Displacement detection wheel, robot chassis and mobile robot

Abstract

The present invention discloses a displacement detection wheel, a robot chassis and a mobile robot, wherein the displacement detection wheel comprises a fixed bracket, a wheel axle and a displacement wheel rotatably mounted on the wheel axle, a magnetoelectric encoder is rigidly connected to the end face of the wheel axle, a strong magnet arranged face-to-face with the magnetoelectric encoder is rigidly connected to the displacement wheel, the wheel axle is connected to the fixed bracket through a Hawken linear mechanism, and a torsion spring for pushing the displacement wheel to be arranged close to the ground is connected between the Hawken linear mechanism and the fixed bracket. The present invention utilizes the Hawken linear mechanism to prevent the displacement wheel from being displaced laterally when it moves upward, so that the displacement detection wheel can be installed conveniently without changing the existing regional space; the displacement wheel is forced downward by the torsion spring, so that the displacement wheel is arranged close to the ground, thereby effectively avoiding the displacement wheel from slipping; a strong magnet and a magnetoelectric encoder are installed on the displacement wheel and its wheel axle, and the magnetoelectric encoder is used to measure the displacement of the robot, which is low in cost.

Description

Technical Field

[0001] The invention relates to the field of autonomous mobile robots, and in particular to a displacement detection wheel, a robot chassis and a mobile robot. Background Art

[0002] Mobile robot is a comprehensive system that integrates multiple functions such as environmental perception, dynamic decision-making and planning, behavior control and execution. It concentrates the research results of multiple disciplines such as sensor technology, information processing, electronic engineering, computer engineering, automatic control engineering and artificial intelligence, represents the highest achievement of mechatronics, and is one of the most active fields of scientific and technological development. With the continuous improvement of robot performance, the application scope of mobile robots has been greatly expanded. It is not only widely used in industries such as industry, agriculture, medical care, and services, but also well used in harmful and dangerous occasions such as urban security, national defense and space exploration. Therefore, mobile robot technology has received widespread attention from countries around the world.

[0003] The research on mobile robots began in the late 1960s. Nils Nilssen and Charles Rosen of Stanford Research Institute (SRI) developed an autonomous mobile robot named Shakey from 1966 to 1972. The purpose was to study the application of artificial intelligence technology to autonomous reasoning, planning and control of robot systems in complex environments.

[0004] At present, there are two main ways to measure the distance when the robot moves:

[0005] 1. Directly install the inertial navigation module, measure the acceleration (inertia) of the robot, automatically perform integral calculations, and obtain the robot's instantaneous speed and position data. This module is expensive, easily interfered with, and has a limited application range.

[0006] Second, a rotary encoder is arranged on the driving wheel or driving motor shaft of the robot, and the distance moved by the robot can be converted according to the cumulative rotation of the rotary encoder, such as the Chinese patent with authorization announcement number CN 205928686U and the Chinese patent with authorization announcement number CN 205766098U. This solution has the advantages of simple structure, small amount of modification and low cost, and is widely used in mobile robots. However, since the encoder is directly arranged on the driving wheel or driving motor, once there is an obstacle or the ground is slippery, the driving wheel will slip, resulting in inaccurate robot movement distance converted by the encoder. Summary of the invention

[0007] The purpose of the present invention is to address the deficiencies of the prior art and provide a displacement detection wheel, a robot chassis and a mobile robot that can be adapted to various outdoor road environments and have high accuracy.

[0008] The displacement detection wheel provided by the present invention comprises a fixed bracket, a wheel axle and a displacement wheel rotatably mounted on the wheel axle, the fixed bracket is fixed on the chassis of the mobile robot, the wheel axle is connected to the fixed bracket through a Hawken linear mechanism, a torsion spring for pushing the displacement wheel to be arranged close to the ground is connected between the Hawken linear mechanism and the fixed bracket, a magnetoelectric encoder is rigidly connected to the end face of the wheel axle, and a strong magnet is rigidly connected to the displacement wheel and is arranged face to face with the magnetoelectric encoder in a gap.

[0009] The Hawken linear mechanism includes connecting rod I, connecting rod II and connecting rod III. The lower end of connecting rod I is fixedly connected to the wheel axle, and the upper end is hinged to the fixed bracket through connecting rod II. Connecting rod III is hinged between connecting rod I and the fixed bracket below connecting rod II. The length of connecting rod III is greater than that of connecting rod II. A torsion spring is installed on the hinge shaft at the connection between connecting rod III and the fixed bracket. Connecting rod III is pushed by the torsion spring to rotate downward around the connection between it and the fixed bracket. The displacement wheel on the wheel axle is driven downward by connecting rod III through connecting rod I to be in close contact with the ground.

