A contact charging control system and method for a wheel-legged robot

Abstract

The application discloses a contact charging control system and method for a wheel-legged robot, and relates to the technical field of robot charging. The system comprises a charging pile, a PDU, a protection plate and a battery pack arranged on the robot; the charging pile is provided with an elastic buffer mechanism, a limit switch and a relay; when the robot moves to the charging pile and sits down, the elastic buffer mechanism is pressed downward to generate displacement, the limit switch is closed, the relay coil is electrified and the main contact is driven to close, the high-voltage charging loop is turned on to charge. In addition, the system is also provided with a three-stage tripping protection circuit, which physically cuts off the negative loop when the charging MOS tube has a sticking fault; and a side-charging and side-balancing strategy based on single pressure difference and a hierarchical heat dissipation control based on environmental temperature are integrated. The application triggers the low-voltage electrical loop to close strong current through pure mechanical pressing, not only realizes low-cost and high-reliable contact charging, but also has the remarkable advantages of safe and absolutely controllable, efficient heat dissipation and long battery life.

Description

Technical Field

[0001] This invention relates to the field of robot charging technology, and more specifically, to a contact charging control system and method for wheeled and legged robots. Background Technology

[0002] With the rapid development of robotics technology, wheeled and legged robots are increasingly widely used in various complex scenarios. However, the issues of robot endurance and charging have always been bottlenecks restricting their efficient operation. Existing robot charging devices typically have the following shortcomings: First, high-end contactless or fully automatic plug-in charging piles are expensive and structurally complex, while low-cost contact charging often lacks reliable safety isolation mechanisms, posing risks of leakage and poor contact; second, high-power charging generates a lot of heat, and if the heat dissipation design is not reasonable, it can easily cause overheating of the battery and internal components of the charging pile, even leading to fire; finally, existing battery management systems (BMS) typically only have two levels of MOSFET cutoff protection. Once a MOSFET sticking and breakdown fault occurs, the protection mechanism will completely fail, and it cannot effectively cope with dangerous conditions such as overvoltage and overcurrent.

[0003] Therefore, there is an urgent need for a low-cost, highly reliable robot contact charging control system with a complete heat dissipation and multi-level safety protection mechanism. Summary of the Invention

[0004] To address the aforementioned technical problems, the present invention aims to provide a contact charging control system and method for wheeled robots. By mechanically pressing down to trigger the low-voltage electrical circuit to close the high-voltage charging circuit, safe contact charging is achieved at low cost, and three-level tripping protection and graded heat dissipation control are provided.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a contact charging control system for a wheeled-legged robot, including a charging pile and a power distribution unit (PDU), a protection board, and a battery pack disposed on the wheeled-legged robot; The charging pile is equipped with positive and negative conductive components, an elastic buffer mechanism, a limit switch and a relay. The bottom of the wheeled robot is equipped with positive and negative conductive components that are connected to the battery pack. The coils of the limit switch and the relay are connected in series in the power supply circuit of the power distribution unit (PDU); the main contacts of the relay are connected in series in the charging circuit of the protection board. When the wheeled robot moves to the charging pile and sits down on it, the robot's positive and negative conductive parts come into contact with the charging pile's positive and negative conductive parts, and press down on the elastic buffer mechanism to cause it to shift, touch and close the limit switch, so that the relay coil is energized, thereby causing the relay's main contacts to close, conducting the charging circuit of the protection board, so that the power distribution unit (PDU) can charge the battery pack through the protection board.

[0006] Furthermore, the limit switch is equipped with a roller, and the elastic buffer mechanism includes an insulating plate, a copper column, and a spring; The positive and negative conductive components of the charging pile are copper sheets fixed on the front side of the insulating plate; the back side of the insulating plate is provided with a plurality of copper pillars, each copper pillar is fitted with a spring, and the other end of the spring is connected to the layer plate inside the charging pile. When the wheeled robot sits down and applies downward pressure, the spring is compressed downward by a set stroke, and the insulating plate touches the roller of the limit switch, causing the roller to be compressed and displaced, thereby closing the limit switch.

