Virtual training-oriented electric actuation force feedback device and design method

Abstract

This invention relates to the field of equipment training technology, and discloses an electro-dynamic feedback device and design method for virtual training, including the following steps: Designing an arm-worn force feedback device based on a DC servo motor; establishing a mapping relationship between virtual environment interaction information and physical feedback force by deriving a mathematical model of feedback force and servo motor rotation angle; designing a phase displacement-torque dual closed-loop control system, controlling the servo motor rotation angle through a phase displacement closed loop and controlling the servo motor output torque through a torque closed loop to achieve precise control of the feedback force amplitude; using the mathematical model and the dual closed-loop control system, driving the arm-worn force feedback device to generate feedback force matching the virtual training scene, achieving rapid response to virtual collisions, and keeping the feedback force and rotation angle error within a preset threshold to enhance the realism and immersion of virtual training. Establishing a mapping relationship between virtual interaction and physical feedback enables precise control of the servo motor rotation angle and output torque.

Description

Technical Field

[0001] This invention relates to the field of equipment training technology, and in particular, to an electrodynamic feedback device and design method for virtual training. Background Technology

[0002] Virtual training technology, by constructing virtual interactive environments, can effectively reduce the cost and safety risks of physical hands-on training, and has significant application value in fields such as industrial maintenance and equipment operation. With the development of virtual reality technology, the immersiveness and realism of human-computer interaction have become key factors in improving the effectiveness of virtual training systems. Force-haptic feedback technology, as one of the core technologies of human-computer interaction, can simulate the mechanical perception in real contact, allowing operators to perceive the hardness, reaction force, and other physical properties of objects in a virtual environment, thereby enhancing the realism of training.

[0003] Existing force feedback devices mainly employ driving technologies such as magnetorheological fluid, electromagnetic, piezoelectric, and pneumatic. For example, existing technologies include force feedback gloves based on magnetorheological fluid actuators, which control fluid viscosity by adjusting a magnetic field to generate damping force; gloves based on electromagnetic drives, which utilize electromagnetic force to provide force feedback; origami structures based on piezoelectric cantilever beams, which achieve multidimensional force feedback through the piezoelectric effect; and tactile sleeves based on pneumatic actuator arrays, which achieve tactile positioning through air pressure control. In addition, there are devices that utilize electrotactile signals, magnetorheological dampers, and other technologies to achieve force feedback.

[0004] However, existing force feedback devices have the following technical problems:

[0005] 1. Insufficient feedback accuracy: Some devices have difficulty in accurately controlling the amplitude and direction of the feedback force, resulting in a large deviation between the mechanical properties perceived in the virtual environment and the actual physical properties, which affects the authenticity of the training.

[0006] 2. Poor wearing comfort: Some devices may cause discomfort when worn for a long time due to unreasonable structural design or arrangement of driving components, which will affect the training experience.

[0007] 3. Real-time performance needs improvement: Some devices experience delays when responding to virtual environment interactions, making it difficult to achieve fast and stable force feedback, thus affecting the real-time performance of the interaction.

[0008] Therefore, there is an urgent need for a force feedback device that can provide high-precision, high-real-time force feedback and is comfortable to wear, in order to enhance the immersion and training effect of virtual training. Summary of the Invention

[0009] This invention provides an electrodynamic force feedback device and design method for virtual training. Based on a DC servo motor, a wearable force feedback device is designed for the arm. A mathematical model of the feedback force and servo motor rotation angle is derived to establish a mapping relationship between virtual environment interaction information and physical feedback force. A phase displacement-torque dual closed-loop control system is designed. The phase displacement closed loop controls the servo motor rotation angle, and the torque closed loop controls the servo motor output torque, achieving precise control of the amplitude and direction of the feedback force. Through the mathematical model and the dual closed-loop control system, the wearable force feedback device is driven to generate a feedback force matching the virtual training scene, enabling rapid response to virtual collisions and keeping the feedback force and rotation angle errors within a preset threshold. This enhances the realism and immersion of virtual training and solves the technical problems of insufficient feedback accuracy, poor wearing comfort, and inadequate real-time performance in existing force feedback devices.

[0010] Furthermore, the wearable force feedback device consists of a fixing module, a wireless communication module, a control drive module, an execution module, and a power module. The fixing module is used to achieve stable positioning of the device and stabilize the servo motor, focusing on force transmission and wearing comfort. It features a split wearable structure to convert the physical force feedback signal and meet ergonomic requirements. The fixing module includes a base and a shell. The base adopts a through-hole horizontal rectangular design, and the watch strap and shell are connected to the base without screws for stable fixation. A strap fixing mechanism is used inside the through-hole horizontal rectangular design to efficiently transmit feedback force while reducing the impact of reaction force on the human body. The shell design includes rounded edges and corners to improve wearing comfort and safety. The power module is powered by a lithium battery and utilizes aluminum-plastic composite thin-film encapsulation technology to optimize safety and lightweight design. The wireless communication module, based on Wi-Fi technology, enables efficient and stable data transmission, ensuring that collision information is transmitted to the control and drive module in real time. The control and drive module uses a miniature servo motor as the drive unit to reduce the structural size. The servo motor integrates a DC motor and gear set, thus achieving the characteristics of small size and high torque, making it suitable for wearable applications. Taking a virtual training scenario as the application scenario, when the operator wears an arm-worn force feedback device and interacts with the virtual environment, the wireless communication module converts the interaction information into electrical signals and transmits them to the control and drive module. After processing the signals, the control and drive module executes the servo motor to act on the cam to generate precise phase shift, realizing real-time monitoring and response to limb interactions in virtual maintenance training, forming a closed-loop force feedback control system. Taking into account the miniaturization requirements and the size constraints of the DC servo motor, this design not only reduces the risk of injury but also enhances the realism of immersive maintenance through force feedback.

[0011] Furthermore, the structured design approach is used to optimize the performance of each module of the wearable force feedback device. This includes: the execution module consists of a servo motor and a cam mechanism. Based on the differentiated action modes at both ends of the cam mechanism, force feedback control is formed within a 120° range below the arm. The feedback force calculation specifically involves simplifying the geometric model of the arm into an ellipse equation based on its actual anatomical structure, i.e.:

[0012] ;

[0013] in, For the semi-major axis, The cam is a semi-minor axis; the cam structure is formed by the intersection of a central circle and two parabolas, and the central circle adopts the standard circle equation; the two ends of the cam are divided into large end and small end structures due to different action modes; force feedback analysis is performed on the small end, and the parabolic equation in the Cartesian coordinate system is adopted, as shown in formula (1):

[0014] (1)

[0015] in, p, q The parameters of the small end of the designed cam; the cam model design, including two action modes: small end and large end; the small end acts below the arm wearing position, forming a feedback force on the arm through the combined compressive and frictional forces of the cam; the large end acts on the lower side of the arm, applying the feedback force directly through the cam. Optionally, the semi-major shaft... It is 20, semi-short axis It is 15. Optionally, p It is 3.3. q It is 13.8.

[0016] Furthermore, the feedback force during the action of the small end is specifically as follows: When analyzing the action of the small end, the cam initially has no contact with the arm. As the cam rotates, the small end gradually approaches the arm. When the rotation angle is 38°, the small end of the cam contacts the surface of the arm. The entire action is approximately assumed to be an increment of cam rotation equal to the amount of compression by the small end intruding into the arm. Since the geometric centers of the parabola and the circle do not coincide, using polar coordinates to calculate the relationship between the rotation angle and the amount of compression would result in a zero denominator. Therefore, a method combining numerical and graphical approaches is used to analyze the cam rotation angle. Compression of the small end invading the arm The relationship is as follows: the small end acts on the arm, the cam rotates, and the elastic force exerted by the arm on the cam is... ,in, Let the base circle radius of the cam be . The elastic coefficient of human skin is given by the frictional force. , Let be the coefficient of friction between the cam and the surface of the human arm; in biomechanical modeling, the Young's modulus of forearm deformation is... Based on actual optical coherence tomography (OCT) data, the effective thickness is The area of ​​force is ,according to It can be seen that the calculation yields k ;Will , Substitution formula (2):

[0017] (2)

[0018] The relationship between the cam rotation angle and the feedback force under the action of the small end is obtained. Optionally, in biomechanical modeling, the Young's modulus of forearm deformation is... Values Based on optical coherence tomography (OCT) measurement data, the effective thickness for Area of ​​force for ,according to It can be known for ;Will , Substitution formula (2):

[0019] (2)

[0020] The relationship between the cam rotation angle and the feedback force under the action of the small end is obtained.

