Robot driving system and differential steering robot walking system

Abstract

The invention discloses a robot large-speed-ratio driving system which comprises a driving motor, a speed reducing mechanism and a driving wheel, the speed reducing mechanism and the driving wheel are matched, the speed reducing mechanism is connected with an output shaft of the driving motor, and the speed reducing mechanism comprises a planetary gear assembly, a fixed left inner gear ring, a planet carrier and a right inner gear ring. After the driving motor achieves the speed reduction and torque increase effects through a left planetary gear ring, a right planetary gear ring and a right inner gear ring of the speed reduction mechanism, power output drives the driving wheel to rotate. The driving system has the advantages of machining and axial size, the speed and torque requirements of the robot can be met by adopting a large-speed-ratio speed-reducing and torque-increasing transmission mechanism and a small-torque and small-size motor, and the power density and the torque density of the driving system can be effectively improved.

Description

Technical Field

[0001] The present invention discloses a robot drive system and a differential steering robot walking system, which belong to the technical field of robot drive manufacturing according to the International Patent Classification (IPC). Background Art

[0002] In recent years, robots have been increasingly widely used and almost penetrated into all fields. The dynamic performance of a robot is mainly determined by the drive motor and the reduction mechanism. The reduction gear generally acts on the reduction, steering, or repeated actions of the drive wheels on the wheel sides of the robot or the drive wheels on both sides of the tracked robot to complete the same process, etc. To ensure reliable handling tasks and handling quality during production, robots have high requirements for positioning accuracy and repeat positioning accuracy. Therefore, to improve and ensure the accuracy of the robot, a reduction gear needs to be used. Another function of the reduction gear in the robot is to transmit a larger torque. When the load is large, it is very uneconomical to only rely on increasing the power of the servo motor. The output torque can be increased through the reduction gear within an appropriate speed range.

[0003] At the same time, the existing robots use steering structures, differential steering, and Mecanum wheel steering solutions for steering. Among them, differential steering can achieve in-situ steering and has simple control, which is widely used in existing robots. Structurally, differential steering realizes steering by driving the drive systems on the left and right sides of the robot at different speeds. After the power is output from the motor, it reaches the wheels through the output of the reduction gear. Since some differential structures require arranging reduction gears to ensure sufficient power output when the robot rotates in place and turns left and right, the internal space deployment of the differential robot is relatively tight or the overall structure is relatively heavy in volume.

[0004] In response to the requirements of the robot for a drive system and a reduction gear with a compact space, a short axial length, and a large radial load. At present, the reduction gears applied to robots in the market include multi-stage parallel gear reduction gears, two-stage planetary reduction gears, and cycloidal pinwheel reduction gears. The parallel gear reduction gear has low precision, and the single-stage reduction ratio is generally 5 or 6, and the maximum is 10. Compared with the other two reduction mechanisms, if the parallel gear reduction gear is to achieve the same large reduction ratio, the volume will increase a lot, which does not meet the extremely compact space requirements of the robot drive system. The single-stage speed ratio of the planetary reduction gear is generally 7 or 8, the maximum can reach 10, and the two-stage can reach 20 - 100. Its advantages are relatively compact structure, small backlash, high precision, long service life, and large rated output torque. However, it has high requirements for the material and machining accuracy of parts, complex structure, and difficult manufacturing and installation. Although the cycloidal pinwheel reduction gear has a small volume, a large transmission ratio, and a long service life, the manufacturing precision requirements for parts are relatively high, the manufacturing process is complex, the swivel arm bearing is subjected to large forces, and the speed of the high-speed shaft and the transmitted power are limited.

[0005] Chinese patent document CN202022991264.1 discloses a wheeled robot drive system. The wheeled robot drive system is equipped with in-wheel motors, and the reducer is a two-stage planetary reducer, which can effectively transmit the torque of the motor to the tires, thereby driving the robot to move. This solution uses a conventional two-stage planetary reducer. Summary of the Invention

[0006] In view of the deficiencies of the prior art, the present invention provides a robot drive system that uses a transmission mechanism with a large transmission ratio to reduce speed and increase torque, and has the function of reducing speed and increasing torque with a large speed ratio.

