An infrared anti-pinch system and control method for an electric bed based on event-triggered dynamic voltage coding

Abstract

The application discloses an electric bed infrared anti-pinch system and control method based on event triggering dynamic voltage coding. The system comprises a master control unit, a three-core event addressing bus and multiple groups of infrared sensing nodes; the three-core bus is composed of VCC, GND and SIG three lines, and each infrared receiving end output end is connected to the SIG line after being connected in series with a unique resistance value voltage division coding resistor. Under normal conditions, the SIG line maintains an idle reference voltage; when an infrared light beam of a certain path is blocked, the corresponding receiving end is turned on, the SIG voltage jumps to the corresponding voltage window, and the master control unit locates the blocking point by matching the window through ADC sampling, and identifies short circuit, open circuit and power supply abnormality in priority with the fault extreme window. The system also integrates a safety state machine, hierarchical fault diagnosis, automatic calibration and environmental adaptive compensation, motion direction linkage, multi-point blocking processing, and invalid event multi-dimensional discrimination based on voltage dynamic behavior fingerprint, vibration baseline coupling and static scene differential tracking. The application realizes the infrared anti-pinch function with simple wiring, point positioning, high-speed response and complete safety bottom-up without increasing a special communication chip.

Description

Technical Field

[0001] This invention belongs to the field of smart home, electric bed functional safety and non-contact sensing and detection technology, specifically relating to a bus-type infrared anti-pinch protection system and its control method for electric bed lifting mechanism in the danger zone of shearing or squeezing. Background Technology

[0002] During the backrest lifting, leg lifting, and resetting processes of an electric bed, there is relative movement between the bed board, connecting rods, push rods, and base frame. If human limbs, pets, fabrics, or foreign objects enter the shearing area, it can easily cause pinching injuries or mechanical jamming. Therefore, electric beds need to be equipped with a reliable anti-pinch protection system.

[0003] Existing infrared anti-pinch solutions mostly use star-shaped wiring, with each sensor group having an independent wiring harness connected back to the main controller. This results in a large amount of wiring, complex assembly paths, and is prone to misinsertion, omissions, and wiring interference during mass production. If specific obstruction areas need to be identified, additional communication chips such as RS485, LIN, and I2C are usually required, or a large number of MCU input / output ports are occupied, significantly increasing hardware costs and software maintenance complexity.

[0004] Regarding addressing technology, the core purpose of existing bus voltage divider addressing technology (such as CN104820653B) is to statically identify the physical installation location of slave devices. This is a one-time power-on configuration technology: after the device is installed, a voltage value is read once to establish a mapping relationship between address and location, and the voltage value remains constant during operation. This solution is essentially an additional function of the digital communication bus, requiring compatibility with digital communication protocols. The voltage window is strictly constrained by noise tolerance, and it neither supports high-frequency dynamic event detection nor has any safety control, failure fallback, or environmental compensation mechanism. Therefore, it cannot be directly applied to real-time anti-pinch scenarios for personal safety in electric beds.

[0005] In terms of safety mechanisms, most anti-pinch solutions only implement basic logic of stopping when obstructed, lacking graded diagnosis and safety safeguards for typical faults encountered during long-term use, such as bus open circuits or short circuits, sensor aging and drift, power supply abnormalities, and poor contact. Some solutions only rely on binary judgment of continuity to detect faults, lacking scenario-based designs such as degraded operation, automatic calibration, and directional linkage, which easily leads to safety risks of false triggering, missed triggering, or operation with faults.

[0006] Regarding long-term reliability, factors such as large variations in home environment temperature and humidity, power supply voltage fluctuations, aging of infrared devices, and resistor temperature drift can all cause voltage sampling value deviations. Fixed threshold solutions are prone to misjudgments after long-term use. Existing solutions lack automatic calibration and dynamic compensation mechanisms, requiring regular manual calibration, resulting in high after-sales maintenance costs.

[0007] Furthermore, in a bedroom setting, the under-bed storage area of ​​an electric bed is subject to typical activities such as pets walking through, manual cleaning and mopping, and long-term storage of items. A pet or person quickly crossing the under-bed storage area constitutes a brief, non-dangerous obstruction; a broom or mop sweeping back and forth constitutes a reciprocating, non-dangerous obstruction; and items such as storage boxes or shoes stored under the bed long-term constitute a pre-existing static obstruction. However, obstructions requiring immediate response include human limbs being caught, fabrics being caught in the mechanism, and hard foreign objects becoming lodged in the under-bed storage area. Existing solutions all use a uniform amplitude threshold for obstruction detection, failing to distinguish between these different types of obstruction events. This leads to frequent false shutdowns triggered by pets walking through or cleaning actions, forcing users to reduce anti-pinch sensitivity or even disable the anti-pinch function, creating greater safety hazards. Furthermore, items stored under the bed can obstruct the power-on baseline. Existing solutions either refuse to start the bed or treat these as newly entered dangerous objects, neither of which is suitable for the real-world use of under-bed storage in a home. Summary of the Invention

[0008] The purpose of this invention is to provide an event-triggered bus anti-pinch system and its control method customized for electric bed safety scenarios. Without adding a dedicated communication chip, it achieves infrared anti-pinch function with extremely simple wiring, locatable points, high-speed response, complete safety backup, long-term reliable operation, and the ability to distinguish between dangerous and invalid obstructions.

[0009] To achieve the above objectives, the technical solution adopted by the present invention is as follows: An infrared anti-pinch system for an electric bed based on event-triggered dynamic voltage encoding, comprising: The main control unit integrates at least one ADC analog sampling channel, an event recognition module, a safety state machine module, and a motor safety output interface; The three-core event addressing bus consists of three wires: VCC, GND, and SIG. It is arranged in a ring or semi-ring topology along the static bed frame of the electric bed. The three-core event addressing bus is a pure analog event dedicated bus and does not carry digital communication protocols. Multiple sets of infrared emitters, each set of infrared emitters is connected to the VCC line and the GND line, and is configured to continuously emit a carrier-modulated infrared beam; Multiple sets of infrared receivers, each set of infrared receivers is connected to the VCC line and the GND line, and the output of each set of infrared receivers is connected to the SIG line after being connected in series with a voltage divider encoding resistor of a unique resistance value. The main control unit is configured as follows: In the normal idle state, each of the infrared receivers is in a high impedance state, and the SIG line voltage is maintained at the idle reference voltage corresponding to the pull-up level; In the event-triggered state, when one infrared beam is blocked, the corresponding infrared receiver is turned on, and its voltage divider encoding resistor is connected to the SIG circuit, causing the SIG line voltage to jump to the voltage window corresponding to the voltage divider encoding resistor. The main control unit locates the corresponding blocking point by matching the ADC sampling value with the preset voltage window table. In a fault state, the main control unit prioritizes identifying bus short circuit, bus open circuit, or power supply abnormality faults based on the state of the SIG line voltage falling into a preset fault extreme window. In the event recovery state, after the obstruction is removed, the corresponding infrared receiver returns to a high-impedance state, and the SIG line voltage returns to the idle reference voltage.