[0021] Furthermore, the feedback force under large-end action is specifically as follows: under large-end action, the arm-worn force feedback device maintains a fixed connection with the arm, based on the motor torque formula. Torque formula Combined with servo motor current The formula for the feedback force of the cam on the arm is derived (3):

[0022] (3)

[0023] in, The effective voltage input to the servo motor. The internal resistance of the servo motor. It is the torque constant of the servo motor. The reduction ratio of the servo motor. For transmission efficiency, This is the distance from the cam profile to the cam center, with the larger end acting on both sides of the arm. Optionally, , , , , Adjust the cam angle. This achieves force feedback control within a certain range (e.g., 120°) below the force feedback device; the effective voltage applied to the servo motor is adjusted using a pulse width modulation (PWM) signal. This changes the feedback force of the servo motor on the arm. Substituting the parameters into equation (3), we obtain the effective voltage of the servo motor. With feedback force The relationship between them, and the results of the analysis.

[0024] Furthermore, a phase displacement-torque dual closed-loop control system is designed, specifically: based on the structural design of the micro servo and the force feedback control command, a phase displacement-torque dual closed-loop control system is designed to achieve precise force feedback control; the phase displacement-torque dual closed-loop control system effectively resists external disturbances through closed-loop feedback, ensuring the servo's rapid tracking command response, while suppressing the negative impact caused by excessive load torque; the control strategy of the phase displacement-torque dual closed-loop control system adopts a hierarchical control concept: the inner loop control first achieves the system's rapid tracking performance, and the outer loop control then adjusts the current to suppress the load torque, ensuring that it meets the design requirements; Simulink simulation of the dual closed-loop control. Optionally, the Simulink simulation of the dual closed-loop control includes inductors... ,resistance Moment of inertia back electromotive force coefficient Torque coefficient Reduction ratio The load torque is .

[0025] Furthermore, a step signal with an amplitude of 1 is input to the phase displacement-torque dual closed-loop control system. By adjusting the parameters of the PID controller, the dynamic response performance of the motor position and torque is optimized. Simultaneously, current loop control is introduced, and the problem of excessive motor current is reduced by adding a PI controller. The torque response is completed in a very short time, exhibiting excellent dynamic performance. Optionally, a proportional gain controller is ultimately selected. Integral gain Differential gain As a control parameter, under this configuration, the phase displacement-torque dual closed-loop control system reaches a steady state within 2 seconds, with an overshoot of less than 6.3% and a steady-state error of 0.012. A current loop control is introduced, using a PI controller to reduce excessive motor current. Under the same input signal conditions, the parameters are optimized using a PI controller self-tuning model to determine the proportional gain of the current loop. and integral gain With these parameters, the motor position response reaches a stable state within 0.5 seconds with no overshoot and a steady-state error of 0.01; the torque response is completed in a very short time, demonstrating excellent dynamic performance.

[0026] Furthermore, it also includes experimental verification of the force feedback device. Specifically, through experimental testing, the relationship between the driving force of the feedback device, the servo feedback angle, and the actual feedback force is analyzed. The maximum relative error between the feedback force and the theoretical feedback angle and driving force is measured, and it is revealed that the magnitude of the driving force is closely related to the servo lever arm length. Then, the lever arm length is optimized to adapt to different application scenarios and improve system performance.

[0027] Furthermore, the experimental setup includes a spring balance and a feedback device. The top of the spring balance is fixed, and the end of the spring balance is connected to a cam. The experiment controls the cam to generate different driving forces by adjusting the effective voltage of the servo motor through the PWM signal, and records the feedback angle and the actual feedback force measured by the spring balance under different driving forces.

[0028] Furthermore, it also includes experimental verification of virtual training, specifically: a virtual environment is constructed based on Jack software and Unity software, and the operator wears an arm-worn force feedback device to perform virtual operations; through experimental results, the response speed of the electric force feedback device to virtual collisions is obtained, as well as the feedback force and the corresponding feedback angle; the feedback force and feedback angle of the virtual experiment are compared with the results of actual physical experiments to verify the accuracy and effectiveness of the force feedback device control, providing physical interaction support for virtual maintenance training.

[0029] This invention provides an electro-dynamic feedback device for virtual training, which is designed and manufactured using the aforementioned design method for an electro-dynamic feedback device for virtual training; an arm-worn force feedback device is designed based on a DC servo motor, and a mathematical model of feedback force and rotation angle is derived and constructed; and a phase displacement-torque dual closed-loop control system is used to achieve precise control.

[0030] The present invention has the following beneficial effects:

[0031] 1. Improve the accuracy of feedback force: By establishing a precise mathematical model of feedback force and servo motor angle, the abstract interactive information in the virtual environment (such as collision force, friction force, etc.) is quantified into specific physical parameters. This mathematical model serves as the core bridge, establishing a mapping relationship between virtual mechanical properties and physical actuators (servos). This overcomes the problem of traditional devices lacking precise mathematical modeling, which leads to a disconnect between feedback force and the mechanical properties of the virtual environment. It ensures that the feedback force perceived by the operator is strictly matched with the virtual scene in both numerical and physical sense, thereby significantly improving the accuracy of force feedback.

[0032] 2. Achieving Precise Control: A phase displacement-torque dual closed-loop control system was developed. The phase displacement closed loop is responsible for precisely controlling the rotation angle of the servo motor to ensure the positional accuracy of the mechanical motion; the torque closed loop is responsible for precisely controlling the output torque of the servo motor to ensure the output force intensity. The synergistic effect of the two closed loops enables the system to independently and precisely adjust the direction and amplitude of the feedback force simultaneously. This dual-variable closed-loop control mechanism solves the technical problem that existing technologies often only focus on controlling a single dimension of displacement or force, making it difficult to take into account the accuracy of amplitude and direction. It achieves refined control of the feedback force in multiple dimensions.

[0033] 3. Enhanced real-time response capability: Utilizing the inherent fast response characteristics of DC servo motors and combining them with the dynamic adjustment capability of the dual closed-loop control system, when interactive events such as collisions occur in the virtual environment, the system can quickly calculate the target feedback force through a mathematical model, and the dual closed-loop control system drives the servo motor to move rapidly to generate the required force feedback. This control mechanism based on electro-actuation technology effectively shortens the delay from the occurrence of virtual interaction to the generation of physical force feedback, realizing a rapid response to virtual collisions, thereby ensuring the real-time performance and continuity of the interaction.

[0034] 4. Optimize wearing comfort: Designed based on an arm-worn structure, the control and execution modules are integrated into an ergonomic wearable device; by optimizing the structural layout, interference from complex cables or bulky execution components is avoided, improving the wearing comfort of the device from the structural design level, and solving the problem of discomfort and long-term training experience caused by unreasonable structure of traditional devices.

[0035] In addition to the objectives, features, and advantages described above, the present invention has other objectives, features, and advantages. The invention will now be described in further detail with reference to the figures. Attached Figure Description

[0036] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0037] Figure 1 This is a schematic diagram of the structure of an electrodynamic feedback device for virtual training according to a preferred embodiment of the present invention;

[0038] Figure 2 This is a schematic diagram of the base structure according to a preferred embodiment of the present invention;

[0039] Figure 3 This is a schematic diagram of the outer shell of a preferred embodiment of the present invention;

[0040] Figure 4 This is a schematic diagram of the servo motor according to a preferred embodiment of the present invention;

[0041] Figure 5 This is a schematic diagram of the structure of the cam according to a preferred embodiment of the present invention;

[0042] Figure 6 This is a schematic diagram of the function of the small end of the cam in a preferred embodiment of the present invention;

[0043] Figure 7 This is a distance and angle measurement diagram of a preferred embodiment of the present invention;

[0044] Figure 8 This is a diagram showing the relationship between feedback force, distance, and rotation angle in a preferred embodiment of the present invention;

[0045] Figure 9 This is a schematic diagram of the function of the large end of the cam according to a preferred embodiment of the present invention, wherein... Figure 9 (a) is a schematic diagram of the function on the left. Figure 9 (b) is a schematic diagram of the action on the right;

[0046] Figure 10 This is a graph showing the relationship between effective voltage and feedback force in a preferred embodiment of the present invention.