[0007] To achieve the above object, the present invention is implemented through the following technical solutions:

[0008] A robot drive system, comprising:

[0009] A drive motor, which is the power source,

[0010] A reduction mechanism, which is connected to the output shaft of the drive motor. The reduction mechanism includes a planetary gear assembly, a fixed left internal gear ring, a planet carrier, and a right internal gear ring: a support shaft is provided on the planet carrier to carry the planetary gear assembly. The planetary gear assembly includes a left planetary gear and a right planetary gear that are coaxially arranged and rotate synchronously. The inner side of the left planetary gear in the planetary gear assembly is rotationally connected to the output shaft of the drive motor, and the outer side of the left planetary gear meshes with the left internal gear ring to make the planetary gear assembly rotate around the support shaft of the planet carrier; the right planetary gear of the planetary gear assembly meshes with the right internal gear ring, and the system composed of the planet carrier and the planetary gear assembly can revolve freely around the axis of the right internal gear ring, so that the power is transmitted to the right internal gear ring;

[0011] A drive wheel, which is connected to the reduction mechanism. After the drive motor realizes the function of reducing speed and increasing torque through the left planetary gear ring, right planetary gear ring, and right internal gear ring of the reduction mechanism, the power output drives the drive wheel to rotate.

[0012] Furthermore, the reduction mechanism can be integrated into the drive wheel to reduce the axial length of the reducer; the reduction mechanism can also be arranged outside the drive wheel to adapt to scenarios with a large layout space.

[0013] The present invention provides a differential steering robot walking system, including a frame carrier and the walking system below it. The walking system can be a wheeled or tracked wheel structure. The walking system under the frame carrier uses the above-mentioned robot drive system. The drive motor is connected to the frame through a connecting plate. After the drive motor realizes the function of reducing speed and increasing torque through the reduction mechanism, the power output drives the drive wheel to rotate, realizing the functions of the whole robot moving forward, backward, or turning. Brief Description of the Drawings

[0014] Figure 1 It is a schematic diagram of a robot car, that is, a differential steering robot walking system, of the present invention.

[0015] Figure 2 It is a cross-sectional view of the robot drive system of the present invention.

[0016] Figure 3 It is a schematic diagram of the reduction mechanism part in the present invention. Specific Embodiments

[0017] The present invention will be further described below in conjunction with the accompanying drawings:

[0018] Embodiment: Please refer to Figures 1 to 3 , a robot drive system 100, which includes a drive motor 1 and a matching reduction mechanism and a drive wheel 12. The drive motor 1 is the power source; the reduction mechanism is connected to the output shaft of the drive motor 1. The reduction mechanism includes a planetary gear assembly 6, a fixed left internal gear ring 3, a planet carrier 9, and a right internal gear ring 7: Among them, a support shaft 9.1 is provided on the planet carrier 9 to carry the planetary gear assembly 6. The planetary gear assembly 6 includes a left planetary gear 6.1 and a right planetary gear 6.2 that are coaxially arranged and rotate synchronously. The inner side of the left planetary gear 6.1 in the planetary gear assembly 6 is rotationally connected to the output shaft of the drive motor. The outer side of the left planetary gear 6.1 meshes with the left internal gear ring 3 for transmission, so that the planetary gear assembly 6 rotates around the support shaft 9.1 of the planet carrier 9; the right planetary gear 6.2 of the planetary gear assembly 6 meshes with the right internal gear ring 7. The system composed of the planet carrier 9 and the planetary gear assembly 6 can revolve freely around the axis of the right internal gear ring 7, so that the power is transmitted to the right internal gear ring 7; the drive wheel 12 is connected to the reduction mechanism. After the drive motor 1 realizes the function of speed reduction and torque increase through the left planetary gear ring 6.1, the right planetary gear ring 6.2, and the right internal gear ring 7 of the reduction mechanism, the power output drives the drive wheel 12 to rotate. The drive motor 1, the output shaft of the drive motor, the left internal gear ring 3, the right internal gear ring 7, and the drive wheel in the present invention are coaxially arranged.

[0019] In the solution of the present invention, there are two layout modes for the reduction mechanism and the drive wheel to suit different working conditions: One is that the reduction mechanism is integrated into the drive wheel 12 as shown in Figure 2 ; the other is that the reduction mechanism is arranged outside the drive wheel. At this time, the output rotating shaft is formed outward from the right internal gear ring of the reduction mechanism, and the output rotating shaft is connected to the drive wheel to make the drive wheel rotate.

