A method and system for remote control of a multifunctional nursing bed

Abstract

This invention relates to the field of general control or regulation system technology, and discloses a remote control method and system for a multifunctional nursing bed. The method includes: before executing a main movement command, applying a pair of equal-sized but opposite-direction micro-excitations to the drive motor, and simultaneously acquiring current and voltage signals to generate forward and reverse instantaneous power signatures. Based on the degree of symmetry breaking of these instantaneous power signatures, the current mobility of the human-machine coupling system is judged, and a decision is made accordingly on whether to execute the command. This invention realizes the transformation of control logic from blind execution to interrogation. It utilizes the analysis of the symmetry of paired excitation responses to enhance the state perception capability of the control system, enabling a reliable assessment of the immediate suitability of the command before executing any large-scale physical displacement, thereby reducing potential risks arising from unclear system states.

Description

Technical Field

[0001] This invention relates to a remote control method and system for a multifunctional nursing bed, belonging to the general technical field of control or adjustment systems. Background Technology

[0002] Currently, in general control or regulation systems, the core task is to accurately reproduce a given set value in the system's output, such as position, speed, or angle, through a closed-loop feedback mechanism. This basic principle has been widely deployed and verified in industrial automation robot technology and various servo drive applications, and its value lies in the system's ability to faithfully execute instructions.

[0003] However, when such classic control systems are applied to scenarios involving close human-machine coupling, especially remotely operated nursing equipment, their inherent limitations begin to emerge. This is because the system is designed to faithfully execute commands, but lacks an internal mechanism to question the appropriateness of those commands at the current moment. When this control method is applied to devices like remote nursing beds, the remote operator issues a macroscopic movement command based on limited visual information, and the control loop is responsible for driving the motor to precisely execute that command. The effectiveness of this model implicitly rests on an idealized assumption: that the controlled object, i.e., the user, is always in a suitable, cooperative, or at least neutral state. However, in practical applications, the user's physiological state, such as unconscious muscle tension causing momentary stiffness due to discomfort or slow shifts in posture during sleep, are dynamic variables that the control system cannot predict. When the control system blindly pursues precise reproduction of commands, its high-fidelity execution capability may become a direct source of applying inappropriate external forces, posing a potential risk to users in non-ideal states.

[0004] To avoid this potential risk, a direct improvement approach is to add external, dedicated sensor arrays for state awareness to the system, such as distributed pressure-sensing thin-film infrared thermal imaging or machine vision systems. This aims to directly monitor the user's state through this additional hardware and use the monitoring results as a prerequisite for the control system to execute commands. However, while this approach brings some improvements, it also introduces new problems that are difficult to reconcile in engineering practice. Specifically, existing technologies mainly suffer from the following shortcomings: 1. Significantly increased system complexity and cost. A large number of external sensors and their data processing units make the originally simple control system bloated, and the high hardware cost also limits its widespread application. 1. Application on adaptable devices; 2. Challenges exist in reliability and environmental adaptability. Pressure sensors are susceptible to misjudgments due to wrinkled sheets or creep after long-term use, while machine vision faces practical challenges such as privacy protection due to changes in lighting and obstruction by bedding; 3. The indirectness of information interpretation: Information obtained from external sensors, such as pressure distribution or images, still requires complex algorithms and models to infer the user's true state, and this inference process itself involves uncertainty and delay. Therefore, without significantly increasing the complexity and cost of the system hardware, relying solely on information within the control system to obtain a judgment of the current state of the human-machine coupled system remains a problem that existing technologies have failed to effectively solve. Thus, how to design a control method that reliably assesses the instantaneous mobility and stability of the coupled system before executing macroscopic movement commands, purely based on signals generated within the control loop, becomes the technical problem this invention aims to solve. Summary of the Invention

[0005] This invention provides a remote control method and system for a multifunctional nursing bed. Its main purpose is to solve the problem of how to effectively determine the current state of the human-machine coupling system before the execution of movement commands by utilizing the endogenous signals of the control system without relying on external sensors.

[0006] To achieve the above objectives, the present invention provides a remote control method for a multifunctional nursing bed. This method establishes a procedure for questioning the system state based on the symmetrical response of paired stimuli before executing instructions, comprising the following steps:

[0007] Step S1: Receive the main movement command;

[0008] Step S2: After receiving the main movement command in step S1, before executing the main movement command, apply a positive micro-excitation to the drive motor in the direction of the main movement command, and apply a reverse micro-excitation to the drive motor in the opposite direction to the main movement command, wherein the drive signals of the positive micro-excitation and the reverse micro-excitation are equal in magnitude and opposite in direction.

[0009] Step S3: During the application of positive micro-excitation and reverse micro-excitation, the current signal and supply voltage signal of the drive motor are collected synchronously, and based on the product of the current signal and the supply voltage signal, positive instantaneous power signature and reverse instantaneous power signature are generated respectively.

[0010] Step S4: Determine the system state indicators based on the degree of symmetry breaking between the forward instantaneous power signature and the reverse instantaneous power signature;

[0011] Step S5: Based on system status indicators, decide whether to execute or abort the main movement command.

[0012] Preferably, the system state index is a symmetry breaking index. After step S4 of determining the system state index, the method further includes: comparing the symmetry breaking index with a preset threshold, wherein the symmetry breaking index... Determined by the following rules: ,in, For positive instantaneous power signature, The step S5, which determines whether to execute or abort the main movement command, is as follows: when the symmetry breaking index is lower than a preset threshold, the main movement command is executed.

