A hand-held variable-stiffness passive force feedback device and method of use thereof

Abstract

The application provides a handheld variable-rigidity passive force feedback device and a use method thereof, which comprise a spring connecting rod structure, a frame, a cushion frame, an interactive structure and a sensing structure, the interactive structure is installed on the cushion frame, horizontal rods are symmetrically arranged on the cushion frame, the horizontal rods are connected with the interactive structure and conform to the displacement of the interactive structure, horizontal sliding blocks are slidingly installed on the horizontal rods, the spring connecting rod structure is symmetrically installed on the frame and is rotationally arranged relative to the frame, the spring connecting rod structure comprises a motor, a spring, a motor frame, a lead screw and an adjusting sliding block, the sensing structure is installed between the cushion frame and the frame and realizes the connection and fixation of the two, and the sensing structure comprises a resistance sensor, a sensor connecting rod and a Hall sensor. The application adopts the symmetric spring connecting rod structure, realizes tactile feedback based on the passive stretching of the spring, has simple structure, continuous output, and can output specific force and torque by adjusting the structure of the spring connecting rod structure, is simple in driving, stable in system, and good in robustness.

Description

Technical Field

[0001] This invention designs a force feedback device that can be used in virtual reality or teleoperation systems, and in particular a handheld variable stiffness passive force feedback device and its usage method. Background Technology

[0002] Force feedback is a crucial requirement for virtual reality (VR) technology and teleoperation systems. It enhances immersion and interactivity by providing users with perceptions of object properties such as stiffness and flexibility within an interactive 3D virtual scene. Existing force feedback devices primarily control interactive forces directly through motors, pneumatic actuators, etc. Such solutions often require sophisticated sensors and actuators, resulting in high R&D, manufacturing, and maintenance costs. Achieving active force feedback necessitates complex control and algorithm systems, leading to high overall system complexity. Furthermore, active force feedback devices are susceptible to malfunction or misoperation, potentially posing safety risks. This invention proposes a passive, controllable force feedback device based on a symmetrical spring-linkage structure, which can conveniently and stably provide force feedback.

[0003] A search revealed that Chinese utility model patent application number CN201520076954.0 proposes a force feedback surgical training device for simulating minimally invasive spinal surgery. The handheld part consists of a handle, a six-dimensional force sensor, and a sensor connector, all connected sequentially. The drive part includes a support plate, a DC motor, a meshing gear, a lead screw, and a guide rail. One end of the guide rail is connected to the sensor connector. The lead screw is placed parallel to the outside of the guide rail via the support plate. The DC motor is connected to the lead screw via the meshing gear. The support plate fixes the DC motor, lead screw, and guide rail to the side near the sensor connector. The drill part includes a linear slider and a bone drill bit, with the bone drill bit connected to the guide rail via the linear slider. This utility model employs closed-loop control to ensure accurate force feedback values; it saves on cadaver specimen costs and related expenses; the culture method is convenient and can shorten the culture period; and rapid assembly and disassembly reduce sterilization procedures and surgical simulation time.

[0004] However, the aforementioned patents use a DC motor to actively drive the guide rail, thereby simulating a specific single-degree-of-freedom force. This limits the system's versatility and places high precision requirements on the DC motor. This paper employs a symmetrical spring-linkage structure, passively outputting feedback force based on the physical properties of the spring. The motor is used to adjust the layout of the spring-linkage structure, resulting in better continuity of the feedback force and system stability. Furthermore, by controlling the layout of the spring-linkage structures on both sides, the force feedback device proposed in this paper can render forces in two degrees of freedom, making it suitable for various scenarios.

[0005] The U.S. invention patent with the application No. US16197949 proposes a system and method for providing haptic feedback related to lifting or manipulating a virtual object. A hand-held device for providing haptic feedback includes an elongated housing, a mass, a mass restriction device, a first sensor and a second sensor. The elongated housing includes at least two chambers. The mass is slidably disposed within the chambers and is slidable by gravity. The mass restriction device restricts the mass within at least one of the chambers. The first sensor is configured to sense an orientation of the elongated housing and the second sensor is configured to sense a location of the mass within the elongated housing relative to the chambers. In response to a command signal indicative of a virtual interaction related to manipulating a virtual object, the mass restriction device restricts the mass within at least one of the chambers to effect a perceived change in weight as the virtual object is manipulated by the user。

[0006] The aforementioned patent uses a method that adjusts the center of gravity of a slender rod to provide tactile feedback, allowing the user to perceive only tactile changes. This invention, however, establishes a geometric and mechanical model of the structure, obtaining a quantified output by adjusting the angle and elongation of a physical spring. This allows the user to perceive not only tactile changes but also specific forces.

[0007] The "System and Method for Providing Tactile Feedback Related to Lifting or Manipulating Virtual Objects" modulates tactile feedback by confining a mass block within a specific cavity. Therefore, the control of this device is discontinuous and cannot provide a constant output. Virtual scenes often involve a variety of objects and complex interactions, and this discontinuous and non-constant output limits the system's application. In contrast, the symmetrical spring-linkage structure proposed in this invention provides a continuously controllable output and can provide constant force, stiffness, or torque regardless of changes in input. Therefore, it has a wide output range and broad application scenarios. Summary of the Invention

[0008] To address the aforementioned technical problems, this invention provides a handheld passive force feedback device based on a symmetrical spring-linkage structure, which provides two degrees of freedom force feedback by adjusting the length and direction of the spring in the spring-linkage structure.