[0010] To further ensure that no lateral displacement occurs during upward movement, the axes on connecting rod I connected to connecting rod II, connecting rod III and the wheel axle are arranged in parallel and coplanar manner, the distance between the two axes on the fixed bracket connected to connecting rod II and connecting rod III is L1, the distance between the two axes on connecting rod II connected to the fixed bracket and connecting rod I is L2, the distance between the two axes on connecting rod I connected to connecting rod II and connecting rod III is L3, the distance between the two axes on connecting rod III connected to the fixed bracket and connecting rod I is L4, the distance between the two axes on connecting rod I connected to connecting rod III and the wheel axle is L5, wherein L2=L1, L3=1.25×L1, L4=1.5×L1, and L5=2×L1.

[0011] The displacement wheel includes a hub I, a hub II and a tire. Hub I and hub II are rotatably mounted on the wheel axle through a bearing respectively. The tire is frictionally connected to the two hubs. Hub I is connected to hub II through a threaded fastener. A strong magnet is mounted on the hub arranged face to face with the magnetoelectric encoder. Each hub is coaxially arranged with the wheel axle.

[0012] In order to ensure the coaxiality, matching flanges and grooves are provided on the butt surfaces of the two hubs, and the two hubs are connected by means of the matching snap-fitting of the flanges and the grooves.

[0013] A concave ring is arranged on the butt ends of the two wheel hubs, and a convex ring for frictionally connecting with the inner walls of the two concave rings is arranged on the inner side of the tire. The tire is clamped and installed on the two wheel hubs through the cooperation of the convex ring and the concave ring.

[0014] The wheel axle, displacement wheel, magnetoelectric encoder and strong magnet are all coaxially mounted with each other.

[0015] The magnetoelectric encoder is a Hall type magnetoelectric encoder, and the Hall element on the magnetoelectric encoder is coaxial with the strong magnet and is arranged at a spacing of 1 mm.

[0016] A robot chassis comprises any one of the above-mentioned displacement detection wheels.

[0017] A mobile robot comprises the above-mentioned robot chassis.

[0018] The present invention connects the axle of the displacement wheel with the fixed bracket through the Hawken linear mechanism, so that the displacement wheel does not undergo lateral displacement when it moves upward, and is convenient for installing the displacement detection wheel without changing the existing regional space, so that the modification cost is effectively controlled; the displacement wheel on the Hawken linear mechanism is forced downward by the torsion spring, so that the displacement wheel is arranged in close contact with the ground, and only when the robot moves can the displacement wheel rotate by relying on the friction with the ground, thereby effectively avoiding the displacement wheel from slipping; correspondingly arranged strong magnets and magnetoelectric encoders are installed on the displacement wheel and its axle, and when moving, the strong magnet rotates around the axle with the displacement wheel, and the magnetoelectric encoder measures the displacement of the robot according to the rotation of the strong magnet instead of the existing encoder, with small modification, low cost, strong versatility, and wide applicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a structural schematic diagram of the present invention.

[0020] Figure 2 for Figure 1 Schematic diagram of the partial cross-section structure along the A axis.

[0021] Figure 3 The figure is a motion principle diagram when the present invention is used.

[0022] The marks and corresponding component names shown in the figure are:

[0023] 1. Fix the bracket;

[0024] 2. Hawken linear mechanism; 21. Connecting rod I; 22. Connecting rod II; 23. Connecting rod III; 211. Through slot;

[0025] 3. axle; 31. axle hole;

[0026] 4. displacement wheel; 41. wheel hub I; 42. wheel hub II; 43. tire; 411. flange; 412. concave ring; 421. groove; 431. convex ring;

[0027] 5. Magnetoelectric encoder; 6. Strong magnet; 7. Torsion spring. DETAILED DESCRIPTION

[0028] from Figure 1 and Figure 2It can be seen that the displacement detection wheel of the present invention includes a fixed bracket 1, a Hawken linear mechanism 2, a wheel shaft 3, a displacement wheel 4, a magnetoelectric encoder 5, a strong magnet 6 and a torsion spring 7.

[0029] The fixing bracket 1 is detachably mounted on the chassis of the mobile robot through threaded fasteners.

[0030] The Hawken linear mechanism 2 includes a connecting rod Ⅰ21, a connecting rod Ⅱ22 and a connecting rod Ⅲ23. The connecting rod Ⅱ22 is hinged between the upper end of the connecting rod Ⅰ21 and the upper end of the fixed bracket 1 through a pin shaft. The connecting rod Ⅲ23 is hinged between the middle part of the connecting rod Ⅰ21 and the lower end of the fixed bracket 1 through a pin shaft. The connecting rod Ⅲ23 is arranged below the connecting rod Ⅱ22. The length of the connecting rod Ⅲ23 is greater than that of the connecting rod Ⅱ22.