[0013] Preferably, the application of positive and negative micro-excitation is completed within 0.05 to 0.2 seconds, and the resulting driving displacement is less than 0.5 degrees; after suspending the main movement command, an alarm message is also sent to the remote operation terminal.

[0014] Preferably, the method further includes: in calibration mode, when the nursing bed is unloaded, performing steps S2 to S4 respectively for one or more joint positions of the nursing bed, measuring and storing the inherent asymmetry index corresponding to each joint position to form an asymmetry fingerprint; after step S4 of determining the system status index, the method further includes: based on the real-time position of the current joint, searching or interpolating the corresponding inherent asymmetry index from the asymmetry fingerprint, and subtracting the inherent asymmetry index from the system status index to generate a compensated system status index; in step S5, making a decision based on the compensated system status index.

[0015] Preferably, the method further includes: during the execution of the main movement command, real-time monitoring of the current signal of the drive motor; extracting a high-frequency residual signal with a frequency higher than a preset cutoff frequency from the current signal using a high-pass filter; calculating the energy value of the high-frequency residual signal within a time window; and suspending the execution of the main movement command when the energy value is higher than a preset energy threshold.

[0016] Preferably, step S5, which determines whether to execute or abort the main movement command based on system status indicators, further includes: comparing the value of the system status indicator with a first threshold and a second threshold to classify it into a safe range, a cautious range, or a dangerous range; selecting a set of motion parameters to generate a motion profile according to the classified range, the motion parameters including maximum speed, maximum acceleration, and jerk; executing the main movement command using the first set of motion parameters when the system status indicator is in the safe range; and executing the main movement command using the second set of motion parameters when the system status indicator is in the cautious range, wherein the motion speed defined by the second set of motion parameters is lower than the motion speed defined by the first set of motion parameters.

[0017] Preferably, the method further includes: after the user is in the initial lying position on the nursing bed, executing steps S2 and S3, and calculating the integral area of ​​the positive instantaneous power signature and the negative instantaneous power signature, storing the difference of the integral area as a benchmark load index; after each subsequent execution of step S4, the method further includes: determining the current static load index based on the currently acquired positive instantaneous power signature and the negative instantaneous power signature; calculating the difference between the current static load index and the benchmark load index, and suspending the execution of the main movement command when the difference exceeds a preset range; and further includes: while determining the system status index in step S4, performing a fast Fourier transform on the positive instantaneous power signature and the negative instantaneous power signature to extract and calculate the energy index in the 5 Hz to 15 Hz frequency band; comparing the energy index with a preset vibration threshold, and generating physiological state information indicating the presence of weak tremors when the energy index is higher than the vibration threshold; and combining the physiological state information with the system status index to generate composite alarm information.

[0018] Preferably, the preset threshold is obtained by measuring and recording the symmetry breaking index at different bed posture angles during the calibrated empty period of the nursing bed, and storing the recorded symmetry breaking index in association with the posture angle information in a non-volatile memory.

[0019] Preferably, the preset energy threshold is determined by collecting the current signal of the drive motor and calculating the energy value of the high-frequency residual signal during the period when the nursing bed is executing the main movement command under no-load conditions, and setting it based on this energy value.

[0020] A remote control system for a multifunctional nursing bed includes a multifunctional nursing bed and a controller communicatively connected to the multifunctional nursing bed. The multifunctional nursing bed includes a drive motor, and the controller is configured to perform the following operations:

[0021] Upon receiving the master move command, but before executing the master move command, enter challenge mode;

[0022] In the interrogation mode, the drive motor is controlled to apply a positive micro-excitation, and the drive motor is also controlled to apply a reverse micro-excitation that is equal in magnitude and opposite in direction to the drive signal of the positive micro-excitation.

[0023] During the application of positive and reverse micro-excitation, the current signal and supply voltage signal of the drive motor are collected, and based on the product of the current signal and the supply voltage signal, positive instantaneous power signature and reverse instantaneous power signature are generated respectively.

[0024] The system state indicators are determined based on the degree of symmetry breaking between the forward and reverse instantaneous power signatures.

[0025] Based on system status indicators, a decision is made to execute or abort the main movement command.

[0026] Compared with the prior art, the beneficial effects of the present invention are:

[0027] 1. Upon receiving the main movement command, the system does not immediately enter the execution phase. Instead, it first applies a pair of micro-excitations in opposite directions to the drive motor and collects their respective current responses. The control system does not simply judge whether the amplitude of the response signal exceeds the limit, but directly compares the symmetry of the response signals in terms of shape to determine whether the current human-machine coupling system is in a linear and stable state. This approach allows the control system to obtain a basis for judging the current mobility of the system before executing a macroscopic physical displacement, avoiding the problem of the command being out of sync with the actual state of the system in traditional control methods.

[0028] 2. During the symmetrical query process, the collected positive and negative response signals have dual information value. The system not only judges the user's muscle tension by analyzing the dynamic shape difference of the response curve, but also obtains a characteristic quantity reflecting the current static load distribution by analyzing the baseline deviation or integral area difference between the two curves. When this characteristic quantity deviates significantly from the pre-stored benchmark value, it indicates that the user's lying posture may have changed unexpectedly. This design uses the same extremely short detection action to simultaneously complete the dual verification of the system's dynamic stability and static rationality, providing a more comprehensive execution premise for subsequent movement commands.