[0047] Figure 11 This is a Simulink simulation diagram of a preferred embodiment of the present invention with dual closed loops;

[0048] Figure 12 This is a position response curve diagram of a single closed-loop control according to a preferred embodiment of the present invention;

[0049] Figure 13 This is a torque response curve diagram of a single closed-loop control according to a preferred embodiment of the present invention;

[0050] Figure 14 This is a position response curve diagram of the dual closed-loop control according to a preferred embodiment of the present invention;

[0051] Figure 15 This is a torque response curve diagram of the dual closed-loop control according to a preferred embodiment of the present invention;

[0052] Figure 16 This is one of the curves showing the relationship between driving force and feedback angle in a preferred embodiment of the present invention;

[0053] Figure 17 This is the second graph showing the relationship between driving force and feedback force in a preferred embodiment of the present invention.

[0054] Figure 18 This is a schematic diagram of force feedback in virtual training according to a preferred embodiment of the present invention, wherein... Figure 18 (a) is an internal view. Figure 18 (b) is the exterior view. Figure 18 (c) is a front view. Detailed Implementation

[0055] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, the present invention can be implemented in many different ways as defined and covered below.

[0056] like Figure 1 As shown, the design method of the electric force feedback device for virtual training in this embodiment includes the following steps: Designing an arm-worn force feedback device based on a DC servo motor; establishing a mapping relationship between virtual environment interaction information and physical feedback force by deriving a mathematical model of feedback force and servo motor rotation angle; designing a phase displacement-torque dual closed-loop control system, controlling the servo motor rotation angle through a phase displacement closed loop and controlling the servo motor output torque through a torque closed loop to achieve precise control of the amplitude and direction of the feedback force; driving the arm-worn force feedback device to generate feedback force matching the virtual training scene through the mathematical model and the dual closed-loop control system, achieving rapid response to virtual collisions, and keeping the feedback force and rotation angle error within a preset threshold to enhance the realism and immersion of virtual training. A phase displacement-torque dual closed-loop control system is designed. The phase displacement closed loop is responsible for precisely controlling the rotation angle of the servo motor, ensuring the positional accuracy of the mechanical motion; the torque closed loop is responsible for precisely controlling the output torque of the servo motor, ensuring the output force intensity. The synergistic effect of the two closed loops enables the system to independently and precisely adjust the direction and amplitude of the feedback force simultaneously. This solves the technical problem that existing technologies often only focus on controlling a single dimension of displacement or force, making it difficult to simultaneously ensure the accuracy of amplitude and direction, thus achieving multi-dimensional and refined control of the feedback force. Utilizing the inherent fast response characteristics of DC servo motors and combining them with the dynamic adjustment capability of the dual closed-loop control system, when interactive events such as collisions occur in the virtual environment, the system can quickly calculate the target feedback force through a mathematical model, and the dual closed-loop control system drives the servo motor to move rapidly, generating the required force feedback. This control mechanism based on electro-actuation technology effectively shortens the delay from the occurrence of virtual interaction to the generation of physical force feedback, achieving a rapid response to virtual collisions, thereby ensuring the real-time performance and continuity of the interaction. Designed based on an arm-worn structure, this invention integrates the control and execution modules into an ergonomically designed wearable device. By optimizing the structural layout, it avoids interference from complex cables or bulky actuators, improving wearing comfort from a structural design perspective and solving the problems of discomfort and poor long-term training experience caused by the unreasonable structure of traditional devices. This invention's design method for an electrodynamic feedback device for virtual training addresses technical problems such as insufficient feedback force accuracy, single control dimension, poor real-time performance, and poor wearing comfort by establishing a precise mathematical model, developing a phase displacement-torque dual closed-loop control system, and employing an optimized arm-worn structure. These technologies work synergistically to achieve high-precision, high-real-time, and high-comfort operation of the force feedback device, effectively enhancing the realism and immersion of virtual training.

[0057] In this embodiment, the wearable force feedback device consists of a fixing module, a wireless communication module, a control and drive module, an execution module, and a power supply module. The fixing module ensures stable positioning of the force feedback device on the operator's limb and simultaneously stabilizes the servo motor, thus establishing a reliable force transmission path and avoiding feedback force distortion caused by device shaking or unstable positioning. The power supply module provides stable power to the control and drive module, ensuring the normal operation of the entire system. The structured design of the wearable force feedback device receives interactive information from the virtual environment through the wireless communication module and converts it into electrical signals. After processing by the control and drive module, these signals drive the execution module, causing the servo motor to act on the cam to generate a precise phase shift, thereby outputting the corresponding feedback force. This "sensing-transmission-processing-execution" process constitutes a complete closed-loop force feedback control system. This closed-loop control mechanism ensures that the system can monitor and respond to limb interactions in the virtual environment in real time, achieving real-time performance and accuracy of force feedback. It solves the technical problems of poor real-time performance and feedback delay in traditional devices, while also achieving systematic integration of power supply, communication, control, and execution functions, providing a stable hardware foundation for accurate force feedback generation. The wearable force feedback device is designed for use in virtual training scenarios. Through the precise force feedback generated by the aforementioned closed-loop control system, operators can realistically perceive the mechanical properties of virtual objects (such as hardness and reaction force) during virtual maintenance training, significantly enhancing the immersion and realism of the training and improving its effectiveness. The design of the wearable force feedback device, through precise force feedback control, avoids the risk of injury to the operator due to uncontrolled or excessive feedback force, thus reducing the risk of injury during training and demonstrating good human-computer interaction safety. Through modular system design, the implementation of a closed-loop force feedback control mechanism, and precise force feedback generation, the wearable force feedback device achieves real-time and accurate responses to limb interactions in virtual training while ensuring stable system operation. This effectively enhances the realism of immersive maintenance and reduces the risk of injury, thereby improving the overall efficiency of the virtual training system.

[0058] In this embodiment, based on a wearable force feedback device, a structured design approach is used to optimize the performance of each module of the wearable force feedback device. The module design comprehensively considers the miniaturization requirements and the size constraints of the DC servo motor. Through structured design, the physical constraints such as the size and weight of the DC servo motor are comprehensively considered during the module design stage. The mechanical structure and electrical layout of the fixing, control drive, and execution modules are optimized, ensuring that each module can be compactly integrated into the wearable device while fulfilling its function. This avoids the problem of the overall device being bulky and cumbersome due to the excessive size of a single module or unreasonable layout, thereby improving the wearing comfort and ergonomic fit of the device. The structured design reduces the complexity of the system design through clear module division and functional definition, facilitates independent testing, maintenance, and replacement of modules, and thus improves the reliability of the device. At the same time, the modular design approach also facilitates subsequent standardized production and manufacturing, helping to reduce production costs. By adopting a structured design approach, the force feedback device modules are miniaturized and their performance optimized while meeting the size constraints of the DC servo motor. This results in a lightweight, compact, and highly integrated device, effectively solving problems such as poor wearing comfort and limited system performance caused by unreasonable structural design in traditional force feedback devices.

[0059] like Figure 2 and Figure 3 As shown, in this embodiment, a structured design approach is used to optimize the performance of each module of the wearable force feedback device. This includes: a split-type wearable structure that, through the coordinated design of the base, strap, and shell, constructs a stable force transmission path; the base employs a through-hole design with a horizontal rectangular opening, combined with a strap fixing mechanism, to efficiently and directly transmit the feedback force generated by the actuator module (servo-driven cam) to the operator's limbs, reducing force loss and deformation during transmission and ensuring high fidelity of the physical feedback signal. This avoids feedback force attenuation caused by loose fixing or an unclear force transmission path, thus ensuring the accuracy of force feedback. The screwless connection method, combined with the strap fixing mechanism, achieves stable fixation of the device on the limb, preventing wobbling or displacement under force feedback; the through-hole and strap design helps disperse the reaction force generated by the feedback force, reducing discomfort at concentrated force points and improving wearing comfort. This effectively solves the problems of discomfort and feedback force distortion caused by unstable fixation or concentrated reaction force in traditional devices. The rounded edges and corners of the outer shell eliminate the potential risk of skin injury from sharp edges and prevent scratches or indentations to the operator during wear or exercise. Combined with the ergonomic design of the split structure, this design significantly improves the wearing comfort and safety of the device from the perspective of structural details, solving the technical problems of poor comfort and low safety caused by the rough structural design of traditional devices.