[0009] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0010] A handheld variable stiffness passive feedback device is characterized by comprising a spring-link structure, a frame, a support frame, an interactive structure, and a sensing structure. The interactive structure is mounted on the support frame, and horizontal rods are symmetrically arranged on the support frame. The horizontal rods connect to the interactive structure and adapt to its displacement. Horizontal sliders are slidably mounted on the horizontal rods.

[0011] The spring-connecting rod structure is symmetrically mounted on the frame and rotatably arranged relative to the frame. The spring-connecting rod structure includes a motor, a spring, a motor frame, a lead screw, and an adjusting slider. The motor is mounted inside the motor frame, the lead screw is connected to the motor's output shaft, and the adjusting slider is slidably mounted on the lead screw. One end of the spring is connected to the adjusting slider, and the other end is connected to the frame. One end of the motor frame is connected to a horizontal slider via a bearing, and the other end is connected to the frame via a bearing.

[0012] The sensing structure is installed between the pad and the frame, connecting and fixing them together. The sensing structure includes a resistance sensor, a sensor connecting rod, and a Hall sensor. The sensor connecting rod is mounted on the resistance sensor, and a rotating shaft is installed at its end. A fixed rod is perpendicularly connected to the side of the sensor connecting rod. The Hall sensor is mounted on the fixed rod, and its central axis is collinear with the rotating axis. When the interactive structure and the pad rotate together around the rotating axis, the Hall sensor outputs the rotation angle of the interactive structure. The sensor connecting rod translates vertically with the interactive structure, and the resistance sensor outputs the displacement distance of this translation.

[0013] Based on mechanical equilibrium and geometric structure, the output force F of the one-sided spring-linkage structure is obtained. p for:

[0014]

[0015]

[0016] Where x represents the length of AC′, controlled by the position of the horizontal slider C, and L b L is the length of the horizontal bar AD. f L is the length of the rack AB. so L is the length of the spring in the force feedback device when it is in its initial state. so The spring's rest length is greater than its maximum length; therefore, the spring can provide an initial force F0. α is the angle between AB and AD when the force feedback device is in its initial state, k is the spring's stiffness, and s is the displacement distance measured by the resistance sensor.

[0017] When the user freely grasps the interactive structure, the system symmetrically controls the motors on both sides to adjust the position of the slider on the lead screw; this is the force rendering mode.

[0018] When the user actively presses the interactive structure, the force feedback device adjusts the layout of the spring linkage structure symmetrically based on the feedback signal, so that the entire force feedback device exhibits different stiffnesses. This is the stiffness rendering mode.

[0019] In force rendering mode and stiffness rendering mode, the force F exerted by the spring linkage structure on both sides on the interactive structure is:

[0020] F = 2F p (3)

[0021] When a user freely grips the interactive system, the system asymmetrically adjusts the layout of the spring-link structure on both sides to generate a specific torque on the user; this is the torque rendering mode.

[0022] In torque rendering mode, the torque M output by the spring linkage structure on both sides to the interactive structure is:

[0023]

[0024] in, and The output forces of the spring linkage structures on both sides are represented by l1 and l2, which represent the left and right lever arms, respectively, and are the distances from the left horizontal slider D1 and the right horizontal slider D2 to the center point E of the interactive structure.

[0025] In the above structure: This invention proposes a handheld variable stiffness passive force feedback device, including a spring linkage structure, a frame, a pad frame, an interactive structure, and a sensing structure. The spring linkage structure is symmetrically mounted on the frame and rotatably arranged relative to the frame. The spring linkage structure includes a motor, a spring, a motor frame, a lead screw, and an adjusting slider. The sensing structure is installed between the pad frame and the frame, connecting and fixing the two. The sensing structure includes a resistance sensor, a sensor connecting rod, and a Hall sensor. The central axis of the Hall sensor is collinear with the rotation axis. When the interactive structure and the pad frame rotate together around the rotation axis, the Hall sensor outputs the rotation angle of the interactive structure. The sensor connecting rod translates vertically with the interactive structure, and the resistance sensor outputs the displacement distance of this translation.

[0026] Based on the geometric relationship of the structure, the output force of this force feedback device can be expressed as a function of the position of the slider on the lead screw, the vertical displacement fed back by the resistance sensor, and the rotation angle fed back by the Hall sensor. When the displacement of the slider in the spring-link structure on both sides is symmetrically controlled, the force feedback device outputs a vertically upward feedback force; when the displacement of the slider in the spring-link structure on both sides is asymmetrically controlled, the force feedback device outputs torque.

[0027] The intelligent control scheme of the present invention includes:

[0028] 1. Force Rendering Mode: During interaction, the user freely grips the interaction pad. This static gripping posture causes a slight displacement of the touchpad, thus activating the force rendering mode. The system symmetrically controls the motors on both sides to adjust the position of the slider on the lead screw, thereby generating the required force on the interaction pad. If the target force input is a continuously changing signal, the system can also symmetrically adjust the layout of the spring linkage structure on both sides to continuously render the required force.

[0029] 2. Stiffness Rendering Mode: During interaction, the user actively presses the interactive pad. Based on the feedback signal, the force feedback device symmetrically adjusts the layout of the spring linkage structure, thus making the entire force feedback device exhibit different stiffnesses. Therefore, the user can feel realistic elastic characteristics when pressing the force feedback device. In addition to rendering a specified stiffness in the vertical direction, fixing the position of the adjustable slider to make it a completely passive structure can render the feedback force of pressing a flexible object.