[0029] 3. This invention establishes a state monitoring logic covering the entire operation cycle. It begins with a symmetrical query before the movement command is executed to determine the safety of the start-up. Once the query passes and the main movement begins, the control system switches the monitoring mode to continuously analyze the high-frequency residual signal in the actual operating current of the motor. Since sudden tension or discomfort of the user during movement will directly manifest as high-frequency disturbances in the current signal that cannot be explained by a smooth physical model, the system can immediately capture such risks and stop the movement. Through this connection between pre-movement query and in-process monitoring, a complete safety closed loop from command reception to task completion is formed. In the system calibration mode, when the nursing bed is unloaded, the response asymmetry at different joint positions is recorded to form a baseline fingerprint. In subsequent routine operation, the system subtracts the baseline fingerprint value at the corresponding position from the real-time measured symmetry breaking index to obtain a net asymmetry index that more accurately reflects the changes in user state. This ensures that each state judgment is free from the interference of individual equipment differences and background factors such as gravity, allowing the entire control method to maintain consistency and reliability in judgment under different equipment and different operating conditions. Attached Figure Description

[0030] Figure 1 This is a flowchart of the safety control process based on symmetry response analysis of the present invention.

[0031] Figure 2 This is a schematic diagram of high-frequency residual energy monitoring in the in-transit monitoring mechanism of the present invention;

[0032] Figure 3 This is a diagram showing the functional modules and hardware architecture of the remote control system of the present invention;

[0033] Figure 4 This is a diagram showing the signal flow and interaction relationships between the core components of the system of this invention. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described in further detail below. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0035] The present invention provides a remote control method and system for a multifunctional nursing bed. Its overall control architecture is built on a procedure. Before any physical displacement command is executed, a status inquiry link is forcibly inserted into the procedure. Then, based on the output of the inquiry link, the system adaptively determines the subsequent control strategy, including immediately executing a stop command or executing the command in an adjusted movement mode. At the same time, during the execution of the command, an accompanying on-the-way monitoring mechanism is activated to deal with the dynamic risks that may occur during the execution, thereby forming a closed-loop control system covering the entire cycle before, during and after the operation.

[0036] In one application scenario, a remote operation terminal communicates with a controller deployed on a multi-functional nursing bed. This controller is the core execution unit of this control method, integrating a microprocessor, memory, drive circuit, and an interface for data interaction with the drive motor. When the remote operator intends to adjust the user's posture on the nursing bed, for example, issuing a main movement command to raise the head of the bed from the current 10 degrees to 45 degrees, this command is received by the controller through the communication network. Since the control system cannot directly know whether the user's physiological state is suitable for this physical displacement, the system does not immediately drive the motor to execute the command. Instead, it initiates a state interrogation procedure based on symmetry response analysis. This state interrogation procedure is an active detection and response analysis process used to evaluate the linearity and stability of the current human-machine coupling system. Specifically, the control... Upon receiving the main movement command, the controller first enters a challenge mode. In this mode, the controller applies a pair of closely sequential micro-excitation signals to the drive motor in the time domain. The first signal is a positive micro-excitation, the direction of which is consistent with the movement direction required by the main movement command. The duration of this excitation is limited to a short range; in a preferred embodiment, this time is set to 100 milliseconds, during which the angular displacement is less than 0.5 degrees. Immediately afterwards, the controller applies the second signal, a reverse micro-excitation. The magnitude of this excitation signal is equal to that of the positive micro-excitation, but the direction is opposite, and its function is to restore the bed to its initial position. To avoid interference from power supply voltage fluctuations on subsequent judgments, this scheme synchronously and at high frequency acquires the real-time current signal of the drive motor through the analog-to-digital converter inside the controller during the application of these two micro-excitations. and real-time power supply bus voltage signal Furthermore, the system combines the two into an instantaneous power signature through a real-time multiplication operation. This resulted in the generation of positive instantaneous power signatures. and reverse instantaneous power signature These two power signatures form the data foundation for all subsequent analyses.

[0037] After obtaining the paired power signatures, the system needs a quantifiable metric to characterize the degree of symmetry breaking between them. To this end, this invention defines a system state metric, specifically a symmetry breaking index. This index evaluates the difference in the shape of two curves through a normalized integral operation, and its calculation procedure is as follows: In the formula, the numerator calculates the absolute area difference between the two power curves over time integral, reflecting the degree of response asymmetry, while the denominator calculates the sum of the areas of the two curves as a normalization factor to avoid the influence of different response energies under different loads. Thus, the calculated... It is a dimensionless numerical value that can stably characterize the nonlinear state of the system; for example, in one instance, when the user's muscles relax, the collected forward and reverse power signature curves highly overlap, and the calculated numerator integral value is 0.05 units, the denominator integral value is 0.625 units, and the final result is... The value is 0.08. However, when the user's muscles are under tension, the two curves show a clear separation, with the numerator integral value increasing to 0.28 units while the denominator integral value remains essentially unchanged, resulting in the final value. The value is 0.45; any physical system, due to manufacturing tolerances, transmission chain friction, and the influence of gravity components at different locations, inherently possesses background asymmetry, which will affect the above... The judgment leads to a systemic bias. To address this challenge, this system is configured with a mechanism that includes offline calibration and online compensation. Specifically, the system provides a calibration mode in which, after confirming that the nursing bed is unloaded, the controller drives specific joints to run at a preset speed within their full range of motion, and automatically executes the aforementioned state challenge procedure once at multiple preset joint position points. It measures and records the inherent asymmetry index corresponding to each position point. These data points collectively constitute an asymmetric fingerprint stored in non-volatile memory. In normal operation, the system calculates the original... Then, based on the current real-time position of the joint, the corresponding inherent asymmetry index will be found or interpolated from the fingerprint. And perform a subtraction operation to obtain a compensated system state index. All subsequent decisions were based on this. conduct.

