Hydraulically driven transport robot

Abstract

The hydraulic drive transport robot has a steering drive mechanism for controlling wheel steering, a rotating speed sensor for detecting wheel rotating speed, a gyroscope for detecting the inclination of the vehicle body, an accelerometer for detecting the acceleration of the vehicle body, and a speed sensor for detecting the speed of the vehicle body, and by using a PID control algorithm to adjust the flow distribution and control of the steering drive mechanisms of each wheel of the transport robot, adaptive matching of different operating conditions (steering, load deviation, etc.) can be achieved, and the transport robot has the characteristics of low cost, high precision, good linearity and fast response; since each wheel has an independent steering drive mechanism in the present application, the steering wheels do not affect each other, so the wheel steering angle can be automatically adjusted, the steering center is always on a straight line perpendicular to the vehicle body, the sliding friction between the wheels and the ground is reduced, and the service life of the wheels is prolonged.

Description

Technical Field

[0001] This invention relates to the field of hydraulic drive control technology, and in particular to a hydraulically driven transport robot. Background Technology

[0002] The hydrostatic drive of mobile robots, such as engineering machinery, refers to the conversion of mechanical energy output by the engine (internal combustion engine or electric motor) into hydraulic energy in the hydraulic pump, which is then transmitted to the hydraulic motor through pipelines and control valves. At the motor, it is converted back into mechanical energy that can overcome the torque caused by the load and reach the required speed. This mechanical energy is then directly or indirectly output by the motor to drive the wheels (or tracks) to rotate, thereby achieving the purpose of robot walking.

[0003] Researchers have conducted some studies on the control of hydraulically driven robots. CN110671376A proposes a load-sensitive flow divider valve, a variable-speed synchronous drive system, and its working method, applicable to hydraulic robots with multiple hydraulic cylinders, which can improve the efficiency and maneuverability of the hydraulic system. CN115636011A proposes a steering control system, method, and robot for an unmanned vehicle's fully hydraulic steering system, which can improve the response speed and dynamic response characteristics of steering switching. However, the turning angle of these robot wheels is limited by the trapezoidal structure of the steering suspension. The two steering wheels on the same suspension affect each other and cannot adjust the turning angle independently. They are highly dependent on the design of the suspension structure, which makes it impossible to ensure that the steering center is always on a straight line perpendicular to the vehicle body. This leads to uncontrollable wheel steering center and unreasonable wheel speeds on both sides, causing wheel sliding friction with the ground and reducing wheel life. Summary of the Invention

[0004] Therefore, the technical problem to be solved by the present invention is to overcome the problem in the prior art that the two steering wheels on the same suspension of the hydraulically driven transport robot affect each other and cannot adjust the steering angle independently.

[0005] To solve the above-mentioned technical problems, the present invention provides a hydraulically driven transport robot, comprising:

[0006] Body;

[0007] Multiple wheels are connected to the vehicle body;

[0008] Multiple independent steering drive mechanisms are connected to each wheel to control the speed, angle, and tilt of each wheel.

[0009] Speed ​​sensors are installed on each wheel to detect the speed of each wheel;

[0010] Multiple gyroscopes are mounted on the vehicle body to detect the vehicle's tilt angle;

[0011] Multiple accelerometers are installed on the vehicle body to detect vehicle acceleration;

[0012] A speed sensor, installed on the vehicle body, is used to detect the vehicle's speed;

[0013] The PID controller is used to receive steering commands and calculate the steering center based on the current wheel speeds, vehicle tilt, vehicle acceleration, and vehicle speed, and then send control commands to the multiple independent steering drive mechanisms.

[0014] Preferably, the steering drive mechanism includes:

[0015] Hydraulic motors are used to control the rotational speed of the wheels;

[0016] Tilt adjustment hydraulic cylinder, used to control wheel tilt;

[0017] Multiple steering adjustment hydraulic cylinders are used to control the wheel angle.

[0018] Preferably, the tilt adjustment hydraulic cylinder is installed on the upper half of the wheel guide plate, and changes the wheel camber angle by extending and retracting.

[0019] Preferably, the plurality of steering adjustment hydraulic cylinders are respectively mounted on the wheel guide discs on both sides of the hydraulic motor, and together control the wheel angle by extension and retraction.

