A step mover system based on a towable recreational vehicle

Abstract

This invention discloses a mobility device system based on a towable caravan, comprising an on-board execution unit, a remote control unit, and a power supply protection unit. The on-board execution unit includes a main controller, dual motor units, a motor drive module, a current detection module, a voltage detection module, a wireless communication module, an audible and visual alarm module, and a crystal oscillator module. This invention utilizes multi-directional drive from dual motor units and short-range wireless remote control to eliminate blind spots and achieve centimeter-level precise positioning, meeting the needs of parking in confined spaces. It eliminates the need for repeated towing operations, allowing a single person to quickly complete positioning adjustments, significantly improving parking efficiency. Through stable power output, full-link status monitoring, and multiple safety protection mechanisms, it reduces operational difficulty and the risk of misjudgment, minimizing safety accidents such as scratches and equipment damage. It also significantly reduces the demands on the driver's skill level and patience, comprehensively improving the convenience, accuracy, and safety of parking and positioning for towable caravans.

Description

Technical Field

[0001] This invention relates to the field of towable caravan technology, and more particularly to a mobility device system based on a towable caravan. Background Technology

[0002] As a mode of transportation that combines travel and living functions, towed caravans are widely used in the tourism sector. However, accurate positioning of towed caravans when stationary has always been a technical challenge in the industry. Currently, when a towed caravan is separated from its towing vehicle, if it is necessary to make minor adjustments to its position, park in a designated campsite parking space, or connect to campsite facilities, the driver can only reconnect the towing vehicle and adjust the caravan's position by repeatedly moving forward and backward.

[0003] The traditional operating methods in the existing technology have many drawbacks: 1. The RV is large and has a limited field of vision, making it difficult for the driver to accurately judge the vehicle's position, resulting in extremely low positioning accuracy and making it difficult to meet the parking needs of narrow spaces (such as family garages and crowded campsites); 2. Repeated towing operations are time-consuming and labor-intensive, seriously affecting parking efficiency; 3. During operation, it is very easy to cause safety accidents such as vehicle scratches and equipment damage due to misjudgment, which requires a high level of skill and patience from the driver. In view of the above, this application proposes a mobility device system based on a towable RV. Summary of the Invention

[0004] Based on the technical problems existing in the background art, the present invention proposes a mobility device system based on a towed caravan.

[0005] The present invention proposes a mobility device system based on a towed caravan, comprising an on-board execution unit, a remote control unit, and a power supply protection unit;

[0006] The vehicle-mounted execution unit includes a main controller, dual motor sets, a motor drive module, a current detection module, a voltage detection module, a wireless communication module, an audible and visual alarm module, and a crystal oscillator module.

[0007] The remote control unit includes a remote control main control chip, a second wireless communication module, and an operation button group;

[0008] The power supply protection unit includes a reverse connection protection circuit, an overvoltage protection circuit, and a multi-stage power conversion circuit.

[0009] The remote control unit sends movement commands to the vehicle-mounted execution unit's wireless communication module 1 via the wireless communication module 2. The main controller controls the dual motor units to move in multiple directions via the motor drive module according to the commands. The voltage detection module monitors the power supply voltage in real time, and the current detection module collects the operating current of the dual motor units in real time. When the voltage or current exceeds the preset range, the main controller controls the audible and visual alarm module to start the alarm, and at the same time, the overvoltage protection circuit and the reverse connection protection circuit trigger the corresponding protection actions.

[0010] Preferably, the main controller is responsible for receiving the command signal from the remote control unit, parsing it, and outputting the control signal to the motor drive module. At the same time, it receives the feedback signals from the voltage detection module and the current detection module to control the start and stop of the audible and visual alarm module.

[0011] The dual-motor unit includes a small motor and a large motor. The small motor is used to drive the large motor to contact the tires of the trailer caravan, while the large motor serves as the main power source to drive the tires to rotate forward and backward and to move differentially.

[0012] Preferably, the motor drive module includes a large motor drive circuit and a small motor drive circuit. The large motor drive circuit is controlled by a JQX-V5012-1ZP relay, and the small motor drive circuit is controlled by an SRA-12VDC-CL relay. Both relays are connected in parallel with a freewheeling diode D2. When the motor stops rotating, the induced electromotive force generated is released through the freewheeling diode D2. The main controller controls the large motor and the small motor by outputting high and low levels through the IO port, which, after passing through the ULN2003A isolation chip, controls the opening and closing of the relays.

[0013] The current detection module includes a small motor current sampling circuit and a large motor current sampling circuit. The small motor current sampling circuit consists of two 10mΩ resistors in parallel and an operational amplifier. When the small motor is stalled, the current is approximately 15A. The sampled voltage is amplified and input to the main controller. The large motor current sampling circuit consists of three 5mΩ constantan wire resistors in parallel and an operational amplifier. When the large motor is stalled, the current is approximately 80A. The sampled voltage is amplified and input to the main controller. A diode clamping circuit is provided between the operational amplifier circuit and the main controller.

[0014] The voltage detection module is used to monitor the input voltage of the power supply protection unit in real time and feed the voltage signal back to the main controller. When the voltage exceeds the normal range, an audible and visual alarm is triggered.

[0015] The sound and light alarm module includes a buzzer circuit and an indicator light circuit. When the voltage is abnormal, the current exceeds the limit, or the system fails, the buzzer sounds an alarm and the indicator light turns red to remind the user to troubleshoot the problem in a timely manner.

[0016] The logical steps for the coordinated operation of the motor drive module, current detection module, voltage detection module, and audible and visual alarm module are as follows:

[0017] S101: The main controller is equipped with 4 motor control IO ports, including IO1 for large motor forward rotation, IO2 for large motor reverse rotation, IO3 for small motor contact, and IO4 for small motor separation. All of them are in output mode and are initially set to high level H.