[0010] Furthermore, the main control unit also integrates a debouncing confirmation module, and the safety state machine module is configured to include the following states and transition logic: S0 Normal Monitoring State: The SIG line voltage is sampled at a preset period, and after sliding median filtering, it is compared with the voltage window table. At the same time, the current movement direction, angle and speed information of the bed are obtained. S1 Event Pre-acknowledgment State: When a sampled value falls into an event window, it enters the pre-acknowledgment state. If a preset number of consecutive samples fall into the same event window and match the current bed movement direction, it is determined to be a valid occlusion event. S2 Safety Execution State: After confirming a valid occlusion event, immediately output a motor stop command through the motor safety output interface, and perform differentiated reverse retraction actions according to the current direction and angle of motion; S3 Lock Waiting State: After performing a safety action, it enters the locked state, prohibiting movement in the corresponding direction. If the obstruction persists, it remains locked and outputs an alarm. If the obstruction is removed, it continues to confirm the absence of abnormalities for a preset period of time before entering the waiting-to-recovery state. S4 Reset Recovery State: After the obstruction is removed and no fault is confirmed, the motion function is automatically unlocked and the system returns to the S0 normal monitoring state.

[0011] Furthermore, the differentiated reverse rollback action in the S2 safe execution state includes: When the headboard descent is triggered, if the current headboard angle is less than 30 degrees, it will retract 5 degrees; if the current headboard angle is greater than or equal to 30 degrees, it will retract 3 degrees. When the leg descent is triggered, if the current leg angle is less than 40 degrees, it will retreat 4 degrees; if the current leg angle is greater than or equal to 40 degrees, it will retreat 2 degrees. When triggered in the side area, it only stops and does not revert.

[0012] Furthermore, the main control unit is configured to read the motion direction and angle information of the motor drive in real time, and trigger a safety action only when the occlusion event occurs on the dangerous side of the current motion direction; occlusion on the non-dangerous side is determined as an invalid event and is not responded to.

[0013] Furthermore, the main control unit also integrates a hierarchical fault diagnosis module, which is configured as follows: When the ADC sampling value of the SIG line voltage is continuously lower than 5% of the full scale and is confirmed 10 times in a row, it is determined to be a bus short circuit fault, the motor enable is cut off and all movement is locked. When the ADC sampled value is continuously higher than 95% of the full scale and is confirmed 10 times in a row, it is determined to be a bus open circuit fault, the motor enable is cut off and all movements are locked. When the sampled value of the power supply voltage VCC exceeds the range of ±15% of the rated voltage, it is determined to be an abnormal power supply, the power output is cut off and the lifting is prohibited, and the self-test will be automatically restarted after the power supply is restored. When the idle reference voltage drifts by more than ±10% of the initial value, automatic temperature drift compensation is triggered and the voltage window threshold is updated; when the drift exceeds ±20% and compensation fails, the system enters degrade mode and retains the basic stop function. When the single-path event trigger voltage continues to deviate and the cumulative operating time exceeds 80% of the design life, mark the corresponding point as aging state and expand the corresponding window margin. When the ADC sampling value changes frequently and irregularly without corresponding motion events, it is determined to be a poor contact and the corresponding area of ​​motion is locked.

[0014] Furthermore, the main control unit also integrates an automatic calibration and environmental adaptive compensation module, which is configured as follows: After the initial power-on or trigger calibration, each infrared receiver is sequentially selected and the corresponding ADC sampling value is recorded. The upper and lower limits of the voltage window for each channel are automatically generated, and a margin of ±15% is reserved before writing to the non-volatile memory. The ambient temperature is collected at preset time intervals, and the voltage window threshold is dynamically corrected based on the temperature coefficient of the voltage divider resistor and the infrared device. The window value is linearly compensated once every 10 degrees Celsius change in temperature. Each time power is applied, the idle reference voltage is recalibrated, and all windows are adjusted synchronously and proportionally in accordance with power supply voltage fluctuations. During the cumulative operation, the trend of trigger voltage changes at each point is recorded periodically to correct the window reference.

[0015] Furthermore, the main control unit is configured to support at least one of the following multi-point occlusion processing modes: Priority mode sorts multiple occlusion events triggered simultaneously according to a preset danger level, with high-priority events being responded to first and all trigger points being recorded; The time-slice polling mode selects the power supply of each infrared receiver in turn with a preset time slice period, and detects the status of each channel in a time-division manner, supporting the identification of at least 16 nodes.

[0016] Furthermore, the main control unit is also configured as follows: Within the event window, calculate the sampling variance, sign flip count, and trend slope for N consecutive ADC sample values, where N is between 10 and 20. Based on the sampling variance within the window, the number of symbol flips, and the trend slope falling into the preset four-mode determination matrix, the occlusion event is determined to be a valid dangerous event or an invalid occlusion event. The four-mode determination matrix includes: a static stable type, where the sampling variance within the window is lower than the first threshold, the trend slope is close to zero, and the number of symbol flips is close to zero, which is determined as a valid dangerous event; a monotonically asymptotic type, where the trend slope is continuously negative and the number of symbol flips is close to zero, which is determined as a valid dangerous event; a reciprocating oscillation type, where the number of symbol flips is higher than the second threshold and the sampling variance within the window is higher than the third threshold, which is determined as an invalid occlusion event; and a brief pulse type, where the baseline is quickly restored after entering the event window, which is determined as an invalid occlusion event.

[0017] Furthermore, the main control unit is also configured as follows: The vibration frequency and vibration amplitude are extracted from the sampling sequence of at least one untriggered ADC channel to form the vibration baseline of the current motion state; When the event window is triggered, it detects whether the frequency and / or amplitude of the vibration baseline of the remaining untriggered channels change abruptly. If a change occurs, it supports the determination of a valid event; if no change occurs, it tends to determine an invalid event.

[0018] Furthermore, the main control unit is also configured as follows: An ADC scan is performed on all channels within a time window of 10 to 50 milliseconds before motor startup. The current blocking voltage of the channel in the event window is recorded as the preset blocking voltage, and the bed is allowed to start normally. During bed movement, differential tracking is performed on the channel that records the preset blocking voltage. When the difference between the current voltage of the channel and the preset blocking voltage exceeds the preset displacement criterion, the channel is upgraded to a dynamic event and a safety action is performed; when the difference does not exceed the preset displacement criterion, the safety judgment of the channel is skipped.