[0007] Furthermore, the protection board is provided with a charging MOS transistor for controlling the on / off state of the charging circuit, and the control system also includes a trip protection circuit, which includes a trip coil and a normally closed trip contact connected in series in the negative circuit of the protection board. The protection board is configured such that during the charging process, if an overvoltage, overcurrent, or communication fault is detected, and after the protection board performs the action of cutting off the charging MOSFET, if the charging current is still greater than or equal to 0.02C, it is determined that the charging MOSFET has a sticking fault. The protection board outputs a power signal to the trip coil, causing the normally closed trip contact to open and cut off the negative terminal circuit of the battery.

[0008] Furthermore, the protection board is also used to control the charging and discharging equalization process of the battery pack, specifically including: During constant current charging, if the voltage difference between any two battery cells in the battery pack is greater than or equal to 50mV and the voltage of any battery cell is greater than or equal to 3.9V, then passive equalization is activated. In the passive balancing state, if the voltage of any single battery cell is detected to be less than 3.9V and the voltage difference between any two single battery cells is less than 20mV, then passive balancing is turned off and the system switches to charging-only mode. During the charging process, when the voltage of any single battery cell reaches 4.2V, the charging process switches to constant voltage charging until the charging current is less than 0.02C, at which point the charging process ends.

[0009] Furthermore, the charging pile is equipped with a cooling fan and a temperature sensor connected to the power distribution unit (PDU); When the temperature sensor detects that the ambient temperature is greater than 60°C, it controls the cooling fan to operate at a first speed; when the ambient temperature is detected to be greater than 70°C, it controls the cooling fan to operate at a higher second speed. The charging pile is equipped with louvers on both sides, and insect-proof nets are installed inside the louvers. The cooling fan is installed at a preset horizontal distance from the louvers.

[0010] Furthermore, it also includes a second controller and a first controller that are respectively communicatively connected to the power distribution unit (PDU), and a motor MCU disposed on the wheeled robot; When the wheeled robot needs to be charged while it is in operation, the second controller receives a remote charging command and sends it to the power distribution unit (PDU). The power distribution unit (PDU) controls the motor MCU through the first controller to make the wheeled robot return to the charging compartment. When the wheeled robot needs to be charged while it is not in operation, the system performs pre-charging in response to the triggering of the power distribution unit (PDU). If the pre-charging voltage reaches 95% of the battery voltage within 1 second, the pre-charging is determined to be successful and the charging process is allowed to proceed.

[0011] Secondly, the present invention also provides a contact charging control method for a wheeled-legged robot, applied to the contact charging control system described in the first aspect above, the method comprising the following steps: S1. Receive charging instructions and control the wheeled robot to identify the charging pile and move to the designated location of the charging pile; S2. Control the wheeled robot to perform a sitting action, and use the robot's own gravity to press down on the elastic buffer mechanism on the charging pile to physically trigger and close the limit switch. S3. In response to the closing of the limit switch, the power supply circuit of the power distribution unit (PDU) is used to conduct the coil of the relay, thereby causing the main contacts of the relay to close, thus connecting the charging circuit of the protection board and starting charging. S4. During the charging process, monitor the individual cell voltage, voltage difference and charging status of the battery pack in real time, and execute the passive balancing strategy and constant current-constant voltage charging state switching accordingly. S5. Safety monitoring is performed during charging. If an abnormal charging current caused by a failure of the protection action is detected, a physical trip is triggered to disconnect the negative circuit.

[0012] Furthermore, the execution of the passive balancing strategy and the constant current-constant voltage charging state switching in step S4 specifically includes: During constant current charging, if the voltage difference between any two battery cells is greater than or equal to 50mV and the voltage of any one battery cell is greater than or equal to 3.9V, then passive equalization is activated. During the passive balancing period, if the voltage of any single battery cell is less than 3.9V and the voltage difference between any two battery cells is less than 20mV, then the passive balancing is turned off. When the voltage of any single battery cell reaches 4.2V, the charging process switches to constant voltage charging until the charging current is less than 0.02C, at which point the charging ends.