[0018] S102: The main controller receives remote control commands through the wireless communication module, parses the commands, determines the motor action type, and maps it to the IO port output logic:

[0019] Instruction Type I01 (Large Forward) I02 (Large Reverse) I03 (Small Engage) I04 (Small Disengage) Small Motor Engage H H L H Small Motor Disengage H H H L Large Motor Forward L H H H Large Motor Reverse H L H H Trailer Left (Differential) PWM (50%) H L H Trailer Right (Differential) H PWM (50%) L H Stop Moving H H H H ;

[0021] S103: The main controller pre-verifies drive safety using a coil current formula to ensure that the current does not exceed the maximum output current of the ULN2003A isolation chip. The formula used is: ,in For the on-state voltage drop of the ULN2003A isolation chip, The power supply voltage, If the calculated current value is abnormal (>500mA), the relay coil resistance is used. If the calculated current value is abnormal (>500mA), the process will jump to step S111 and trigger an audible and visual alarm.

[0022] S104: When the IO port outputs a low level L, the corresponding output terminal of the ULN2003A isolation chip is turned on, a voltage difference is formed across the relay coil, and the coil is energized. When the IO port outputs a PWM signal, the ULN2003A isolation chip is turned on / off according to the PWM frequency, and the coil receives pulsating current.

[0023] S105: If the instruction includes "small motor engages", the SRA-12VDC-CL relay coil is energized, the contacts close, the 12V power supply is connected to the small motor, the small motor rotates forward, driving the large motor to engage with the RV tire; if the instruction includes "small motor disengages", the SRA-12VDC-CL relay coil is de-energized, the disengagement control circuit is activated, the small motor reverses, the large motor disengages from the tire, the main controller delays for 1 second, and then executes the subsequent large motor action.

[0024] S106: If the command is "large motor forward rotation", the JQX-V5012-1ZP relay coil is energized, the contacts close, the 12V power supply is connected to the forward rotation winding of the large motor, the large motor rotates at full speed, and the RV moves forward. If the command is "large motor reverse rotation", the reverse control relay coil is energized, the contacts close, the power supply is connected to the reverse rotation winding of the large motor, the large motor reverses, and the RV moves backward.

[0025] S107: If the instruction is "turn left", then perform the following steps:

[0026] S1071: Calculate PWM duty cycle and set differential coefficient. Then the duty cycle of the left motor Right motor duty cycle The duty cycle formula is: ;

[0027] S1072: Calculate the average supply voltage of the motor using the following formula: ;

[0028] S1073: Calculate the actual speed of the motor using the following formula: ;

[0029] S1074: The main controller outputs a corresponding PWM signal, and the ULN2003A isolation chip drives the relay. The left and right large motors rotate at different speeds to realize the RV turning left. The logic for turning right is the same as that for turning left, except that the duty cycle of the right motor is set to 50% and that of the left motor is set to 100%.

[0030] S108: The current detection module collects the current of the large / small motor in real time. The main controller calculates the actual current according to the current conversion formula. The formula is: to determine whether there is a stall. At the same time, the voltage detection module collects the supply voltage in real time. The main controller calculates the actual voltage according to the voltage conversion formula and determines whether there is undervoltage or overvoltage. If an abnormality is detected, jump to step S111; if normal, maintain the current motor operation.

[0031] The formula for calculating the actual voltage is: ,in This refers to the actual voltage of the vehicle's 12V battery. The ADC samples the digital value for the voltage detection module. This is the ADC reference voltage. For the quantization level of a 12-bit ADC, For the voltage detection module, use voltage divider resistors. This is the voltage divider resistor for the voltage detection module;

[0032] Formula for calculating the current of a small motor: ,in This represents the actual operating current of the small motor. This refers to the digital input sampled by the ADC of the small motor current detection module. This is the operational amplification factor for small motor current detection. This represents the total resistance of the shunt resistor in the small motor.

[0033] Formula for calculating the current of a large motor: ,in This represents the actual operating current of the large motor. This refers to the digital input sampled by the ADC of the large motor current detection module. This is the operational amplification factor for current detection of large motors. This represents the total resistance of the shunt resistor in the large motor.

[0034] S109: When the main controller receives the "stop moving" command, it sets all IO1~IO4 to high level H, the ULN2003A isolation chip output is cut off, the relay coil is de-energized, the electromagnet is released, the contacts are opened, and the motor power supply circuit is cut off.

[0035] S110: When the motor stops, the coil generates a reverse induced electromotive force, with a peak value of approximately When the freewheeling diode D2 is forward-biased, the induced electromotive force forms a freewheeling circuit through the coil → freewheeling diode D2 → coil, slowly releasing energy.

[0036] S111: The main controller immediately sets all IO1~IO4 to high level, cuts off all motor drives, and triggers the sound and light alarm module. The buzzer sounds, the red light stays on for 2 seconds, and an abnormal feedback signal is sent to the remote control unit to prompt the user to troubleshoot the fault.

[0037] S112: The motor stops completely, the freewheeling process ends, the freewheeling diode is cut off, the relay remains open, the main controller clears the instruction buffer, the IO port remains high, and the module returns to the standby state after initialization, waiting for the next instruction input.

[0038] Preferably, the wireless communication module consists of a WL500B wireless transceiver chip and a spring antenna, and is responsible for receiving command signals sent by the remote control unit. The communication distance can reach 30 meters, ensuring that the user can perform remote control operations within a safe range.

[0039] The wireless communication module 2 uses a VG4455 wireless transceiver chip, the remote control unit is powered by two AA batteries, and the remote control main control chip is STC8H1K08-36I-TSSOP20.

