Pull type vehicle body stability control vehicle-mounted control system based on mechanical pull rope brake

Abstract

The invention discloses a pull type vehicle body stability control vehicle-mounted control system based on a mechanical pull rope brake. The pull type vehicle body stability control vehicle-mounted control system comprises a controller box, a fixing device, a transmission mechanism, a sound-light alarm unit and a power supply. Lateral acceleration data of a vehicle body are collected through an LSM6DSOWTR three-axis acceleration sensor in a high frequency mode, a five-level graded braking rule and precise PWM control are combined, precise matching of the swing degree and the braking force of the pull type motor home is achieved, vehicle body swing is effectively restrained, the risk of dead swing is avoided, and the driving safety is remarkably improved; meanwhile, voltage and current dual detection protection and sound-light alarm functions are integrated, the abnormal operation risk of the system can be avoided in time, and the mechanical pull rope transmission mechanism which is simple in structure and small in force transmission loss and the power supply circuit matched with the vehicle-mounted environment are matched, so that installation and maintenance are convenient, adaptability is high, and cost is low. And the driving stability can be guaranteed by dynamically adjusting the braking power, and the service life of core components is prolonged.

Description

Technical Field

[0001] This invention relates to the field of towable caravan technology, and in particular to a vehicle-mounted control system for towable vehicle stability control based on a mechanical cable brake. Background Technology

[0002] The vehicle stability control system for trailers is mainly used for the cornering balance control of trailer caravans. Its core function is to ensure that the following vehicle runs smoothly when the preceding vehicle is cornering, and to prevent the following vehicle from swaying. Currently, trailer caravans lack a reliable anti-sway control system. When the preceding vehicle is cornering at high speed, the following vehicle is prone to swaying significantly, which can lead to accidents and pose a great safety risk to the driver and passengers.

[0003] In the prior art, there is a lack of effective solutions for the stability control of towed caravans. It is impossible to detect changes in acceleration in the lateral direction of the vehicle body in real time, nor can it dynamically adjust the braking force according to the vehicle body posture, resulting in poor vehicle stability and difficulty in ensuring driving safety. In view of the above, this application proposes a vehicle-mounted control system for towed caravan stability control based on a mechanical cable brake. Summary of the Invention

[0004] Based on the technical problems existing in the background technology, the present invention proposes a towed vehicle stability control system based on a mechanical cable brake.

[0005] The present invention proposes a vehicle-mounted control system for towed vehicle stability control based on a mechanical cable brake, comprising a controller box, a fixing device, a transmission mechanism, an audible and visual alarm unit, and a power supply.

[0006] The controller box is used to output stable control commands. The controller box includes a main control board and a DC brushed motor.

[0007] The fixing device is used to install and fix the system to the vehicle body;

[0008] The transmission mechanism is signal-connected to the controller box and is used to perform stable control actions;

[0009] The audible and visual alarm unit is connected to the controller box and is used to provide feedback on the system's operating status. The audible and visual alarm unit includes a buzzer and an indicator light.

[0010] The power supply is connected to the controller box and is used to supply power to the controller box.

[0011] Preferably, a connection port is provided on one side of the controller box, and the controller box is connected to the transmission mechanism through the connection port; a cable is led out from one side of the controller box, the power input end of the cable is used to connect to the power supply, which is a vehicle 12V battery, and the signal output end of the cable is connected to an indicator light, which is embedded and fixed on one side of the controller box.

[0012] Preferably, the fixing device is made of sheet metal material with a thickness of 4mm;

[0013] The transmission mechanism includes a driving reversing gear, a driven reversing gear, a metal rod, and connecting bolts. The driving reversing gear meshes with the driven reversing gear. The central shaft of the driven reversing gear is connected to one end of the metal rod via a threaded connection. The end of the metal rod away from the driven reversing gear has a bolt hole. The end connector of the brake cable is aligned with the bolt hole of the metal rod. The connecting bolt is passed through the brake cable connector hole and the bolt hole of the metal rod, and tightened with a nut to fix it, so that the brake cable and the metal rod form a rigid fixed connection. The other end of the brake cable is directly connected to the mechanical cable brake of the towing vehicle. The initial state of the mechanical cable brake is "released". The mechanical cable brake has a built-in brake shoe control mechanism inside the brake drum.

[0014] The transmission mechanism is used to convert the torque of the DC brushed motor into a pulling force to pull the brake cable and achieve braking. The specific logical steps are as follows:

[0015] S101: The output shaft of the DC brushed motor is fixed to the drive commutator gear of the transmission mechanism by a key. After the DC brushed motor starts, the rotational torque of the output shaft is directly transmitted to the drive commutator gear, causing the drive commutator gear to rotate in the set direction.

[0016] S102: The driving gear rotates, which drives the driven reversing gear to rotate in the opposite direction through tooth surface meshing. When the driven reversing gear rotates, its threaded engagement with the metal rod converts the "rotational motion" into the "linear motion of the metal rod": if the driven reversing gear rotates counterclockwise, the metal rod will extend forward along the gear axis; if the driven reversing gear rotates clockwise, the metal rod will retract backward.