[0013] Furthermore, the step S5 of triggering a physical trip to disconnect the negative circuit specifically includes: When an overvoltage, overcurrent, or communication failure occurs, the charging MOSFET is disconnected. If the charging current is still greater than or equal to 0.02C after the charging MOSFET is disconnected, it is determined that the charging MOSFET has a sticking fault. The power supply signal is output to the system's trip coil to disconnect the normally closed trip contact connected in series in the negative circuit.

[0014] Furthermore, prior to step S1, the method further includes: When the wheeled robot is not in working state, it performs system fault detection in response to the power-on trigger operation; After the fault is detected, a pre-charge power-on operation is performed. If the pre-charge voltage reaches 95% of the battery's nominal voltage within 1 second, the power-on is considered successful and the system waits to receive the charging command.

[0015] Compared with the prior art, the beneficial effects of this invention are as follows: 1. The robot's own gravity compresses the spring, physically triggering the limit switch. This, in turn, uses a 24V low-voltage power supply to activate the relay's main contacts, thereby connecting the 60V high-voltage charging circuit. This structure is simple, easy to implement, and inexpensive. Furthermore, it ensures that the high-voltage contacts are not energized when the robot is not fully docked, significantly improving safety.

[0016] 2. In the extreme case of failure of the secondary protection of the traditional protection board (i.e., the charging MOSFET fails to stick), a third-level physical cut-off protection based on the trip coil is creatively introduced, realizing the absolute controllability of the charging process.

[0017] 3. The design incorporates louvers and an inner insect screen to prevent insects from entering and affecting insulation; by offsetting the cooling fan horizontally inward by a preset distance (e.g., 100mm), the heat dissipation efficiency is significantly improved compared to traditional natural cooling methods, effectively preventing high temperatures from accumulating inside the cabin.

[0018] 4. It provides a refined strategy of "charging and balancing simultaneously", which dynamically switches between constant current, constant voltage and passive balancing states based on the voltage difference and voltage of individual battery cells, thereby extending the service life of the battery pack. Attached Figure Description

[0019] Figure 1 The electrical schematic diagram of the contact charging control system provided in the embodiment of the present invention.

[0020] Figure 2 This is a system architecture diagram provided for an embodiment of the present invention.

[0021] Figure 3 A logic flowchart of a charging system provided for an embodiment of the present invention.

[0022] Figure 4 This is a schematic diagram of a charging pile provided in an embodiment of the present invention.

[0023] Explanation of the attached diagram labels: 1 Charging pile, 2 Copper sheet, 3 Limit switch, 4 Spring, 5 Cooling fan. Detailed Implementation

[0024] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0025] To completely resolve the safety hazards caused by contact charging, heat dissipation, and MOS failure between robots and charging stations, this embodiment provides a contact charging control system for wheeled robots. For example... Figures 1 to 4 As shown, the system mainly consists of a charging pile 1 and related electrical modules mounted on the wheeled robot.

[0026] Specifically, the wheeled robot is equipped with a power distribution unit (PDU), a protection board, a battery pack, a second controller, a first controller, and a motor MCU. The PDU's nominal input power is single-phase 220V (input range 180VAC-240VAC), and it integrates low-voltage output power supplies such as 60VDC, 24VDC, 12VDC, and 5VDC. The PDU is physically connected to the protection board and the first controller via a CAN communication bus.

[0027] Specifically, the first controller and the second controller are the smart box and the 4G controller, respectively.

[0028] The charging pile 1 is equipped with positive and negative conductive components, an elastic buffer mechanism, a limit switch 3, and a relay KM. Correspondingly, positive and negative conductive components for the robot are located on the underside of the robot. In this embodiment, the elastic buffer mechanism includes an insulating plate, copper pillars, and springs 4. The positive and negative conductive components of the charging pile are copper sheets 2 fixed to the front of the insulating plate. The back of each copper sheet 2 is connected to the insulating plate by bolts. A copper pillar is located at each of the four corners of the back of the insulating plate, and a high-strength, high-elasticity spring 4 is fitted on each copper pillar. The other end of the spring 4 is rigidly connected to the intermediate layer plate inside the charging pile 1.