[0040] The crystal oscillator module consists of an external passive crystal oscillator X49SD8MSD2SC and an external starting capacitor, which provides a stable clock signal to the main controller and ensures the stable operation of the main controller.

[0041] Preferably, the operation button group includes a wake-up button, a pairing button, a forward button, a backward button, a left turn button, a right turn button, and a move away from the tire button; the remote control unit needs to be paired with the vehicle-mounted actuator unit first through the pairing button, and automatically enters a sleep state after 30 seconds of inactivity, and is activated by the wake-up button.

[0042] Preferably, the input power of the power supply protection unit is a vehicle-mounted 12V battery. The multi-stage power conversion circuit includes a 12V to 5V circuit and a 5V to 3.3V circuit. The 12V to 5V circuit uses an XL1509-5.0 chip U1, and the 5V to 3.3V circuit uses an AMS1117-3.3 chip U2. Pin 5 of both chip U1 and chip U2 is electrically connected to the main power supply of the system. A capacitor C1 is connected in parallel to pin 1 of chip U1. Pins 1 and 2 of chip U1 are electrically connected to the vehicle-mounted 12V battery. A capacitor C2 is connected in parallel to pin 3 of chip U1. Pins 3 of both chip U1 and chip U2 output 5V voltage. Pins 4 of both chip U1 and chip U2 are grounded. A capacitor C3 and a capacitor C4 are connected in parallel to pins 1 and 3 of chip U2, respectively. Pin 1 of chip U2 is also connected to a 5V voltage.

[0043] Preferably, the reverse connection protection circuit is used to automatically disconnect the circuit and stop the system from working when the positive and negative terminals of the vehicle 12V battery are reversed, so as to prevent the components from being burned out due to reverse power connection; the reverse connection protection circuit includes a MOSFET Q1, the gate of the MOSFET Q1 is electrically connected to one end of a resistor R1, the other end of the resistor R1 is electrically connected to the positive terminal of the vehicle 12V battery, the source of the MOSFET Q1 is grounded and electrically connected to the negative terminal of the vehicle 12V battery.

[0044] Preferably, the maximum protection voltage of the overvoltage protection circuit does not exceed 58V. When the input voltage is higher than the normal operating voltage, the circuit automatically triggers protection to prevent damage to the vehicle actuator due to overvoltage. When the input voltage is lower than a preset threshold, the system stops working and triggers an audible and visual alarm. The overvoltage protection circuit includes a resettable fuse F1 and a diode D1. One end of the resettable fuse F1 and the positive terminal of the diode D1 are electrically connected to the positive terminal of the vehicle 12V battery. The other end of the resettable fuse F1 is electrically connected to the main power supply of the system, and the negative terminal of the diode D1 is grounded.

[0045] Compared with existing technologies, the beneficial effects of this invention are:

[0046] 1. Driven by dual motor units, the RV can move forward and backward, move left and right, and turn precisely. Combined with the remote control unit's 30-meter visual operation, it eliminates blind spots for the driver. With the help of real-time feedback and precise control logic from the current / voltage detection module, the positioning accuracy reaches the centimeter level, perfectly adapting to the parking needs of narrow spaces such as family garages and crowded campsites, and completely solving the pain point of insufficient positioning accuracy in traditional systems.

[0047] 2. During movement, there is no need to rely on a towing vehicle. A single person can issue movement commands through the remote control unit, and the on-board execution unit responds quickly, eliminating the repetitive operation process of "connecting to the towing vehicle → adjusting → disconnecting". The dual motor units provide independent power, and with the efficient execution of the motor drive module, the positioning and adjustment time is greatly shortened, the docking efficiency is significantly improved, and the waste of manpower and time in traditional operations is avoided.

[0048] 3. The remote control unit allows for real-time observation of the vehicle's position, reducing the probability of misjudgment; the dual-motor unit provides smooth power output, and the differential control logic prevents skidding caused by excessive steering; the voltage / current detection module is linked with the audible and visual alarm module, immediately cutting off motor drive and triggering an alarm in case of abnormality; overvoltage and reverse connection protection circuits prevent equipment damage caused by system failures; the overall operation requires no professional driving skills, significantly reducing the demands on the driver's skill level and patience, and effectively reducing safety accidents such as scratches and equipment damage.

[0049] This invention utilizes dual-motor multi-directional drive and short-range wireless remote control to eliminate blind spots and achieve centimeter-level precise positioning, meeting the needs of parking in narrow spaces. It eliminates the need for repeated towing operations, allowing a single person to quickly complete positioning adjustments, significantly improving parking efficiency. Through stable power output, end-to-end status monitoring, and multiple safety protection mechanisms, it reduces operational difficulty and the risk of misjudgment, minimizing safety accidents such as scratches and equipment damage. It also significantly reduces the demands on the driver's skill level and patience, comprehensively improving the convenience, accuracy, and safety of parking and positioning for towed caravans. Attached Figure Description

[0050] Figure 1 This is a block diagram of a mobility device system based on a towed caravan proposed in this invention;

[0051] Figure 2 This is a circuit diagram of a reverse connection protection circuit in a mobility system based on a towed caravan proposed in this invention.

[0052] Figure 3 This is a circuit diagram of an overvoltage protection circuit in a mobility aid system based on a towed caravan, as proposed in this invention.

[0053] Figure 4 This is a circuit diagram of a multi-stage power conversion circuit in a mobility system based on a towed caravan, as proposed in this invention. Detailed Implementation

[0054] The present invention will be further explained below with reference to specific embodiments.