[0031] The wheel axle 3 adopts a stepped shaft and is vertically fixed to the inner side of the lower end of the connecting rod Ⅰ21 through a threaded fastener. An axial hole 31 is provided at the axis center of the wheel axle 3. A through groove 211 connected to the axial hole 31 is provided on the end of the connecting rod Ⅰ21 connected to the wheel axle 3. The wheel axle 3 is connected to the fixed bracket 1 through the Hawken linear mechanism 2 and can move up and down on the fixed bracket 1.

[0032] The displacement wheel 4 includes a hub Ⅰ41, a hub Ⅱ42 and a tire 43. The hub Ⅱ42 is rotatably mounted between the step of the axle 3 and the connecting rod Ⅰ21 through a bearing. The hub Ⅰ41 is mounted on the inner end face of the step of the axle 3 through a bearing rotatable cover. The inner wall of the hub Ⅰ41 and the inner end face of the axle 3 are arranged with a gap. The tire 43 is mounted on the two hubs by elastic sleeves. The tire 43 is frictionally connected with the connecting surface of the hubs. The tire 43 is fixedly connected by elasticity and the friction between the two hubs. The hub Ⅰ41 and the hub Ⅱ42 are detachably connected together by threaded fasteners. Each hub is coaxially arranged with the axle 3.

[0033] The magnetoelectric encoder 5 is fixed to the inner end surface of the axle 3 by screws, and the wire harness of the magnetoelectric encoder 5 passes through the shaft hole 31 on the axle 3 and out of the through slot 211 on the connecting rod I 21.

[0034] The strong magnet 6 is mounted on the inner wall of the hub Ⅰ41 which is arranged face to face with the magnetoelectric encoder 5. The wheel shaft 3, the displacement wheel 4, the magnetoelectric encoder 5 and the strong magnet 6 are all coaxially mounted.

[0035] The torsion spring 7 is installed on the hinge shaft at the connection between the connecting rod III 23 and the fixed bracket 1. The connecting rod III 23 is pushed by the torsion spring 7 to rotate downward around the connection between the connecting rod III 23 and the fixed bracket 1.

[0036] When in use, the connecting rod III 23 swings downward under the action of the torsion spring 7, driving the wheel axle 3 and the displacement wheel 4 on the connecting rod I 21 to move downward, so that the displacement wheel 4 can be closely attached to the ground or the surface of the object being measured;

[0037] When rolling on the ground, the displacement wheel 4 and the strong magnet 6 move around the wheel shaft 3 through the bearing, and the magnetoelectric encoder 5 can detect the rotation angle of the strong magnet 6, that is, the displacement of the displacement wheel 4 can be detected by the following formula:

[0038] Displacement = (π×outer diameter of displacement wheel×rotation angle) / 360.

[0039] from Figure 3 It can be seen that in the present invention, the axis of the hinge connection between the fixed bracket 1 and the connecting rod II 22 is a, the axis of the hinge connection between the connecting rod II 22 and the connecting rod I 21 is b, the axis of the hinge connection between the connecting rod I 21 and the connecting rod III 23 is c, the axis of the connecting rod I 21 fixed to the wheel axle 3 is d, and the axis of the hinge connection between the connecting rod III 23 and the fixed bracket 1 is e. The axis b, the axis c and the axis d are arranged in a coplanar manner parallel to each other.

[0040] The distance from the axis a to the axis e on the fixed bracket 1 is L1, the distance from the axis a to the axis b on the connecting rod II 22 is L2, the distance from the axis b to the axis c on the connecting rod I 21 is L3, the distance from the axis c to the axis e on the connecting rod III 23 is L4, and the distance from the axis c to the axis d on the connecting rod I 21 is L5, where:

[0041] L2=L1;

[0042] L3 = 1.25 × L1;

[0043] L4 = 1.5 × L1;

[0044] L5=2×L1,

[0045] By using the Hawken linear mechanism 2 that satisfies the above-mentioned arm length ratio, when the wheel axle 3 moves up and down within the range of 2×L1, it basically presents a straight up and down linear motion, which can make the displacement wheel move up and down easily, and is more suitable for installation in small front and rear space areas.

[0046] from Figure 2 It can be seen that in order to ensure coaxiality, an annular flange 411 is provided on the outer end face of the wheel hub Ⅰ41 of the present invention, and a groove 421 arranged corresponding to the flange 411 is provided on the inner end face of the wheel hub Ⅱ42. The wheel hub Ⅰ41 and the wheel hub Ⅱ42 are connected by the flange 411 and the groove 421.

[0047] from Figure 2 It can be seen that an identical concave ring 412 is provided on the butt ends of the two wheel hubs of the present invention, and a convex ring 431 arranged corresponding to the two concave rings 412 is provided on the inner side of the tire 43, and the concave rings 412 of the two wheel hubs are connected with the convex ring 431 of the tire 43 by interference fit, and the tire 43 is clamped and mounted on the two wheel hubs by the convex ring 431 and the concave ring 412, and by utilizing elasticity and the friction between the two wheel hubs.