[0020] Please refer to Figure 2As shown in the figure, in one embodiment of the present invention, the drive wheel includes a drive wheel inner hub 10 and a rim 11. The drive wheel is provided with an inner cavity with an opening on one side for assembling a speed reduction mechanism, and the inner cavity on the drive wheel is the inner cavity of the drive wheel inner hub 10. The opening side of the drive wheel 12 is connected to the drive motor through a connecting disc 3. The output shaft on the drive motor 1 passes through the connecting disc 2 and extends into the inner cavity of the drive wheel. An output shaft gear 1.3 is provided on the output shaft, and the output shaft gear 1.3 meshes with the left planetary gear 6.1 of the speed reduction mechanism for transmission. The connecting disc 2 is fixedly connected to the left internal gear ring 3. The left planetary gear 6.1 and the right planetary gear 6.2 are coaxially arranged and are an integral part to form a planetary gear assembly 6. Each gear hole of the planetary gear assembly 6 is matched with each support shaft of the planet carrier 9 to achieve radial positioning; the outside of the right planetary gear 6.2 meshes with the right internal gear ring 7, and the right internal gear ring 7 is fixedly connected to the drive wheel by a fixed connection method.

[0021] Please refer to Figure 2 As shown in the figure, in one embodiment of the present invention, the inner cavity of the drive wheel, that is, the inner cavity of the drive wheel inner hub 10, is a multi-stage stepped groove structure. The left side of the drive wheel is connected and freely rotated through the installation of a left bearing between the inner cavity of the drive wheel and the outer ring of the left internal gear ring 3. The left bearing is a sealed bearing 5, which is used to prevent dust from entering the inside of the drive wheel assembly; a snap ring 4 is installed on the left side of the left bearing, which is used to limit the axial movement of the speed reduction mechanism and the drive wheel; the right end of the right internal gear ring 7 is matched with the inner end face of the multi-stage stepped groove structure of the drive wheel to achieve axial positioning, and the right end face of the right internal gear ring is fixedly connected to the drive wheel by interference fit.

[0022] Please refer to Figure 2 and Figure 3 As shown in the figure, in one embodiment of the present invention, the left planetary gear 6.1 and the right planetary gear 6.2 are integrally fixed components. The integrally fixed components are rowed gears with a gap in the middle. The planetary gear assembly includes more than 1 integrally fixed component, and 3 to 5 are selected according to the system load requirements.

[0023] The technical solution of the present invention is as follows: The drive motor 1 is fixedly connected to the motor mounting hole 2.1 of the connecting disc 2 by bolts through the mounting holes 1.2 on the motor flange 1.1; the connecting disc 2 is fixedly connected to the left internal gear ring mounting hole 3.1 by bolts through the mounting holes 2.2, and the connecting disc 2 is fixedly connected to the trolley bracket, so that the connecting disc does not rotate when the driving wheel works, and thus the left internal gear ring does not rotate either; the drive motor 1 serves as the power source of this transmission system, and the output shaft gear 1.3 on the drive motor 1 serves as the power input end, and together with the left internal gear ring 3, planetary gear assembly 6, right internal gear ring 7, needle roller bearing 8, planet carrier 9, etc. arranged in the driving wheel inner hub 10, a reduction mechanism is formed; in the reduction mechanism, the output shaft gear 1.3 on the drive motor 1 meshes with the left planetary gear 6.1 of the planetary gear assembly 6, the left planetary gear 6.1 meshes with the left internal gear ring 3, and the right planetary gear 6.2 meshes with the right internal gear ring 7; the left planetary gear 6.1 and the right planetary gear 6.2 are coaxially arranged and are an integral structure to form the planetary gear assembly 6. The planetary gear assembly 6 is radially positioned and assembled on the planet carrier 9 through the planet carrier assembly shaft or support shaft 9.1. A needle roller bearing 8 is assembled between the planetary gear assembly and the planet carrier to support and increase the radial load; the bottom support surface of the planet carrier 9 cooperates with the bottom end face of the inner cavity of the right internal gear ring 7 to achieve axial positioning, and the right end face of the right internal gear ring 7 cooperates with the inner end face of the driving wheel inner hub 10 to achieve axial positioning, and the right end face of the right internal gear ring 7 is fixedly connected to the driving wheel inner hub 10 by interference fit; the number of teeth of the left internal gear ring 3 is greater than the number of teeth of the right internal gear ring 7; the left side of the driving wheel inner hub 10 is connected and freely rotated through the installation of a sealed bearing 5 between the inner cavity of the driving wheel inner hub and the outer ring of the left internal gear ring 3. A strong and thick snap ring 4 is assembled on the left side of the sealed bearing to limit the axial movement of the sealed bearing, reduction mechanism, and driving wheel assembly including the driving wheel inner hub 10 and the driving wheel rim.