[0055] Example

[0056] Reference Figures 1-4This embodiment proposes a mobility device system based on a towed caravan, including an on-board execution unit, a remote control unit, and a power supply protection unit;

[0057] The vehicle-mounted actuator includes a main controller, dual motor units, a motor drive module, a current detection module, a voltage detection module, a wireless communication module, an audible and visual alarm module, and a crystal oscillator module.

[0058] The main controller is responsible for receiving command signals from the remote control unit, parsing them, and outputting control signals to the motor drive module. It also receives feedback signals from the voltage detection module and the current detection module to control the start and stop of the audible and visual alarm module.

[0059] The dual-motor unit includes a small motor and a large motor. The small motor is used to drive the large motor to contact the tires of the trailer caravan, while the large motor serves as the main power source to drive the tires to rotate forward and backward and to move differentially.

[0060] The wireless communication module consists of a WL500B wireless transceiver chip and a spring antenna. It is responsible for receiving command signals sent by the remote control unit. The communication distance can reach 30 meters, ensuring that users can perform remote control operations within a safe range.

[0061] The crystal oscillator module consists of an external passive crystal oscillator X49SD8MSD2SC and an external starting capacitor, which provides a stable clock signal to the main controller and ensures the stable operation of the main controller.

[0062] The remote control unit includes a remote control main control chip, a wireless communication module 2, and an operation button group;

[0063] The wireless communication module 2 uses the VG4455 wireless transceiver chip, the remote control unit is powered by two AA batteries, and the remote control main control chip is STC8H1K08-36I-TSSOP20.

[0064] The operation button group includes a wake-up button, a pairing button, a forward button, a reverse button, a left turn button, a right turn button, and a move away from the tires button; the remote control unit must first be paired with the vehicle actuator unit via the pairing button, and automatically enters sleep mode after 30 seconds of inactivity, and is activated by the wake-up button;

[0065] The power supply protection unit includes a reverse connection protection circuit, an overvoltage protection circuit, and a multi-stage power conversion circuit;

[0066] The power supply protection unit's input power is the vehicle's 12V battery. The multi-stage power conversion circuit includes a 12V to 5V circuit and a 5V to 3.3V circuit. The 12V to 5V circuit uses XL1509-5.0 chip U1, and the 5V to 3.3V circuit uses AMS1117-3.3 chip U2. Pin 5 of both chip U1 and chip U2 is electrically connected to the system's main power supply. A capacitor C1 is connected in parallel to pin 1 of chip U1. Pins 1 and 2 of chip U1 are electrically connected to the vehicle's 12V battery. A capacitor C2 is connected in parallel to pin 3 of chip U1. Pins 3 of both chip U1 and chip U2 output 5V voltage. Pins 4 of both chip U1 and chip U2 are grounded. Capacitors C3 and C4 are connected in parallel to pins 1 and 3 of chip U2, respectively. Pin 1 of chip U2 is also connected to a 5V voltage.

[0067] The reverse connection protection circuit is used to automatically disconnect the circuit and stop the system from working when the positive and negative terminals of the vehicle 12V battery are reversed, preventing the components from being burned out due to the reverse power connection. The reverse connection protection circuit includes a MOSFET Q1, with one end of a resistor R1 electrically connected to the gate of the MOSFET Q1, and the other end of the resistor R1 electrically connected to the positive terminal of the vehicle 12V battery. The source of the MOSFET Q1 is grounded and electrically connected to the negative terminal of the vehicle 12V battery.

[0068] The maximum protection voltage of the overvoltage protection circuit does not exceed 58V. When the input voltage is higher than the normal operating voltage, the circuit will automatically trigger protection to prevent the vehicle actuator from being damaged due to overvoltage. When the input voltage is lower than the preset threshold, the system will stop working and trigger an audible and visual alarm. The overvoltage protection circuit includes a resettable fuse F1 and a diode D1. One end of the resettable fuse F1 and the positive terminal of the diode D1 are electrically connected to the positive terminal of the vehicle 12V battery. The other end of the resettable fuse F1 is electrically connected to the main power supply of the system, and the negative terminal of the diode D1 is grounded.

[0069] The remote control unit sends movement commands to the vehicle-mounted execution unit's wireless communication module 1 via the wireless communication module 2. The main controller controls the dual motor units to move in multiple directions according to the commands through the motor drive module. The voltage detection module monitors the power supply voltage in real time, and the current detection module collects the operating current of the dual motor units in real time. When the voltage or current exceeds the preset range, the main controller controls the audible and visual alarm module to start the alarm. At the same time, the overvoltage protection circuit and the reverse connection protection circuit trigger the corresponding protection actions.

[0070] The motor drive module includes a large motor drive circuit and a small motor drive circuit. The large motor drive circuit is controlled by a JQX-V5012-1ZP relay, and the small motor drive circuit is controlled by an SRA-12VDC-CL relay. Both relays are connected in parallel with a freewheeling diode D2. When the motor stops rotating, the induced electromotive force generated is released through the freewheeling diode D2. The main controller controls the large and small motors by outputting high and low levels through the ULN2003A isolation chip and controlling the relays to turn on and off.

[0071] The current detection module includes a small motor current sampling circuit and a large motor current sampling circuit. The small motor current sampling circuit consists of two 10mΩ resistors in parallel and an operational amplifier. When the small motor is stalled, the current is approximately 15A. The sampled voltage is amplified and then input to the main controller. The large motor current sampling circuit consists of three 5mΩ constantan wire resistors in parallel and an operational amplifier. When the large motor is stalled, the current is approximately 80A. The sampled voltage is amplified and then input to the main controller. A diode clamping circuit is provided between the operational amplifier circuit and the main controller.

[0072] The voltage detection module is used to monitor the input voltage of the power supply protection unit in real time and feed the voltage signal back to the main controller. When the voltage exceeds the normal range, an audible and visual alarm is triggered.