[0030] 3. Torque Rendering Mode: During the interaction, the user can hold the interaction pad at will, and the system will asymmetrically adjust the layout of the spring linkage structure on both sides to generate a specific torque on the user.

[0031] Based on mechanical equilibrium and geometric structure, the output force F of the one-sided spring-linkage structure is obtained. p for:

[0032]

[0033]

[0034] Where x represents the length of AC′, controlled by the position of the horizontal slider C, and L b L is the length of the horizontal bar AD. f L is the length of rack AB. so L is the length of the spring in the force feedback device when it is in its initial state. so The spring's rest length is greater than its maximum length; therefore, the spring can provide an initial force F0. α is the angle between AB and AD when the force feedback device is in its initial state, k is the spring's stiffness, and s is the displacement distance measured by the resistance sensor.

[0035] When the user freely grasps the interactive structure, the system symmetrically controls the motors on both sides to adjust the position of the slider on the lead screw; this is the force rendering mode.

[0036] When the user actively presses the interactive structure, the force feedback device adjusts the layout of the spring linkage structure symmetrically based on the feedback signal, so that the entire force feedback device exhibits different stiffnesses. This is the stiffness rendering mode.

[0037] In force rendering mode and stiffness rendering mode, the force F exerted by the spring linkage structure on both sides on the interactive structure is:

[0038] F = 2F p (3)

[0039] When a user freely grips the interactive system, the system asymmetrically adjusts the layout of the spring-link structure on both sides to generate a specific torque on the user; this is the torque rendering mode.

[0040] In torque rendering mode, the torque M output by the spring linkage structure on both sides to the interactive structure is:

[0041]

[0042] in, and The output forces of the spring linkage structures on both sides are represented by l1 and l2, which represent the left and right lever arms, respectively, and are the distances from the left horizontal slider D1 and the right horizontal slider D2 to the center point E of the interactive structure.

[0043] As a preferred technical solution of the present invention, it further includes a limiting structure, which is installed below the frame. The limiting structure includes a limiting connecting rod, a vertical slider, a vertical rod, and a limiting structure fixing frame. The upper end of the limiting connecting rod is connected to the rotating shaft through a bearing, and the lower end is fixed on the vertical slider. The vertical slider is slidably installed on the vertical rod, and the vertical rod is vertically fixed on the limiting structure fixing frame.

[0044] As a preferred technical solution of the present invention: the limiting structure further includes a support frame, and the limiting structure fixing frame is installed on the support frame and assembled on the frame through the support frame.

[0045] In the above structure, a limiting structure is also set to restrict other degrees of freedom of the interactive structure, so that it can only move back and forth in the vertical direction. The limiting structure is installed below the frame and includes a limiting connecting rod, a vertical slider, a vertical rod, and a limiting structure fixing frame. The upper end of the limiting connecting rod is connected to the rotation axis through a bearing, and the lower end is fixed to the vertical slider. The limiting structure fixing frame is assembled on the frame through a support frame, thereby fixing the vertical rod. Therefore, the slider can only move on the vertical rod, thus restricting other degrees of freedom of the interactive structure. The limiting structure fixing frame is installed on the support frame and assembled on the frame through the support frame to achieve installation and fixation.

[0046] As a preferred technical solution of the present invention, it also includes a tracking structure for motion tracking, the tracking structure including a tracker (7), a mounting platform is provided above the tracker (7), and the tracker (7) is fixedly mounted below the support frame (21) by screws and the mounting platform.

[0047] In the above structure: the tracker is used for motion tracking of the force feedback device in this invention. The tracker has three fixed feet at the bottom for easy placement, and an installation platform is provided at the top. The tracker is fixedly installed under the support frame by screws and the installation platform to achieve its installation and fixation.

[0048] As a preferred technical solution of the present invention, it also includes a hand strap, which is movably installed on the side of the frame. When the hand strap is strapped to the user's forearm, the user's palm presses on the interactive structure.

[0049] In the above structure: the hand strap is movably installed on the side of the frame. After the force feedback device is bound to the user's forearm by the hand strap, the user's palm presses on the interactive structure. When the user presses the interactive structure with his palm, the interactive structure is displaced. The spring linkage structure generates a supporting force on the interactive structure, and the user feels tactile feedback.

[0050] As a preferred technical solution of the present invention: the sensing structure further includes a resistance sensor frame and a Hall sensor frame, the resistance sensor is mounted on the resistance sensor frame, the upper end of the resistance sensor is fixedly connected to the bottom of the pad frame, and the lower end is fixedly connected to the top of the frame, the Hall sensor frame is fixed on the fixing rod, and the Hall sensor is mounted on the Hall sensor frame.

[0051] In the above structure, the sensing structure also includes a resistance sensor frame and a Hall sensor frame. The sensing structure connects and fixes the pad and the frame through the resistance sensor frame. The upper end of the resistance sensor is fixedly connected to the bottom of the pad, and the lower end is fixedly connected to the top of the frame.

[0052] As a preferred technical solution of the present invention: the interactive structure includes an interactive pad, the interactive pad is installed above the pad frame, and the horizontal bars on both sides of the pad frame are respectively connected to the interactive pad.