[0029] The limit switch 3 is equipped with a roller, and the coil of the limit switch 3 and the relay KM are connected in series in the 24V power supply circuit of the PDU; the main contacts of the relay KM are connected in series in the P+ high voltage charging circuit of the protection board.

[0030] When the robot returns to the vicinity of charging station 1, it recognizes the QR code on the charging station via its camera, adjusts its position, and walks towards charging station 1. Once it confirms it has reached the designated location, the robot begins to "sit" on charging station 1. At this time, the positive and negative conductive components on the robot's abdomen make flexible contact with the copper plate 2 on the charging station. Due to the robot's downward pressure, each spring 4 begins to compress downwards (e.g., by 5mm). After compression, the insulating plate touches the roller of the limit switch 3, causing the roller to displace downwards (e.g., by 5mm), thus closing the limit switch 3. After the limit switch 3 closes, 24V low-voltage power flows through the coil of relay KM, energizing and engaging the relay KM, simultaneously closing its main contacts connected in series in the P+ circuit of the protection board. The closure of the main contacts causes the P+ and P- circuits on the protection board to conduct, and the 60VDC on the PDU charges the battery pack through the protection board, officially putting the system into charging mode. This structure ensures that the external copper plate 2 is in a safe, power-off state when not under downward pressure.

[0031] The protection board contains a charging MOSFET for controlling the on / off state of the charging circuit and integrates a charging logic control module. In the initial charging stage, the system performs constant current charging until the voltage of any single battery cell in the battery pack reaches 4.2V. During charging, the system monitors the voltage in real time. If the voltage difference between any two battery cells is ≥50mV and the voltage of any single battery cell is ≥3.9V, the system activates passive balancing with a balancing current of approximately 100mA; at this point, the system is in a "charging and balancing simultaneously" state. During this process, if the voltage of any single battery cell is <3.9V and the voltage difference between any two battery cells is <20mV, passive balancing is deactivated, and the system switches to charging-only mode. If all battery cell voltages are <4.2V, constant current charging continues until any single cell reaches 4.2V, at which point constant voltage charging switches to constant voltage charging. The constant voltage charging current is approximately 0.02C; constant voltage charging ends when the charging current is <0.02C.

[0032] Conventional protection boards only have a first-level alarm and a second-level protection (cutting off the charging MOSFET). However, if the charging MOSFET physically sticks together and breaks down, the second-level protection will fail. Therefore, this embodiment adds a trip protection circuit consisting of a trip coil QF and a normally closed trip contact QF connected in series in the negative circuit of the protection board. During charging, if overvoltage, overcurrent, or communication failure occurs, the protection board first executes the conventional second-level protection action (attempting to cut off the charging MOSFET). After the action is issued, if the protection board detects that the charging current is still ≥0.02C, it determines that the charging MOSFET has sticked together. At this time, the protection board actively outputs a power signal to the trip coil QF, energizing the trip coil QF, thereby forcibly opening the normally closed trip contact QF, completely cutting off the negative circuit of the battery, achieving the third-level protection, and ensuring the safety of the battery pack.

[0033] The charging pile 1 is equipped with a temperature sensor probe and a cooling fan 5. The two side shells of the charging pile 1 are designed as louvers, with insect screens affixed to the inside of the louvers to prevent foreign objects from entering and affecting insulation and heat dissipation. To achieve optimal hydrodynamic heat dissipation, each cooling fan 5 is installed at a preset horizontal distance (e.g., 100mm) from the louvers, significantly improving heat dissipation efficiency compared to traditional natural cooling. When the temperature sensor probe detects that the ambient temperature inside the chamber exceeds a first temperature threshold (e.g., 60℃), the PDU controls the cooling fan 5 to start at a first speed (e.g., 6000rpm); when the ambient temperature exceeds a second temperature threshold (e.g., 70℃), the cooling fan 5 switches to a second speed (e.g., 8000rpm) for powerful exhaust.