[0073] The audible and visual alarm module includes a buzzer circuit and an indicator light circuit. When there is an abnormal voltage, excessive current, or system failure, the buzzer will sound an alarm and the indicator light will turn red to alert the user to troubleshoot the problem.

[0074] The logical steps for the coordinated operation of the motor drive module, current detection module, voltage detection module, and audible and visual alarm module are as follows:

[0075] S101: The main controller is equipped with 4 motor control IO ports, including IO1 for large motor forward rotation, IO2 for large motor reverse rotation, IO3 for small motor contact, and IO4 for small motor separation. All of them are in output mode and are initially set to high level H.

[0076] S102: The main controller receives remote control commands through the wireless communication module, parses the commands, determines the motor action type, and maps it to the IO port output logic:

[0077] Instruction Type I01 (Large Forward) I02 (Large Reverse) I03 (Small Engage) I04 (Small Disengage) Small Motor Engage H H L H Small Motor Disengage H H H L Large Motor Forward L H H H Large Motor Reverse H L H H Trailer Left (Differential) PWM (50%) H L H Trailer Right (Differential) H PWM (50%) L H Stop Moving H H H H ;

[0079] S103: The main controller pre-verifies drive safety using a coil current formula to ensure that the current does not exceed the maximum output current of the ULN2003A isolation chip. The formula used is: ,in For the on-state voltage drop of the ULN2003A isolation chip, The power supply voltage, If the calculated current value is abnormal (>500mA), the relay coil resistance is used. If the calculated current value is abnormal (>500mA), the process will jump to step S111 and trigger an audible and visual alarm.

[0080] S104: When the IO port outputs a low level L, the corresponding output terminal of the ULN2003A isolation chip is turned on, a voltage difference is formed across the relay coil, and the coil is energized. When the IO port outputs a PWM signal, the ULN2003A isolation chip is turned on / off according to the PWM frequency, and the coil receives pulsating current.

[0081] S105: If the instruction includes "small motor engages", the SRA-12VDC-CL relay coil is energized, the contacts close, the 12V power supply is connected to the small motor, the small motor rotates forward, driving the large motor to engage with the RV tire; if the instruction includes "small motor disengages", the SRA-12VDC-CL relay coil is de-energized, the disengagement control circuit is activated, the small motor reverses, the large motor disengages from the tire, the main controller delays for 1 second, and then executes the subsequent large motor action.

[0082] S106: If the command is "large motor forward rotation", the JQX-V5012-1ZP relay coil is energized, the contacts close, the 12V power supply is connected to the forward rotation winding of the large motor, the large motor rotates at full speed, and the RV moves forward. If the command is "large motor reverse rotation", the reverse control relay coil is energized, the contacts close, the power supply is connected to the reverse rotation winding of the large motor, the large motor reverses, and the RV moves backward.

[0083] S107: If the instruction is "turn left", then perform the following steps:

[0084] S1071: Calculate PWM duty cycle and set differential coefficient. Then the duty cycle of the left motor Right motor duty cycle The duty cycle formula is: ;

[0085] S1072: Calculate the average supply voltage of the motor using the following formula: ;

[0086] S1073: Calculate the actual speed of the motor using the following formula: ;

[0087] S1074: The main controller outputs a corresponding PWM signal, and the ULN2003A isolation chip drives the relay. The left and right large motors rotate at different speeds to realize the RV turning left. The logic for turning right is the same as that for turning left, except that the duty cycle of the right motor is set to 50% and that of the left motor is set to 100%.

[0088] S108: The current detection module collects the current of the large / small motor in real time. The main controller calculates the actual current according to the current conversion formula. The formula is: to determine whether there is a stall. At the same time, the voltage detection module collects the supply voltage in real time. The main controller calculates the actual voltage according to the voltage conversion formula and determines whether there is undervoltage or overvoltage. If an abnormality is detected, jump to step S111; if normal, maintain the current motor operation.

[0089] The formula for calculating the actual voltage is: ,in This refers to the actual voltage of the vehicle's 12V battery. The ADC samples the digital value for the voltage detection module. This is the ADC reference voltage. For the quantization level of a 12-bit ADC, For the voltage detection module, use voltage divider resistors. This is the voltage divider resistor for the voltage detection module;

[0090] Formula for calculating the current of a small motor: ,in This represents the actual operating current of the small motor. This refers to the digital input sampled by the ADC of the small motor current detection module. This is the operational amplification factor for small motor current detection. This represents the total resistance of the shunt resistor in the small motor.

[0091] Formula for calculating the current of a large motor: ,in This represents the actual operating current of the large motor. This refers to the digital input sampled by the ADC of the large motor current detection module. This is the operational amplification factor for current detection of large motors. This represents the total resistance of the shunt resistor in the large motor.

[0092] S109: When the main controller receives the "stop moving" command, it sets all IO1~IO4 to high level H, the ULN2003A isolation chip output is cut off, the relay coil is de-energized, the electromagnet is released, the contacts are opened, and the motor power supply circuit is cut off.

[0093] S110: When the motor stops, the coil generates a reverse induced electromotive force, with a peak value of approximately When the freewheeling diode D2 is forward-biased, the induced electromotive force forms a freewheeling circuit through the coil → freewheeling diode D2 → coil, slowly releasing energy.

[0094] S111: The main controller immediately sets all IO1~IO4 to high level, cuts off all motor drives, and triggers the sound and light alarm module. The buzzer sounds, the red light stays on for 2 seconds, and an abnormal feedback signal is sent to the remote control unit to prompt the user to troubleshoot the fault.