[0017] S103: The linear movement of the metal bar will directly drive the brake cable to move synchronously: when the metal bar retracts, it will generate a linear pulling force on the brake cable along the axis of the metal bar; when the metal bar extends forward, the brake cable will move forward accordingly.

[0018] S104: When the metal bar pulls the brake cable to generate tension, the brake cable overcomes the elastic force of the return spring in the mechanical cable brake, pulls the control lever of the brake shoes, and causes the brake shoes to expand outward and fit tightly against the inner wall of the brake drum.

[0019] S105: When the DC brushed motor rotates in reverse, it drives the active reversing gear to rotate in reverse, which in turn causes the driven reversing gear to rotate in reverse. The threaded engagement between the driven gear and the metal bar works again, and the metal bar changes from the "retracted state" to the "extended state," moving away from the brake cable. The tension in the brake cable disappears, the return spring in the mechanical pull-cord brake returns to its original shape, pulls the brake pads to reset, and the brake cable naturally loosens as the brake pads reset. The transmission mechanism returns to its initial state, waiting for the next braking command.

[0020] Preferably, the power supply includes a two-stage DC step-down circuit. The first stage uses an XL1509-5.0 chip to convert 12V to 5V, and the second stage uses an AMS1117-3.3 chip to convert 5V to 3.3V to power each functional module.

[0021] Preferably, the main control board uses an STM32F103C8T6 control chip, and the main control board integrates a crystal oscillator circuit, a voltage detection circuit, a current detection circuit, and a braking control unit;

[0022] The crystal oscillator circuit consists of an external passive crystal oscillator of model X32258MOB4SI and a matching peripheral starting capacitor.

[0023] The voltage detection circuit is used to detect the power supply voltage. When the voltage detection circuit detects an abnormal power supply voltage, the braking control unit automatically prohibits the braking operation, and the audible and visual alarm unit triggers the buzzer to sound and the indicator light to illuminate as an alarm.

[0024] The current detection circuit includes a 10mΩ sampling resistor and an operational amplifier circuit. The operational amplifier circuit uses an LMV358IDR operational amplifier to amplify the voltage signal across the sampling resistor and input it to the control chip. A diode clamping circuit is provided between the operational amplifier circuit and the control chip.

[0025] The braking control unit includes a MOSFET drive circuit, which adjusts the PWM signal by switching the MOSFET on and off to control the operation of the DC brushed motor.

[0026] Preferably, the main control board integrates an LSM6DSOWTR three-axis accelerometer. The LSM6DSOWTR three-axis accelerometer is used to realize real-time measurement of vehicle body attitude changes. The LSM6DSOWTR three-axis accelerometer establishes a Cartesian coordinate system with the origin and sets the reference state parameters. When the RV is stationary on a level road, the acceleration in the X-axis direction is 1g, 1g = 9.8m / s², and the acceleration in the Y-axis and Z-axis directions is 0. When the towed RV sways, the acceleration in the Y-axis direction increases. Once this acceleration value exceeds a preset threshold, the system triggers braking actions in stages according to the current Y-axis acceleration to implement braking control on the towed vehicle.

[0027] The specific rules for hierarchical trigger braking are as follows: when the Y-axis acceleration value > 0.5g, the mechanical cable pull brake outputs 100% power; when 0.4g < Y-axis acceleration value ≤ 0.5g, the mechanical cable pull brake outputs 80% power; when 0.3g < Y-axis acceleration value ≤ 0.4g, the mechanical cable pull brake outputs 60% power; when 0.2g < Y-axis acceleration value ≤ 0.3g, the mechanical cable pull brake outputs 40% power; when the Y-axis acceleration value ≤ 0.2g, the mechanical cable pull brake outputs 20% power.

[0028] Preferably, the specific logic steps for the main control board to implement attitude change measurement and braking based on the LSM6DSOWTR three-axis acceleration sensor are as follows:

[0029] S201: When the system is powered on and initialized, the main control board sends a "reference calibration instruction" to the LSM6DSOWTR three-axis acceleration sensor. At this time, it is required that the towed caravan is stationary on a horizontal road surface, without tilt and without sway;

[0030] S202: The LSM6DSOWTR three-axis acceleration sensor takes the physical center of its own chip as the origin to establish a Cartesian coordinate system. The X-axis is parallel to the driving direction of the caravan, the Y-axis is perpendicular to the driving direction, the Z-axis is perpendicular to the horizontal road surface and is consistent with the direction of gravity. Its reference acceleration is the acceleration due to gravity. At the same time, the LSM6DSOWTR three-axis acceleration sensor continuously collects the original X, Y, and Z-axis acceleration data within 3 seconds, and calculates the reference value through the sliding average algorithm. The formula used is: , where N = 300, and the finally calibrated reference state parameters are: = 1g, = 0g, = 0g, and the main control board stores the reference value = 1g, = 0g, = 0g in the cache as the "deviation correction reference" for subsequent real-time measurement;