[0034] The system is designed with corresponding wake-up and scheduling logic for different robot states: (1) In working state: When charging is required, the second controller can issue a charging buzzer reminder on mobile devices such as WeChat mini-program; at the same time, the robot PDU’s built-in buzzer can also emit an alarm sound (stopping after 10 seconds, which can be manually turned off). The user clicks “One-click charging” through the mobile mini-program, and the second controller sends a remote charging command to the PDU through CAN communication. The PDU forwards the command to the first controller, and the first controller then sends a control command to the motor MCU, so that the robot automatically switches to the return charging route, identifies the charging pile 1, and moves to the charging pile 1.

[0035] (2) In non-working state (sleep): Wake up the system by pressing the PDU switch on the robot. The software first checks for faults, and if no faults are found, it begins pre-charging. Within the 1-second pre-charging time window, if the pre-charging voltage reaches 95% of the battery's nominal total voltage, the pre-charging is considered successful and the robot is successfully powered on. Then, it can receive charging instructions from the second controller to execute the above-mentioned return-to-basket charging action.

[0036] Based on the above system structure, this embodiment also provides a contact charging control method, the overall process of which is as follows: Figure 3 As shown, the specific steps correspond to the working principle of the system described above, and will not be repeated here.

[0037] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A contact-type charging control system for a wheeled-legged robot, characterized in that, Includes a charging pile (1) and a power distribution unit (PDU), a protection board, and a battery pack installed on the wheeled robot; The charging pile (1) is provided with positive and negative conductive components, an elastic buffer mechanism, a limit switch (3) and a relay. The bottom of the wheeled robot is provided with positive and negative conductive components connected to the battery pack. The coils of the limit switch (3) and the relay are connected in series in the power supply circuit of the power distribution unit (PDU); the main contacts of the relay are connected in series in the charging circuit of the protection board. When the wheeled robot moves to the charging pile (1) and sits on the charging pile (1), the positive and negative conductive parts of the robot contact the positive and negative conductive parts of the charging pile and press down on the elastic buffer mechanism to cause it to move, touch and close the limit switch (3), so that the coil of the relay is energized, thereby driving the main contacts of the relay to close, conducting the charging circuit of the protection board, so that the power distribution unit (PDU) charges the battery pack through the protection board.

2. The contact charging control system according to claim 1, characterized in that, The limit switch (3) is provided with a roller, and the elastic buffer mechanism includes an insulating plate, a copper column and a spring (4). The positive and negative conductive components of the charging pile are copper sheets (2) fixed on the front side of the insulating plate; the back side of the insulating plate is provided with a plurality of copper pillars, and each copper pillar is fitted with a spring (4), the other end of the spring (4) is connected to the layer plate inside the charging pile (1); When the wheeled robot sits down and applies downward pressure, the spring (4) is compressed downward to a set stroke, and the insulating plate touches the roller of the limit switch (3), causing the roller to be compressed and displaced, thereby closing the limit switch (3).

3. The contact charging control system according to claim 1, characterized in that, The protection board is equipped with a charging MOS transistor for controlling the on / off state of the charging circuit. The control system also includes a trip protection circuit, which includes a trip coil and a normally closed trip contact connected in series in the negative circuit of the protection board. The protection board is configured such that during the charging process, if an overvoltage, overcurrent, or communication fault is detected, and after the protection board performs the action of cutting off the charging MOSFET, if the charging current is still greater than or equal to 0.02C, it is determined that the charging MOSFET has a sticking fault. The protection board outputs a power signal to the trip coil, causing the normally closed trip contact to open and cut off the negative terminal circuit of the battery.

4. The contact charging control system according to claim 1, characterized in that, The protection board is also used to control the charging and discharging equalization process of the battery pack, specifically including: During constant current charging, if the voltage difference between any two battery cells in the battery pack is greater than or equal to 50mV and the voltage of any battery cell is greater than or equal to 3.9V, then passive equalization is activated. In the passive balancing state, if the voltage of any single battery cell is detected to be less than 3.9V and the voltage difference between any two single battery cells is less than 20mV, then passive balancing is turned off and the system switches to charging-only mode. During the charging process, when the voltage of any single battery cell reaches 4.2V, the charging process switches to constant voltage charging until the charging current is less than 0.02C, at which point the charging process ends.