[0048] In the present invention, in order to ensure that the displacement wheel 4 can rotate reliably and smoothly, with less resistance and not prone to sliding, and can also withstand the shaking caused by uneven road surface for a long time to ensure reliable movement, the bearing between the displacement wheel 4 and the wheel axle 3 is a 6005 deep groove ball bearing.

[0049] The magnetoelectric encoder is a new type of angle or displacement measuring device. Its principle is to use magnetic resistance or Hall element to measure the angle or displacement value of the changing magnetic material. The change of the angle or displacement of the magnetic material will cause a certain change in resistance or voltage. The change is amplified by the amplifier circuit, and a pulse signal or analog signal is output after processing by the single-chip microcomputer to achieve the purpose of measurement. The magnetoelectric encoder 5 of the present invention is a Hall type magnetoelectric encoder. The Hall element on the magnetoelectric encoder 5 is coaxial with the strong magnet and is arranged at a distance of 1mm.

[0050] The present invention also provides a robot chassis provided with the displacement detection wheel.

[0051] The present invention also provides a mobile robot provided with the robot chassis.

Claims

1. A displacement detection wheel, characterized in that: The invention comprises a fixed support (1), a wheel axle (3) and a displacement wheel (4) rotatably mounted on the wheel axle, wherein the fixed support is fixed on the chassis of the mobile robot, the wheel axle is connected to the fixed support through a Hawken linear mechanism (2), a torsion spring (7) for pushing the displacement wheel to be arranged close to the ground is connected between the Hawken linear mechanism and the fixed support, a magnetoelectric encoder (5) is rigidly connected to the end surface of the wheel axle, and a strong magnet (6) arranged face to face with the magnetoelectric encoder is rigidly connected to the displacement wheel; the Hawken linear mechanism comprises a connecting rod I (21), a connecting rod II (22) and a connecting rod III (23), the lower end of the connecting rod I is fixedly connected to the wheel axle, the upper end is hingedly connected to the fixed support through the connecting rod II, the connecting rod III is hingedly connected between the connecting rod I and the fixed support below the connecting rod II, the length of the connecting rod III is greater than that of the connecting rod II, the torsion spring is mounted on the hinge shaft at the connection between the connecting rod III and the fixed support, the connecting rod III is pushed by the torsion spring to rotate downward around the connection between the connecting rod III and the fixed support, and the displacement wheel on the wheel axle is driven by the connecting rod III through the connecting rod I The dynamic downward pressure is in close contact with the ground; the axes of the connecting rod I connected with the connecting rod II, the connecting rod III and the wheel axle are arranged in parallel and coplanar, the distance between the two axes of the connecting rod II and the connecting rod III on the fixed bracket is L1, the distance between the two axes of the connecting rod II connected with the fixed bracket and the connecting rod I is L2, the distance between the two axes of the connecting rod I connected with the connecting rod II and the connecting rod III is L3, the distance between the two axes of the connecting rod III connected with the fixed bracket and the connecting rod I is L4, the distance between the two axes of the connecting rod I connected with the connecting rod III and the wheel axle is L5. The distance is L5, L2=L1, L3=1.25×L1, L4=1.5×L1, L5=2×L1; the displacement wheel comprises a hub I (41), a hub II (42) and a tire (43), the hub I and the hub II are respectively rotatably mounted on the wheel axle through a bearing, the tire is frictionally connected to the two hubs, the hub I is connected to the hub II through a threaded fastener, a strong magnet is mounted on the hub arranged face to face with the magnetoelectric encoder, and each hub is coaxially arranged with the wheel axle.

2. The displacement detection wheel according to claim 1, characterized in that: Matching flanges and grooves are arranged on the butt joint surfaces of the two wheel hubs, and the two wheel hubs are connected by the matching snap-fit ​​connection of the flanges and the grooves.

3. The displacement detection wheel according to claim 1, characterized in that: A concave ring is arranged on the butt ends of the two wheel hubs, and a convex ring for frictionally connecting with the inner walls of the two concave rings is arranged on the inner side of the tire. The tire is clamped and installed on the two wheel hubs through the cooperation of the convex ring and the concave ring.

4. The displacement detection wheel according to claim 1, characterized in that: The wheel axle, displacement wheel, magnetoelectric encoder and strong magnet are all coaxially mounted with each other.

5. The displacement detection wheel according to claim 1, characterized in that: The magnetoelectric encoder is a Hall type magnetoelectric encoder, and the Hall element on the magnetoelectric encoder is coaxial with the strong magnet and is arranged at a spacing of 1 mm.

6. A robot chassis, comprising the displacement detection wheel according to any one of claims 1 to 5.

7. A mobile robot, comprising the robot chassis according to claim 6.

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