[0038] After receiving compensation After indexing, the system employs a multi-threshold adaptive decision-making logic. The system internally presets a first threshold and a second threshold, which are determined through a standardized calibration process. For example, in calibration mode, test subjects are invited to simulate different levels of muscle tension on a bed, and the corresponding values ​​are recorded. The numerical distribution is used, and its statistical boundary is taken as the basis for setting the threshold; when When the value is below the first threshold, the system determines that the user's state is stable and within a safe range. The controller will then use the first set of motion parameters to generate a motion profile and execute the main movement command. This set of parameters has a high maximum speed and maximum acceleration. When the user's position is between the first and second thresholds, the system determines that the user may be experiencing slight discomfort and enters a cautious zone. At this point, the controller does not abort the command but automatically selects a second set of motion parameters. This set of parameters defines a maximum speed and acceleration lower than the first set, while increasing the acceleration value to ensure a smooth start and stop process. When the value exceeds the second threshold, the system determines that the user's state is unstable or resistant, entering a danger zone. At this point, the execution of the main movement command will be immediately suspended, and an alarm message will be sent to the remote operation terminal. The first and second thresholds in the multi-threshold adaptive decision-making logic are determined through a standardized procedure based on external mechanical calibration. This procedure first rigidly connects a calibrated force sensor to a specific location on the bed board, such as when the headboard is raised 30 degrees. Then, a force sensor is applied to the bed board with a value of [value missing]. The static resistance force, under this state, involves executing the state challenge procedure multiple times consecutively and calculating the compensated system state index. average with standard deviation And thus the first threshold Set as ,in, It is a statistical coefficient; similarly, applying a value much larger than... static resistance Measure its corresponding average value with standard deviation and the second threshold Set as ,in, This is another statistical coefficient, and the two thresholds obtained from it define the transition boundary of the system response from the linear region to the nonlinear region and the boundary for entering the nonlinear region, respectively.

[0039] The status challenge procedure addresses the security issue before command initiation, but the user's state may change during movement. To mitigate this risk, the system also integrates an in-transit monitoring mechanism. This mechanism activates after the main movement command begins execution. Its core lies in real-time frequency domain analysis of the motor current signal. Specifically, based on the current motion profile and load model, the system can predict the baseline of normal low-frequency changes caused by motion in the current signal. Sudden user tension during the journey will manifest as high-frequency disturbances superimposed on this baseline. To capture this feature, the system processes the acquired current signal in real-time using a digital high-pass filter, extracts the high-frequency residual signal, and continuously calculates the residual signal within a sliding time window. The system presets an energy threshold for energy values. This threshold is determined based on calibration, specifically by performing standard movement under no-load conditions, recording the energy value of the high-frequency residual signal, and adding a safety margin to this value. During operation, if the calculated instantaneous energy value exceeds the preset energy threshold, the system determines an anomaly and immediately stops command execution. The high-frequency residual signal extraction and energy over-limit judgment in the in-transit monitoring mechanism also rely on key parameters that are calibrated through an offline calibration process. This process first drives the joints of the nursing bed to run along multiple preset speed profiles under no-load conditions, simultaneously collecting the drive motor current signal and performing spectrum analysis to determine the upper limit of the characteristic frequency corresponding to normal mechanical and electrical noise. and the cutoff frequency of the high-pass filter. Set as ,in The frequency scaling factor is greater than 1; subsequently, a filter at this cutoff frequency is applied to process the current signal acquired under the same no-load operating conditions, and the signal is scaled with a width of... The energy of the high-frequency residual signal is calculated using a sliding time window, and the maximum energy value is recorded throughout the entire operation. The energy threshold that will ultimately be used for in-transit monitoring Determined as ,in As a safety margin factor, this process directly links the judgment criteria of the monitoring mechanism with the inherent electrical and mechanical characteristics of the equipment itself.

[0040] Furthermore, to utilize the information obtained from each probe, this system performs parallel analysis of the collected power signatures in two additional dimensions alongside symmetry analysis. The first dimension is the evaluation of static load distribution, used to identify unexpected deviations in user posture. Specifically, after the user is in an ideal initial supine position, the operator can trigger a baseline setting operation. The system then performs a state challenge, calculating the integral area of ​​the forward and reverse instantaneous power signatures respectively. The difference between these two integral areas is used as a feature reflecting the load under the current posture, defined as the baseline load index, and stored in association with the current posture information. In each subsequent regular challenge, the system synchronously calculates the current static load index and compares it with the stored baseline load index. The system compares the two values. When the difference exceeds a preset range, the system determines that the user's body position may have deviated. At this time, the system will also stop the movement command and issue a specific alarm indicating body position deviation. The second dimension is the analysis of micro-physiological state. While calculating the symmetry breaking index, the system sends copies of the forward and reverse instantaneous power signatures to a parallel processing module. This module performs a fast Fourier transform on them to analyze their spectral characteristics. Specifically, the system calculates the energy index in a specific physiological frequency band, such as the 5 Hz to 15 Hz band, and compares the energy index with a preset vibration threshold. If it is higher than the threshold, it generates physiological state information indicating the presence of weak tremors. This information can be combined with the symmetry breaking index to form a composite alarm information sent to the remote terminal.