[0060] In this embodiment, a structured design approach is used to optimize the performance of each module of the wearable force feedback device. This includes a wireless communication module that uses Wi-Fi technology to achieve efficient and stable data transmission. This ensures that interactive data such as collision information in the virtual environment is transmitted to the control and drive module in real time and accurately, avoiding lag in force feedback response due to communication delays or data loss. This provides a reliable data transmission foundation for the real-time response of the closed-loop force feedback control system, thus guaranteeing the continuity and realism of force interaction in virtual training. The control and drive module uses a micro servo motor integrating a DC motor and gear set as the drive unit. Utilizing the speed reduction and torque amplification characteristics of the gear set, high torque output is achieved while reducing the structural volume. This "small size, high torque" design not only meets the stringent requirements of wearable applications for device size and weight but also ensures that the execution module can generate sufficient feedback force. This solves the technical problem that traditional drive units are large and lack sufficient torque, making them unsuitable for wearable devices, thereby improving the wearing comfort and force feedback efficiency of the device. The power module utilizes a lithium battery and incorporates aluminum-plastic composite film encapsulation technology, achieving both lightweight design and optimized safety while ensuring energy supply. This technology enhances the battery's mechanical strength and thermal stability, reducing safety risks in wearable applications. The lightweight design further improves the device's wearing comfort and addresses the bulkiness and poor safety issues of traditional power supply solutions. Through targeted structural design optimization of the wireless communication module, control drive module, and power module, Wi-Fi technology ensures real-time data transmission, micro-servos achieve small-size, high-torque drive, and lithium battery and aluminum-plastic composite film encapsulation technology optimize power supply safety and lightweight design. This collaborative approach addresses technical challenges in force feedback devices, including data transmission, drive unit size and torque, power supply safety, and weight, providing structured support for the high efficiency, high comfort, and safe operation of wearable force feedback devices. Figure 4 As shown, the composition and control principle of the servo motor are illustrated. Its structure consists of a DC motor driving a "T"-shaped output arm through a reduction gear set. At the same time, the shaft of the potentiometer is coaxially connected to the output arm to feed back the angular position change of the output arm to the control circuit. The control circuit controls the start, stop and direction of the motor by comparing the feedback signal with the target position signal, thereby forming a closed-loop control of the output arm's rotation angle and achieving high-precision position and torque control.

[0061] like Figure 5As shown, in this embodiment, a structured design method is used to optimize the performance of each module of the wearable force feedback device. It also includes an execution module composed of a servo motor and a cam mechanism. Based on the differentiated action modes at both ends of the cam mechanism, force feedback control is formed within a 120° range below the arm. Through the specific geometric contour of the cam, the rotational motion of the servo motor is converted into linear displacement or pressure acting on a specific area of ​​the arm (120° range), ensuring that force feedback is generated only at the limb corresponding to the virtual interaction, avoiding ineffective diffusion or interference of the feedback force, thereby achieving controllability of the feedback force's action area and improving the targeting and effectiveness of the force feedback. The cam mechanism utilizes its non-circular geometric characteristics to convert the continuous rotational motion of the servo motor into periodic pressure or displacement changes conforming to specific mechanical laws (such as sine, parabola, etc.). This motion-force conversion mechanism, combined with the servo motor's precise control of the rotation angle, can accurately reproduce the mechanical characteristics required in the virtual environment (such as the reaction force variation law of objects with different hardness), thus ensuring the accuracy of the feedback force. The 120° effective range design takes into account the physiological structure of the lower arm, ensuring that force feedback is applied evenly and reasonably to the skin surface. This avoids pressure concentration due to an insufficient effective range or ineffective feedback due to an excessively large effective range. From an ergonomic perspective, this design optimizes the force feedback mechanism, improving the device's wearing comfort and the naturalness of force perception. Optionally, the micro servo motor uses the SG90 micro servo motor.

[0062] Based on the actual anatomical structure of the arm, its geometric model is simplified to an ellipse equation, namely:

[0063]

[0064] Among them, the semi-major axis It is 20, semi-short axis The value is 15; the cam structure is formed by the intersection of a central circle and two parabolas, and the central circle adopts the standard circle equation; the two ends of the cam are divided into large end and small end structures due to different action modes; force feedback analysis is performed on the small end, and the parabolic equation in the Cartesian coordinate system is adopted, as shown in formula (1):

[0065] (1)

[0066] in, p It is 3.3. qThe model design of the cam includes two modes of action: small end and large end. The calculation basis of force feedback is solved by establishing an accurate geometric and mathematical model. By simplifying the actual anatomical structure of the arm into an elliptical equation, a standardized and quantifiable geometric constraint model is provided for the interaction between the cam and the arm, overcoming the difficulty of force analysis caused by the irregular structure of the human body and the difficulty of quantifying and modeling in traditional design. At the same time, the parabolic equation under the Cartesian coordinate system is used to accurately describe the profile of the small end of the cam, so that the relationship between the cam profile and the feedback force can be theoretically analyzed and calculated through equation (1). This design mechanism based on the mathematical model transforms the complex biomechanical interaction problem into an analytically calculable geometric and mechanical problem, thereby ensuring the accuracy of the feedback force calculation and the predictability of the design process in principle, and providing a mathematical basis for solving the problem of insufficient feedback force accuracy. Based on the model, the cam is divided into two action modes: a small end and a large end. The small end acts on the underside of the arm, forming a feedback force through a combination of compression and friction. This composite force action can simulate richer tactile sensations, such as the feeling of pressure and sliding of an object. The large end acts on the underside of the arm, applying feedback force directly through the cam, suitable for providing direct pressure feedback. This differentiated action mode design allows a single cam structure to adapt to the different needs for force feedback characteristics in different virtual interaction scenarios (such as the need for friction prompts or pure pressure), thereby enhancing the expressiveness and realism of force feedback. Combined with the limitation of a 120° action range under the arm, it ensures that the feedback force can effectively and centrally act on the target perception area, avoiding the dispersion of force signals and improving the efficiency and perception clarity of force feedback. By constructing a simplified elliptical model of the arm and a parabolic equation model of the cam, a precise and calculable theoretical basis is provided for force feedback design. Furthermore, by designing differentiated action modes at the large and small ends of the cam, the optimization of feedback force types and centralized control of the action area are achieved. These technical means work together to improve the force control accuracy, action stability, and virtual interactive performance of the force feedback device from both mathematical model and mechanical structure perspectives.

[0067] like Figure 6 As shown, in this embodiment, the feedback force when the small end acts is as follows: when analyzing the small end's action, the cam initially has no contact with the arm. As the cam rotates, the small end gradually approaches the arm. When the rotation angle is 38°, the parabola and the arc together contact the surface of the arm. The entire action is approximately assumed to be an increment of cam rotation equal to the compression amount of the small end intruding into the arm.

[0068] like Figure 7 and Figure 8 As shown; the small end acts on the arm, and the elastic force exerted by the arm on the cam during cam rotation is... ,in, Let the base circle radius of the cam be . The elastic coefficient of human skin is given by the frictional force. , The coefficient of friction between the cam and the surface of the human arm; the Young's modulus of forearm deformation in biomechanical modeling. Values Based on optical coherence tomography (OCT) measurement data, the effective thickness for Area of ​​force for ,according to It can be known for ;Will , Substitution formula (2):

[0069] (2)