[0031] S203: The LSM6DSOWTR three-axis acceleration sensor continuously collects the real-time original acceleration data of the X, Y, and Z axes at a frequency of 100Hz, denoted as , where t is the sampling time;

[0032] S204: The main control board performs "reference deviation correction" on the original data to eliminate the zero drift error after initial calibration, and obtains the true acceleration value , where is the core monitoring value, , is used for auxiliary judgment;

[0033] For the revised Low-pass filtering is performed to filter out high-frequency interference such as road bumps. The formula used is: ,in =0.1, The filtered value from the previous time step, finally This refers to the "effective lateral acceleration value used for threshold determination";

[0034] S205: The main control board collects the 12V battery power supply voltage through a voltage detection circuit. Determine whether the braking conditions are met: If ,or If this occurs, a "voltage abnormality" will be triggered, prohibiting subsequent braking actions and activating both audible and visual alarms. If so, it will proceed to the "current detection stage";

[0035] S206: The main control board collects the real-time current of the DC brushed motor through a current sampling circuit. Calculate the effective value of the current. Where T=20ms, and a current threshold judgment is performed, if If this triggers an "abnormal current" signal, braking will be disabled and an alarm will sound. If the system status is normal, the system will proceed to the "graded braking judgment stage".

[0036] S207: The main control board will The braking power level is compared with the preset 5-level acceleration threshold and matched according to the following rules:

[0037] (1) When To provide maximum braking force in response to severe swaying;

[0038] (2) When This provides high braking force.

[0039] (3) When , for the braking force;

[0040] (4) When This results in low braking force.

[0041] (5) When As the basic braking force, it only suppresses slight swaying; if three consecutive samples are taken... If all values ​​fall within the same threshold range, then the braking power level is locked.

[0042] S208: The main control board is based on the braking power level. Calculate the PWM signal duty cycle D required for a DC brushed motor: ,in This is the minimum starting duty cycle for the motor to prevent stalling. This is the maximum safe duty cycle for the motor to avoid overcurrent.

[0043] S209: The main control board outputs a PWM signal with a duty cycle of D to the DC brushed motor through a MOSFET drive circuit, controlling the DC brushed motor to rotate at the target torque. The motor's rotational torque is converted into tension through the transmission mechanism, pulling the brake cable, and the mechanical pull-cord brake is activated. Output braking force to suppress vehicle lateral sway; during braking, sensors continuously sample data. ,like If the value drops to a lower threshold range, repeat steps S207-S209 to dynamically adjust the braking power. If the condition persists for 1 second, a "brake release command" will be output, the DC brushed motor will stop rotating, and the brake cable will be reset.

[0044] Preferably, the connecting bolt is an M8×20 socket head cap screw, and the inner diameter of the bolt hole and the inner diameter of the connector hole are both 8mm. The connecting bolt is fastened to the bolt hole of the metal bar and the connector hole of the brake cable. The external thread of the metal bar is an M8×1.25 fine thread, which is precisely matched with the internal thread of the driven reversing gear.

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

[0046] 1. By using the LSM6DSOWTR three-axis accelerometer to monitor lateral acceleration in real time and combining it with a 5-level braking rule, the system achieves precise matching between the degree of swaying and the braking force. This effectively solves the problem of unreliable anti-swaying control in existing towed caravans, avoids accidents caused by "death swaying," and ensures the safety of passengers. Furthermore, the LSM6DSOWTR three-axis accelerometer's 100Hz high-frequency sampling, combined with the main control board's fast calculation, results in low braking command response delay. During braking, it continuously monitors acceleration data and dynamically adjusts braking power to avoid vehicle body swaying caused by sudden changes in braking force, thus improving driving stability.

[0047] 2. Integrated voltage and current detection dual protection: when the power supply voltage is abnormal or the motor is overcurrent, braking is immediately prohibited and an audible and visual alarm is triggered to prevent equipment damage or braking failure and improve system reliability.

[0048] 3. The transmission mechanism adopts a mechanical rope-pulling design of "gear + thread + bolt", which is simple in structure and has low force transmission loss. The fixing device is made of 4mm sheet metal material, which ensures stable installation. The system relies on the vehicle's 12V battery for power supply. The two-stage step-down circuit adapts to the voltage requirements of each module and can be directly applied to mainstream towable caravans without additional modifications.

[0049] 4. Improve data accuracy through sliding average calibration and low-pass filtering. Limit the motor PWM duty cycle to the range of 20%-90%, which avoids motor stalling, prevents overcurrent burnout, and extends the service life of core components.