[0041] Meanwhile, in the control method of this invention, when the user's muscles tense or generate unconscious resistance, the human-machine coupling system transforms from a relatively linear system into a nonlinear system, and its symmetry in response to external forces is thus disrupted. Therefore, by actively applying a pair of precisely symmetrical micro-excitations and quantifying the degree of symmetry disruption in the instantaneous power response of the motor, a reliable index that can directly reflect the current mobility of the system is obtained. At the same time, to ensure the practical feasibility of this method, the system also pre-calibrates and stores the asymmetry fingerprint of the device in the no-load state and performs online compensation during actual operation, thereby effectively removing the inherent asymmetry introduced by background factors such as mechanical structure and gravity, ensuring that the final system state index can truly reflect the response differences caused by changes in the user's physiological state, and providing a stable and reliable basis for subsequent adaptive safety decisions. All of these are extended implementation methods known to those skilled in the art.

[0042] Example 1: In a remote nursing application, a multi-functional nursing bed is used to support a user recovering from surgery. This user is sensitive to physical disturbances while asleep and is prone to unconscious muscle tension. Simultaneously, when the headboard drive mechanism of the nursing bed is near a 45-degree angle, due to lever effects and changes in gravity load, its drive system exhibits an inherent response asymmetry. This makes it difficult for conventional control systems to balance safety settings and operational efficiency. When the remote terminal issues a command to raise the headboard from 40 degrees to 50 degrees, the controller receives this main movement command, initiates a status interrogation procedure, and the system immediately applies a pair of positive and negative micro-excitations, simultaneously acquiring voltage and current signals to generate a positive instantaneous power signature. With reverse instantaneous power signature To address the inherent response asymmetry of the device, the controller first retrieves the inherent asymmetry index corresponding to the pre-calibrated asymmetry fingerprint from its internal memory, based on the current 40-degree joint position. Its value is 0.15. At the same time, the system calculates the original symmetry breaking exponent based on the collected power signature. The value is 0.50. Therefore, the system performs online compensation calculations to obtain the compensated system status indicators. The result of this compensation calculation eliminates the influence of inherent device asymmetry, enabling the indicator to more directly reflect the response differences caused by changes in user status.

[0043] At this point, the multi-threshold adaptive decision-making logic is triggered, and the system will set the value to 0.35. Comparing the system with the internally set first threshold of 0.2 and second threshold of 0.5, the system determined that the state was in the caution range. This determination caused the control system to automatically select a second set of motion parameters to generate a motion profile with a lower maximum speed and maximum acceleration. The controller then drove the motor based on this motion profile, and the headboard began to move in a smoother manner. During this process, the on-the-go monitoring mechanism was activated to continuously monitor the current signal of the drive motor in real time. The energy value of the high-frequency residual signal extracted by the high-pass filter was always lower than the preset energy threshold, indicating that the user did not experience any sudden tension reaction during the entire movement. Finally, the physical displacement of the headboard was completed in a smooth manner without any stress reaction from the user. After the instruction was executed, the remote operation terminal received a confirmation message that the task was completed, along with a status prompt, indicating that the operation was completed in the caution range through an adaptive motion method. In this scenario, the synergy between the status inquiry procedure and the asymmetric fingerprint compensation mechanism provided a reliable decision input for the subsequent adaptive motion profile generation mechanism, enabling the control system to achieve the predetermined nursing goals when facing a complex situation of uncertain user physiological state and non-ideal hardware conditions.

[0044] Example 2: To objectively verify the ability of the method of the present invention to distinguish different human-machine coupled system states, the following experiment was conducted. The purpose of the experiment was to quantitatively characterize the compensated system state indicators calculated by the system under different loads and user physiological states. To establish the correspondence between the system's physical state and the experimental platform, a multi-functional nursing bed was used. The headboard joint was driven by a DC servo motor and integrated with a controller that implemented the control method of this invention. The controller's data acquisition unit could synchronously acquire the motor's terminal voltage and current signals at a sampling frequency of 1kHz, with a resolution of 12 bits. The key parameters in the experiment were set as follows: the duration of a single micro-excitation in the state challenge procedure was set to 100ms. This value was selected as a result of a trade-off between user perception and signal effectiveness. Excitations below 50ms generated lower signal energy, while excitations above 200ms posed a risk of being perceived by the user. 100ms was determined as an operating point that would not interfere with the user and could obtain a clear response signature. The first threshold in the multi-threshold decision logic, i.e., the boundary between the safe and cautious intervals, was determined to be 0.20 through the preliminary calibration process.