[0070] The relationship between cam rotation angle and feedback force under the action of the small end was obtained. Through theoretical analysis, the precise starting point from disengagement of the small end to the generation of effective feedback force (contact at 38° rotation) was clarified, and the cam rotation increment was defined. △θ Approximately equal to little-endian compression l θ The key simplifying assumption transforms the complex spatial geometric compression problem into a direct proportional relationship between the rotation angle and the linear compression amount. This provides an operable, linear input variable for establishing a mathematical model of rotation angle-feedback force, fundamentally ensuring the computability and physical clarity of the final mapping relationship. The study identifies a mathematical obstacle where polar coordinate calculations result in a zero denominator due to the non-coincidence of the geometric centers of the parabola and the circular arc. A graphical approach is then used to analyze the cam rotation angle. α With compression l θ By combining geometric analysis and numerical computation, the mathematical singularity was bypassed, and the relationship between the two was successfully obtained, thus avoiding the dilemma of direct analytical solutions. l θ With corner θ The functional relationship cleared away key technical obstacles for subsequent mechanical calculations, demonstrating its practicality in handling complex engineering problems. The human arm was simplified as an elastic body, and Hooke's Law was applied (…). ) and Coulomb's law of friction ( ), geometric compression l θ Directly converted into quantifiable normal elastic force F N and friction f By introducing biomechanically measured parameters (Young's modulus) E Effective thickness L Area of ​​force AThe calculation yielded an elastic coefficient of human skin, k = 11.2 N / mm, transforming the model from a theoretical formula into an engineering model with actual physical parameters that can be quantitatively calculated. This allows for the integration of the force perception required by the virtual environment with the physical parameters of the actuators (rotation angles). θ This is firmly linked to the biomechanical characteristics of the human body, ensuring the authenticity and reliability of the feedback force calculation. The diagram showing the relationship between the cam angle and the feedback force under the action of the small end, obtained through the above steps, is essentially the control variable (cam angle) under this specific structure. θ ) and the controlled variable (feedback force) F The static transfer function or lookup table between the phase displacement and torque double closed-loop control system can be used as the given target value or feedforward compensation model for the torque loop. The system can quickly determine the required cam target angle (phase displacement) by querying this relationship based on the target feedback force calculated from the virtual environment, thus achieving a precise and rapid conversion from "target force" to "actuator position command." Through a series of theoretical analyses, model simplifications, and parameter quantifications, the complex modeling and calculation problems between cam geometric motion and human-perceived force feedback were solved. A precise, reliable, and biomechanical parameter-based quantitative mapping model of "cam angle-feedback force" was established, which not only has clear physical meaning and computational feasibility but also provides an indispensable key input and theoretical basis for the precise control system of the entire force feedback device.

[0071] In this embodiment, the feedback force when the large end is applied is specifically as follows: when the large end is applied, the arm-worn force feedback device maintains a fixed connection with the arm, based on the motor torque formula. Torque formula Combined with servo motor current The formula for the feedback force of the cam on the arm is derived (3):

[0072] (3)

[0073] in, The effective voltage input to the servo motor. The internal resistance of the servo motor. It is the torque constant of the servo motor. The reduction ratio of the servo motor. For transmission efficiency, The distance from the cam profile to the cam center is given, with the large end acting on both sides of the arm. Through theoretical derivation, starting from the motor torque formula, torque formula, and servo motor current relationship, a direct analytical relationship between the effective input voltage U of the servo motor and the feedback force F ultimately acting on the arm is established, formula (3). This relationship shows that the feedback force F is proportional to the effective voltage U. Its proportional coefficient integrates all key physical parameters such as the torque constant, reduction ratio, transmission efficiency, internal resistance, and cam arm length of the servo motor. The force output characteristics of the complex motor-transmission-cam mechanism are finally simplified into a linear input-output model that can be directly controlled by voltage. This makes it possible to accurately and linearly control the magnitude of the output feedback force by precisely adjusting the duty cycle of the PWM signal (i.e., adjusting the effective voltage U). In principle, this solves the problem of insufficient control accuracy and unstable force output caused by the complexity and strong nonlinearity of the intermediate conversion links in traditional force feedback devices. The feedback force is limited to a 120° range below the force feedback device, achieved by adjusting the cam angle α. The rotational motion of the servo motor is converted into directional pressure feedback within a specific angular range through the contact between the large end of the cam and the lower side of the arm. This directional angular range design allows the feedback force to act concentrated and stably on the target sensing area of ​​the arm, avoiding dispersion or unclear application points. This improves the clarity and accuracy of force feedback perception, enhancing the intuitiveness and realism of user interaction. Because a direct linear relationship is established between the feedback force and the effective voltage, and the voltage can be digitally adjusted with high resolution and high response speed using mature pulse width modulation (PWM) technology, the system possesses great control flexibility. Operators can quickly and continuously change the magnitude of the feedback force using simple voltage (or PWM duty cycle) commands to adapt to complex and ever-changing mechanical interaction scenarios in the virtual environment. This voltage-based direct control mechanism simplifies control system design and improves the dynamic response and real-time performance of force feedback adjustment. By establishing a linear control model for feedback force and voltage based on key physical parameters, and combining it with the cam rotation angle to achieve directional force action within a 120° range, precise, linear, and digital control of the magnitude of the feedback force and stable, directional control of the feedback force action area are achieved. The combination of these two approaches effectively solves the shortcomings of traditional devices in terms of force control accuracy, stability, and adaptability, and provides a clear and feasible technical path for achieving flexible, precise, and reliable force feedback control within a specific ergonomic range.

[0074] like Figure 9 As shown, in this embodiment, the cam rotation angle is adjusted. This achieves force feedback control within a 120° range below the force feedback device; the effective voltage applied to the servo motor is adjusted using a pulse width modulation (PWM) signal. This changes the feedback force of the servo motor on the arm. Substituting the parameters into equation (3), we obtain the effective voltage of the servo motor. With feedback force The relationship, and the analysis results, such as Figure 10 As shown.

[0075] In this embodiment, a phase displacement-torque dual closed-loop control system is designed. Specifically, based on the structural design of the micro servo and the force feedback control command, a phase displacement-torque dual closed-loop control system is designed to achieve precise force feedback control. The phase displacement-torque dual closed-loop control system effectively resists external disturbances through closed-loop feedback, ensuring the servo's rapid tracking command response, while suppressing the negative impact caused by excessive load torque. The control strategy of the phase displacement-torque dual closed-loop control system adopts a hierarchical control concept: the inner loop control first achieves the system's rapid tracking performance, and the outer loop control then adjusts the current to suppress the load torque, ensuring it meets design requirements. The Simulink simulation of the dual closed-loop control includes the inductor... ,resistance Moment of inertia back electromotive force coefficient Torque coefficient Reduction ratio The load torque is By designing a control strategy that prioritizes rapid tracking through the inner loop (phase shift loop), the system leverages the fast response speed of the inner loop to enable the servo motor to quickly respond to changes in force feedback control commands and adjust the output angle in a timely manner. This solves the technical problems of force feedback delay and asynchrony with the virtual environment caused by response lag in open-loop or single-loop control systems, thus ensuring the real-time performance of force feedback interaction. The outer loop (torque loop) regulates the current to suppress load torque. The outer loop uses current as the control target and directly adjusts the drive current of the motor through feedback regulation. When the load torque fluctuates due to external disturbances (such as changes in arm posture or sudden changes in contact force), the torque loop can quickly detect the deviation and adjust the current output to maintain the stability of the target torque. This hierarchical control structure effectively suppresses negative effects caused by excessively high or unstable load torque, such as motor stall, force output jitter, or loss of control, thereby significantly improving the stability and reliability of force feedback. The dual-loop structure achieves independent and coordinated control of displacement (phase displacement) and torque. The phase displacement loop ensures the precision of the mechanical position (cam angle), which is the foundation for the correct direction and area of ​​force application. The torque loop ensures the precision of the output torque, which is the foundation for the correct magnitude of force feedback. The combination of these two loops achieves precise closed-loop control of the feedback force vector (magnitude and direction), solving the problem that single-variable control cannot simultaneously address force and position accuracy, thus ensuring the overall accuracy of the feedback force. This is achieved by setting explicit motor parameters (such as...) in the Simulink environment. L , R , J , Ce , C m , K Simulations were performed using various methods to construct an accurate digital twin model of the motor and control system. This allows for the prediction of the system's dynamic performance, tuning of control parameters, and verification of the effectiveness of the control strategy during the design phase. This avoids the problems of long cycles and high costs associated with traditional trial-and-error methods. A hierarchical control strategy with fast inner-loop tracking and load suppression outer-loop is adopted to achieve rapid response, high-precision tracking, strong anti-interference, and stable output of the force feedback actuator (servo motor). Combined with Simulink simulation based on an accurate physical model, a reliable design and verification tool is provided for the system's implementation, effectively solving key technical problems commonly encountered in force feedback devices, such as response delay, high susceptibility to load disturbances, and insufficient control accuracy.