[0053] In the above structure: the interactive structure is an interactive pad, which is convenient for users to grasp and press. After the force feedback device is tied to the user's forearm through the hand strap, the user presses the interactive pad with his palm, and the interactive pad will be displaced. The spring linkage structure generates a supporting force on the interactive pad, and the user feels tactile feedback. During this period, the sensing structure detects the vertical displacement and rotation angle of the interactive pad. By adjusting the spring linkage structure, specific tactile feedback can be output.

[0054] As a preferred embodiment of the present invention, a sliding joint and a rotary joint are installed between the horizontal slider and the horizontal rod.

[0055] As a preferred embodiment of the present invention, a rotating pair is installed between the motor frame, the adjusting slider, and the frame.

[0056] A method for using a handheld variable stiffness passive feedback device, characterized by comprising the following steps:

[0057] The user straps their forearm to the hand strap and then presses the interactive pad according to the 3D scene of virtual reality. The interactive pad produces vertical displacement, the horizontal slider slides horizontally, the spring is stretched, and the spring linkage structure generates a supporting force on the interactive pad. The user receives feedback from the force feedback device. At the same time, a resistance sensor and a Hall sensor detect the vertical displacement and rotation angle of the interactive pad, respectively. Based on the feedback signals from the resistance sensor and the Hall sensor, the motor controls the position of the adjustment slider, thereby affecting the length and direction of the spring, and thus controlling the amplitude of the force feedback.

[0058] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0059] 1. This invention adopts a symmetrical spring linkage structure, which realizes tactile feedback based on the passive stretching of the spring. The structure is simple and the output is continuous.

[0060] 2. By adjusting the structure of the spring connecting rod, this invention can output specific force and torque, which is simple to drive, stable, and robust.

[0061] 3. This invention is assembled from standard parts and simple non-standard parts, making it easy to manufacture and low in cost.

[0062] 4. This invention is a passive structure that will not be damaged in abnormal situations such as power outages, has high safety and reliability, and is suitable for users of all ages.

[0063] 5. The force and torque output by this invention can be determined based on the structural geometry and the feedback values ​​of the resistance sensor and Hall sensor. The output can be quantified and adjusted, making it suitable for various application scenarios. Attached Figure Description

[0064] Figure 1 This is a schematic diagram of the overall assembly structure in an embodiment of the present invention.

[0065] Figure 2 This is a schematic diagram of the single-sided spring connecting rod structure in an embodiment of the present invention.

[0066] Figure 3 This is a schematic diagram of the sensing structure in an embodiment of the present invention.

[0067] Figure 4 This is a schematic diagram of the limiting structure in an embodiment of the present invention.

[0068] Figure 5 This is a schematic diagram of the spring connecting rod structure on the left side in an embodiment of the present invention;

[0069] Figure 6 This is a schematic diagram of the overall structure of the force feedback device in the initial state in an embodiment of the present invention;

[0070] Figure 7 This is a schematic diagram of the symmetrical control pressure feedback device in an embodiment of the present invention;

[0071] Figure 8 This is a schematic diagram of the asymmetric control pressure feedback device in an embodiment of the present invention.

[0072] List of reference numerals in the attached diagram:

[0073] 1. Spring linkage structure; 2. Frame; 3. Pad frame; 4. Interactive pad; 5. Sensing structure; 6. Hand strap frame; 7. Tracker; 8. Limiting structure; 9. Motor; 10. Spring; 11. Motor frame; 12. Horizontal rod; 13. Horizontal slider; 14. Lead screw; 15. Adjusting slider; 16. Resistance sensor; 17. Sensor connecting rod; 18. Hall sensor frame; 19. Hall sensor; 20. Rotating shaft; 21. Support frame; 22. Limiting connecting rod; 23. Vertical slider; 24. Vertical rod; 25. Limiting structure fixing frame; 26. Resistance sensor frame. Detailed Implementation

[0074] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments:

[0075] This invention proposes a handheld variable stiffness passive force feedback device, comprising a spring linkage structure 1, a frame 2, a support frame 3, an interactive structure, and a sensing structure 5. The interactive structure is mounted on the support frame 3, and horizontal rods 12 are symmetrically arranged on the support frame 3. The horizontal rods 12 are connected to the interactive structure and adapt to the displacement of the interactive structure. A horizontal slider 13 is slidably mounted on the horizontal rods 12.

[0076] The spring-link structure 1 is symmetrically mounted on the frame 2 and rotatably arranged relative to the frame 2. The spring-link structure 1 includes a motor 9, a spring 10, a motor frame 11, a lead screw 14, and an adjusting slider 15. The motor 9 is mounted inside the motor frame 11. The lead screw 14 is connected to the output shaft of the motor 9. The adjusting slider 15 is slidably mounted on the lead screw 14. One end of the spring 10 is connected to the adjusting slider 15, and the other end is connected to the frame 2. One end of the motor frame 11 is connected to a horizontal slider 13 via a bearing, and the other end is connected to the frame 2 via a bearing.

[0077] The sensing structure 5 is installed between the pad 3 and the frame 2, connecting and fixing the two. The sensing structure 5 includes a resistance sensor 16, a sensor connecting rod 17, and a Hall sensor 19. The sensor connecting rod 17 is mounted on the resistance sensor 16, and a rotating shaft 20 is installed at the end of the sensor connecting rod 17. A fixed rod is perpendicularly connected to the side of the sensor connecting rod 17. The Hall sensor 19 is mounted on the fixed rod, and the central axis of the Hall sensor 19 is collinear with the rotating shaft 20. When the interactive structure and the pad 3 rotate together around the rotating shaft 20, the Hall sensor 19 outputs the rotation angle of the interactive structure. The sensor connecting rod 17 moves up and down with the interactive structure, and the resistance sensor 16 outputs the displacement distance of this translation.