[0045] The experimental procedure is as follows: First, the test bed is calibrated for asymmetry fingerprint to obtain inherent asymmetry indices at different angles. Subsequently, under five different operating conditions, the same master movement command was sent to the controller, namely, raising the headboard from 10 degrees to 45 degrees, and the compensated system status indicators calculated by the system before executing the command were recorded. And the final decision, under three working conditions as a benchmark: no load, static load (75kg homogeneous load body), and user cooperation (75kg test subject relaxed and lying flat), the system measured the following: The values ​​were 0.02, 0.04, and 0.08, respectively, all significantly lower than the decision threshold of 0.20, and the system accordingly executed the main movement command in all cases. In contrast, in two other scenarios, when the same test subject perceived signs of movement, simulating slight back muscle tension, the system calculated... The value rose to 0.45; when the test subject was asked to actively apply force to resist the headboard movement, the value further increased to 0.84. Both values ​​were above the decision threshold, so the system therefore suspended the execution of the main movement command in both situations. The significant change in the value of this indicator is because when the user's muscles are in a state of tension or active force exertion, the human-machine coupling system becomes a nonlinear system. The mechanical response of its muscle tissue to micro-excitations of equal magnitude and opposite direction loses symmetry. This change in physical state directly leads to morphological differences between the forward and reverse instantaneous power signatures, which are ultimately reflected in... The index value increased; experimental data shows that the system state index after compensation... There is a clear and stable quantitative correspondence between the physical state of the human-machine coupled system and the control system. This method provides a criterion for distinguishing between linear stable state and nonlinear unstable state, enabling the control system to assess the suitability of the operation before executing physical displacement.

[0046] Example 3: This example combines Figures 1 to 3 This paper describes a remote control method and system for a multifunctional nursing bed, such as... Figure 1 As shown, the process begins with receiving the main movement command, but it is not executed immediately. Instead, it enters a state questioning phase, where paired micro-excitations are applied to the drive motor to make it move in both directions, and voltage and current signals are collected simultaneously. Based on the product of voltage and current, the system generates an instantaneous power signature to construct forward and reverse power curves. Then, the original symmetry breaking index is calculated to quantify the morphological difference between the two curves, and online compensation is performed. The inherent asymmetry of the device, derived from the asymmetry fingerprint database, is subtracted from the original index. After compensation, the system enters a multi-threshold adaptive decision-making phase. By evaluating the compensated system state index, it is divided into a safe zone, a cautious zone, or a dangerous zone. If it is in the safe zone, the first set of motion parameters is used to execute the main movement command at a standard speed until the command is completed. If it is in the cautious zone, the second set of motion parameters is used to execute the main movement command at a reduced speed until the command is completed. If it is in the dangerous zone, the main movement command is aborted and an alarm message is sent to the remote terminal. At the same time, a parallel on-the-way monitoring mechanism for monitoring the high-frequency residual of the current continues to run. Once the monitored energy value exceeds the limit, an emergency stop is triggered, causing the command to be aborted.

[0047] like Figure 2 As shown, the horizontal axis represents time in seconds (s), and the vertical axis represents the normalized energy value. In the figure, the solid line represents the energy value of the high-frequency residual signal of the motor current calculated in real time during the execution of the main movement command, while the dotted line represents the preset energy threshold. As can be seen from the figure, at approximately 3.0s and 6.2s, the high-frequency residual energy value shows a significant instantaneous increase and exceeds the preset energy threshold. This indicates that the system has detected an anomaly that may be caused by the user's sudden tension or discomfort during the journey, and will trigger a security strategy to stop the movement command accordingly.

[0048] like Figure 3As shown, the system includes a remote operation terminal that connects to the multi-functional nursing bed via a communication network. It is used to send main movement commands and receive status and alarm information. The core of the multi-functional nursing bed is a controller, which contains a status inquiry procedure module, an in-transit monitoring mechanism module, an adaptive decision-making module, and a data acquisition and processing module. The controller also has a built-in non-volatile memory to store key calibration data such as asymmetric fingerprints and baseline load indicators. At the physical level, the controller sends control signals to the drive motor and receives position, current, and voltage sensor data from the position encoder and current and voltage acquisition unit, respectively.

[0049] like Figure 4 As shown, the instructions sent by the remote operation terminal are transmitted to the controller via a wireless or wired communication network. The controller integrates a microprocessor, memory, and drive circuit. After receiving the instruction, the controller sends a challenge trigger signal to start the status challenge procedure. The procedure specifically includes steps such as applying positive micro-excitation, applying reverse micro-excitation, acquiring current and voltage signals, and calculating symmetry indicators. During the execution of the main movement instruction, the controller simultaneously activates the on-the-go monitoring mechanism to monitor the current signal of the drive motor in real time, especially to perform high-frequency residual analysis to achieve anomaly detection and termination. Finally, the controller generates and sends a drive signal based on the results of the status challenge and on-the-go monitoring, which drives the drive motor on the multi-functional nursing bed through the mechanical transmission mechanism to adjust the posture of the user or patient on the bed.

[0050] Example 4: To eliminate the inherent response asymmetry differences caused by manufacturing tolerances and mechanical wear of different devices, and to ensure that the control method of the present invention has a consistent judgment benchmark on different hardware units, the system is configured to execute a standardized asymmetry fingerprint calibration procedure. This procedure measures and generates a unique database of inherent asymmetry indicators related to joint positions for each independent nursing bed device. The initial state of the calibration procedure is defined as follows: the object of the procedure is a fully assembled multifunctional nursing bed, all of which are connected to the controller. A prerequisite of the procedure is that the nursing bed is placed on a level surface, connected to a stable DC power supply with a voltage ripple of less than 5%, and it must be confirmed that the nursing bed is in a completely unloaded state, that is, there is no mattress or any other load on the bed surface.