[0019] Furthermore, N is 16; the sampling variance within the window is normalized to the full-scale square, and the sampling variance within the window for the statically stable type is less than 0.5% of the full-scale square; the absolute value of the trend slope is less than 0.02% of the full-scale per millisecond; and the number of sign flips is less than or equal to 2.

[0020] Furthermore, the ADC analog sampling channel is a 12-bit ADC, and the system power supply is 5V DC; the resistance values ​​of the voltage divider encoding resistors include seven levels: 1k ohm, 2.2k ohm, 3.3k ohm, 4.7k ohm, 5.6k ohm, 6.8k ohm, and 8.2k ohm, with a voltage difference of no less than 200 millivolts between adjacent windows; the main control unit samples the SIG line voltage at a 1-millisecond cycle, and completes anti-jitter confirmation when three consecutive samples fall into the same event window, with a total response time of no more than 80 milliseconds.

[0021] According to a second aspect of the present invention, an infrared anti-pinch control method for an electric bed based on event-triggered dynamic voltage encoding is provided, comprising: A three-core event addressing bus is constructed, and multiple sets of infrared transmitters and infrared receivers are connected in parallel to the three-core event addressing bus. Each infrared receiver output is connected in series with a voltage divider encoding resistor of a unique resistance value. The SIG line voltage is sampled at a preset period, filtered, and then compared with a preset voltage window table. When the sampled value falls into the event window, it is determined to be a valid occlusion event after being confirmed by anti-shake measures for a preset number of consecutive times and matching the current direction of bed movement. Based on the location of the occlusion event and the current movement state of the bed, execute differentiated safety response actions; After the obstruction is removed and no abnormalities are confirmed, the system will automatically unlock and return to normal monitoring.

[0022] Furthermore, it also includes fault diagnosis steps: When the sampled value is consistently below 5% of the full scale and confirmed 10 times consecutively, it is determined to be a bus short circuit fault; when the sampled value is consistently above 95% of the full scale and confirmed 10 times consecutively, it is determined to be a bus open circuit fault; in both cases, the motor enable is immediately cut off and all movements are locked. When the sampled value of the power supply voltage exceeds ±15% of the rated voltage, it is determined to be an abnormal power supply and the power output is cut off. Automatic temperature drift compensation is triggered when the idle reference voltage drifts by more than ±10% of the initial value; if it exceeds ±20% and compensation fails, it enters degrade mode. When the single-channel event trigger voltage continues to deviate and the cumulative operating time exceeds 80% of the design life, mark the aging state and expand the corresponding window margin; When the ADC sampling value changes frequently and irregularly without corresponding motion events, it is determined to be a poor contact and the corresponding area of ​​motion is locked.

[0023] Furthermore, it also includes automatic calibration and environmental adaptive compensation steps: After the initial power-on or trigger calibration, each infrared receiver is selected sequentially and the ADC sampling value is recorded. The upper and lower limits of the voltage window for each channel are automatically generated and a margin of ±15% is reserved. During operation, ambient temperature is collected at preset time intervals, and linear compensation is performed on the window value every 10 degrees Celsius change in temperature. Each time power is applied, the idle reference voltage is recalibrated, and all windows are adjusted synchronously and proportionally in response to power supply voltage fluctuations.

[0024] Furthermore, it also includes invalid event identification steps: Within the event window, calculate the sampling variance, sign flip count, and trend slope for N consecutive ADC sample values, where N is between 10 and 20. Based on the sampling variance within the window, the number of symbol flips, and the trend slope falling into the preset four-mode determination matrix, the occlusion event is determined to be a valid dangerous event or an invalid occlusion event. Among them, static and stable types and monotonically progressive types are judged as valid hazardous events, while reciprocating oscillation types and brief pulse types are judged as invalid blocking events.

[0025] Furthermore, it also includes a vibration baseline coupling step: The vibration frequency and vibration amplitude are extracted from the sampling sequence of at least one untriggered ADC channel to form a vibration baseline; When the event window is triggered, detect whether the frequency and / or amplitude of the vibration baseline of the remaining untriggered channels change abruptly. If a change occurs, it supports the determination of a valid event; if no change occurs, it tends to determine an invalid event.

[0026] Furthermore, it also includes static scene learning and differential tracking steps: ADC scans are performed on all channels within a time window of 10 to 50 milliseconds before motor startup. For channels within the event window, preset blocking voltages are recorded and the bed is allowed to start normally. Differential tracking is performed on the channel during bed movement. When the difference between the current voltage and the preset blocking voltage exceeds the preset displacement criterion, it is upgraded to a dynamic event and a safety action is performed.

[0027] According to a third aspect of the present invention, a method for identifying invalid infrared anti-pinch events in an electric bed includes: During the occlusion event, acquire N consecutive ADC samples of the SIG line voltage, and calculate the sampling variance, sign flip count, and trend slope within the window, where N is between 10 and 20. Based on the sampling variance within the window, the number of symbol flips, and the trend slope falling into the preset four-mode determination matrix, the occlusion event is determined to be a valid dangerous event or an invalid occlusion event. Obtain the vibration baseline of at least one untriggered channel during the event, and detect whether the frequency and / or amplitude of the vibration baseline undergo a sudden change, as an auxiliary basis for determining a valid event; Before the bed movement starts, static scene learning is performed on all channels to record the preset blocking voltage of the preset blocking channel. During the bed movement, differential tracking is performed on the preset blocking channel. When the difference between the current voltage and the preset blocking voltage exceeds the preset displacement criterion, the preset blocking channel is upgraded to a dynamic event. The four-mode determination matrix includes: static stable type and monotonically progressive type are determined as valid dangerous events, while reciprocating oscillation type and brief pulse type are determined as invalid occlusion events.

[0028] Beneficial effects 1) The wiring is extremely simple, and the cost is significantly reduced. The three-core bus parallel architecture replaces the star wiring, which reduces the amount of wire used by about 70%, shortens the assembly time by about 50%, and reduces the material cost per unit by about 8 to 12 yuan; no additional communication chip is required, and point-level recognition can be achieved solely by the MCU's built-in ADC.

[0029] 2) High safety level and fast response. The complete safety state machine and graded fault fallback ensure that the total response time is no more than 80 milliseconds, which is better than the industry standard of 200 milliseconds; the differentiated reverse backoff strategy can reduce the maximum clamping force by more than 70%, meeting the functional safety level B requirements.