[0076] like Figure 11 The figure shown is a Simulink simulation model of the phase shift-torque dual closed-loop control system of the present invention. This simulation clearly illustrates the structural connections and closed-loop working principle of the system. Structurally, the system consists of two control loops: the outer loop is an angle control loop, whose input is a given target angle θ. ref The angle error e is obtained by comparing it with the actual feedback angle θ of the motor. θ The error signal is processed by the PID controller, and the output current reference value I is... ref The outer loop control is completed; the inner loop is the current control loop, which takes the current reference value I output from the outer loop. ref The current error e is obtained by comparing it with the actual motor current i. i The error signal is then processed by the PI controller to generate the final motor drive voltage u. This drive voltage, through an "inductor / resistor" electrical model, produces an actual current i, which is then converted into the motor's electromagnetic torque T via the torque constant Cm. e In terms of working principle, this model achieves coordinated closed-loop control of phase displacement and torque. The mechanical motion of the motor is modeled as a dynamic system containing rotational inertia J, and electromagnetic torque T. e With load torque T L The combined effects generate an angular velocity ω, which is integrated to obtain the actual angle θ and fed back to the outer loop input, thus forming a complete closed loop. This simulation model closely integrates the electrical and mechanical characteristics of the system, intuitively demonstrating the hierarchical control concept of "outer loop angle setting command, inner loop current rapid response and interference suppression," providing an accurate digital simulation environment for analyzing and optimizing the dynamic performance of the control system.

[0077] In this embodiment, a step signal with an amplitude of 1 is input to the phase displacement-torque dual closed-loop control system. The dynamic response performance of the motor position and torque is optimized by adjusting the parameters of the PID controller; ultimately, a proportional gain controller is selected. Integral gain Differential gain As control parameters; under this control parameter configuration, the phase displacement-torque dual closed-loop control system reaches a steady state within 2 seconds, with an overshoot of less than 6.3% and a steady-state error of 0.012. The dynamic response performance of the motor position and torque is optimized by adjusting the PID controller parameters; the PID controller constructs the control quantity through a linear combination of the proportional (P), integral (I), and derivative (D) actions of the error; adjusting the proportional gain... K p Integral gain K i Differential gain K d These three core parameters can systematically optimize the response characteristics of the closed-loop system; the proportional gain directly affects the response speed and steady-state accuracy, the integral gain is used to eliminate steady-state error, and the derivative gain helps to suppress overshoot and oscillation. Through targeted adjustment of these three parameters, the system's response speed, stability, accuracy, and other multi-dimensional dynamic qualities can be systematically designed and optimized, thus enabling the control system to possess the preset dynamic response qualities. By adjusting and ultimately determining a set of effective PID controller parameters, not only is the designed phase shift-torque dual closed-loop control structure proven to be reasonable and effective, but a direct reference benchmark is also provided for setting the control parameters of the actual physical device. This allows the control system to achieve excellent response quality in practical applications without complex online debugging, reducing debugging complexity and ensuring the performance reliability of the physical device. The torque response did not achieve the expected suppression effect. The system response results are as follows: Figure 12 and Figure 13 As shown in the figure. The analysis results indicate that the failure to effectively suppress the motor current is the main reason for the insufficient torque response.

[0078] In this embodiment, current loop control is introduced, and a PI controller is added to reduce the problem of excessive motor current. Under the same input signal conditions, the parameters are optimized through the PI controller's self-adjusting model to determine the proportional gain of the current loop. and integral gain Under these parameter configurations, the motor position response reaches a stable state within 0.5 seconds with no overshoot and a steady-state error of 0.01. The torque response is completed in an extremely short time, demonstrating excellent dynamic performance. By introducing current loop control and a PI controller, the problem of excessive motor current is reduced. The current loop, as the innermost control loop, can directly and quickly adjust the motor's armature current. Through the proportional and integral actions of the PI controller, the error between the current command and the actual current can be compensated in real time and accurately, thereby strictly limiting the motor's operating current within a safe and reasonable range. This effectively prevents current spikes or continuous overcurrent caused by sudden load changes, command surges, or parameter mismatches, avoiding risks such as motor overheating and driver damage, and significantly improving the electrical safety and long-term operational reliability of the entire force feedback device. The high-performance current loop itself forms a strong first line of defense against changes in motor electrical parameters (such as resistance changes caused by winding temperature variations) and external voltage fluctuations. The PI controller, through integral action, eliminates steady-state current errors, ensuring that the motor outputs precise torque even under disturbances. This enhances the overall dual-loop control system's ability to resist electrical disturbances and improves system robustness. By introducing a current loop and configuring a self-adjusting optimized PI controller into the original dual-loop control system, precise, rapid, and safe closed-loop regulation of the motor current is achieved starting from the innermost current control layer. This effectively suppresses the risk of excessive current, ensuring system safety; significantly optimizes the dynamic response performance of position and torque, resulting in faster response speed, no overshoot, and higher steady-state accuracy; and enhances the system's ability to suppress electrical disturbances. This comprehensively improves the control quality of the entire phase displacement-torque dual-loop control system. The control effect is as follows: Figure 14 and Figure 15 As shown.

[0079] This embodiment also includes experimental verification of the force feedback device. Specifically, through experimental testing, the relationship between the driving force of the feedback device, the servo feedback angle, and the actual feedback force is analyzed. The maximum relative error between the feedback force and the theoretical feedback angle and driving force is measured, revealing that the magnitude of the driving force is closely related to the servo lever arm length. Furthermore, the lever arm length is optimized to adapt to different application scenarios and improve system performance. Through experimental testing, the relationship between the driving force of the feedback device, the servo feedback angle, and the actual feedback force is analyzed, and the maximum relative error between the relevant parameters is measured. By comparing the physical experimental measurement results with the theoretical prediction values ​​of the mathematical model of "cam angle-feedback force," the accuracy of the theoretical model and the manufacturing and control precision of the actual device can be quantitatively evaluated. The measured maximum relative error is a key quantitative indicator for measuring the comprehensive performance of the entire system (from model and control to execution), confirming the effectiveness of the design scheme and clarifying its actual accuracy level, providing a benchmark for subsequent improvements. The experiment revealed a close relationship between the magnitude of the driving force and the length of the servo lever arm. According to mechanical principles, under the condition of constant servo output torque, the force acting at the end (driving force) is inversely proportional to the lever arm length. This mechanism indicates that the lever arm length is a key mechanical design parameter for adjusting the final output force range and resolution of the system. A shorter lever arm can achieve a larger output force but may sacrifice the range of motion or accuracy, while a longer lever arm can provide finer force control but limits the maximum output force. This experimental conclusion directly links abstract system performance with specific, designable mechanical parameters (lever arm length). Based on the revealed mechanism, this paper proposes optimizing the lever arm length to adapt to different application scenarios and improve system performance. It provides a clear, physics-based method for system performance tuning. The optimal lever arm length can be selected or designed specifically according to the different requirements of feedback force magnitude, accuracy, and range in different virtual training scenarios. This allows the same core system to flexibly adapt to diverse application needs through adjustments to key mechanical parameters, achieving customized performance improvements. Through experimental verification, not only was the actual performance of the force feedback device quantitatively evaluated and its consistency with the theoretical model assessed, but more importantly, the experimental data revealed the decisive influence of the mechanical parameter "servo lever arm length" on the final output driving force. This makes it possible to specifically adjust the system's force output characteristics and adapt to different application scenarios by optimizing the lever arm length. The solution embodies a complete closed-loop iterative process of "design-experiment-analysis-optimization," transforming system performance optimization from empirical attempts to scientific design based on physical mechanisms and experimental data. This effectively solves the technical problems of lacking clear guidance for force feedback device performance tuning and difficulty in adapting to changing scenarios.