[0050] This invention utilizes the LSM6DSOWTR triaxial accelerometer to collect high-frequency lateral acceleration data of the vehicle body. Combined with a 5-level braking rule and precise PWM control, it achieves a precise match between the degree of swaying and the braking force of the towed caravan, effectively suppressing vehicle swaying, avoiding the risk of "death swaying," and significantly improving driving safety. Simultaneously, it integrates dual voltage and current detection protection and audible and visual alarm functions to promptly avoid the risk of abnormal system operation. Coupled with a simple, low-loss mechanical rope transmission mechanism and a power supply circuit adapted to the vehicle environment, it is not only easy to install and maintain and highly adaptable, but also ensures driving stability by dynamically adjusting braking power, extending the service life of core components. This comprehensively solves the problems of existing towed caravans lacking reliable anti-sway control, poor vehicle stability, and insufficient safety guarantees. Attached Figure Description

[0051] Figure 1 This is a block diagram of a towed vehicle stability control system based on a mechanical cable brake proposed in this invention.

[0052] Figure 2 This is a flowchart of a towed vehicle stability control system based on a mechanical cable brake, as proposed in this invention. Detailed Implementation

[0053] The present invention will be further explained below with reference to specific embodiments.

[0054] Example

[0055] Reference Figure 1-2 This embodiment proposes a towed vehicle stability control system based on a mechanical cable brake, including a controller box, a fixing device, a transmission mechanism, an audible and visual alarm unit, and a power supply.

[0056] The controller box is used to output stable control commands. The controller box includes a main control board and a DC brushed motor. A connection port is opened on one side of the controller box, and the controller box is connected to the transmission mechanism through the connection port. A cable is led out from one side of the controller box. The power input end of the cable is used to connect to the power supply, which is a vehicle 12V battery. The signal output end of the cable is connected to the indicator light, which is embedded and fixed on one side of the controller box.

[0057] The mounting device is used to secure the system to the vehicle body. The mounting device is made of sheet metal with a thickness of 4mm.

[0058] The transmission mechanism is connected to the controller box via signal transmission and is used to perform stable control actions;

[0059] The transmission mechanism includes a driving reversing gear, a driven reversing gear, a metal rod, and connecting bolts. The driving reversing gear meshes with the driven reversing gear. The central shaft of the driven reversing gear is connected to one end of the metal rod via a threaded connection. The end of the metal rod away from the driven reversing gear has a bolt hole. The end connector of the brake cable is aligned with the bolt hole of the metal rod. The connecting bolt is passed through the brake cable connector hole and the bolt hole of the metal rod, and tightened with a nut to form a rigid connection between the brake cable and the metal rod. The connecting bolt is an M8×20 hexagon socket head cap screw. The inner diameter of both the bolt hole and the connector hole is 8mm. The connecting bolt is tightened by fitting with the bolt hole of the metal rod and the connector hole of the brake cable. The external thread of the metal rod is an M8×1.25 fine thread, which precisely matches the internal thread of the driven reversing gear. The other end of the brake cable is directly connected to the mechanical cable brake of the towing vehicle. The initial state of the mechanical cable brake is "released". The mechanical cable brake has a built-in brake shoe control mechanism inside the brake drum.

[0060] The transmission mechanism is used to convert the torque of the DC brushed motor into a pulling force to pull the brake cable and achieve braking. The specific logical steps are as follows:

[0061] S101: The output shaft of the DC brushed motor is fixed to the drive commutator gear of the transmission mechanism by a key. After the DC brushed motor starts, the rotational torque of the output shaft is directly transmitted to the drive commutator gear, causing the drive commutator gear to rotate in the set direction.

[0062] S102: The driving gear rotates, which drives the driven reversing gear to rotate in the opposite direction through tooth surface meshing. When the driven reversing gear rotates, its threaded engagement with the metal rod converts the "rotational motion" into the "linear motion of the metal rod": if the driven reversing gear rotates counterclockwise, the metal rod will extend forward along the gear axis; if the driven reversing gear rotates clockwise, the metal rod will retract backward.

[0063] S103: The linear movement of the metal bar will directly drive the brake cable to move synchronously: when the metal bar retracts, it will generate a linear pulling force on the brake cable along the axis of the metal bar; when the metal bar extends forward, the brake cable will move forward accordingly.

[0064] S104: When the metal bar pulls the brake cable to generate tension, the brake cable overcomes the elastic force of the return spring in the mechanical cable brake, pulls the control lever of the brake shoes, and causes the brake shoes to expand outward and fit tightly against the inner wall of the brake drum.

[0065] S105: When the DC brushed motor rotates in reverse, it drives the active reversing gear to rotate in reverse, which in turn causes the driven reversing gear to rotate in reverse. The threaded engagement between the driven gear and the metal bar works again, and the metal bar changes from the "retracted state" to the "extended state" and moves away from the brake cable. The tension in the brake cable disappears, the return spring in the mechanical pull-cord brake returns to its original shape, pulls the brake pads to reset, and the brake cable naturally loosens as the brake pads reset. The transmission mechanism returns to its initial state and waits for the next braking command.

[0066] The audible and visual alarm unit is connected to the controller box and is used to provide feedback on the system's operating status. The audible and visual alarm unit includes a buzzer and an indicator light.