[0020] Preferably, the plurality of gyroscopes and the plurality of accelerometers are installed in pairs at different locations on the vehicle body.

[0021] Preferably, receiving steering commands and calculating the steering center based on the current wheel speeds, vehicle tilt, vehicle acceleration, and vehicle speed, and then sending control commands to the plurality of independent steering drive mechanisms includes:

[0022] Upon receiving a steering command, the steering center is calculated in real time based on the Ackermann steering principle, using the current wheel speeds, vehicle tilt, vehicle acceleration, and vehicle speed.

[0023] The steering drive mechanism is controlled in real time according to the steering center.

[0024] Preferably, the step of calculating the steering center in real time after receiving a steering command, based on the Ackermann steering principle and utilizing the current wheel speeds, vehicle tilt, vehicle acceleration, and vehicle speed, includes:

[0025] When the vehicle body tilt meets the preset steering conditions, the steering center is set at a first preset distance close to the vehicle body until the vehicle body returns to the steering path of the steering command. Then, the steering center is gradually moved away from the vehicle body at a preset speed to maintain the steering trajectory.

[0026] When the vehicle speed is higher than the first preset threshold, the steering center is set at a second preset distance from the vehicle until the vehicle speed meets the preset conditions, and then the steering center is gradually moved closer to the vehicle at a preset speed.

[0027] Preferably, when the vehicle body tilt does not meet the preset steering conditions, the steering route is recalculated.

[0028] Preferably, the real-time control of the steering drive mechanism based on the steering center includes:

[0029] The wheel speed is calculated based on the steering center, and the wheel speed is positively correlated with the distance between the steering center and the vehicle body;

[0030] The wheel angle is adjusted in real time according to the steering center so that the wheel center normal passes through the steering center.

[0031] Preferably, the PID controller is further configured to:

[0032] When the vehicle body tilt reaches the second preset threshold, the upper part of the wheel will be retracted inward and the wheel camber angle will be increased.

[0033] The technical solution of the present invention has the following advantages compared with the prior art:

[0034] The hydraulically driven transport robot of this invention is equipped with a steering drive mechanism for controlling wheel steering, a speed sensor for detecting wheel rotation speed, a gyroscope for detecting vehicle tilt, an accelerometer for detecting vehicle acceleration, and a speed sensor for detecting vehicle speed. By employing a PID control algorithm to adjust the flow distribution and control of the steering drive mechanisms of each wheel of the transport robot, adaptive matching under different operating conditions (steering, off-center loading, etc.) can be achieved. It features low cost, high precision, good linearity, and fast response. Since each wheel in this invention has an independent steering drive mechanism, the steering wheels do not affect each other, thus automatically adjusting the wheel angle to ensure that the steering center is always on a straight line perpendicular to the vehicle body, reducing wheel-to-ground sliding friction and extending wheel life. Attached Figure Description

[0035] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings, wherein:

[0036] Figure 1 This is a schematic diagram of the structure of a hydraulically driven transport robot provided by the present invention;

[0037] Figure 2 This is a schematic diagram of the PID feedback control of the hydraulically driven transport robot provided by the present invention;

[0038] Figure 3 This is a schematic diagram of a wheel hydraulic drive structure;

[0039] Explanation of reference numerals in the attached diagram: 1-Body body; 2-Wheel; 3-Steering drive mechanism; 4-Speed ​​sensor; 5-Gyroscope; 6-Accelerometer; 7-Speed ​​sensor; 8-Hydraulic motor; 9-Tilting adjustment hydraulic cylinder; 10-Steering adjustment hydraulic cylinder; 11-Guide plate. Detailed Implementation

[0040] The core of this invention is to provide a hydraulically driven transport robot in which each steering wheel does not affect the others, thus automatically adjusting the wheel angle to ensure that the steering center is always on a straight line perpendicular to the vehicle body, reducing wheel sliding friction with the ground and extending wheel life.