[0080] In this embodiment, the experimental setup includes a spring balance and a feedback device. The top of the spring balance is fixed, and the end of the spring balance is connected to a cam. The experiment controls the cam to generate different driving forces by adjusting the effective voltage of the servo motor through a PWM signal, and records the feedback angle and the actual feedback force measured by the spring balance under different driving forces. By fixing the top of the spring balance and connecting its end to the cam, a stable and quantifiable force feedback testing environment is established. The spring balance provides a known and calibrable elastic load, replacing the complex and unstable biomechanical load of the human arm. This standardized testing device eliminates the influence of uncontrollable factors such as individual differences and changes in muscle tension on the experimental results, providing a benchmark platform for objectively and repeatably testing the performance of the force feedback device, and ensuring the reliability and comparability of the experimental data. The actual feedback force data obtained through the above experimental methods can be directly compared with the theoretical feedback force calculated based on the theoretical model, thereby quantitatively verifying the accuracy of the theoretical model and calculating the error between the actual system and the theoretical model; at the same time, the experimental data can also be used to calibrate the key parameters of the control system, such as verifying whether the linear proportional coefficient of the effective voltage U of the servo motor and the feedback force F in formula (3) is consistent with the theoretical value; this verification and calibration based on experimental data is a key step to ensure that the control system can achieve the expected performance in practical applications. By designing an experimental device containing a fixed spring force gauge and a feedback device, and adopting the standardized experimental method of "controlling voltage - measuring angle and force", an objective and repeatable force feedback performance test platform was constructed, which can accurately obtain the input and output characteristic data of the force feedback device under different control conditions, providing a reliable data basis for verifying the accuracy of the theoretical model, calibrating the control system parameters, and analyzing system errors. It is an important experimental verification link to ensure that the design of the force feedback device meets the expected performance indicators and achieves precise control. The experiment controls the cam to generate different driving forces by adjusting the effective voltage of the servo motor through the PWM signal, and records the feedback angle and the actual feedback force measured by the spring force gauge under different driving forces, such as Figure 16 and Figure 17 As shown in the figure, the experimental results indicate that the maximum driving force of the feedback device is approximately 32.37 N, corresponding to a maximum blade rotation angle of 90.7°, reaching the maximum stroke of the compression depth. The maximum relative errors between the measured feedback force and the theoretical feedback angle and driving force are 3.6% and 4.8%, respectively. The experiment also reveals that the magnitude of the driving force is closely related to the length of the servo lever arm, indicating that optimizing the lever arm length can adapt to different application scenarios and improve system performance.

[0081] This embodiment also includes experimental verification of virtual training. Specifically, a virtual environment is constructed based on Jack and Unity software, and the operator performs virtual operations wearing a wearable force feedback device. The experimental results are used to obtain the response speed of the electro-dynamic feedback device to virtual collisions, as well as the feedback force and corresponding feedback angle. The feedback force and feedback angle of the virtual experiment are compared with the results of actual physical experiments to verify the accuracy and effectiveness of the force feedback device control, providing physical interaction support for virtual maintenance training. By constructing a virtual environment based on Jack and Unity software and having the operator perform virtual operations wearing a wearable force feedback device, the device's performance is tested in a virtual training scenario close to real-world applications. This not only tests the device's force output characteristics but also its overall performance within the "human-device-virtual environment" closed-loop system. The experimental results obtain key performance indicators such as the response speed, feedback force, and corresponding feedback angle of the electro-dynamic feedback device to virtual collisions, thereby verifying the device's real-time performance, accuracy, and usability in actual interaction processes, overcoming the limitation that simple physical experiments cannot simulate complex virtual interaction scenarios. By comparing the feedback force and feedback angle measured in the virtual experiment with the results of the actual physical experiment, and by comparing the feedback force in the virtual environment with the actual feedback force measured by the physical experimental device, it can be verified whether the force feedback device can accurately reproduce the mechanical properties in the virtual environment, that is, verify whether the mapping relationship between "virtual force and physical force" is accurate. This data comparison combining virtual and real elements forms a complete closed loop from the virtual environment to the physical device and then to experimental verification. It can comprehensively evaluate the control accuracy and effectiveness of the force feedback device in the virtual training system, ensuring that the mechanical interaction in the virtual environment can be transmitted to the operator realistically and accurately. Through the above verification, it is confirmed that the force feedback device can provide accurate and real-time force feedback for virtual maintenance training; it elevates virtual training from a simple visual interaction to an immersive interaction that includes real force feedback; the operator can perceive the physical properties of virtual objects such as hardness and reaction force through the device, thereby obtaining a more realistic operating experience. This physical interaction support is a key factor in improving the realism, immersion, and training effect of virtual maintenance training, and solves the technical problem of the lack of real force feedback in traditional virtual training. By constructing a virtual training environment and conducting virtual experimental verification, a comprehensive evaluation of the force feedback device's overall performance in real-world application scenarios was achieved. Through closed-loop verification combining virtual and real elements, not only was the accuracy and effectiveness of the device's control verified, but its ability to provide reliable physical interaction support for virtual maintenance training was also confirmed. This verification method based on real-world application scenarios provides technical support for the practical application of force feedback devices in the field of virtual training.

[0082] In the experiment, the operator performed engine maintenance tasks in a virtual environment. After the system detected a collision between the operator's arm and a virtual component, it calculated the virtual feedback force based on the degree of collision and used this force feedback device to precisely adjust the feedback angle. The visualization of the test process and collision locations (front, inside, outside) is shown below. Figure 18 As shown in the figure. Experimental results show that the force feedback device responds rapidly to virtual collisions: the feedback forces for inner and outer collisions are 11.57 N and 11.86 N, respectively, with corresponding feedback angles of 59.4° and 60.1°; the feedback force for a frontal collision reaches 32.37 N, with a feedback angle of 90.7°. The feedback forces and angles of the virtual experiment are consistent with the results of the actual physical experiment, with the error controlled within 4.6%, verifying the accuracy and effectiveness of the force feedback device control and providing reliable physical interaction support for virtual maintenance training.

[0083] This embodiment of the electro-dynamic feedback device for virtual training is designed and manufactured using the aforementioned design method for electro-dynamic feedback devices for virtual training. It designs an arm-worn force feedback device based on a DC servo motor, derives and constructs a mathematical model of feedback force and rotation angle, and achieves precise control through a phase displacement-torque dual closed-loop control system. The electro-dynamic feedback device for virtual training of this invention is designed and manufactured according to the aforementioned design method (designing an arm-worn structure based on a DC servo motor, deriving a mathematical model of feedback force and rotation angle, and developing a phase displacement-torque dual closed-loop control system). This device inherits all the technical advantages established by the aforementioned method in its design principle; it provides a stable and controllable power source through a DC servo motor, ensures accurate mapping between virtual force and physical force through a precise mathematical model, and achieves independent and coordinated precise control of the servo motor rotation angle and output torque through a dual closed-loop control system. Therefore, the device, in principle, possesses the ability to achieve high-precision, high-real-time force feedback, and is a concrete material manifestation of the design method. Based on a phase displacement-torque dual closed-loop control system, this device achieves precise control over the amplitude and direction of the feedback force. The phase displacement loop (inner loop) ensures the accuracy of the servo motor's rotation angle, thereby controlling the direction and area of ​​the force feedback. The torque loop (outer loop) ensures the accuracy of the servo motor's output torque, thereby controlling the magnitude of the force feedback. The synergistic effect of these two closed loops enables the device to respond quickly and accurately to interactive commands in the virtual environment and stably output the preset feedback force, effectively overcoming the problems of insufficient control precision and susceptibility to interference in traditional devices. This device, through an arm-worn structure, directly applies the precisely controlled force feedback to the operator's limbs. Combined with virtual training scenarios, when the operator interacts with the virtual environment, the device can generate corresponding force feedback in real time, allowing the operator to perceive the physical properties of virtual objects, such as hardness and reaction force. This immersive interaction based on precise force feedback significantly enhances the realism and training effect of virtual training, solving the technical problem of traditional virtual training lacking realistic force feedback. This invention relates to an electrodynamic force feedback device for virtual training, which is the physical embodiment of the aforementioned design method. Through a structural design based on a DC servo motor, a precise mathematical model, and a phase displacement-torque dual closed-loop control system, it achieves high-precision and high-real-time control of force feedback. It can provide accurate and stable force feedback for virtual training, thereby significantly improving the realism, immersion, and training efficiency of virtual training. It is an effective technical solution to solve the problems of insufficient accuracy, poor real-time performance, and unsatisfactory wearing comfort of traditional force feedback devices.

[0084] Matters not covered in this invention are common knowledge.