[0095] S112: The motor stops completely, the freewheeling process ends, the freewheeling diode is cut off, the relay remains open, the main controller clears the instruction buffer, the IO port remains high, and the module returns to the standby state after initialization, waiting for the next instruction input.

[0096] This embodiment utilizes dual-motor multi-directional drive and short-range wireless remote control to eliminate blind spots and achieve centimeter-level precise positioning, meeting the needs of parking in narrow spaces. No repeated towing operations are required; a single person can quickly complete the positioning adjustment, significantly improving parking efficiency. Through stable power output, full-link status monitoring, and multiple safety protection mechanisms, it reduces operational difficulty and the risk of misjudgment, minimizing safety accidents such as scratches and equipment damage. It also significantly reduces the demands on the driver's skill level and patience, comprehensively improving the convenience, accuracy, and safety of parking and positioning for towed caravans.

[0097] In this embodiment, during use, the system is first started and paired: the vehicle's 12V battery provides input power to the power supply protection unit. The reverse connection protection circuit determines the power polarity; when connected correctly, MOSFET Q1 conducts, and when connected incorrectly, Q1 is cut off to prevent component burnout. The overvoltage protection circuit is on standby, automatically cutting off power when the input voltage exceeds 58V. The multi-stage power conversion circuit of the power supply protection unit converts the 12V voltage to the system's compatible voltage: the XL1509-5.0 chip U1 converts 12V to 5V, and the AMS1117-3.3 chip U2 converts 5V to 3.3V, providing stable power to the motor drive module, main controller, and wireless communication module, respectively. Capacitors C1-C4 are used for filtering and noise reduction to ensure stable power supply. The remote control unit is powered by two AA batteries. When the user presses the pairing button, the remote control main control chip establishes a pairing connection with the vehicle-mounted actuator's wireless communication module one through wireless communication module two. The communication distance can reach 30 meters, meeting the needs of close-range visual operation. The remote control unit automatically goes into sleep mode after 30 seconds of inactivity and can be activated by the wake-up button. At the same time, the main controller starts up with the support of a stable clock signal provided by the crystal oscillator module, and configures four motor control I / O ports (IO1-IO4) as output mode, all of which are initially set to high level. It also completes the initialization of ADC, wireless communication, timers, etc., and presets safety parameters such as normal voltage range (9V-14V), small motor stall current threshold (15A), and large motor stall current threshold (80A).

[0098] After configuration, the command issuance and action execution phase begins: The user inputs movement commands via the operation button group of the remote control unit. The remote control main control chip encodes the commands into standard data frames, which are then sent to the vehicle-mounted execution unit's wireless communication module one via wireless communication module two, achieving wireless transmission of commands with a response time of <100ms. The main controller of the vehicle-mounted execution unit receives the command frames via wireless communication module one, parses them to determine the motor action type, and maps it to the IO port output logic. Specifically: Small motor engagement command: IO3 outputs a low level (L), and the remaining IO ports are high level (H); Large motor forward rotation command: IO1 outputs L, and the remaining IO ports are H; Left turn (differential) command: IO1 outputs a 50% duty cycle PWM signal, IO3 outputs L, and the remaining IO ports are H; Stop command: all IO ports are H. The main controller uses the formula... Calculate the relay coil current to ensure it does not exceed the ULN2003A isolation chip's maximum output current of 500mA. In case of an abnormality, an alarm is triggered directly. The I / O port level output by the main controller is amplified by the ULN2003A isolation chip and drives the corresponding relay—when the level is low (L), the chip conducts, and the relay coil is energized and engaged; with a PWM signal, the chip turns on / off according to the frequency, and the coil receives a pulsating current. Specifically, the small motor operates as follows: when the engagement command is triggered, the SRA-12VDC-CL relay contacts close, and the small motor rotates forward, driving the large motor to engage with the RV tires; when the separation command is triggered, the relay de-energizes, and the small motor reverses, moving the large motor away from the tires. A 1-second delay ensures the action is complete. The large motor operates as follows: when the forward / reverse command is triggered, the corresponding JQX-V5012-1ZP relay contacts close, and the large motor rotates forward (RV forward) or reverses (RV backward); when the steering command is triggered, the formula... Calculate the PWM duty cycle, and then... and By determining the average voltage and speed of the motor, differential speed between the left and right motors can be achieved, thus enabling precise steering.

[0099] During execution, real-time status monitoring is performed: the voltage detection module collects the supply voltage through resistor voltage division, and the main controller uses a formula... The ADC sampled value is converted into an actual voltage to determine whether there is undervoltage or overvoltage. Simultaneously, the current detection module collects the operating current of the two motors—the smaller motor's current is sampled through two 10mΩ parallel resistors and an operational amplifier, and the main controller uses a formula... Calculate the actual current; the large motor is sampled by three 5mΩ constantan wire parallel resistors + operational amplifier, and the result is obtained using the formula... The actual current is calculated to determine if it exceeds the stall threshold. When the voltage / current exceeds the preset range or a system fault occurs, the main controller immediately sets all motor control I / O ports to high level, cutting off the motor drive circuit to prevent the fault from escalating. At the same time, the buzzer sounds and the indicator light turns red for 2 seconds to remind the user. Simultaneously, an abnormal feedback signal is sent to the remote control unit to inform it of the fault type. Upon receiving a stop command, all I / O ports are set to high level, and the relay is de-energized to disconnect the motor power supply circuit. The reverse induced electromotive force generated by the motor stopping is released through the freewheeling diode D2 connected in parallel across the relay coil to form a circuit, preventing high voltage from damaging the components. After the motor stops completely and the freewheeling process ends, the main controller clears the command buffer, the I / O ports remain high level, and the system returns to the initialization standby state, waiting for the next command input.