[0067] The power supply is connected to the controller box and is used to power the controller box;

[0068] The power supply includes a two-stage DC step-down circuit. The first stage uses the XL1509-5.0 chip to convert 12V to 5V, and the second stage uses the AMS1117-3.3 chip to convert 5V to 3.3V to power the various functional modules.

[0069] The main control board uses an STM32F103C8T6 control chip, which integrates a crystal oscillator circuit, a voltage detection circuit, a current detection circuit, and a braking control unit.

[0070] The crystal oscillator circuit consists of an external passive crystal oscillator of model X32258MOB4SI and a matching peripheral starting capacitor.

[0071] The voltage detection circuit is used to detect the power supply voltage. When the voltage detection circuit detects an abnormal power supply voltage, the brake control unit automatically prohibits the braking operation, and the audible and visual alarm unit triggers the buzzer to sound and the indicator light to illuminate as an alarm.

[0072] The current detection circuit includes a 10mΩ sampling resistor and an operational amplifier circuit. The operational amplifier circuit uses an LMV358IDR operational amplifier to amplify the voltage signal across the sampling resistor and input it to the control chip. A diode clamping circuit is provided between the operational amplifier circuit and the control chip.

[0073] The brake control unit includes a MOS transistor drive circuit, which adjusts the PWM signal through the on / off of the MOS transistor to control the operation of the DC brush motor. An LSM6DSOWTR three-axis acceleration sensor is integrated on the main control board. The LSM6DSOWTR three-axis acceleration sensor is used to realize the real-time measurement of the body attitude change. The LSM6DSOWTR three-axis acceleration sensor establishes a Cartesian coordinate system with the origin, sets the reference state parameters. When the RV is stationary on a horizontal road surface, the acceleration in the X-axis direction is 1g, 1g = 9.8m / s², and the accelerations in the Y-axis and Z-axis directions are both 0; when the towed RV undergoes a swaying motion, the acceleration in the Y-axis direction climbs. Once the acceleration value exceeds the preset threshold, the system triggers the braking action in stages according to the current Y-axis acceleration and implements braking control on the towed rear vehicle;

[0074] And the specific rules for triggering braking in stages are as follows: when the Y-axis acceleration value > 0.5g, the mechanical cable pull brake outputs 100% power; when 0.4g < Y-axis acceleration value ≤ 0.5g, the mechanical cable pull brake outputs 80% power; when 0.3g < Y-axis acceleration value ≤ 0.4g, the mechanical cable pull brake outputs 60% power; when 0.2g < Y-axis acceleration value ≤ 0.3g, the mechanical cable pull brake outputs 40% power; when the Y-axis acceleration value ≤ 0.2g, the mechanical cable pull brake outputs 20% power;

[0075] The specific logic steps for the main control board to realize attitude change measurement and braking based on the LSM6DSOWTR three-axis acceleration sensor are as follows:

[0076] S201: When the system is powered on and initialized, the main control board sends a "reference calibration instruction" to the LSM6DSOWTR three-axis acceleration sensor. At this time, it is required that the towed RV is stationary on a horizontal road surface, without inclination and without swaying;

[0077] S202: The LSM6DSOWTR three-axis acceleration sensor takes its own chip physical center as the origin to establish a Cartesian coordinate system. The X-axis is parallel to the RV driving direction, the Y-axis is perpendicular to the driving direction, the Z-axis is perpendicular to the horizontal road surface and is consistent with the gravity direction. Its reference acceleration is the gravitational acceleration. At the same time, the LSM6DSOWTR three-axis acceleration sensor continuously collects the original data of the X, Y, and Z-axis accelerations within 3 seconds, and calculates the reference value through the moving average algorithm. The formula used is: , where N = 300. The finally calibrated reference state parameters are: = 1g, = 0g, = 0g. The main control board stores the reference value = 1g, = 0g, = 0g into the cache as the "deviation correction reference" for subsequent real-time measurement;

[0078] S203: The LSM6DSOWTR triaxial accelerometer continuously acquires real-time raw acceleration data along the X, Y, and Z axes at a frequency of 100Hz, denoted as... , where t is the sampling time;

[0079] S204: The main control board performs "reference deviation correction" on the raw data to eliminate the zero drift error after initial calibration and obtain the true acceleration value. ,in As the core monitoring value, , Used to assist in judgment;

[0080] For the revised Low-pass filtering is performed to filter out high-frequency interference such as road bumps. The formula used is: ,in =0.1, The filtered value from the previous time step, finally This refers to the "effective lateral acceleration value used for threshold determination";

[0081] S205: The main control board collects the 12V battery power supply voltage through a voltage detection circuit. Determine whether the braking conditions are met: If ,or If this occurs, a "voltage abnormality" will be triggered, prohibiting subsequent braking actions and activating both audible and visual alarms. If so, it will proceed to the "current detection stage";

[0082] S206: The main control board collects the real-time current of the DC brushed motor through a current sampling circuit. Calculate the effective value of the current. Where T=20ms, and a current threshold judgment is performed, if If this triggers an "abnormal current" signal, braking will be disabled and an alarm will sound. If the system status is normal, the system will proceed to the "graded braking judgment stage".

