed to an outer periphery of the rotor yoke, and a light shielding ring fitted over the end of the motor shaft close to the top housing, the light shielding ring being provided with a sampling position; a rotational speed sampling device arranged on the top housing and corresponding to the light shielding ring; and a plurality of speed measuring devices arranged on the bottom housing and corresponding to a bottom end of the rotor yoke, the plurality of speed measuring devices being in circuit connection with the rotational speed sampling device to form a double closed-loop control system, wherein when the sampling position is turned to the rotational speed sampling device, the rotational speed sampling device collects a rotational speed signal of the motor once, and the rotational speed of the motor is controlled and adjusted by the double closed-loop control system.

Optionally, the outer-rotor motor further comprises a circuit board, the circuit board comprising: a first portion arranged on the bottom housing, the speed measuring device being arranged on the first portion; a second portion fixedly arranged on the top housing, the rotational speed sampling device being arranged at a bottom of the second portion; and a third portion connected between the first portion and the second portion.

Optionally, the speed measuring devices are position sensors, the number of which is three and which are arranged on the first portion at intervals in a circumferential direction.

Optionally, an upper end surface of the bottom housing is provided with a first recess recessed downwardly, and the first portion is fixedly arranged in the first recess.

Optionally, the rotational speed sampling device is an encoder.

Optionally, an upper surface of the top housing is provided with a second recess recessed downwardly, the second portion is fixed in the second recess, and the second recess is provided with a through hole for allowing the rotational speed sampling device to extend to a lower surface of the top housing.

Optionally, an outer edge of the bottom housing is further provided with an upwardly extending ring wall structure, there is a gap between the ring wall structure and the optical reflecting mirror, the second portion is located on the outside of the ring wall structure, and a connection between the ring wall structure and the bottom housing is provided with an avoidance hole for passage of the second portion.

Optionally, the ring wall structure is a non-closed ring.

Optionally, the sampling position is a notch formed in the light shielding ring and extending in an axial direction.

Another objective of the present invention is to provide a laser radar comprising the outerrotor motor for a laser radar with a rotational speed monitoring function according to any one as described above.

Compared with the prior art, the present invention has the following advantages.

In the outer-rotor motor for a laser radar with a rotational speed monitoring function of the present invention, through a rational structural design, on the compact structure of the motor of the laser radar, the double closed-loop control system formed by the speed measuring devices and the rotational speed sampling device collects the rotational speed data of the motor once to obtain the rotational speed of the motor in real time, and the rotational speed of the motor is adjusted to facilitate the control of the motor so as to improve the stability of the rotational speed of the motor and ensure the stability of point cloud imaging of the laser radar.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be further described below in conjunction with the accompanying drawings and the embodiments.

Fig. 1 is a schematic cross-sectional structural diagram of an outer-rotor motor for a laser radar with a rotational speed monitoring function according to an embodiment of the present invention;

Fig. 2 is a schematic perspective structural diagram of an outer-rotor motor for a laser radar with a rotational speed monitoring function according to an embodiment of the present invention;

Fig. 3 is a top schematic structural diagram of a bottom housing and a ring wall of an outerrotor motor for a laser radar with a rotational speed monitoring function according to an embodiment of the present invention;

Fig. 4 is a top schematic structural diagram of a top housing of an outer- rotor motor for a laser radar with a rotational speed monitoring function according to an embodiment of the present invention;

Fig. 5 is a schematic structural diagram of a circuit board of an outer-rotor motor for a laser radar with a rotational speed monitoring function according to an embodiment of the present invention; and

Fig. 6 is a schematic structural diagram of a light shielding ring of an outer- rotor motor for a laser radar with a rotational speed monitoring function according to an embodiment of the present invention.

In the figures: 1. Motor shaft; 2.Rotor assembly; 21. Rotor yoke; 22. Optical reflecting mirror; 23. Light shielding ring; 231. Notch; 3. top housing; 31. Second recess; 32. Through hole; 4. Bottom housing; 41. Ring wall; 411. Avoidance hole; 42. First recess; 5. Bearing; 6. Circuit board; 61. First portion; 62. Second portion; 63. Third portion; 7. Rotational speed sampling device; 8. Speed measuring device; 9. Stator assembly; and 10. Steel magnet. DETAILED DESCRIPTION OF EMBODIMENTS

In order to illustrate the objectives, technical solutions and advantages of the present invention more clearly, the present invention will be further described in detail below in conjunction with the detailed description of embodiments and with reference to the accompanying drawings. It should be understood that these descriptions are exemplary only, rather than limiting the scope of the present invention. Moreover, in the following illustration, the description of the known structures and techniques are omitted to avoid unnecessary confusion of the concept of the present invention.