[0030] 3) High long-term reliability and low maintenance cost. Automatic calibration and environmental compensation mechanisms can offset the effects of temperature drift, aging and power fluctuations, with a mean time between failures (MTBF) of no less than 50,000 hours; fault codes directly locate the fault points, reducing after-sales troubleshooting time from an average of 30 minutes to approximately 2 minutes.

[0031] 4) Low false trigger rate and good user experience. The motion direction linkage logic and multi-level anti-shake confirmation can reduce the false trigger rate by more than 90% in non-dangerous scenarios such as bedding, clothing, and pets passing by quickly.

[0032] 5. Accurate identification of invalid events. Through voltage dynamic behavior fingerprinting, vibration baseline coupling and static scene differential tracking, it can distinguish between pets walking through, cleaning tools passing by, objects stored under the bed and human limbs being caught, fabric being rolled up and foreign objects getting stuck without adding any additional sensors. This effectively reduces the false stop rate and prevents users from accidentally turning off the anti-pinch function. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0034] Figure 1 This is a block diagram of the overall hardware architecture of the electric bed infrared anti-pinch system of the present invention.

[0035] Figure 2 This is a schematic diagram illustrating the principle of the event-triggered dynamic voltage encoding interval of the present invention.

[0036] Figure 3 This is the flow logic diagram of the anti-pinch safety state machine of the present invention.

[0037] Figure 4 This is a fault tree diagram for hierarchical fault diagnosis and failure safety of the present invention.

[0038] Figure 5 This is a flowchart of the automatic calibration and environmental compensation method of the present invention.

[0039] Figure label: 101-Main control unit; 102-Three-core event addressing bus; 103-Infrared transmitter; 104-Infrared receiver; 105-Voltage divider encoder resistor; 106-Power supply protection circuit; 107-Motor drive interface; 108-Status reporting module. Detailed Implementation

[0040] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0041] To ensure clarity, the abbreviations used in this application are explained below: ADC refers to Analog-to-Digital Converter; SIG refers to Event Signal Line; VCC refers to Positive Power Supply; GND refers to Ground Power Supply; FS refers to ADC Full Scale; N_flip refers to the number of sign flips in adjacent sampled differential sequences; σ² refers to the sampling variance within the window; k refers to the slope of the linear regression trend of the sampled sequences within the window; and MTBF refers to Mean Time Between Failures (MTBF).

[0042] Example 1 like Figure 1As shown, the electric bed infrared anti-pinch system of the present invention includes a main control unit 101, a three-core event addressing bus 102, multiple sets of infrared transmitters 103, multiple sets of infrared receivers 104, a voltage divider encoding resistor 105, a power protection circuit 106, a motor drive interface 107, and a status reporting module 108.

[0043] The main control unit 101 uses a general-purpose 32-bit MCU with a 12-bit ADC, and the system is powered by 5V DC. The main control unit 101 integrates an event recognition module, a de-jitter confirmation module, a safety state machine module, a hierarchical fault diagnosis module, an automatic calibration and environmental adaptive compensation module, and a motor safety output interface.

[0044] The 102 three-core event-addressable bus is a dedicated analog event bus, consisting of three wires: a brown VCC wire, a blue GND wire, and a black SIG wire. The bus uses three-core, highly flexible sheathed cable, arranged in a ring along the inner side of the static bed frame of the electric bed, avoiding the movement paths of push rods, connecting rods, etc., with a 10mm micro-motion margin reserved at the transition points. The bus does not carry any digital communication protocol; it can be used for event encoding across the entire voltage range and is not constrained by the noise tolerance of digital protocols.

[0045] The headboard lifting area is equipped with infrared beam sensors, including one pair along the top edge, one pair along each of the left and right sides, and one pair along the bottom edge. The leg lifting area 202 is equipped with three pairs of infrared beam sensors, including one pair along the bottom edge and one pair along each of the left and right sides. Each transmitter 103 uses 38kHz carrier modulation for transmission and is connected in parallel to the VCC and GND lines. Each receiver 104 is a synchronous demodulation receiver, and its output is connected to the SIG line after being connected in series with the corresponding voltage divider encoding resistor 105.

[0046] The resistance values ​​of the voltage divider encoder resistor 105 are configured with different values ​​according to the number of points. In this embodiment, the resistance values ​​are 1k ohms, 2.2k ohms, 3.3k ohms, 4.7k ohms, 5.6k ohms, 6.8k ohms, and 8.2k ohms, increasing sequentially, with the voltage difference between adjacent windows not less than 200 millivolts. The resolution of the 12-bit ADC under 5V power supply is approximately 1.2 millivolts, which can reliably distinguish the voltage difference between the aforementioned adjacent windows.

[0047] The power supply protection circuit 106 integrates reverse connection protection, overvoltage protection, overcurrent protection, and electromagnetic compatibility filtering functions. The motor drive interface 107 is used to perform safety actions such as stop, reverse retraction, and locking. The status reporting module 108 is used to output trigger point positions, fault codes, and operating status information.

[0048] Example 2 like Figure 2 As shown, the core of this invention lies in the event-triggered dynamic voltage encoding mechanism, which differs from existing static address recognition technology.

[0049] In the normal idle state, all infrared light paths are unobstructed, and the outputs of each infrared receiver 104 are in a high-impedance state. The SIG line voltage is maintained at the pull-up level by the pull-up resistor inside the main control unit 101. This voltage value serves as the idle reference voltage and falls into the range. Figure 2 The idle reference voltage window 301 is shown.

[0050] When a certain infrared beam is blocked, the corresponding infrared receiver 104 is turned on. The voltage divider encoding resistor 105 connected in series at its output terminal is connected to the SIG circuit, forming a voltage divider circuit with the pull-up resistor. This causes the SIG line voltage to jump from the idle reference voltage to the normal event encoding voltage window corresponding to the voltage divider encoding resistor. The main control unit 101 samples the SIG line voltage at a 1-millisecond period using a 12-bit ADC. After sliding median filtering, the sample is matched with a preset voltage window table to uniquely determine the location of the blocked optical path.

[0051] Fault state code correspondence Figure 2 The fault extreme voltage windows shown are as follows: when the bus is short-circuited, the SIG voltage is close to 0V; when the bus is open-circuited, the SIG voltage is close to VCC; and when the power supply is abnormal, the SIG voltage deviates overall. The priority of the above extreme windows is higher than that of the normal event coded voltage windows.

[0052] Example 3 like Figure 3 As shown, the anti-pinch safety state machine includes five states, S0 to S4.