[0100] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A mobility device system based on a towed caravan, characterized in that, Includes onboard actuators, remote control units, and power supply protection units; The vehicle-mounted execution unit includes a main controller, dual motor sets, a motor drive module, a current detection module, a voltage detection module, a wireless communication module, an audible and visual alarm module, and a crystal oscillator module. The remote control unit includes a remote control main control chip, a second wireless communication module, and an operation button group; The power supply protection unit includes a reverse connection protection circuit, an overvoltage protection circuit, and a multi-stage power conversion circuit. The remote control unit sends movement commands to the vehicle-mounted execution unit's wireless communication module 1 via the wireless communication module 2. The main controller controls the dual motor units to move in multiple directions via the motor drive module according to the commands. The voltage detection module monitors the power supply voltage in real time, and the current detection module collects the operating current of the dual motor units in real time. When the voltage or current exceeds the preset range, the main controller controls the audible and visual alarm module to start the alarm, and at the same time, the overvoltage protection circuit and the reverse connection protection circuit trigger the corresponding protection actions.

2. The mobility device system based on a towed caravan according to claim 1, characterized in that, The main controller is responsible for receiving command signals from the remote control unit, parsing them, and outputting control signals to the motor drive module. It also receives feedback signals from the voltage detection module and the current detection module to control the start and stop of the audible and visual alarm module. The dual-motor unit includes a small motor and a large motor. The small motor is used to drive the large motor to contact the tires of the trailer caravan, while the large motor serves as the main power source to drive the tires to rotate forward and backward and to move differentially.

3. The mobility device system based on a towed caravan according to claim 1, characterized in that, The motor drive module includes a large motor drive circuit and a small motor drive circuit. The large motor drive circuit is controlled by a JQX-V5012-1ZP relay, and the small motor drive circuit is controlled by an SRA-12VDC-CL relay. Both relays are connected in parallel with a freewheeling diode D2. When the motor stops rotating, the induced electromotive force generated is released through the freewheeling diode D2. The main controller controls the large motor and the small motor by outputting high and low levels through the ULN2003A isolation chip and controlling the relays to turn on and off. The current detection module includes a small motor current sampling circuit and a large motor current sampling circuit. The small motor current sampling circuit consists of two parallel circuits of 10mΩ resistors and an operational amplifier. When the small motor is stalled, the current is about 15A. The sampled voltage is amplified and then input to the main controller. The large motor current sampling circuit consists of three parallel circuits of 5mΩ constantan wire resistors and an operational amplifier. The current of the large motor is about 80A when it is stalled. The sampled voltage is amplified and then input to the main controller. A diode clamping circuit is provided between the operational amplifier circuit and the main controller. The voltage detection module is used to monitor the input voltage of the power supply protection unit in real time and feed the voltage signal back to the main controller. When the voltage exceeds the normal range, an audible and visual alarm is triggered. The sound and light alarm module includes a buzzer circuit and an indicator light circuit. When the voltage is abnormal, the current exceeds the limit, or the system fails, the buzzer sounds an alarm and the indicator light turns red to remind the user to troubleshoot the problem in a timely manner. The logical steps for the coordinated operation of the motor drive module, current detection module, voltage detection module, and audible and visual alarm module are as follows: S101: The main controller is equipped with 4 motor control IO ports, including IO1 for large motor forward rotation, IO2 for large motor reverse rotation, IO3 for small motor contact, and IO4 for small motor separation. All of them are in output mode and are initially set to high level H. S102: The main controller receives remote control commands through the wireless communication module, parses the commands, determines the motor action type, and maps it to IO port output logic; S103: The main controller pre-verifies drive safety using a coil current formula to ensure that the current does not exceed the maximum output current of the ULN2003A isolation chip. The formula used is: ,in For the on-state voltage drop of the ULN2003A isolation chip, The power supply voltage, If the calculated current value is abnormal (>500mA), the relay coil resistance is used. If the calculated current value is abnormal (>500mA), the process will jump to step S111 and trigger an audible and visual alarm. S104: When the IO port outputs a low level L, the corresponding output terminal of the ULN2003A isolation chip is turned on, a voltage difference is formed across the relay coil, and the coil is energized. When the IO port outputs a PWM signal, the ULN2003A isolation chip is turned on / off according to the PWM frequency, and the coil receives pulsating current. S105: If the instruction includes "small motor engages", the SRA-12VDC-CL relay coil is energized, the contacts close, the 12V power supply is connected to the small motor, the small motor rotates forward, driving the large motor to engage with the RV tire; if the instruction includes "small motor disengages", the SRA-12VDC-CL relay coil is de-energized, the disengagement control circuit is activated, the small motor reverses, the large motor disengages from the tire, the main controller delays for 1 second, and then executes the subsequent large motor action. S106: If the command is "large motor forward rotation", the JQX-V5012-1ZP relay coil is energized, the contacts close, and the 12V power supply is connected to the forward rotation winding of the large motor. The large motor rotates at full speed, and the RV moves forward. If the command is "large motor reverse rotation", the reverse control relay coil is energized, the contacts close, and the power supply is connected to the reverse rotation winding of the large motor. The large motor reverses, and the RV moves backward. S107: If the instruction is "turn left", then perform the following steps: S1071: Calculate PWM duty cycle and set differential coefficient. Then the duty cycle of the left motor Right motor duty cycle The duty cycle formula is: ; S1072: Calculate the average supply voltage of the motor using the following formula: ; S1073: Calculate the actual speed of the motor using the following formula: ; S1074: The main controller outputs a corresponding PWM signal, and the ULN2003A isolation chip drives the relay. The left and right large motors rotate at different speeds to realize the RV turning left. The logic for turning right is the same as that for turning left, except that the duty cycle of the right motor is set to 50% and that of the left motor is set to 100%. S108: The current detection module collects the current of the large / small motor in real time. The main controller calculates the actual current according to the current conversion formula. The formula is: to determine whether there is a stall. At the same time, the voltage detection module collects the supply voltage in real time. The main controller calculates the actual voltage according to the voltage conversion formula and determines whether there is undervoltage or overvoltage. If an abnormality is detected, jump to step S111; if normal, maintain the current motor operation. The formula for calculating the actual voltage is: ,in This refers to the actual voltage of the vehicle's 12V battery. The ADC samples the digital value for the voltage detection module. This is the ADC reference voltage. For the quantization level of a 12-bit ADC, For the voltage detection module, use voltage divider resistors. This is the voltage divider resistor for the voltage detection module; Formula for calculating the current of a small motor: ,in This represents the actual operating current of the small motor. This refers to the digital input sampled by the ADC of the small motor current detection module. This is the operational amplification factor for small motor current detection. This represents the total resistance of the shunt resistor in the small motor. Formula for calculating the current of a large motor: ,in This represents the actual operating current of the large motor. This refers to the digital input sampled by the ADC of the large motor current detection module. This is the operational amplification factor for current detection of large motors. This represents the total resistance of the shunt resistor in the large motor. S109: When the main controller receives the "stop moving" command, it sets all IO1~IO4 to high level H, the ULN2003A isolation chip output is cut off, the relay coil is de-energized, the electromagnet is released, the contacts are opened, and the motor power supply circuit is cut off. S110: When the motor stops, the coil generates a reverse induced electromotive force, with a peak value of approximately When the freewheeling diode D2 is forward-biased, the induced electromotive force forms a freewheeling circuit through the coil → freewheeling diode D2 → coil, slowly releasing energy. S111: The main controller immediately sets all IO1~IO4 to high level, cuts off all motor drives, and triggers the sound and light alarm module. The buzzer sounds, the red light stays on for 2 seconds, and an abnormal feedback signal is sent to the remote control unit to prompt the user to troubleshoot the fault. S112: The motor stops completely, the freewheeling process ends, the freewheeling diode is cut off, the relay remains open, the main controller clears the instruction buffer, the IO port remains high, and the module returns to the standby state after initialization, waiting for the next instruction input.