[0041] To enable those skilled in the art to better understand the present invention, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are merely some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0042] Please refer to Figure 1 and Figure 2 , Figure 1 This is a schematic diagram of the structure of a hydraulically driven transport robot provided by the present invention. Figure 2 The schematic diagram of the PID feedback control for the hydraulically driven transport robot provided by the present invention is as follows:

[0043] Body 1;

[0044] Multiple wheels 2 are connected to the vehicle body;

[0045] Multiple independent steering drive mechanisms 3 are connected to each wheel respectively, and are used to control the speed, angle and tilt of each wheel;

[0046] Speed ​​sensor 4 is installed on each wheel to detect the speed of each wheel;

[0047] Multiple gyroscopes 5 are mounted on the vehicle body to detect the vehicle body tilt.

[0048] Multiple accelerometers 6 are installed on the vehicle body to detect the vehicle body acceleration;

[0049] Speed ​​sensor 7 is installed on the vehicle body to detect the vehicle speed;

[0050] The PID controller is used to receive steering commands and calculate the steering center based on the current wheel speeds, vehicle tilt, vehicle acceleration, and vehicle speed, and then send control commands to the multiple independent steering drive mechanisms.

[0051] like Figure 3 As shown, based on the above embodiments, the steering drive mechanism includes:

[0052] Hydraulic motor 8 is used to control the wheel speed. The closer the steering center is to the vehicle body, the lower the output power of the hydraulic motor and the slower the wheel speed. The tilt adjustment hydraulic cylinder is used to control the tilt of the wheel, and the steering adjustment hydraulic cylinder is used to control the steering angle of the wheel. The steering drive mechanisms of the four wheels are independent of each other and do not affect each other.

[0053] The tilt adjustment hydraulic cylinder 9 is used to control the wheel tilt angle; it is installed on the upper half of the guide plate 11 and can change the wheel camber angle by extending and retracting. The closer the steering center is to the vehicle body, the greater the wheel camber angle, and the camber angle range can reach 0 to 20°.

[0054] Multiple steering adjustment hydraulic cylinders 10 are used to control the wheel angle. They are respectively installed on the wheel guide plates on both sides of the hydraulic motor, and control the wheel angle together by extension and retraction.

[0055] Based on the above embodiments, the plurality of gyroscopes and accelerometers are installed in pairs at different locations on the vehicle body. In one embodiment, there are three sets of gyroscopes and accelerometers, installed at the front and sides of the vehicle body respectively, to ensure measurement accuracy.

[0056] Based on the above embodiments, the PID controller is used to distribute and control the flow of the steering drive mechanism of each wheel. The steering drive mechanism includes components such as a hydraulic motor and a hydraulic cylinder. The hydraulic motor controls the wheel speed, the tilt adjustment hydraulic cylinder controls the wheel tilt angle, and the steering adjustment hydraulic cylinder controls the wheel angle. A speed sensor detects the wheel speed; a gyroscope detects the vehicle tilt angle; an accelerometer detects the vehicle acceleration; and a speed sensor detects the vehicle speed. The PID controller can continuously receive information such as the current vehicle tilt angle, wheel speed, vehicle acceleration, and vehicle speed according to steering requirements, automatically calculate a suitable steering center, and then control the steering drive mechanism of each wheel, achieving feedback control of the wheel angle, vehicle tilt angle, and wheel speed. Specifically:

[0057] The process of receiving steering commands, calculating the steering center based on the current wheel speeds, vehicle tilt, vehicle acceleration, and vehicle speed, and sending control commands to the multiple independent steering drive mechanisms includes:

[0058] 1. Upon receiving a steering command, based on the Ackermann steering principle, the steering center is calculated in real time using the current wheel speeds, vehicle tilt, vehicle acceleration, and vehicle speed.

[0059] When the vehicle body tilt meets the preset steering conditions, the steering center is set at a first preset distance close to the vehicle body until the vehicle body returns to the steering path of the steering command. Then, the steering center is gradually moved away from the vehicle body at a preset speed to maintain the steering trajectory. When the vehicle body tilt does not meet the preset steering conditions, the steering path is recalculated.

[0060] When the vehicle speed is higher than the first preset threshold, the steering center is set at a second preset distance from the vehicle until the vehicle speed meets the preset conditions, and then the steering center is gradually moved closer to the vehicle at a preset speed.