[0053] S0 Normal Monitoring State: The main control unit 101 samples the SIG line voltage at a 1-millisecond cycle, performs sliding median filtering on the most recent 5 sampled values, compares them with the preset voltage window table, and simultaneously reads the current bed's motion direction, angle, and speed parameters.

[0054] S1 Event Pre-acknowledgment State: When a sampled value falls into a certain event window, the system enters the pre-acknowledgment state; if three consecutive samples (totaling 3 milliseconds) fall into the same event window and match the current bed movement direction, it is determined to be a valid occlusion event. For example, occlusion at the lower edge when the bed backrest is lowering is a valid event, while occlusion at the same position when the bed backrest is rising is an invalid event.

[0055] S2 Safety Execution State: After confirming a valid obstruction event, the main control unit 101 immediately outputs a motor stop command through the motor drive interface 107, and simultaneously executes differentiated reverse retraction: When the bed backrest is triggered, if the current bed backrest angle is less than 30 degrees, it retracts by 5 degrees; if it is greater than or equal to 30 degrees, it retracts by 3 degrees. When the leg descent is triggered, if the current leg angle is less than 40 degrees, it retracts by 4 degrees; if it is greater than or equal to 40 degrees, it retracts by 2 degrees. When the side area is triggered, it only stops and does not retract to avoid secondary compression.

[0056] S3 Locked Waiting State: After performing a safety action, it enters a locked state, prohibiting movement in the corresponding direction; if the obstruction persists, it remains locked and outputs an alarm; if the obstruction is removed, it continues to confirm for 500 milliseconds that there are no abnormalities before entering a waiting state.

[0057] S4 Reset Recovery State: After the obstruction is removed and no fault is confirmed, the motion function will be automatically unlocked and the system will return to the S0 normal monitoring state. If the fault is triggered, a manual reset and a self-test will be required before the system can be restored.

[0058] The basis for segmented retraction at an angle is that when the backrest angle is small, the gap between the bed board and the bed frame is large, and the retraction stroke needs to be long enough to release the clamp; when the angle is large, the gap has become significantly smaller, and an excessive retraction stroke may cause other parts to enter a new compression zone. Therefore, the retraction amount decreases as the angle increases.

[0059] Example 4 like Figure 4 As shown, a graded diagnosis mechanism is designed for typical faults in electric beds used over a long period of time, which are divided into two categories: hard faults and soft faults.

[0060] Hard fault (Level 1 fault, direct lockout): Bus short circuit, ADC sampling value continuously below 5% of full scale for 10 consecutive confirmations, immediately cut off motor enable, lock all movement and report bus short circuit fault code, manual troubleshooting and reset required; Bus open circuit, ADC sampling value continuously above 95% of full scale for 10 consecutive confirmations, same action as above; Power supply abnormality, VCC sampling value exceeds rated voltage ±15%, cut off power output and prohibit lifting, automatically retest after power supply is restored.

[0061] Soft faults (Level 2 faults, degraded or self-repairing): Reference temperature drift: When the idle reference voltage drifts more than ±10% of the initial value, automatic temperature drift compensation is triggered and the voltage window threshold is updated. When the drift exceeds ±20% and compensation fails, degraded mode is entered, only the basic stop function is retained and a calibration prompt is reported; Sensor aging: When the single-channel event trigger voltage continuously deviates and the cumulative running time exceeds 80% of the design life, the corresponding point is marked as aging, the corresponding window margin is expanded, and a sensor failure warning is reported; Poor contact: When the ADC sampling value changes frequently and irregularly without corresponding motion events, it is determined to be poor wiring harness contact, the corresponding area is locked, and a poor contact fault code is reported.

[0062] The measured average fault detection response time is 85 milliseconds, with a worst of 98 milliseconds, which meets the design specification of no more than 100 milliseconds.

[0063] Example 5 like Figure 5 As shown, a three-layer compensation mechanism is designed to solve the accuracy drift problem during long-term use.

[0064] Initial power-on self-calibration: After the device is powered on for the first time or calibration is manually triggered, the main control unit 101 sequentially selects each infrared receiver 104 and records the corresponding ADC sampling value. It automatically generates the upper and lower limits of the voltage window for each channel, reserves a margin of ±15%, and writes it into the non-volatile memory without requiring manual parameter input. After self-calibration, the window center error does not exceed ±1.5% of the full scale, which is better than ±8% of the full scale when parameters are manually entered.

[0065] Periodic temperature drift compensation: The system has a built-in temperature sampling channel that collects the ambient temperature every 10 minutes and dynamically corrects the voltage window threshold based on the temperature coefficient of the voltage divider resistor 105 and the infrared device; the window value is linearly compensated once every 10 degrees Celsius change in temperature.

[0066] Aging and Power Follow-up Compensation: The idle reference voltage is recalibrated each time it is powered on, and the entire window is automatically adjusted proportionally to follow the power supply voltage fluctuations. For example, when the 5V power supply drops to 4.8V, all windows are adjusted proportionally. During the cumulative operation, the change trend of the trigger voltage at each point is recorded periodically to slowly correct the window reference and offset the drift caused by device aging.

[0067] Example 6 The main control unit 101 reads the motion direction and angle information of the motor drive in real time, and only triggers the safety action when the obstruction event occurs on the dangerous side of the current motion direction; obstruction on the non-dangerous side is judged as an invalid event and no response is given. For example, during the bed backrest raising process, obstruction in the upper edge area of ​​the bed backrest will not trigger a stop; during the bed backrest lowering process, obstruction in the same area will trigger a stop and retraction.

[0068] For scenarios where multiple sensors are simultaneously blocked, the system supports two configurable processing modes. The priority mode sorts events by hazard level, in the order of lower edge of the headboard, lower edge of the legs, side areas, and end areas, responding first to higher priority events and recording all trigger points. The time-slice polling mode uses 10-millisecond time slices to alternately power each infrared receiver 104, detecting the status of each receiver in a time-division manner. This avoids voltage superposition issues caused by multiple receivers being simultaneously active, preventing identification problems. It supports accurate identification of up to 16 nodes.

[0069] Example 7 In this embodiment, after the S1 event pre-confirmation stage, multi-dimensional discrimination is performed on the ADC sampled values ​​within N consecutive windows, where N is 16, corresponding to a 16-millisecond sampling sequence.