5. The contact charging control system according to claim 1, characterized in that, The charging pile (1) is equipped with a cooling fan (5) and a temperature sensor connected to the power distribution unit (PDU); When the temperature sensor detects that the ambient temperature is greater than 60°C, it controls the cooling fan (5) to operate at a first speed; when the ambient temperature is detected to be greater than 70°C, it controls the cooling fan (5) to operate at a higher second speed. The charging pile (1) is provided with louvers on both sides, and insect-proof nets are provided on the inner side of the louvers. The cooling fan (5) is installed at a preset horizontal distance from the louvers.

6. The contact charging control system according to claim 1, characterized in that, It also includes a second controller and a first controller that are respectively connected to the power distribution unit (PDU) in communication, and a motor MCU located on the wheeled robot; When the wheeled robot needs to be charged while it is in operation, the second controller receives a remote charging command and sends it to the power distribution unit (PDU). The power distribution unit (PDU) controls the motor MCU through the first controller to make the wheeled robot return to the charging compartment. When the wheeled robot needs to be charged while it is not in operation, the system performs pre-charging in response to the triggering of the power distribution unit (PDU). If the pre-charging voltage reaches 95% of the battery voltage within 1 second, the pre-charging is determined to be successful and the charging process is allowed to proceed.

7. A contact charging control method for a wheeled-legged robot, applied to the contact charging control system as described in any one of claims 1-6, characterized in that, The method includes the following steps: S1. Receive charging instructions and control the wheeled robot to identify the charging pile (1) and move to the designated position of the charging pile (1); S2. Control the wheeled robot to perform a sitting action, and use the robot's own gravity to press down on the elastic buffer mechanism on the charging pile (1) to physically trigger and close the limit switch (3). S3. In response to the closing of the limit switch (3), the power supply circuit of the power distribution unit PDU is used to conduct the coil of the relay, thereby driving the main contacts of the relay to close, thus connecting the charging circuit of the protection board and starting charging. S4. During the charging process, monitor the individual cell voltage, voltage difference and charging status of the battery pack in real time, and execute the passive balancing strategy and constant current-constant voltage charging state switching accordingly. S5. Safety monitoring is performed during charging. If an abnormal charging current caused by a failure of the protection action is detected, a physical trip is triggered to disconnect the negative circuit.

8. The contact charging control method according to claim 7, characterized in that, Step S4, which involves executing the passive balancing strategy and switching between constant current and constant voltage charging states, specifically includes: During constant current charging, if the voltage difference between any two battery cells is greater than or equal to 50mV and the voltage of any one battery cell is greater than or equal to 3.9V, then passive equalization is activated. During the passive balancing period, if the voltage of any single battery cell is less than 3.9V and the voltage difference between any two battery cells is less than 20mV, then the passive balancing is turned off. When the voltage of any single battery cell reaches 4.2V, the charging process switches to constant voltage charging until the charging current is less than 0.02C, at which point the charging ends.

9. The contact charging control method according to claim 7, characterized in that, The step S5, which involves triggering a physical trip to disconnect the negative circuit, specifically includes: When an overvoltage, overcurrent, or communication failure occurs, the charging MOSFET is disconnected. If the charging current is still greater than or equal to 0.02C after the charging MOSFET is disconnected, it is determined that the charging MOSFET has a sticking fault. The power supply signal is output to the system's trip coil to disconnect the normally closed trip contact connected in series in the negative circuit.

10. The contact charging control method according to claim 7, characterized in that, Prior to step S1, the method further includes: When the wheeled robot is not in working state, it performs system fault detection in response to the power-on trigger operation; After the fault is detected, a pre-charge power-on operation is performed. If the pre-charge voltage reaches 95% of the battery's nominal voltage within 1 second, the power-on is considered successful and the system waits to receive the charging command.

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