[0061] Second: Control the steering drive mechanism in real time according to the steering center.

[0062] The wheel speed is calculated based on the steering center, and the wheel speed is positively correlated with the distance between the steering center and the vehicle body;

[0063] The wheel angle is adjusted in real time according to the steering center so that the wheel center normal passes through the steering center.

[0064] Based on the above embodiments, the PID controller is further used for:

[0065] When the vehicle body tilt reaches the second preset threshold (i.e., when encountering an uneven road surface), the upper part of the wheel will retract inward and the wheel camber angle will be increased.

[0066] In this invention, the PID controller of the hydraulically driven transport robot can determine the robot's walking path and mode based on the working conditions and vehicle body status acquired by the sensors on the robot. It then sends control commands to the hydraulic system, which executes the robot's movement actions, enabling automatic operation and functions such as forward, backward, and turning. Furthermore, during turning, the PID controller continuously collects information such as vehicle tilt angle, wheel speed, vehicle acceleration, and vehicle speed, and then adjusts the wheel angle, vehicle tilt angle, wheel speed, and steering center to ensure that the Ackerman ratio is always equal to 100%, achieving closed-loop control of the robot's steering.

[0067] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A hydraulically driven transport robot, characterized in that The application relates to a vehicle body and a plurality of wheels connected to the vehicle body. A plurality of independent steering drive mechanisms are respectively connected to the wheels to control the rotation speed, rotation angle and inclination of the wheels. A rotation speed sensor is arranged on each wheel to detect the rotation speed of each wheel. A plurality of gyroscopes are arranged on the vehicle body to detect the inclination of the vehicle body. A plurality of accelerometers are arranged on the vehicle body to detect the acceleration of the vehicle body. A speed sensor is arranged on the vehicle body to detect the speed of the vehicle body. A PID controller is used to calculate a steering center in real time according to the Ackerman steering principle after receiving a steering instruction, and to control the steering drive mechanism in real time according to the steering center. The steering drive mechanism comprises a hydraulic motor for controlling the rotation speed of the wheel, an inclination adjusting hydraulic cylinder for controlling the inclination of the wheel, and a plurality of steering adjusting hydraulic cylinders for controlling the rotation angle of the wheel. The inclination adjusting hydraulic cylinder is installed on the upper half of the wheel guide disc to change the camber angle of the wheel through extension and retraction.

2. The hydraulically driven transport robot of claim 1, wherein, The plurality of steering adjusting hydraulic cylinders are respectively installed on the wheel guide discs on the two sides of the hydraulic motor to jointly control the rotation angle of the wheel through extension and retraction. The plurality of gyroscopes and the plurality of accelerometers are arranged in pairs at different positions of the vehicle body. The PID controller is used to calculate the steering center in real time according to the Ackerman steering principle after receiving a steering instruction, and to gradually move the steering center away from the vehicle body at a preset speed after the vehicle body returns to the steering route of the steering instruction, so as to maintain the steering track. When the speed of the vehicle body is higher than a first preset threshold, the steering center is arranged at a second preset distance away from the vehicle body, and the steering center is gradually moved close to the vehicle body at a preset speed after the speed of the vehicle body meets a preset condition.

3. The hydraulically driven transport robot of claim 2, wherein, When the inclination of the vehicle body does not meet the preset steering condition, the steering route is recalculated.

4. The hydraulically driven transport robot of claim 2, wherein, The PID controller is used to calculate the rotation speed of the wheel according to the steering center, and the rotation speed of the wheel is positively correlated with the distance between the steering center and the vehicle body.

5. The hydraulically driven transport robot of claim 1, wherein, The rotation angle of the wheel is adjusted in real time according to the steering center, so that the normal line of the wheel center passes through the steering center.

6. The hydraulically driven transport robot of claim 1, wherein, When the inclination of the vehicle body reaches a second preset threshold, the upper half of the wheel is inwardly retracted, and the camber angle of the wheel is increased. ​ ​ 7. The hydraulically driven transport robot of claim 6, wherein, ​ 8. The hydraulically driven transport robot of claim 1, wherein, ​ ​ ​ 9. The hydraulically driven transport robot of claim 1, wherein, ​ ​

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