[0070] Method 1 is voltage dynamic behavior fingerprint recognition. For N sampled values, the sampling variance σ² within the window, the number of sign flips N_flip between adjacent sampled difference sequences, and the linear regression trend slope k are calculated. σ² is normalized to the full-scale square; for the static stable type, σ² is less than 0.5% of the full-scale square, |k| is less than 0.02% of the full-scale per millisecond, and N_flip is less than or equal to 2; for the reciprocating oscillation type, N_flip is significantly higher and σ² is higher than the third threshold; for the monotonically progressive type, k is consistently negative and N_flip approaches zero. Based on the four-mode judgment matrix: the static stable type corresponds to a human limb clamping or a hard foreign object completely cutting off the light path, judged as a valid dangerous event; the monotonically progressive type corresponds to fabric being dragged and pulled in one direction by the bed movement, judged as a valid dangerous event; the reciprocating oscillation type corresponds to a broom or mop repeatedly sweeping across, judged as an invalid occlusion event; and the short-pulse type corresponds to a pet or person rapidly crossing the shear zone, judged as an invalid occlusion event.

[0071] Method 2 involves baseline coupling analysis of bed motion vibration. During operation, the electric bed's push rod motor transmits regular mechanical vibrations to the SIG bus via the bed frame, manifesting as small periodic disturbances in the idle reference voltage. The main control unit 101 continuously extracts the vibration frequency and amplitude from the ADC sampling sequence of untriggered channels in the S0 normal monitoring state, forming a real-time vibration baseline. In this embodiment, the unloaded vibration baseline frequency is 15 Hz ± 2 Hz, and the amplitude is 40 mV ± 8 mV. When an event window is triggered, the vibration baselines of the remaining untriggered channels are simultaneously detected: if the frequency change exceeds 3 Hz or the amplitude increases by more than 30%, it indicates a change in motor load or a mechanical interaction between the obstruction and the mechanism, supporting a valid event determination; if there is no sudden change, it tends to be considered an invalid event.

[0072] Method 3 involves static scene learning and differential tracking before movement. After the user presses the control key, within the delay window before the motor starts (30 milliseconds in this embodiment), the main control unit 101 performs a fast ADC scan on all channels: for channels in the event window, the current blocking voltage is recorded as the preset blocking voltage V_pre, and the bed is allowed to start normally; channels in the idle reference state are marked as unobstructed before movement. During the movement of the bed, differential tracking is performed on the preset blocking channels: if the difference between the current voltage and V_pre does not exceed the preset displacement criterion (10% of the event window width in this embodiment), it is determined that the preset object has not moved, and the safety judgment is skipped; if the difference exceeds the criterion, it indicates that the preset object has been pushed and displaced by the bed mechanism, and it is immediately upgraded to a dynamic event. After confirmation by Method 1 and Method 2, a safety action is triggered.

[0073] Example 8 Performance tests were performed on the complete prototype, and the main results are summarized as follows: The three-core bus solution reduces the amount of wiring by 70% compared to the star-shaped wiring, shortens assembly time by 50%, and reduces the material cost per unit by approximately 8 to 12 yuan; the total response time is no more than 80 milliseconds, with a measured average of 52 milliseconds; the fault detection response time is no more than 100 milliseconds, with a measured average of 85 milliseconds; the maximum clamping force after reverse rollback is reduced by an average of 71.6%; the false trigger rate of non-dangerous obstruction is reduced by 90.3%; the false trigger rate of invalid events is 1.33%, and the recall rate of valid events is 100%; the mean time between failures (MTBF) calculated based on accelerated aging tests is no less than 50,000 hours.

[0074] No individual calibration is required during the production phase; the equipment automatically completes calibration upon initial power-on before leaving the factory. Customers can recalibrate via a button after replacing sensors on-site. Fault codes directly pinpoint the fault location, reducing after-sales troubleshooting time from an average of 30 minutes to approximately 2 minutes.

[0075] Those skilled in the art will understand that the following alternatives are all equivalent variations of the present invention: 1. Bus configuration replacement: The three-core bus can be equivalently replaced by a two-core power supply and shielded signal cable, flat ribbon cable or flexible printed circuit board, as long as the three electrical functions of VCC, GND and SIG are maintained.

[0076] 2. Sensing method replacement: The infrared through-beam receiver can be replaced with a diffuse reflection photoelectric sensor, a slotted photoelectric switch, or a pyroelectric sensor; the carrier modulation frequency is not limited to 38kHz, and other carrier frequencies or pulse modulation methods can be used.

[0077] 3. Alternative encoding methods: The voltage divider encoding resistor can be implemented using constant current source voltage divider, resistor network switching, or potentiometer preset methods; the voltage window division can be increased or decreased with the number of nodes, and is not limited to seven levels.

[0078] 4. Sampling and confirmation parameter substitution: The sampling period, filter window length, number of consecutive confirmations, N value, and thresholds for σ², N_flip, and k can be adjusted according to the MCU computing power and scene false triggering requirements.

[0079] 5. State machine replacement: The S3 lock-waiting state can be merged into the S2 safe execution state, or an S5 manual reset state can be added; the retraction angle threshold and retraction amount can be adjusted according to the bed structure.

[0080] 6. Multi-point processing alternative: The time slice length, polling order, and hazard level order in the priority mode of time slice polling can be configured according to the actual site layout.

[0081] 7. Calibration compensation alternative: Temperature sampling period, linear compensation slope, self-calibration margin ratio, and aging correction period can be adjusted according to the device temperature coefficient and expected lifespan.

[0082] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An infrared anti-pinch system for an electric bed based on event-triggered dynamic voltage encoding, characterized in that, include: The main control unit integrates at least one ADC analog sampling channel, an event recognition module, a safety state machine module, and a motor safety output interface; The three-core event addressing bus consists of three wires: VCC, GND, and SIG. It is arranged in a ring or semi-ring topology along the static bed frame of the electric bed. The three-core event addressing bus is a pure analog event dedicated bus and does not carry digital communication protocols. Multiple sets of infrared emitters, each set of infrared emitters is connected to the VCC line and the GND line, and is configured to continuously emit a carrier-modulated infrared beam; Multiple sets of infrared receivers, each set of infrared receivers is connected to the VCC line and the GND line, and the output of each set of infrared receivers is connected to the SIG line after being connected in series with a voltage divider encoding resistor of a unique resistance value. The main control unit is configured as follows: In the normal idle state, each of the infrared receivers is in a high impedance state, and the SIG line voltage is maintained at the idle reference voltage corresponding to the pull-up level; In the event-triggered state, when one infrared beam is blocked, the corresponding infrared receiver is turned on, and its voltage divider encoding resistor is connected to the SIG circuit, causing the SIG line voltage to jump to the voltage window corresponding to the voltage divider encoding resistor. The main control unit locates the corresponding blocking point by matching the ADC sampling value with the preset voltage window table. In a fault state, the main control unit prioritizes identifying bus short circuit, bus open circuit, or power supply abnormality faults based on the state of the SIG line voltage falling into a preset fault extreme window. In the event recovery state, after the obstruction is removed, the corresponding infrared receiver returns to a high-impedance state, and the SIG line voltage returns to the idle reference voltage.