[0083] S207: The main control board will The braking power level is compared with the preset 5-level acceleration threshold and matched according to the following rules:

[0084] (1) When To provide maximum braking force in response to severe swaying;

[0085] (2) When This provides high braking force.

[0086] (3) When , for the braking force;

[0087] (4) When This results in low braking force.

[0088] (5) When As the basic braking force, it only suppresses slight swaying; if three consecutive samples are taken... If all values ​​fall within the same threshold range, then the braking power level is locked.

[0089] S208: The main control board is based on the braking power level. Calculate the PWM signal duty cycle D required for a DC brushed motor: ,in, This is the minimum starting duty cycle for the motor to avoid stalling. This is the maximum safe duty cycle for the motor to avoid overcurrent.

[0090] S209: The main control board outputs a PWM signal with a duty cycle of D to the DC brushed motor through a MOSFET drive circuit, controlling the DC brushed motor to rotate at the target torque. The motor's rotational torque is converted into tension through the transmission mechanism, pulling the brake cable, and the mechanical pull-cord brake is activated. Output braking force to suppress vehicle lateral sway; during braking, sensors continuously sample data. ,like If the value drops to a lower threshold range, repeat steps S207-S209 to dynamically adjust the braking power. If the condition persists for 1 second, a "brake release command" will be output, the DC brushed motor will stop rotating, and the brake cable will be reset.

[0091] This embodiment utilizes the LSM6DSOWTR triaxial accelerometer to collect high-frequency lateral acceleration data of the vehicle body. Combined with a 5-level braking rule and precise PWM control, it achieves a precise match between the degree of swaying and the braking force of the towed caravan, effectively suppressing vehicle swaying, avoiding the risk of "death swaying," and significantly improving driving safety. Simultaneously, it integrates dual voltage and current detection protection and audible and visual alarm functions to promptly avoid the risk of abnormal system operation. Coupled with a simple, low-loss mechanical rope transmission mechanism and a power supply circuit adapted to the vehicle environment, it is not only easy to install and maintain and highly adaptable, but also ensures driving stability by dynamically adjusting braking power, extending the service life of core components. This comprehensively solves the problems of existing towed caravans lacking reliable anti-sway control, poor vehicle stability, and insufficient safety guarantees.

[0092] In this embodiment, after the system is powered on, it is first powered by the vehicle's 12V battery. The voltage is then converted to 5V and 3.3V by a two-stage DC step-down circuit to power the main control board and various functional modules. Simultaneously, the main control board sends calibration commands to the LSM6DSOWTR triaxial accelerometer. When the RV is stationary on a level road, a Cartesian coordinate system is established with the sensor chip as the origin. The reference parameters (X-axis 1g, Y-axis 0g, Z-axis 0g) are calculated and stored using a moving average algorithm (N=300) to provide a deviation correction reference for subsequent attitude measurements. During driving, the LSM6DSOWTR triaxial accelerometer continuously collects raw X, Y, and Z-axis acceleration data of the vehicle body at a frequency of 100Hz. The main control board performs deviation correction and low-pass filtering on the core Y-axis data to obtain the effective lateral acceleration value. Meanwhile, the voltage detection circuit collects the supply voltage in real time. The current detection circuit acquires and amplifies the operating current of the DC brushed motor through a 10mΩ sampling resistor and an LMV358IDR operational amplifier, and calculates the effective value of the current. The main control board judges the collected voltage and current data: if Exceeding the 10.5V-14.5V range, or If the value is greater than 15A, the system is deemed abnormal. The brake control unit immediately disables the braking operation, triggers the buzzer of the audible and visual alarm unit to sound, and illuminates the red indicator light. If the status is normal, the system enters the graded braking judgment stage.

[0093] The main control board will display the effective lateral acceleration value. Compare with the preset threshold, match the corresponding braking power level, and use the formula The PWM signal duty cycle is calculated, and the brake control unit outputs a PWM signal with this duty cycle through the MOSFET drive circuit. This signal controls the DC brushed motor to rotate at the target torque. The motor torque is converted into linear tension through the transmission mechanism, pulling the brake cable to overcome the brake return spring force, causing the brake shoes to engage with the brake drum, achieving graded braking. When the sensor detects... For one second, the main control board outputs a brake release command, the motor rotates in the opposite direction, driving the transmission mechanism to reset, the metal bar extends, the brake cable tension disappears, the mechanical pull-rope brake reset spring pulls the brake shoes to reset, the brake cable loosens, and the system returns to its initial state to wait for the next command. By monitoring lateral acceleration in real time through the LSM6DSOWTR three-axis accelerometer and combining it with the 5-level graded braking rules, it achieves precise matching of "sway degree and braking force", effectively solving the problem of unreliable anti-sway control in existing towed caravans, avoiding accidents caused by "death sway", and ensuring the safety of passengers.