[0078] Based on mechanical equilibrium and geometric structure, the output force F of the single-sided spring-linkage structure 1 is obtained. p for:

[0079]

[0080]

[0081] Where x represents the length of AC′, controlled by the position of the horizontal slider 13C, L b L is the length of the horizontal bar 12AD. f L is the length of frame 2AB. so L is the length of spring 10 when the force feedback device is in its initial state. so The spring 10 has a rest length greater than that of spring 10, therefore, spring 10 can provide an initial force F0. α is the angle between AB and AD when the force feedback device is in its initial state, k is the stiffness of spring 10, and s is the displacement distance measured by resistance sensor 16.

[0082] When the user freely grasps the interactive structure, the system symmetrically controls the motors 9 on both sides to adjust the position of the slider 15 on the lead screw 14. This is the force rendering mode.

[0083] When the user actively presses the interactive structure, the force feedback device adjusts the layout of the spring linkage structure 1 symmetrically based on the feedback signal, so that the entire force feedback device exhibits different stiffnesses. This is the stiffness rendering mode.

[0084] In force rendering mode and stiffness rendering mode, the force F exerted by the spring linkage structure 1 on both sides on the interactive structure is:

[0085] F = 2F p (3)

[0086] When the user freely grips the interactive system, the system asymmetrically adjusts the layout of the spring-link structure 1 on both sides to generate a specific torque on the user; this is the torque rendering mode.

[0087] In torque rendering mode, the torque M output by the spring linkage structure 1 on both sides to the interactive structure is:

[0088]

[0089] in, and The output forces of the spring linkage structure 1 on both sides are represented by l1 and l2, which represent the left lever arm and the right lever arm, respectively. They are the distances from the left horizontal slider 13D1 and the right horizontal slider 13D2 to the center point E of the interactive structure.

[0090] This invention proposes a handheld variable stiffness passive feedback device, comprising a spring-link structure 1, a frame 2, a support frame 3, an interactive structure, and a sensing structure 5. The spring-link structure 1 is symmetrically mounted on the frame 2 and rotatably arranged relative to the frame 2. The spring-link structure 1 includes a motor 9, a spring 10, a motor frame 11, a lead screw 14, and an adjusting slider 15. The sensing structure 5 is installed between the support frame 3 and the frame 2, connecting and fixing the two. The sensing structure 5 includes a resistance sensor 16, a sensor connecting rod 17, and a Hall sensor 19. The central axis of the Hall sensor 19 is collinear with the rotation axis 20. When the interactive structure and the support frame 3 rotate together around the rotation axis 20, the Hall sensor 19 outputs the rotation angle of the interactive structure, the sensor connecting rod 17 translates vertically with the interactive structure, and the resistance sensor 16 outputs the displacement distance of this translation.

[0091] Figure 1 This is a schematic diagram of the overall assembly structure in an embodiment of the present invention. After the device is secured to the user's forearm by the hand strap 6, the user presses the interactive pad 4 with their palm, causing the interactive pad 4 to displace. The spring-link structure 1 provides support to the interactive pad 4, and the user experiences tactile feedback. During this process, the sensing unit detects the vertical displacement and rotation angle of the interactive pad 4. By adjusting the spring-link structure 1, specific tactile feedback can be output. The limiting structure 8 restricts the degrees of freedom of the interactive pad 4, allowing it to only translate vertically and rotate around its center point.

[0092] Figure 2 This is a schematic diagram of the single-sided spring linkage structure 1 in this embodiment of the invention. The horizontal rod 12 moves in accordance with the displacement of the interactive pad 4, causing the horizontal slider 13 to translate along the horizontal rod 12. Rotating pairs exist between the motor frame 11, the adjusting slider 15, and the frame 2. The left and right ends of the spring 10 are fixed to the frame 2 and the adjusting slider 15, respectively, causing the spring 10 to stretch. The horizontal slider 13 generates a support force perpendicular to the horizontal rod 12. A specific force can be output by adjusting the position of the adjusting slider 15 on the lead screw 14 using the motor 9.

[0093] Figure 3 This is a schematic diagram of the sensing unit in an embodiment of the present invention. The Hall sensor 19 is mounted on the pad 3 by the Hall sensor holder 18, and its central axis is collinear with the rotation axis 20. When the interactive pad 4 and the pad 3 rotate together around the rotation axis 20, the Hall sensor 19 can output the rotation angle of the interactive pad 4. The resistance sensor 16 is mounted on the frame 2 by the resistance sensor holder 26. The sensor connecting rod 17 moves up and down with the interactive pad 4, and the resistance sensor 16 can output the translational displacement.

[0094] Figure 4This is a schematic diagram of the limiting structure 8 in this embodiment of the invention. The upper end of the limiting connecting rod 22 is connected to the rotating shaft 20 via a bearing, and the lower end is fixed to the vertical slider 23. The limiting structure fixing frame 25 is assembled on the frame 2 via a support frame 21, thereby fixing the vertical rod 24. Therefore, the vertical slider 23 can only move on the vertical rod 24, thus restricting the other degrees of freedom of the interactive pad 4.