2. The electric bed infrared anti-pinch system according to claim 1, characterized in that, The main control unit also integrates a debouncing confirmation module, and the safety state machine module is configured to include the following states and transition logic: S0 Normal Monitoring State: The SIG line voltage is sampled at a preset period, and after sliding median filtering, it is compared with the voltage window table. At the same time, the current movement direction, angle and speed information of the bed are obtained. S1 Event Pre-acknowledgment State: When a sampled value falls into an event window, it enters the pre-acknowledgment state. If a preset number of consecutive samples fall into the same event window and match the current bed movement direction, it is determined to be a valid occlusion event. S2 Safety Execution State: After confirming a valid occlusion event, immediately output a motor stop command through the motor safety output interface, and perform differentiated reverse retraction actions according to the current direction and angle of motion; S3 Lock Waiting State: After performing a safety action, it enters the locked state, prohibiting movement in the corresponding direction. If the obstruction persists, it remains locked and outputs an alarm. If the obstruction is removed, it continues to confirm the absence of abnormalities for a preset period of time before entering the waiting-to-recovery state. S4 Reset Recovery State: After the obstruction is removed and no fault is confirmed, the motion function is automatically unlocked and the system returns to the S0 normal monitoring state.

3. The electric bed infrared anti-pinch system according to claim 2, characterized in that, The differentiated reverse rollback actions in the S2 safe execution state include: When the headboard descent is triggered, if the current headboard angle is less than 30 degrees, it will retract 5 degrees; if the current headboard angle is greater than or equal to 30 degrees, it will retract 3 degrees. When the leg descent is triggered, if the current leg angle is less than 40 degrees, it will retreat 4 degrees; if the current leg angle is greater than or equal to 40 degrees, it will retreat 2 degrees. When triggered in the side area, it only stops and does not revert.

4. The electric bed infrared anti-pinch system according to claim 1, characterized in that, The main control unit is configured to read the motion direction and angle information of the motor drive in real time, and trigger a safety action only when the occlusion event occurs on the dangerous side of the current motion direction. Occlusion on the non-dangerous side is determined to be an invalid event and is not responded to.

5. The electric bed infrared anti-pinch system according to claim 1, characterized in that, The main control unit also integrates a hierarchical fault diagnosis module, which is configured as follows: When the ADC sampling value of the SIG line voltage is continuously lower than 5% of the full scale and is confirmed 10 times in a row, it is determined to be a bus short circuit fault, the motor enable is cut off and all movement is locked. When the ADC sampled value is continuously higher than 95% of the full scale and is confirmed 10 times in a row, it is determined to be a bus open circuit fault, the motor enable is cut off and all movements are locked. When the sampled value of the power supply voltage VCC exceeds the range of ±15% of the rated voltage, it is determined to be an abnormal power supply, the power output is cut off and the lifting is prohibited, and the self-test will be automatically restarted after the power supply is restored. When the idle reference voltage drifts by more than ±10% of the initial value, automatic temperature drift compensation is triggered and the voltage window threshold is updated; when the drift exceeds ±20% and compensation fails, the system enters degrade mode and retains the basic stop function. When the single-path event trigger voltage continues to deviate and the cumulative operating time exceeds 80% of the design life, mark the corresponding point as aging state and expand the corresponding window margin. When the ADC sampling value changes frequently and irregularly without corresponding motion events, it is determined to be a poor contact and the corresponding area of ​​motion is locked.

6. The electric bed infrared anti-pinch system according to claim 1, characterized in that, The main control unit also integrates an automatic calibration and environmental adaptive compensation module, which is configured as follows: After the initial power-on or trigger calibration, each infrared receiver is sequentially selected and the corresponding ADC sampling value is recorded. The upper and lower limits of the voltage window for each channel are automatically generated, and a margin of ±15% is reserved before writing to the non-volatile memory. The ambient temperature is collected at preset time intervals, and the voltage window threshold is dynamically corrected based on the temperature coefficient of the voltage divider resistor and the infrared device. The window value is linearly compensated once every 10 degrees Celsius change in temperature. Each time power is applied, the idle reference voltage is recalibrated, and all windows are adjusted synchronously and proportionally in accordance with power supply voltage fluctuations. During the cumulative operation, the trend of trigger voltage changes at each point is recorded periodically to correct the window reference.

7. The electric bed infrared anti-pinch system according to claim 1, characterized in that, The main control unit is configured to support at least one of the following multi-point occlusion processing modes: Priority mode sorts multiple occlusion events triggered simultaneously according to a preset danger level, with high-priority events being responded to first and all trigger points being recorded; The time-slice polling mode selects the power supply of each infrared receiver in turn with a preset time slice period, and detects the status of each channel in a time-division manner, supporting the identification of at least 16 nodes.

8. The electric bed infrared anti-pinch system according to claim 1, characterized in that, The main control unit is also configured to: Within the event window, calculate the sampling variance, sign flip count, and trend slope for N consecutive ADC sample values, where N is between 10 and 20. Based on the sampling variance within the window, the number of symbol flips, and the trend slope falling into the preset four-mode determination matrix, the occlusion event is determined to be a valid dangerous event or an invalid occlusion event. The four-mode determination matrix includes: a static stable type, where the sampling variance within the window is lower than the first threshold, the trend slope is close to zero, and the number of symbol flips is close to zero, which is determined as a valid dangerous event; a monotonically asymptotic type, where the trend slope is continuously negative and the number of symbol flips is close to zero, which is determined as a valid dangerous event; a reciprocating oscillation type, where the number of symbol flips is higher than the second threshold and the sampling variance within the window is higher than the third threshold, which is determined as an invalid occlusion event; and a brief pulse type, where the baseline is quickly restored after entering the event window, which is determined as an invalid occlusion event.

9. The infrared anti-pinch system for electric beds according to claim 8, characterized in that, The main control unit is also configured to: The vibration frequency and vibration amplitude are extracted from the sampling sequence of at least one untriggered ADC channel to form the vibration baseline of the current motion state; When the event window is triggered, it detects whether the frequency and / or amplitude of the vibration baseline of the remaining untriggered channels change abruptly. If a change occurs, it supports the determination of a valid event; if no change occurs, it tends to determine an invalid event.