[0094] 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 vehicle-mounted control system for towed vehicle stability control based on a mechanical cable brake, characterized in that, Includes controller box, fixing device, transmission mechanism, audible and visual alarm unit and power supply; The controller box is used to output stable control commands. The controller box includes a main control board and a DC brushed motor. The fixing device is used to install and fix the system to the vehicle body; The transmission mechanism is signal-connected to the controller box and is used to perform stable control actions; The audible and visual alarm unit is connected to the controller box and is used to provide feedback on the system's operating status. The audible and visual alarm unit includes a buzzer and an indicator light. The power supply is connected to the controller box and is used to supply power to the controller box.

2. The on-board control system for trailer vehicle stability control based on a mechanical cable brake as described in claim 1, characterized in that, The controller box has a connection port on one side, through which it is connected to the transmission mechanism. A cable is led out from one side of the controller box. The power input end of the cable is used to connect to a power supply, which is a vehicle 12V battery. The signal output end of the cable is connected to an indicator light, which is embedded and fixed on one side of the controller box.

3. The on-board control system for trailer vehicle stability control based on a mechanical cable brake as described in claim 1, characterized in that, The fixing device is made of sheet metal material with a thickness of 4mm; The transmission mechanism is used to convert the torque of the DC brushed motor into a pulling force to pull the brake cable and achieve braking. The specific logical steps are as follows: S101: The output shaft of the DC brushed motor is fixed to the drive commutator gear of the transmission mechanism by a key. After the DC brushed motor starts, the rotational torque of the output shaft is directly transmitted to the drive commutator gear, causing the drive commutator gear to rotate in the set direction. S102: The driving gear rotates, which drives the driven reversing gear to rotate in the opposite direction through tooth surface meshing. When the driven reversing gear rotates, its threaded engagement with the metal rod converts the "rotational motion" into the "linear motion of the metal rod": if the driven reversing gear rotates counterclockwise, the metal rod will extend forward along the gear axis; if the driven reversing gear rotates clockwise, the metal rod will retract backward. S103: The linear movement of the metal bar will directly drive the brake cable to move synchronously: when the metal bar retracts, it will generate a linear pulling force on the brake cable along the axis of the metal bar; when the metal bar extends forward, the brake cable will move forward accordingly. S104: When the metal bar pulls the brake cable to generate tension, the brake cable overcomes the elastic force of the return spring in the mechanical cable brake, pulls the control lever of the brake shoes, and causes the brake shoes to expand outward and fit tightly against the inner wall of the brake drum. S105: When the DC brushed motor rotates in reverse, it drives the active reversing gear to rotate in reverse, which in turn causes the driven reversing gear to rotate in reverse. The threaded engagement between the driven gear and the metal bar works again, and the metal bar changes from the "retracted state" to the "extended state", moving away from the brake cable. The tension in the brake cable disappears, the return spring in the mechanical pull-cord brake returns to its original shape, pulls the brake pads to reset, and the brake cable naturally loosens as the brake pads reset. The transmission mechanism returns to its initial state, waiting for the next braking command.

4. The on-board control system for trailer vehicle stability control based on a mechanical cable brake according to claim 1, characterized in that, The power supply includes a two-stage DC step-down circuit. The first stage uses an XL1509-5.0 chip to convert 12V to 5V, and the second stage uses an AMS1117-3.3 chip to convert 5V to 3.3V to power the various functional modules.

5. The on-board control system for trailer vehicle stability control based on a mechanical cable brake according to claim 1, characterized in that, The main control board uses a control chip with the model number STM32F103C8T6. A crystal oscillator circuit, a voltage detection circuit, a current detection circuit, and a braking control unit are integrated on the main control board; The crystal oscillator circuit consists of an external passive crystal oscillator with the model number X32258MOB4SI and supporting peripheral oscillation capacitors; The voltage detection circuit is used to detect the supply voltage. When the voltage detection circuit detects an abnormal supply voltage, the braking control unit automatically prohibits the braking operation, and the sound and light alarm unit triggers an alarm prompt of the buzzer sounding and the indicator light turning red; The current detection circuit includes a 10mΩ sampling resistor and an operational amplifier circuit. The operational amplifier circuit uses an LMV358IDR operational amplifier to amplify the voltage signal at both ends of the sampling resistor and then input it to the control chip; A diode clamping circuit is provided between the operational amplifier circuit and the control chip; The braking control unit includes a MOS tube drive circuit, which adjusts the PWM signal through the on and off of the MOS tube to control the operation of the DC brushed motor.