Embodiments:

Referring to Figs. 1 to 6, an outer-rotor motor for a laser radar with a rotational speed monitoring function according to an embodiment of the present invention includes a motor shaft 1, a housing, a bearing 5, a rotor assembly 2, a circuit board 6, speed measuring devices 8, a rotational speed sampling device 7, a steel magnet 10 and a stator assembly 9. The housing includes a top housing 3 and a bottom housing 4. The top housing 3 and the bottom housing 4 are respectively arranged at two ends of the shaft. Specifically, the top housing 3 is fixed to an upper end of the shaft via screws, and a lower end of the shaft is pressed and fixed into the bottom housing 4 in an interference fit. The bearing 5 is fitted over the upper end of the shaft close to the top housing 3, an O-ring is arranged on the shaft at a position corresponding to the bearing 5, and the bearing 5 is closely fitted and fixed to the O-ring. The rotor assembly 2 includes a rotor yoke 21, an optical reflecting mirror 22 and a light shielding ring 23. The rotor yoke 21 is fitted over an outer periphery of the bearing 5. An outer periphery of the rotor yoke 21 is in the shape of two steps. The optical reflecting mirror 22 is fixed to the outer periphery of the rotor yoke 21 and overlapped with a surface of the lower step of the rotor yoke 21. The light shielding ring 23 is fitted over the end of the motor shaft 1 close to the top housing 3 and is overlapped with and pressed against the rotor yoke 21 and the optical reflecting mirror 22, and the light shielding ring 23 is provided with a sampling position. The steel magnet 10 is provided on an inner wall of the rotor yoke 21 at the end close to the bottom housing 4. The stator assembly 9 is fixed to the end of the motor shaft 1 close to the bottom housing 4 and is located inside the steel magnet 10. The circuit board 6 is arranged on the housing. The speed measuring devices 8 are arranged on the bottom housing 4 and correspond to a bottom end of the rotor yoke 21, and the rotational speed sampling device 7 is arranged on the top housing 3 and corresponds to the light shielding ring 23. The speed measuring devices 8 are in circuit connection with the rotational speed sampling device 7 to form a double closed-loop control system. When the sampling position is turned to the rotational speed sampling device 7, the rotational speed sampling device 7 collects a rotational speed of the motor signal once, and the rotational speed of the motor is controlled and adjusted by the double closed-loop control system. The circuit and working principle of the double closed-loop control system are not detailed and limited here, and are the working principle and the circuit structure of the existing conventional double closed-loop control system for speed and current. Due to the compact structure of the motor of the laser radar, it is difficult to design the double closed-loop control system. In the present application, the rotational speed sampling device 7 and the speed measuring devices 8 are rationally designed, with one of the two being arranged on the bottom housing 4 and the other being arranged on the top housing 3, the rotational speed sampling device 7 is arranged using the gap between the bottom housing 4 and the bottom end of the rotor yoke 21, the speed measuring devices 8 are arranged using the gap between the top housing 3 and the light shielding ring 23, and the circuit connection between the two is constructed to form a double closed-loop speed control system so as to monitor, control and adjust the rotational speed of the motor in real time, which greatly improves the stability of the rotational speed of the motor and ensures the stability of point cloud imaging of the laser radar. The speed measuring devices 8 and the rotational speed sampling device 7 do not occupy the space outside the original motor of the laser radar, and the structure design is rational, solving the design and installation problems of the speed measuring devices of the existing motor of the laser radar.