4. The mobility device system based on a towed caravan according to claim 1, characterized in that, The wireless communication module consists of a WL500B wireless transceiver chip and a spring antenna. It is responsible for receiving command signals sent by the remote control unit. The communication distance can reach 30 meters, ensuring that users can perform remote control operations within a safe range. The wireless communication module 2 uses a VG4455 wireless transceiver chip, the remote control unit is powered by two AA batteries, and the remote control main control chip is STC8H1K08-36I-TSSOP20. The crystal oscillator module consists of an external passive crystal oscillator X49SD8MSD2SC and an external starting capacitor, which provides a stable clock signal to the main controller and ensures the stable operation of the main controller.

5. A mobility device system based on a towed caravan according to claim 1, characterized in that, The operation button group includes a wake-up button, a pairing button, a forward button, a reverse button, a left turn button, a right turn button, and a move away from the tire button; the remote control unit must first be paired with the vehicle-mounted actuator unit via the pairing button, and automatically enters sleep mode after 30 seconds of inactivity, and is activated via the wake-up button.

6. A mobility device system based on a towed caravan according to claim 1, characterized in that, The input power of the power supply protection unit is a vehicle-mounted 12V battery. The multi-stage power conversion circuit includes a 12V to 5V circuit and a 5V to 3.3V circuit. The 12V to 5V circuit uses XL1509-5.0 chip U1, and the 5V to 3.3V circuit uses AMS1117-3.3 chip U2. Pin 5 of both chip U1 and chip U2 is electrically connected to the main power supply of the system. A capacitor C1 is connected in parallel to pin 1 of chip U1. Pins 1 and 2 of chip U1 are electrically connected to the vehicle-mounted 12V battery. A capacitor C2 is connected in parallel to pin 3 of chip U1. Pins 3 of both chip U1 and chip U2 output 5V voltage. Pins 4 of both chip U1 and chip U2 are grounded. A capacitor C3 and a capacitor C4 are connected in parallel to pins 1 and 3 of chip U2, respectively. Pin 1 of chip U2 is also connected to a 5V voltage.

7. A mobility device system based on a towed caravan according to claim 1, characterized in that, The reverse connection protection circuit is used to automatically disconnect the circuit and stop the system from working when the positive and negative terminals of the vehicle 12V battery are reversed, preventing the components from being burned out due to reverse power connection. The reverse connection protection circuit includes a MOSFET Q1, with one end of a resistor R1 electrically connected to the gate of the MOSFET Q1, the other end of the resistor R1 electrically connected to the positive terminal of the vehicle 12V battery, and the source of the MOSFET Q1 grounded and electrically connected to the negative terminal of the vehicle 12V battery.

8. A mobility device system based on a towed caravan according to claim 1, characterized in that, The maximum protection voltage of the overvoltage protection circuit does not exceed 58V. When the input voltage is higher than the normal operating voltage, the circuit automatically triggers protection to prevent damage to the vehicle actuator due to overvoltage. When the input voltage is lower than the preset threshold, the system stops working and triggers an audible and visual alarm. The overvoltage protection circuit includes a resettable fuse F1 and a diode D1. One end of the resettable fuse F1 and the positive terminal of the diode D1 are electrically connected to the positive terminal of the vehicle's 12V battery. The other end of the resettable fuse F1 is electrically connected to the system's main power supply, and the negative terminal of the diode D1 is grounded.

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