[0095] Based on the geometric relationship of the structure, the output force of this force feedback device can be expressed as a function of the position of the adjusting slider 15 on the lead screw 14, the vertical displacement fed back by the resistance sensor 16, and the rotation angle fed back by the Hall sensor 19. When the displacement of the adjusting slider 15 in the spring linkage structure 1 on both sides is symmetrically controlled, the force feedback device outputs a vertically upward feedback force; when the displacement of the adjusting slider 15 in the spring linkage structure 1 on both sides is asymmetrically controlled, the force feedback device outputs torque.

[0096] The intelligent control scheme of the present invention includes:

[0097] 1. Force Rendering Mode: During interaction, the user freely grips the interaction pad 4. This static gripping posture causes a slight displacement of the touchpad, thereby activating the force rendering mode. The system symmetrically controls the motors 9 on both sides to adjust the position of the slider 15 on the lead screw 14, thereby generating the required force on the interaction pad 4. If the target force input is a continuously changing signal, the system can also symmetrically adjust the layout of the spring linkage structure 1 on both sides to continuously render the required force.

[0098] 2. Stiffness Rendering Mode: During interaction, the user actively presses the interactive pad 4. The force feedback device symmetrically adjusts the layout of the spring linkage structure 1 based on the feedback signal, thereby making the entire force feedback device exhibit different stiffnesses. Therefore, the user can feel realistic elastic characteristics when pressing the force feedback device. In addition to rendering a specified stiffness in the vertical direction, fixing the position of the adjustable slider 15 to make it a completely passive structure can render the feedback force of pressing a flexible object.

[0099] 3. Torque rendering mode: During the interaction, the user can hold the interaction pad 4 at will, and the system will asymmetrically adjust the layout of the spring linkage structure 1 on both sides to generate a specific torque to the user.

[0100] Figure 5 This is a schematic diagram of the spring connecting rod structure 1 on the left side in an embodiment of the present invention. Figure 6 This is a schematic diagram of the overall structure of the force feedback device in its initial state. Based on mechanical equilibrium and geometric structure, the output force F of the single-sided spring-linkage structure 1 can be obtained. p for:

[0101]

[0102]

[0103] Where x represents the length of AC′, controlled by the position of the horizontal slider 13C, L b L is the length of the horizontal bar 12AD. f L is the length of frame 2AB. so L is the length of spring 10 when the force feedback device is in its initial state. so The spring 10 is greater than the rest length of the spring 10, so the spring 10 can provide an initial force F0. α is the angle between AB and AD when the force feedback device is in the initial state. k is the stiffness of the spring 10, and s is the displacement measured by the resistance sensor 16.

[0104] Figure 7 This is a schematic diagram of a symmetrical control pressure feedback device. The force feedback device is currently in force rendering mode and stiffness rendering mode. In this mode, the force F exerted by the spring linkage structure 1 on the interaction pad 4 is:

[0105] F = 2F p (3)

[0106] Figure 8 This is a schematic diagram of an asymmetric control pressure feedback device. The force feedback device is in torque rendering mode. In this mode, the torque M output by the spring-link structure 1 on both sides to the interactive pad 4 is:

[0107]

[0108] in and The left and right spring linkage structures 1 represent the output forces on the left and right sides, respectively. l1 and l2 represent the left lever arm and the right lever arm, respectively, and are the distances from the left horizontal slider 13D1 and the right horizontal slider 13D2 to the center point E of the interactive pad.

[0109] In this embodiment, a limiting structure 8 is also included. The limiting structure 8 is installed below the frame 2. The limiting structure 8 includes a limiting connecting rod 22, a vertical slider 23, a vertical rod 24, and a limiting structure fixing frame 25. The upper end of the limiting connecting rod 22 is connected to the rotating shaft 20 via a bearing, and the lower end is fixed to the vertical slider 23. The vertical slider 23 is slidably mounted on the vertical rod 24, and the vertical rod 24 is vertically fixed to the limiting structure fixing frame 25. The limiting structure 8 also includes a support frame 21. The limiting structure fixing frame 25 is mounted on the support frame 21 and assembled onto the frame 2 via the support frame 21.

[0110] The other degrees of freedom of the interactive structure are also restricted by setting a limiting structure 8, which allows it to move back and forth only in the vertical direction. The limiting structure 8 is installed below the frame 2 and includes a limiting connecting rod 22, a vertical slider 23, a vertical rod 24, and a limiting structure fixing frame 25. The upper end of the limiting connecting rod 22 is connected to the rotating shaft 20 through a bearing, and the lower end is fixed to the vertical slider 23. The limiting structure fixing frame 25 is assembled on the frame 2 through a support frame 21, thereby fixing the vertical rod 24. Therefore, the slider can only move on the vertical rod 24, thus restricting the other degrees of freedom of the interactive structure. The limiting structure fixing frame 25 is installed on the support frame 21 and assembled on the frame 2 through the support frame 21 to achieve installation and fixation.

[0111] In this embodiment, a tracking structure for motion tracking is also included. The tracking structure includes a tracker 7, with a mounting platform positioned above it. The tracker 7 is fixedly mounted to the support frame 21 using screws and the mounting platform. The tracker 7 is used for motion tracking in the force feedback device of this invention. The tracker 7 has three fixed feet at its bottom for easy placement, and a mounting platform is positioned above it. The tracker 7 is fixedly mounted to the support frame 21 using screws and the mounting platform, thus achieving its installation and fixation.