[0024] The working principle of the solution of the present invention is as follows: The output shaft of the drive motor 1 is fixedly connected to the output shaft gear 1.3. The motor provides the power of the motor output shaft to drive the output shaft gear 1.3 to rotate actively. The left internal gear ring 3 is fixed to the connecting disc 2, and the connecting disc is fixed to the trolley bracket, so that the left internal gear ring is fixed. At this time, in the reduction mechanism, the sun gear (output shaft gear) actively drives the left planetary gear 6.1 to rotate at a reduced speed. The left planetary gear 6.1 and the right planetary gear 6.2 are an integral part, and the sun gear also drives the right planetary gear 6.2 to rotate at a reduced speed through the left planetary gear 6.1; the right planetary gear 6.2 meshes with the right internal gear ring 7, and the rotation of the right planetary gear 6.2 drives the right internal gear ring 7 to rotate at a reduced speed as a driven part, realizing further reduction of the speed ratio by amplification. The right internal gear ring 7 is fixedly connected to the driving wheel inner hub 10, and then drives the outer surface of the driving wheel, that is, the wheel rim 11, to rotate. Through the reduction mechanism, a large speed ratio reduction is achieved to realize the rotation of the driving wheel assembly with a large torque output.

[0025] The drive system of the present invention can be widely used in the walking systems of wheeled or tracked robots, and can form a differential steering robot walking system or other robot walking systems.

[0026] As Figure 1 shown, the present invention also provides a differential steering robot walking system, including a vehicle frame 101 and the wheels below it. The two front wheels or two rear wheels under the vehicle frame adopt the robot drive system 100. The drive motor 1 is connected to the vehicle frame 101 through a connecting plate. After the drive motor 1 realizes the function of speed reduction and torque increase through a speed reduction mechanism, the power output drives the wheels to rotate, realizing the functions of the robot car moving forward, backward or turning. The differential steering robot walking system of the present invention is, for example, an AGV car or a food delivery car or other differential steering intelligent cars with similar functions.

[0027] The solution of the present invention has the following advantages:

[0028] 1. Compared with the existing solution of arranging the speed reducer outside the wheels of the differential drive robot car, in this solution, the speed reducer is directly integrated inside the drive wheel, making the structure more compact, not occupying additional external layout space, greatly reducing the layout difficulty, and meeting the requirements of the wheeled robot for the axial length of the speed reducer.

[0029] 2. Comparing with the parallel-axis gear reduction mechanism, the transmission ratio of a single-stage one is generally 5 or 6, and that of a two-stage one is around 30. Comparing with the single-stage planetary reducer commonly used in robot cars on the market, the transmission ratio is less than 10, generally 7 or 8, and the reduction ratio of the two-stage planetary reducer is around 60. If the transmission ratio increases further on this basis, the transmission efficiency is not high. The transmission ratio of the present invention can reach 10 - 160, with a large speed ratio range, capable of outputting a greater torque, meeting the requirements of large reduction ratio and large torque of the drive wheels; and it can reduce the requirements for the motor and save costs: when the motor power is the same and under the same technical conditions, the speed and torque of the motor are inversely proportional. The higher the motor speed, the lower the torque. Due to the characteristics of the motor, the higher the motor speed, the smaller the motor torque, the smaller the volume, and the greater the power density. Therefore, under the same power, a high-speed motor has a lower cost, a smaller volume, and higher efficiency. The present invention can perform reduction and torque increase with a large transmission ratio, reducing the requirements for the motor torque. When selecting a suitable motor according to the actual working conditions, a small motor with high speed and low torque can be selected, reducing the motor volume, cost, making the structure more compact, and reducing the layout difficulty. For example, the running speed of an ordinary food delivery robot car is about the same as the normal walking speed of a human, which is 5 km / h, approximately 1.4 m / s. Assuming the diameter of the car wheel is 0.1 m, that is, it needs to rotate 4.45 circles per second, which is 267 rpm. When the transmission ratio of the mechanism of the present invention is 50, only a small-torque and small-volume motor with 11350 rpm is required to meet the speed and torque requirements of the food delivery vehicle. The small-torque motors that meet this speed on the existing market are cheap, and with the future trend of motors towards high speed, they can better adapt to this large-reduction-ratio transmission mechanism, and the present invention has forward-looking.