10. The infrared anti-pinch system for electric beds according to claim 8, characterized in that, The main control unit is also configured to: An ADC scan is performed on all channels within a time window of 10 to 50 milliseconds before motor startup. The current blocking voltage of the channel in the event window is recorded as the preset blocking voltage, and the bed is allowed to start normally. During bed movement, differential tracking is performed on the channel that records the preset blocking voltage. When the difference between the current voltage of the channel and the preset blocking voltage exceeds the preset displacement criterion, the channel is upgraded to a dynamic event and a safety action is performed. If the difference does not exceed the preset displacement criterion, the safety determination of this channel is skipped.

11. The infrared anti-pinch system for electric beds according to claim 8, characterized in that, N is 16; the sampling variance within the window is normalized to the full-scale square, and the sampling variance within the window for the statically stable type is less than 0.5% of the full-scale square; the absolute value of the trend slope is less than 0.02% of the full-scale per millisecond; the number of sign flips is less than or equal to 2.

12. The infrared anti-pinch system for electric beds according to claim 1, characterized in that, The ADC analog sampling channel is a 12-bit ADC, and the system power supply is 5V DC; the resistance values ​​of the voltage divider encoding resistors include seven levels: 1k ohm, 2.2k ohm, 3.3k ohm, 4.7k ohm, 5.6k ohm, 6.8k ohm and 8.2k ohm, and the voltage difference between adjacent windows is not less than 200 millivolts; the main control unit samples the SIG line voltage at a period of 1 millisecond, and completes the anti-jitter confirmation when three consecutive samples fall into the same event window, with a total response time of not more than 80 milliseconds.

13. A method for infrared anti-pinch control of an electric bed based on event-triggered dynamic voltage encoding, characterized in that, include: A three-core event addressing bus is constructed, and multiple sets of infrared transmitters and infrared receivers are connected in parallel to the three-core event addressing bus. Each infrared receiver output is connected in series with a voltage divider encoding resistor of a unique resistance value. The SIG line voltage is sampled at a preset period, filtered, and then compared with a preset voltage window table. When the sampled value falls into the event window, it is determined to be a valid occlusion event after being confirmed by anti-shake measures for a preset number of consecutive times and matching the current direction of bed movement. Based on the location of the occlusion event and the current movement state of the bed, execute differentiated safety response actions; After the obstruction is removed and no abnormalities are confirmed, the system will automatically unlock and return to normal monitoring.

14. The infrared anti-pinch control method for an electric bed according to claim 13, characterized in that, It also includes fault diagnosis steps: When the sampled value is consistently below 5% of the full scale and confirmed 10 times consecutively, it is determined to be a bus short circuit fault; when the sampled value is consistently above 95% of the full scale and confirmed 10 times consecutively, it is determined to be a bus open circuit fault; in both cases, the motor enable is immediately cut off and all movements are locked. When the sampled value of the power supply voltage exceeds ±15% of the rated voltage, it is determined to be an abnormal power supply and the power output is cut off. Automatic temperature drift compensation is triggered when the idle reference voltage drifts by more than ±10% of the initial value; if it exceeds ±20% and compensation fails, it enters degrade mode. When the single-channel event trigger voltage continues to deviate and the cumulative operating time exceeds 80% of the design life, mark the aging state and expand the corresponding window margin; When the ADC sampling value changes frequently and irregularly without corresponding motion events, it is determined to be a poor contact and the corresponding area of ​​motion is locked.

15. The infrared anti-pinch control method for an electric bed according to claim 13, characterized in that, It also includes automatic calibration and environmental adaptive compensation steps: After the initial power-on or trigger calibration, each infrared receiver is selected sequentially and the ADC sampling value is recorded. The upper and lower limits of the voltage window for each channel are automatically generated and a margin of ±15% is reserved. During operation, ambient temperature is collected at preset time intervals, and linear compensation is performed on the window value every 10 degrees Celsius change in temperature. Each time power is applied, the idle reference voltage is recalibrated, and all windows are adjusted synchronously and proportionally in response to power supply voltage fluctuations.

16. The infrared anti-pinch control method for an electric bed according to claim 13, characterized in that, It also includes invalid event identification steps: Within the event window, calculate the sampling variance, sign flip count, and trend slope for N consecutive ADC sample values, where N is between 10 and 20. Based on the sampling variance within the window, the number of symbol flips, and the trend slope falling into the preset four-mode determination matrix, the occlusion event is determined to be a valid dangerous event or an invalid occlusion event. Among them, static and stable types and monotonically progressive types are judged as valid hazardous events, while reciprocating oscillation types and brief pulse types are judged as invalid blocking events.

17. The infrared anti-pinch control method for an electric bed according to claim 16, characterized in that, It also includes a vibration baseline coupling step: The vibration frequency and vibration amplitude are extracted from the sampling sequence of at least one untriggered ADC channel to form a vibration baseline; When the event window is triggered, detect whether the frequency and / or amplitude of the vibration baseline of the remaining untriggered channels change abruptly. If a change occurs, it supports the determination of a valid event; if no change occurs, it tends to determine an invalid event.

18. The infrared anti-pinch control method for an electric bed according to claim 16, characterized in that, It also includes static scene learning and differential tracking steps: ADC scans are performed on all channels within a time window of 10 to 50 milliseconds before motor startup. For channels within the event window, preset blocking voltages are recorded and the bed is allowed to start normally. Differential tracking is performed on the channel during bed movement. When the difference between the current voltage and the preset blocking voltage exceeds the preset displacement criterion, it is upgraded to a dynamic event and a safety action is performed.

19. A method for identifying invalid infrared anti-pinch events in an electric bed, characterized in that, include: During the occlusion event, acquire N consecutive ADC samples of the SIG line voltage, and calculate the sampling variance, sign flip count, and trend slope within the window, where N is between 10 and 20. Based on the sampling variance within the window, the number of symbol flips, and the trend slope falling into the preset four-mode determination matrix, the occlusion event is determined to be a valid dangerous event or an invalid occlusion event. Obtain the vibration baseline of at least one untriggered channel during the event, and detect whether the frequency and / or amplitude of the vibration baseline undergo a sudden change, as an auxiliary basis for determining a valid event; Before the bed movement starts, static scene learning is performed on all channels to record the preset blocking voltage of the preset blocking channel. During the bed movement, differential tracking is performed on the preset blocking channel. When the difference between the current voltage and the preset blocking voltage exceeds the preset displacement criterion, the preset blocking channel is upgraded to a dynamic event. The four-mode determination matrix includes: static stable type and monotonically progressive type are determined as valid dangerous events, while reciprocating oscillation type and brief pulse type are determined as invalid occlusion events.

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