[0085] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0086] The embodiments described above are merely examples of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

[0087] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A design method for an electrodynamic feedback device for virtual training, characterized in that, Includes the following steps: A wearable force feedback device for arms is designed based on a DC servo motor. By deriving a mathematical model of the feedback force and the servo motor rotation angle, the mapping relationship between virtual environment interaction information and physical feedback force is established. Design a phase displacement-torque dual closed-loop control system. The phase displacement closed loop controls the servo motor rotation angle, and the torque closed loop controls the servo motor output torque, so as to achieve precise control of the feedback force amplitude. Through mathematical models and a dual closed-loop control system, the arm-worn force feedback device is driven to generate feedback force that matches the virtual training scenario, enabling a rapid response to virtual collisions and keeping the feedback force and rotation angle error within a preset threshold, thereby enhancing the realism and immersion of virtual training. The structured design approach optimizes the performance of each module in the wearable force feedback device. This includes: an execution module composed of a servo motor and a cam mechanism; based on the differentiated action modes at both ends of the cam mechanism, force feedback control is achieved within a 120° range below the arm; and different calculation methods are set for the large and small ends. The specific force feedback calculation is as follows: Based on the actual anatomical structure of the arm, its geometric model is simplified to an ellipse equation, namely: in, For the semi-major axis, It is the semi-minor axis; The cam structure is formed by the intersection of a central circle and two parabolas, with the central circle using the standard circle equation; The two ends of the cam are divided into a large end and a small end structure due to their different modes of operation; Force feedback analysis is performed on the small end, using the parabolic equation in Cartesian coordinates, as shown in formula (1): （1） in, p, q The parameters for the small end of the designed cam; When analyzing the action of the small end, the cam initially has no contact with the arm. As the cam rotates, the small end gradually approaches the arm. When the rotation angle reaches a certain angle, the parabola and the arc together come into contact with the surface of the arm. The entire action is approximately assumed to be equal to the amount of compression of the small end intruding into the arm. Since the geometric centers of the parabola and the circle do not coincide, using polar coordinates to calculate the relationship between the rotation angle and the compression would result in a zero denominator. Therefore, a method combining numerical and graphical approaches is used to analyze the cam rotation angle. Compression of the small end invading the arm Relationship; The small end acts on the arm, and the elastic force exerted by the arm on the cam during cam rotation is... ,in, Let the base circle radius of the cam be . The elastic coefficient of human skin is given by the frictional force. , The coefficient of friction between the cam and the surface of the human arm; In biomechanical modeling, the Young's modulus of forearm deformation is: Based on actual optical coherence tomography (OCT) data, the effective thickness is The area of ​​force is ,according to It can be seen that the calculation yields k ;Will , Substitution formula (2): （2） Obtain the relationship between the cam rotation angle and the feedback force under the action of the small end; When the large end is in action, the wearable force feedback device remains fixedly connected to the arm, based on the motor torque formula. Torque formula Combined with servo motor current The formula for the feedback force of the cam on the arm is derived (3): （3） in, The effective voltage input to the servo motor. The internal resistance of the servo motor. It is the torque constant of the servo motor. The reduction ratio of the servo motor. For transmission efficiency, The distance from the cam profile to the cam center is the large end, which acts on both sides of the arm. The cam model design includes two modes of action: a small end and a large end. The small end acts below the arm where it is worn, and the cam's compressive force and friction force together form a feedback force on the arm. The large end acts on the lower side of the arm, and the feedback force is applied directly through the cam. Adjusting the cam angle To achieve force feedback control acting within a certain range below the force feedback device; The effective voltage applied to the servo motor is adjusted using a pulse width modulation (PWM) signal. This changes the feedback force of the servo motor on the arm. ; Substituting the parameters into equation (3), we obtain the effective voltage of the servo motor. With feedback force The relationship between them, and the results of the analysis.

2. The design method of the electrodynamic feedback device for virtual training according to claim 1, characterized in that, Based on the structured composition of the arm-worn force feedback device, the arm-worn force feedback device consists of a fixed module, a wireless communication module, a control and drive module, an execution module, and a power supply module; The fixing module is used to achieve stable positioning of the device and stabilize the servo motor. The base adopts a through-hole horizontal rectangular design. It is connected to the base with the strap and shell without screws to achieve stable fixation. The through-hole horizontal rectangular design uses a strap fixing mechanism to efficiently transmit feedback force while reducing the impact of reaction force on the human body. The shell design includes rounded edges and corners to improve wearing comfort and safety. Focusing on force transmission and wearing comfort, the design adopts a split wearable structure to realize the conversion of force feedback physical signals and meet ergonomic requirements. The wireless communication module uses Wi-Fi technology to achieve efficient and stable data transmission, ensuring that collision information is transmitted to the control and drive module in real time. The control and drive module uses a micro servo motor as the drive unit to reduce the structural size. The servo motor integrates a DC motor and a gear set, thereby achieving the characteristics of small size and high torque, making it suitable for wearable applications. The power module is powered by a lithium battery and utilizes aluminum-plastic composite film encapsulation technology to optimize safety and lightweight design; The execution module consists of a servo motor and a cam mechanism. Based on the differentiated action modes at both ends of the cam mechanism, force feedback control is formed within a 120° range of action below the arm. Using virtual training scenarios as the application scenario, when the operator wears an arm-worn force feedback device and interacts with the virtual environment, the wireless communication module converts the interaction information into electrical signals and transmits them to the control and drive module. After the control and drive module processes the signals, the drive execution module executes the control servo to act on the cam to generate a precise phase shift, realizing real-time monitoring and response of limb interaction in virtual maintenance training, forming a closed-loop force feedback control system. The module design takes into account the miniaturization requirements and the size constraints of the DC servo servo. This design not only reduces the risk of injury, but also enhances the realism of immersive repair through force feedback.

3. The design method of the electrodynamic feedback device for virtual training according to claim 1 or 2, characterized in that, Design a phase displacement-torque dual closed-loop control system, specifically: Based on the structural design and force feedback control commands of a micro servo motor, a phase displacement-torque dual closed-loop control system is designed to achieve precise force feedback control. The phase displacement-torque dual closed-loop control system effectively resists external disturbances through closed-loop feedback, ensuring that the servo motor can quickly track command responses, while suppressing the negative impact caused by excessive load torque. The control strategy of the phase displacement-torque dual closed-loop control system adopts a hierarchical control concept: The inner loop control first achieves the system's fast tracking performance, while the outer loop control then adjusts the current to suppress load torque and ensure that it meets the design requirements. Simulink simulation of dual closed-loop control.

4. The design method of the electrodynamic feedback device for virtual training according to claim 3, characterized in that, A step signal with an amplitude of 1 is input to the phase displacement-torque dual closed-loop control system. The dynamic response performance of the motor position and torque is optimized by adjusting the parameters of the PID controller. At the same time, current loop control is introduced, and the problem of excessive motor current is reduced by adding a PI controller. The torque response is completed in a very short time, showing excellent dynamic performance.

5. The design method of the electrodynamic feedback device for virtual training according to claim 1 or 2, characterized in that, It also includes experimental verification of force feedback devices, specifically: Through experimental testing, the relationship between the driving force of the feedback device, the servo feedback angle, and the actual feedback force was analyzed. The maximum relative error between the feedback force and the theoretical feedback angle and driving force was measured, and it was revealed that the magnitude of the driving force is closely related to the servo lever arm length. Furthermore, by optimizing the lever arm length, we can adapt to different application scenarios and improve system performance.

6. The design method of the electrodynamic feedback device for virtual training according to claim 5, characterized in that, The experimental setup includes a spring balance and a feedback device. The top of the spring balance is fixed, and the end of the spring balance is connected to a cam. The experiment controlled the cam to generate different driving forces by adjusting the effective voltage of the servo motor through the PWM signal, and recorded the feedback angle and the actual feedback force measured by the spring balance under different driving forces.

7. The design method of the electrodynamic feedback device for virtual training according to claim 1 or 2, characterized in that, It also includes experimental verification using virtual training, specifically: A virtual environment is built using Jack and Unity software, and the operator wears a force feedback arm device to perform virtual operations. The experimental results were used to obtain the response speed of the electric dynamic feedback device to a virtual collision, as well as the feedback force and the corresponding feedback angle. The feedback force and feedback angle of the virtual experiment are compared with the results of the actual physical experiment to verify the accuracy and effectiveness of the force feedback device control, and to provide physical interaction support for virtual maintenance training.

8. An electrodynamic feedback device for virtual training, characterized in that, The device is designed and manufactured using the design method of any one of claims 1 to 7 for an electric power feedback device for virtual training; an arm-worn force feedback device is designed based on a DC servo motor, and a mathematical model of feedback force and rotation angle is derived and constructed; and precise control is achieved through a phase displacement-torque dual closed-loop control system.

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