[0030] 3. The system of the present invention has only a simple planetary carrier structure, and the left and right planetary gears are an integral structure. Comparing with the commonly used two-stage planetary reduction mechanism: one planetary carrier is cancelled, reducing the axial length and making the structure more compact; at the same time, the second-stage sun gear with weak strength is cancelled, and the planetary gear input is used to replace the sun gear to bear the torque; because the outer contour size of the planetary gear can be significantly larger than that of the sun gear, and there are at least three planetary gears in the planetary system to share the system load, this structure can effectively improve the problem of insufficient strength of the sun gear in the planetary reduction system caused by a large speed ratio and large torque of the system; comparing with the two-stage planetary row reduction mechanism on the market, the present invention has many advantages such as simple structure, few parts, low cost, short axial length, and strong torque bearing capacity.

[0031] As described above, only the embodiments using the technical content of this creation are recorded. Any modification and change made by those skilled in this art using this creation fall within the scope of the patent claimed by this creation, and are not limited to those disclosed in the embodiments.

Claims

1. A robot drive system, characterized in that, comprising: a drive motor, which is a power source, a reduction mechanism connected to the output shaft of the drive motor. The reduction mechanism includes a planetary gear assembly, a fixed left internal gear ring, a planet carrier, and a right internal gear ring: wherein a support shaft is provided on the planet carrier to carry the planetary gear assembly. The planetary gear assembly includes a left planetary gear and a right planetary gear arranged coaxially and rotating synchronously. The inner side of the left planetary gear in the planetary gear assembly is rotatably connected to the output shaft of the drive motor, and the outer side of the left planetary gear meshes with the left internal gear ring to cause the planetary gear assembly to rotate about the support shaft of the planet carrier; the right planetary gear of the planetary gear assembly meshes with the right internal gear ring, and the system composed of the planet carrier and the planetary gear assembly can revolve freely about the axis of the right internal gear ring, so that power is transmitted to the right internal gear ring; a drive wheel connected to the reduction mechanism. After the drive motor realizes the functions of speed reduction and torque increase through the left planetary gear ring, right planetary gear ring, and right internal gear ring of the reduction mechanism, the power output drives the drive wheel to rotate.

2. A robot drive system according to claim 1, characterized in that: the reduction mechanism is integrated in the drive wheel.

3. A robot drive system according to claim 2, characterized in that: the drive wheel is provided with an inner cavity with an opening on one side for assembling the reduction mechanism. The opening side of the drive wheel is connected to the drive motor through a connection disk. The output shaft on the drive motor passes through the connection disk and extends into the inner cavity of the drive wheel. An output shaft gear is provided on the output shaft, and the output shaft gear meshes with the left planetary gear of the reduction mechanism.

4. A robot drive system according to claim 3, characterized in that: the connection disk is fixedly connected to the left internal gear ring. The left planetary gear and the right planetary gear are coaxially arranged and are an integral part structure to form a planetary gear assembly. The gear holes of the planetary gear assembly are matched with the support shafts of the planet carrier to achieve radial positioning; the outer side of the right planetary gear meshes with the right internal gear ring, and the right internal gear ring is fixed to the drive wheel by a fixed connection method.

5. A robot drive system according to claim 2, characterized in that: the inner cavity of the drive wheel is a multi-stage stepped groove structure. The left side of the drive wheel is connected and freely rotated through a left bearing installed between the outer ring of the left internal gear ring and the inner cavity of the drive wheel. The left bearing is a sealed bearing for preventing dust from entering the interior of the drive wheel assembly; a snap ring is installed on the left side of the left bearing for restricting the axial movement of the reduction mechanism and the drive wheel; the right end of the right internal gear ring is matched with the inner end face of the multi-stage stepped groove structure of the drive wheel to achieve axial positioning, and the right end face of the right internal gear ring is fixedly connected to the drive wheel by an interference fit.

6. A robot drive system according to claim 1, characterized in that: the reduction mechanism is arranged outside the drive wheel, and an output rotating shaft is formed outward from the right internal gear ring. The output rotating shaft is connected to the drive wheel to cause the drive wheel to rotate.

7. A robot drive system according to claim 1, characterized in that: the drive motor, the output shaft of the drive motor, the left internal gear ring, the right internal gear ring, and the drive wheel are coaxially arranged.

8. A robot drive system according to claim 1, characterized in that: The left planetary gear and the right planetary gear are integrally fixed components, the number of teeth of the left internal gear ring is greater than that of the right internal gear ring, the planetary gear assembly includes more than 1 integrally fixed component, and 3 to 5 are selected according to the system load requirements.

9. A differential steering robot walking system, characterized in that: It includes the robot drive system according to any one of claims 1 to 8, and this walking system is a wheeled or tracked robot walking system.

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