[0112] In this embodiment, a hand strap 6 is also included. The hand strap 6 is movably mounted on the side of the frame 2. When the hand strap 6 is strapped to the user's forearm, the user's palm presses on the interactive structure. With the hand strap 6 movably mounted on the side of the frame 2, after the force feedback device is strapped to the user's forearm using the hand strap 6, the user's palm presses on the interactive structure. When the user presses the interactive structure with their palm, the interactive structure displaces, and the spring-linkage structure 1 provides support force to the interactive structure, allowing the user to experience tactile feedback.

[0113] In this embodiment: the sensing structure 5 further includes a resistance sensor holder 26 and a Hall sensor holder 18. The resistance sensor 16 is mounted on the resistance sensor holder 26, with its upper end fixedly connected to the lower part of the pad 3 and its lower end fixedly connected to the upper part of the frame 2. The Hall sensor holder 18 is fixed to a fixing rod, and the Hall sensor 19 is mounted on the Hall sensor holder 18. The sensing structure 5 further includes the resistance sensor holder 26 and the Hall sensor holder 18. The sensing structure 5 achieves the connection and fixation between the pad 3 and the frame 2 through the resistance sensor holder 26. The upper end of the resistance sensor 16 is fixedly connected to the lower part of the pad 3, and its lower end is fixedly connected to the upper part of the frame 2.

[0114] In this embodiment: the interactive structure includes an interactive pad 4, which is mounted above a pad holder 3. Horizontal rods 12 on both sides of the pad holder 3 are connected to the interactive pad 4. The interactive structure, the interactive pad 4, facilitates user gripping and pressing. After the force feedback device is secured to the user's forearm via a hand strap 6, the user presses the interactive pad 4 with their palm, causing displacement. The spring linkage structure 1 provides support to the interactive pad 4, and the user experiences tactile feedback. During this process, the sensing structure 5 detects the vertical displacement and rotation angle of the interactive pad 4. By adjusting the spring linkage structure 1, specific tactile feedback can be output.

[0115] In this embodiment, a sliding joint and a rotary joint are installed between the horizontal slider 13 and the horizontal rod 12.

[0116] In this embodiment, rotating pairs are respectively installed between the motor frame 11, the adjusting slider 15, and the frame 2.

[0117] A method for using a handheld variable stiffness passive feedback device, characterized by comprising the following steps:

[0118] The user straps their forearm to the hand strap 6 and then presses the interactive pad 4 according to the virtual reality 3D scene. The interactive pad 4 generates vertical displacement, the horizontal slider 13 slides horizontally, the spring 10 is stretched, and the spring linkage structure 1 generates a supporting force on the interactive pad 4. The user receives feedback from the force feedback device. At the same time, the resistance sensor 16 and the Hall sensor 19 detect the vertical displacement and rotation angle of the interactive pad 4, respectively. Based on the feedback signals from the resistance sensor 16 and the Hall sensor 19, the motor 9 controls the position of the adjusting slider 15, thereby affecting the length and direction of the spring 10, and thus controlling the amplitude of the force feedback.

[0119] 1. The present invention adopts a symmetrical spring-linkage structure 1, which realizes tactile feedback based on the passive stretching of spring 10. The structure is simple and the output is continuous.

[0120] 2. By adjusting the structure of the spring connecting rod 1, the present invention can output specific force and torque, which is simple to drive, stable, and robust.

[0121] 3. This invention is assembled from standard parts and simple non-standard parts, making it easy to manufacture and low in cost.

[0122] 4. This invention is a passive structure that will not be damaged in abnormal situations such as power outages, has high safety and reliability, and is suitable for users of all ages.

[0123] 5. The force and torque output by this invention can be determined based on the structural geometry and the feedback values ​​of the resistance sensor 16 and the Hall sensor 19. The output can be quantified and adjusted, making it suitable for various application scenarios.

[0124] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any other way. Any modifications or equivalent changes made based on the technical essence of the present invention shall still fall within the scope of protection claimed by the present invention.