6. The on-board control system for trailer vehicle stability control based on a mechanical cable brake according to claim 1, characterized in that, An LSM6DSOWTR three-axis acceleration sensor is integrated on the main control board. The LSM6DSOWTR three-axis acceleration sensor is used to realize the real-time measurement of the body attitude change. The LSM6DSOWTR three-axis acceleration sensor establishes a Cartesian coordinate system with the origin, sets the reference state parameters. When the motorhome is stationary on a horizontal road surface, the acceleration in the X-axis direction is 1g, 1g = 9.8m / s², and the accelerations in the Y-axis and Z-axis directions are both 0; When the towed motorhome undergoes a swaying motion, the acceleration in the Y-axis direction climbs. Once this acceleration value exceeds the preset threshold, the system triggers the braking action in stages according to the current Y-axis acceleration and implements braking control on the towed rear vehicle; And the specific rules for triggering braking in stages are as follows: When the Y-axis acceleration value > 0.5g, the mechanical pull rope brake outputs 100% power; When 0.4g < Y-axis acceleration value ≤ 0.5g, the mechanical pull rope brake outputs 80% power; When 0.3g < Y-axis acceleration value ≤ 0.4g, the mechanical pull rope brake outputs 60% power; When 0.2g < Y-axis acceleration value ≤ 0.3g, the mechanical pull rope brake outputs 40% power; When the Y-axis acceleration value ≤ 0.2g, the mechanical pull rope brake outputs 20% power.

7. The on-board control system for trailer vehicle stability control based on a mechanical cable brake according to claim 6, characterized in that, The specific logic steps for the main control board to realize attitude change measurement and braking based on the LSM6DSOWTR three-axis acceleration sensor are as follows: S201: When the system is powered on and initialized, the main control board sends a "reference calibration instruction" to the LSM6DSOWTR three-axis acceleration sensor. At this time, it is required that the towed motorhome is stationary on a horizontal road surface, without inclination and without sway; S202: The LSM6DSOWTR triaxial accelerometer establishes a Cartesian coordinate system with its own chip's physical center as the origin. The X-axis is parallel to the RV's driving direction, the Y-axis is perpendicular to the driving direction, and the Z-axis is perpendicular to the horizontal road surface and aligned with the direction of gravity. Its reference acceleration is the acceleration due to gravity. Simultaneously, the LSM6DSOWTR triaxial accelerometer continuously collects raw X, Y, and Z-axis acceleration data over 3 seconds and calculates the reference value using a moving average algorithm. The formula used is: Where N=300, the final calibrated reference state parameters are: =1g, =0g, =0g, the main control board will set the reference value =1g, =0g, =0g is stored in the cache as a "deviation correction benchmark" for subsequent real-time measurements; S203: The LSM6DSOWTR triaxial accelerometer continuously acquires real-time raw acceleration data along the X, Y, and Z axes at a frequency of 100Hz, denoted as... , where t is the sampling time; S204: The main control board performs "reference deviation correction" on the raw data to eliminate the zero drift error after initial calibration and obtain the true acceleration value. ,in As the core monitoring value, , Used to assist in judgment; For the revised Low-pass filtering is performed to filter out high-frequency interference such as road bumps. The formula used is: ,in =0.1, The filtered value from the previous time step, finally "The effective lateral acceleration value used for threshold determination"; S205: The main control board collects the 12V battery power supply voltage through a voltage detection circuit. Determine whether the braking conditions are met: If ,or If this occurs, a "voltage abnormality" will be triggered, prohibiting subsequent braking actions and activating both audible and visual alarms. Then it enters the "current detection stage"; S206: The main control board collects the real-time current of the DC brushed motor through a current sampling circuit. Calculate the effective value of the current. Where T=20ms, and a current threshold judgment is performed, if If this triggers an "abnormal current" signal, braking will be disabled and an alarm will sound. If the system status is normal, the system will proceed to the "graded braking judgment stage". S207: The main control board will The braking power level is compared with the preset 5-level acceleration threshold and matched according to the following rules: (1) When To provide maximum braking force in response to severe swaying; (2) When This provides high braking force; (3) When , for the braking force; (4) When This results in low braking force; (5) When As the basic braking force, it only suppresses slight swaying; if three consecutive samples are taken... If all values ​​fall within the same threshold range, then the braking power level is locked. S208: The main control board is based on the braking power level. Calculate the PWM signal duty cycle D required for a DC brushed motor: ,in This is the minimum starting duty cycle for the motor to prevent stalling. This is the maximum safe duty cycle for the motor to avoid overcurrent. S209: The main control board outputs a PWM signal with a duty cycle of D to the DC brushed motor through a MOSFET drive circuit, controlling the DC brushed motor to rotate at the target torque. The motor's rotational torque is converted into tension through the transmission mechanism, pulling the brake cable, and the mechanical pull-cord brake is activated. Output braking force to suppress vehicle lateral sway; during braking, sensors continuously sample data. ,like If the value drops to a lower threshold range, repeat steps S207-S209 to dynamically adjust the braking power. If the condition persists for 1 second, a "brake release command" will be output, the DC brushed motor will stop rotating, and the brake cable will be reset.

8. The on-board control system for trailer vehicle stability control based on a mechanical cable brake according to claim 3, characterized in that, The connecting bolt uses an M8×20 hexagon socket head bolt. The inner diameters of the bolt hole and the joint hole are both 8mm. The connecting bolt is tightly fitted with the bolt hole of the metal bar and the joint hole of the brake wire. The external thread specification of the metal bar is M8×1.25 fine thread, which is precisely matched with the internal thread of the driven reversing gear.

Images