[0051] After the calibration procedure is initiated, the controller enters calibration mode and performs the following automated steps for the headboard drive joint: First, the controller drives the motor to move the headboard upwards from its lowest mechanical limit position of 0 degrees at a constant angular velocity of 2 degrees per second; Second, during this process, the position encoder coaxial with the joint reports the real-time angle value to the controller at a frequency of no less than 100 Hz; Third, when the real-time angle value reaches the preset sampling point of 1 degree, the controller pauses the joint movement and immediately performs a complete state challenge procedure at that position, i.e., applying a pair of positive and negative micro-excitations with a duration of 100 ms, and calculating the original symmetry breaking index at that position. Fourth, the controller stores the current angle value and the calculated original symmetry breaking index as a data pair (1.0, 0.09) in its internal non-volatile memory. Then, the controller resumes joint movement until the next sampling point at 2 degrees, and repeats steps three and four until the headboard reaches its highest mechanical limit position of 70 degrees. After this procedure is completed, a discrete dataset consisting of multiple data pairs is generated and fixed in the controller's memory. This dataset is the asymmetry fingerprint of the headboard joint of the device. In normal operation mode, when the system needs to obtain the inherent asymmetry index at a non-integer angle of 35.5 degrees... At that time, the controller will look up the corresponding values ​​of two adjacent integer angles, 35 degrees and 36 degrees, from the dataset. The value is calculated using linear interpolation. By executing this calibration procedure, the compensated system state indicators calculated during subsequent normal operation are obtained. This can reduce measurement bias caused by individual hardware differences.

[0052] Example 5: To enable the static load monitoring and in-transit monitoring mechanisms to be adapted to different users, the control system of this invention is configured to execute a user baseline calibration procedure before providing services to a new user. In a specific application, when the caregiver initially places the user on the nursing bed and positions them in a reference supine position with the headboard at 15 degrees, the caregiver triggers the function of setting the user baseline once through a remote operation terminal. After receiving the instruction, the controller executes the status interrogation procedure three times in succession and calculates the difference between the positive and negative instantaneous power signature integral areas in each interrogation. The controller then calculates the arithmetic mean of these three differences and uses this average as a reference load index bound to the current user and posture, storing it in non-volatile memory. The system then sets the judgment conditions for body position deviation based on this reference. If the absolute value of the deviation between the static load index measured in subsequent interrogations and the reference load index exceeds 20% of the reference value, the system determines that there is a body position deviation.

[0053] After setting the baseline load parameters, the user baseline setting function automatically enters the second stage, namely, the calibration of the in-transit monitoring energy threshold. The controller sends a prompt to the remote operation terminal, notifying the operator that a calibration movement is about to be performed. After receiving confirmation, the controller drives the headboard to move smoothly from the current 15 degrees to 30 degrees at a preset low-speed motion profile. Throughout this movement, the signal processing link of the in-transit monitoring mechanism is activated. The controller continuously extracts the high-frequency residual signal in the motor current through a high-pass filter and calculates its energy value within the sliding time window. The controller records the maximum energy value monitored during this interference-free and stable operation. The final preset energy threshold is determined by... The operations are determined and stored.

[0054] Example 6: To establish a system state judgment benchmark unaffected by power supply conditions, this example describes a procedure for verifying and solidifying the robustness of the core algorithm under a non-ideal power supply environment. In a specific test, a nursing bed system equipped with the control method of this invention was connected to a regulated power supply and a programmable power supply, respectively. Under both power supply conditions, a test subject was required to maintain a slightly tense state. When the system performed a state challenge, the symmetry breaking index was calculated based on the instantaneous current signal and the instantaneous power signature, respectively. When powered by the regulated power supply, the index value based on current was 0.46, while the compensated system state index based on power was... The value is 0.45; switching to the programmable power supply and applying a 15% instantaneous voltage drop during reverse micro-excitation causes the current-based metric to drop to 0.15 due to the disturbance. The value stabilized at 0.44. This comparison verified that the calculation method based on instantaneous power signature can offset the impact of power supply voltage fluctuations, thus establishing it as the benchmark calculation method upon which all subsequent monitoring functions rely.

[0055] After confirming the stability of the core state judgment model, the system further establishes a characteristic frequency band energy baseline model for weak tremor monitoring. In this procedure, firstly, with the user in a relaxed, lying-down baseline state, a state challenge is performed and a parallel spectral analysis of the power signature is conducted to measure the energy index baseline value within the characteristic frequency band from 5 Hz to 15 Hz. Subsequently, an exciter capable of generating micro-amplitude vibrations at a frequency of 10 Hz was installed on the bed frame to simulate physiological tremors, and measurements were performed again to obtain an energy index under tremor conditions. The vibration threshold used to determine the presence of weak vibrations is determined by... The calculations are determined and fixed in the system configuration parameters.

[0056] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention.