As shown in Fig. 5, the circuit board 6 includes three portions, respectively a first portion 61 arranged on the bottom housing 4, a second portion 62 arranged on the top housing 3, and a third portion 63 connected to the first portion 61 and the second portion 62 and located outside a ring wall 41 of the outer periphery of the rotor yoke 21, the rotational speed sampling device 7 is arranged on the top housing 3, and the speed measuring devices 8 are arranged on the bottom housing 4. More specifically, as shown in Fig. 3, an upper surface of the bottom housing 4 on the left side is provided with a first recess 42 recessed downwardly, and the first portion 61 is fastened in the first recess 42. As shown in Fig. 4, an upper surface of the top housing 3 on the left side is provided with a second recess 31 recessed downwardly, and the second portion 62 is fixed in the second recess 31 via a fastener such as s screw. Correspondingly, the second recess 31 is provided with a connecting hole to be connected to the fastener such as the screw. In order to enable the rotational speed sampling device 7 to correspond to a sampling point on the light shielding ring 23 below the top housing 3 to sample a rotational speed of the light shielding ring 23, the second recess 31 is provided with a through hole 32 penetrating the top housing 3, and the rotational speed sampling device 7 is fixed to a bottom of the second portion 62, extends into the through hole 32 to a bottom surface of the top housing 3 and is suspended right above the light shielding ring 23. More specifically, as shown in Fig. 5, the rotational speed sampling device 7 is of an inverted U- shaped structure, and two side walls of the inverted U-shaped structure correspond to inner and outer peripheral walls of the light shielding ring 23. That is, the light shielding ring 23 is located between the two side walls of the U-shaped structure. When the light shielding ring 23 rotates with the rotor yoke 21 such that its sampling point reaches the in-between of the two side walls of the rotational speed sampling device 7, the rotational speed sampling device 7 collects a rotational speed once. Preferably, the rotational speed sampling device 7 in this embodiment is a conventional encoder in the existing market, and its working principle and specific structure are not detailed and limited here. As shown in Fig. 6, the sampling position is a notch 231 formed on the light shielding ring 23 and extending from top to bottom in an axial direction of the light shielding ring 23, and a bottom of the notch 231 does not extend to a bottom circumferential surface of the light shielding ring 23.

The speed measuring devices 8 are conventional position sensors in the existing market, preferably Hall sensors in this embodiment, and the specific structure and the working principle thereof are not detailed and limited, which belong to the prior art. As shown in Fig. 5, there are three Hall sensors in this embodiment, which are arranged on the first portion 61 at intervals in a circumferential direction. That is to say, the three Hall sensors are located within a projection of a lower circumferential surface of the rotor yoke 21 on the bottom housing 4.

According to a preferred embodiment of the present embodiment, in order to prevent the second portion 62 of the circuit board 6 from scratching the rotor assembly 2, as shown in Figs. 1 to 3, a protective ring wall 41 is further provided on an outer periphery of the optical reflecting mirror 22, a gap is reserved between an inner wall of the protective ring wall 41 and an outer wall of the optical reflecting mirror 22, a bottom of the protective ring wall 41 is connected to an outer peripheral rim of the bottom housing 4, and the second portion 62 is located outside the protective ring wall 41. That is to say, the ring wall 41 and the bottom housing 4 form a U-shaped structure with an open top. In order to enable the second portion 62 to extend to the outside of the ring wall 41, an avoidance hole 411 is formed in the second portion 62 or at the connection between the second portion 62 and the ring wall 41 , and the second portion 62 extends to the outside of the ring wall 41 through the avoidance hole 411. Preferably, the ring wall 41 and the bottom housing 4 are of an integrally formed structure. As for the ring wall 41, as shown in Fig. 3, the inner wall of the ring wall 41 has an inverted tapered structure gradually approaching the optical reflecting mirror 22 from top to bottom. Formation of a cradle structure can not only prevent the circuit board 6 from scratching the rotor assembly 2, but can also protect the optical reflecting mirror 22 to avoid collision and damage to the optical reflecting mirror 22. More preferably, the surface of the inner wall of the ring wall 41 is an arc-shaped surface. Optionally, the ring wall 41 is in the shape of a non-closed ring. As shown in Fig. 3, a front surface of the ring wall 41 is provided with an opening.

As shown in Figs. 1 and 6, the light shielding ring 23 includes two portions, the upper portion of which is a ring portion provided with the sampling position, and the lower portion is a T-shaped press plate portion pressed against the rotor yoke 21 and the optical reflecting mirror 22.

The optical reflecting mirror 22 may be an existing conventional prism for the laser radar. Specifically, the prism is a multi-faceted frustum, each facet is a uniform slope for reflecting the laser light, and the prism is of a glass material or a high reflectivity material (not specifically detailed and limited, which is a conventional reflective material for the optical reflecting mirror 22 in the existing market) coated on the surface of the frustum.

An embodiment of the present invention further provides a laser radar, including the outerrotor motor for a laser radar with a rotational speed monitoring function of the above embodiments. The structures other than the motor in the laser radar are not detailed and limited, and are existing conventional structures. Thanks to the use of the outer-rotor motor of the embodiment as described above, the laser radar has at least the advantageous effects of the outer-rotor motor of the embodiment as described above.

It should be understood that the detailed description of the embodiments of the present invention is merely used for illustration or explanation of the principle of the present invention and is not construed as limiting the present invention. Therefore, any modifications, equivalent substitutions, improvements, etc. made within the spirit and scope of the present invention should be included within the scope of protection of the present invention. In addition, the appended claims of the present invention are intended to cover all the variations and modifications that fall within the scope and boundary of the appended claims thereof or equivalents of the scope and boundary.