Magnetic force type haptic representation system and method based on universal rotating structure

Abstract

The invention discloses a magnetic force type haptic representation system and method based on a universal rotating structure, and the method comprises the steps: constructing a fingertip magnet module based on the universal rotating structure, and adjusting the intensity and direction of a three-dimensional controllable background electromagnetic field through adjusting the excitation of a three-dimensional background electromagnet; the electromagnetic acting force of the electromagnet at the universal rotating structure is regulated and controlled; the universal rotating structure allows the fingertip magnet module to rotate at any angle, so that the possible influence of the magnetic field acting moment is eliminated, the magnetic moment of the electromagnet always coincides with the magnetic field direction to provide electromagnetic attraction force, and multi-point fingertip force touch representation facing an operator is achieved. The three-dimensional controllable background electromagnet is composed of a plurality of coils and can generate a needed three-dimensional controllable background electromagnetic field, the optimal electromagnetic excitation scheme is determined according to the current finger pose detection result, and the magnetic force type haptic representation method based on the universal rotating structure is easy to implement and high in algorithm efficiency.

Description

Technical Field

[0001] The present invention belongs to the technical field of force tactile reproduction in human-computer interaction, and in particular relates to a magnetic force tactile reproduction method of a universal rotating structure. Background Art

[0002] At present, tactile reproduction technology is mainly divided into several types: mechanical tactile reproduction, vibration tactile reproduction, electrostatic force tactile reproduction, and the airbag and pneumatic jet tactile reproduction methods that have emerged in recent years. Among them, electromagnetic force tactile reproduction technology has good development prospects and a wide range of applications.

[0003] He Ziping et al. from South China University of Technology used magnetic force as feedback force, and electromagnets and magnetic induction gloves as force generation and sensing devices. Through electromagnetic theory and finite element analysis, the magnetic field distribution of the electromagnet and the force magnitude of the magnetic induction gloves were analyzed and calculated. The direction of the feedback force was calculated using a three-dimensional platform movement tracking algorithm. However, the accuracy was low due to the limitation of the activity distance.

[0004] Nikolas Kastor et al. proposed an electromagnetic actuator that drives one or more permanent magnets through electromagnetic force, calculated the forces generated by the permanent magnets and electromagnetic coils, and how they interact with ferrofluids to produce mechanical motion, thereby stimulating the skin. It can accurately reproduce high dynamic range tactile vibrations in the entire tactile perceptible frequency range.

[0005] Hwan Kim et al. designed HAPmini, which has low mechanical complexity and a minimum number of actuators, while being able to provide force feedback and tactile feedback. By changing the polarity of the current flowing through the solenoid, the direction of the electromagnetic field can be changed, thereby generating a pulling or pushing force on the permanent magnet. But it can only operate in a two-dimensional plane.

[0006] The flexible three-dimensional force tactile sensor and capacitive fingertip three-dimensional force tactile sensor proposed by Jiangsu University can measure three-dimensional force through multi-electrode design and signal acquisition and control system construction, so as to calculate more accurate grip force and provide scientific grasping strategies for the robot.

[0007] Abler et al. designed a single-actuated spherical needle array device Hedgehog, which controls the extension and retraction of 86 active pins made of permanent magnets through a spherical omnidirectional electromagnet, achieving a force of 200mN under maximum load. The device restricts the movement of the hand, and the hand can only feel force when holding the device.

[0008] A multi-finger rope force tactile feedback device based on ultrasonic phased array and its feedback method (patent number CN201910246962.8) is proposed. A multi-finger rope force tactile feedback device based on ultrasonic phased array and its feedback method are proposed. Through a line-driven rope force unit, it provides high-degree-of-freedom, high-precision, and strong-feeling force tactile feedback.

[0009] Southeast University has proposed a wearable flexible force tactile feedback device for fingers (patent number CN201811301176.5), which provides force tactile feedback information to the fingers through internal and external transmission rods and drivers. It has a lightweight structure, is easy to wear, allows flexible movement of the fingers, and allows natural interaction.

[0010] Both air pressure-based and acoustic radiation force-based methods can achieve truly natural interaction. They have the advantages of low cost, low power consumption and controllable force, but they can usually only provide rough force feedback, with low resolution and accuracy, and perform poorly in obstructed environments. The electromagnetic force-based force tactile reproduction method of the present invention is a relatively promising method among non-contact methods. It can provide fine, multi-dimensional, unconstrained multi-point force tactile reproduction. Summary of the invention

[0011] In view of the above technical problems, the purpose of the present invention is to provide a new force tactile reproduction device and electromagnetic field control method.

[0012] A magnetic force tactile reproduction system based on a universal rotating structure, the system comprises a three-dimensional background electromagnet module, a universal rotating structure, a fingertip magnet module, a system central control module and a position detection module; wherein,

[0013] The universal rotating structure comprises three layers of ring frames, namely, inner, middle and outer layers, and mutually perpendicular rotation axes. The inner ring frame rotates around the rotation axis fixed to the middle ring frame, and the middle ring frame rotates around the rotation axis fixed to the outer ring frame. A fingertip magnet module is placed on the inner ring frame of the universal rotating structure, allowing the fingertip magnet module to rotate at any angle.