Claims

1. A handheld variable stiffness passive force feedback device, characterized in that: The system includes a spring linkage structure (1), a frame (2), a pad frame (3), an interaction structure, and a sensing structure (5). The interaction structure is mounted on the pad frame (3). Horizontal rods (12) are symmetrically arranged on the pad frame (3). The horizontal rods (12) connect to the interaction structure and adapt to its displacement. A horizontal slider (13) is slidably mounted on the horizontal rods (12). The spring-link structure (1) is symmetrically mounted on the frame (2) and rotatably arranged relative to the frame (2). The spring-link structure (1) includes a motor (9), a spring (10), a motor frame (11), a lead screw (14), and an adjusting slider (15). The motor (9) is mounted inside the motor frame (11). The lead screw (14) is connected to the output shaft of the motor (9). The adjusting slider (15) is slidably mounted on the lead screw (14). One end of the spring (10) is connected to the adjusting slider (15), and the other end is connected to the frame (2). One end of the motor frame (11) is connected to the horizontal slider (13) via a bearing, and the other end is connected to the frame (2) via a bearing. The sensing structure (5) is installed between the pad (3) and the frame (2) to connect and fix the two. The sensing structure (5) includes a resistance sensor (16), a sensor connecting rod (17), and a Hall sensor (19). The sensor connecting rod (17) is installed on the resistance sensor (16). A rotating shaft (20) is installed at the end of the sensor connecting rod (17). A fixed rod is vertically connected to the side of the sensor connecting rod (17). The Hall sensor (19) is installed on the fixed rod. The central axis of the Hall sensor (19) is collinear with the rotating shaft (20). When the interactive structure and the pad (3) rotate together around the rotating shaft (20), the Hall sensor (19) outputs the rotation angle of the interactive structure. The sensor connecting rod (17) moves up and down with the interactive structure. The resistance sensor (16) outputs the displacement distance of this translation. Based on mechanical equilibrium and geometric structure, the output force F of the one-sided spring-linkage structure (1) is obtained. p for: Where x represents the length of AC′, controlled by the position of the horizontal slider (13)C, L b It is the length of the horizontal bar (12)AD, L f L is the length of frame (2)AB. so L is the length of the spring (10) when the force feedback device is in its initial state. so The initial force F0 is greater than the rest length of the spring (10), therefore, the spring (10) can provide an initial force F0, α is the angle between AB and AD when the force feedback device is in the initial state, k is the stiffness of the spring (10), and s is the displacement distance measured by the resistance sensor (16). When the user grasps the interactive structure at will, the system symmetrically controls the motors (9) on both sides to adjust the position of the slider (15) on the lead screw (14), which is the force rendering mode. When the user actively presses the interactive structure, the force feedback device adjusts the layout of the spring linkage structure (1) symmetrically based on the feedback signal, so that the entire force feedback device presents different stiffnesses. At this time, it is the stiffness rendering mode. In force rendering mode and stiffness rendering mode, the force F exerted by the spring linkage structure (1) on the interactive structure on both sides is: F=2F p (3) When the user freely grasps the interactive system, the system asymmetrically adjusts the layout of the spring linkage structure (1) on both sides to generate a specific torque on the user. This is the torque rendering mode. In torque rendering mode, the torque M output by the spring linkage structure (1) on both sides to the interactive structure is: in, and The output forces of the spring linkage structure (1) on both sides are represented respectively. l1 and l2 represent the left lever arm and the right lever arm respectively. They are the distances from the left horizontal slider (13)D1 and the right horizontal slider (13)D2 to the center point E of the interactive structure.

2. The handheld variable stiffness passive force feedback device according to claim 1, characterized in that: It also includes a limiting structure (8), which is installed below the frame (2). The limiting structure (8) includes a limiting connecting rod (22), a vertical slider (23), a vertical rod (24), and a limiting structure fixing frame (25). The upper end of the limiting connecting rod (22) is connected to the rotating shaft (20) through a bearing, and the lower end is fixed on the vertical slider (23). The vertical slider (23) is slidably installed on the vertical rod (24), and the vertical rod (24) is vertically fixed on the limiting structure fixing frame (25).

3. The handheld variable stiffness passive force feedback device according to claim 2, characterized in that: The limiting structure (8) also includes a support frame (21), and the limiting structure fixing frame (25) is installed on the support frame (21) and assembled on the frame (2) through the support frame (21).

4. A handheld variable stiffness passive force feedback device according to claim 1 or 3, characterized in that: It also includes a tracking structure for motion tracking, the tracking structure including a tracker (7) with a mounting platform above the tracker (7), the tracker (7) being fixedly mounted under the support frame (21) by screws and the mounting platform.

5. A handheld variable stiffness passive force feedback device according to claim 1, characterized in that: It also includes a hand strap (6), which is movably installed on the side of the frame (2). When the hand strap (6) is strapped to the user's forearm, the user's palm presses on the interactive structure.

6. A handheld variable stiffness passive force feedback device according to claim 1, characterized in that: The sensing structure (5) further includes a resistance sensor frame (26) and a Hall sensor frame (18). The resistance sensor (16) is mounted on the resistance sensor frame (26). The upper end of the resistance sensor (16) is fixedly connected to the bottom of the pad frame (3), and the lower end is fixedly connected to the top of the frame (2). The Hall sensor frame (18) is fixed on the fixing rod, and the Hall sensor (19) is mounted on the Hall sensor frame (18).

7. A handheld variable stiffness passive force feedback device according to claim 1, characterized in that: The interactive structure includes an interactive pad (4), which is installed above the pad frame (3). The horizontal bars (12) on both sides of the pad frame (3) are respectively connected to the interactive pad (4).

8. A handheld variable stiffness passive force feedback device according to claim 1, characterized in that: A sliding joint and a rotary joint are installed between the horizontal slider (13) and the horizontal rod (12).

9. A handheld variable stiffness passive force feedback device according to claim 1, characterized in that: Rotary pairs are respectively installed between the motor frame (11), the adjusting slider (15), and the frame (2).

10. A method of using a handheld variable stiffness passive force feedback device as described in any one of claims 1-9, characterized in that: Includes the following steps: The user binds their forearm to the hand strap (6) and then presses the interactive pad (4) according to the three-dimensional scene of virtual reality. The interactive pad (4) generates a vertical displacement, the horizontal slider (13) slides horizontally, the spring (10) is stretched, and the spring linkage structure (1) generates a supporting force on the interactive pad (4). The user receives feedback from the force feedback device. At the same time, the resistance sensor (16) and the Hall sensor (19) detect the vertical displacement and rotation angle of the interactive pad (4) respectively. Based on the feedback signals of the resistance sensor (16) and the Hall sensor (19), the motor (9) controls the position of the adjustment slider (15), thereby affecting the length and direction of the spring (10) and thus controlling the amplitude of the force feedback.

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