[0057] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A remote control method for a multifunctional nursing bed, characterized in that, This method establishes a procedure for questioning the system state based on the symmetric response of paired stimuli before executing instructions, including the following steps: Step S1: Receive the main movement command; Step S2: After receiving the main movement command in step S1, before executing the main movement command, apply a positive micro-excitation to the drive motor in the direction of the main movement command, and apply a reverse micro-excitation to the drive motor in the opposite direction to the main movement command, wherein the drive signals of the positive micro-excitation and the reverse micro-excitation are equal in magnitude and opposite in direction. Step S3: During the application of positive micro-excitation and reverse micro-excitation, the current signal and supply voltage signal of the drive motor are collected synchronously, and based on the product of the current signal and the supply voltage signal, positive instantaneous power signature and reverse instantaneous power signature are generated respectively. Step S4: Determine the system state indicators based on the degree of symmetry breaking between the forward instantaneous power signature and the reverse instantaneous power signature; Step S5: Based on system status indicators, decide whether to execute or abort the main movement command.

2. The remote control method for a multifunctional nursing bed according to claim 1, characterized in that, The system state index is the symmetry breaking index. After step S4, which determines the system state index, the method further includes: comparing the symmetry breaking index with a preset threshold, wherein the symmetry breaking index... Determined by the following rules: ,in, For positive instantaneous power signature, The step S5, which determines whether to execute or abort the main movement command, is as follows: when the symmetry breaking index is lower than a preset threshold, the main movement command is executed.

3. The remote control method for a multifunctional nursing bed according to claim 1, characterized in that, The application of positive and negative micro-stimuli is completed within 0.05 to 0.2 seconds, and the resulting driving displacement is less than 0.5 degrees; after the main movement command is aborted, alarm information is also sent to the remote operation terminal.

4. The remote control method for a multifunctional nursing bed according to claim 1, characterized in that, Also includes: In calibration mode, when the nursing bed is unloaded, steps S2 to S4 are performed for one or more joint positions of the nursing bed to measure and store the inherent asymmetry index corresponding to each joint position to form an asymmetric fingerprint. After step S4, which determines the system state indicators, the method further includes: finding or interpolating the corresponding inherent asymmetric indicators from the asymmetric fingerprint based on the real-time position of the current joint, and subtracting the inherent asymmetric indicators from the system state indicators to generate compensated system state indicators; in step S5, a decision is made based on the compensated system state indicators.

5. The remote control method for a multifunctional nursing bed according to claim 1, characterized in that, Also includes: During the execution of the main movement command, the current signal of the drive motor is monitored in real time; A high-frequency residual signal with a frequency higher than a preset cutoff frequency is extracted from the current signal using a high-pass filter; the energy value of the high-frequency residual signal within the time window is calculated, and the execution of the main movement command is stopped when the energy value is higher than a preset energy threshold.

6. The remote control method for a multifunctional nursing bed according to claim 1, characterized in that, Step S5, which determines whether to execute or abort the main movement command based on system status indicators, further includes: comparing the value of the system status indicators with a first threshold and a second threshold to classify them into a safe range, a cautious range, or a dangerous range; selecting a set of motion parameters to generate a motion profile based on the classified range, the motion parameters including maximum speed, maximum acceleration, and jerk; executing the main movement command using the first set of motion parameters when the system status indicators are in the safe range; and executing the main movement command using the second set of motion parameters when the system status indicators are in the cautious range, wherein the motion speed defined by the second set of motion parameters is lower than the motion speed defined by the first set of motion parameters.

7. The remote control method for a multifunctional nursing bed according to claim 1, characterized in that, Also includes: After the user is in the initial lying position on the nursing bed, steps S2 and S3 are executed, and the integral area of ​​the positive instantaneous power signature and the reverse instantaneous power signature is calculated. The difference of the integral area is stored as the benchmark load index. After each subsequent execution of step S4, the process further includes: determining the current static load index based on the currently acquired forward and reverse instantaneous power signatures; calculating the difference between the current static load index and the baseline load index, and suspending the execution of the main movement command when the difference exceeds a preset range; and simultaneously determining the system status index in step S4, performing a fast Fourier transform on the forward and reverse instantaneous power signatures to extract and calculate the energy index within the 5 Hz to 15 Hz frequency band; comparing the energy index with a preset vibration threshold, and generating physiological state information indicating the presence of weak tremors when the energy index is higher than the vibration threshold; and combining the physiological state information with the system status index to generate composite alarm information.

8. The remote control method for a multifunctional nursing bed according to claim 2, characterized in that, The preset threshold is obtained by measuring and recording the symmetry breaking index at different bed posture angles during the unloaded calibration of the nursing bed, and storing the recorded symmetry breaking index in association with the posture angle information in non-volatile memory.

9. A remote control system for a multifunctional nursing bed, comprising a multifunctional nursing bed and a controller communicatively connected to the multifunctional nursing bed, wherein the multifunctional nursing bed includes a drive motor, characterized in that, The controller is configured to perform the following operations: Upon receiving the master move command, but before executing the master move command, enter challenge mode; In the interrogation mode, the drive motor is controlled to apply a positive micro-excitation, and the drive motor is also controlled to apply a reverse micro-excitation that is equal in magnitude and opposite in direction to the drive signal of the positive micro-excitation. During the application of positive and reverse micro-excitation, the current signal and supply voltage signal of the drive motor are collected, and based on the product of the current signal and the supply voltage signal, positive instantaneous power signature and reverse instantaneous power signature are generated respectively. The system state indicators are determined based on the degree of symmetry breaking between the forward and reverse instantaneous power signatures. Based on system status indicators, a decision is made to execute or abort the main movement command.

Images