[0014] The three-dimensional background electromagnet module is composed of multiple coils, and generates the required three-dimensional controllable background electromagnetic field through the current excitation signal sent by the system central control module;

[0015] The fingertip magnet module is composed of a permanent magnet or an electromagnet.

[0016] When a permanent magnet is used as the fingertip magnet, the fingertip magnet has a fixed magnetic moment; when an electromagnet is used as the fingertip magnet, the magnetic moment of the fingertip magnet is adjustable, and the strength and direction of the magnetic field are adjusted by changing the current passing through the coil.

[0017] Based on the above magnetic force tactile reproduction system based on the universal rotating structure, the present application also provides a corresponding reproduction method, which includes the following steps:

[0018] Step 1: Establish a mapping relationship between the operation space and the virtual space. First, use the finite element method to simulate the three-dimensional controllable background electromagnetic field distribution generated by the three-dimensional background electromagnet in the operation space under various excitations, and determine the optimal excitation scheme data for each point; establish a virtual scene including a virtual hand and a virtual object model, and establish a spatial mapping relationship between the real operation space inside the background electromagnet module and the virtual scene, as well as a three-dimensional position mapping relationship between the human hand and the virtual hand, and establish a multi-point force tactile reproduction model of the virtual object and multiple fingertip proxy points in the virtual reality environment:

[0019] The excitation scheme is as follows: establish a three-dimensional background electromagnet simulation model, set the spatial finite element simulation step size according to the accuracy requirements and traverse each group of excitation currents to determine the magnitude of the magnetic field force in the space, and the magnetic field force at any position (x, y, z) in the space The specific relationship with the excitation current is as follows:

[0020] F=AI

[0021]

[0022] in is the ratio of the force produced by each coil to the current at a given position, is the coil driving current vector.

[0023] By solving:

[0024] A -1 F=I

[0025] The virtual interaction force can be determined to determine the current excitation I required to generate the corresponding magnetic field force.

[0026] Acquire the three-dimensional position information of the human hand in real time, and transmit the three-dimensional position information of the human hand to the virtual hand in the virtual scene in (1);

[0027] The control strategy is as follows:

[0028] The camera module obtains the 3D position information of the human hand in real time and converts it into the coordinates of the human hand in the virtual environment. When the operator's fingertips interact with the virtual object, the interpolation method is used to select the spatial discrete point x closest to the current interaction point among the n points in the excitation scheme. m ,y m , z m , and determine the optimal excitation scheme current combination value (I1, I2, I3...I m )

[0029] Finally, electromagnetic force The permanent magnet is rotated by the universal rotating structure to maximize the electromagnetic force and complete the force tactile feedback.

[0030] Step 2: Obtain the fingertip position information P(P x , P y , P z , α, β, γ), where P x , P y and P z is the three-dimensional coordinate information of the fingertip electromagnet, and α, β and γ are the rotation angle information of the fingertip electromagnet.

[0031] Step 3: According to the force tactile reproduction model, the force exerted on the operator's fingertips when interacting with the virtual object at the current moment is calculated and generated as the target force in the control method. The calculation of the magnetic torque of the fingertip electromagnet is specifically as follows:

[0032]

[0033] in, It represents the magnetic torque of the electromagnet at the fingertip. It represents the magnetic moment of the fingertip electromagnet as a whole. It indicates the magnetic induction intensity generated by the background magnetic field at the fingertip electromagnet position; when the direction of the magnetic induction intensity of the background magnetic field is consistent with the direction of the equivalent magnetic moment of the fingertip magnet, the magnetic moment of the fingertip electromagnet is the smallest;

[0034] The calculation of the magnetic moment of the fingertip electromagnet is specifically as follows:

[0035]

[0036] Among them, S xa S represents the area enclosed by the ath coil on the fingertip electromagnet with the central axis in the X direction. yb S represents the area enclosed by the bth coil on the fingertip electromagnet with the central axis in the Y direction. zc represents the area enclosed by the cth coil whose central axis is in the Z direction on the fingertip electromagnet, nx, ny, nz are the numbers of coils whose central axis is in the X, Y, and Z directions on the fingertip electromagnet, respectively, FTx ,I FTy ,I FTz They respectively represent the magnitude of the excitation current of the coils with the central axis in the X, Y, and Z directions on the fingertip electromagnet; Indicates the direction of the magnetic moment generated by the coil with the central axis X, which is related to the current I FTx The flow direction obeys the right-hand screw rule, and the same can be said for the Y and Z directions. The overall magnetic moment of the fingertip electromagnet is formed by the superposition of vectors in three orthogonal directions.

[0037] The magnetic field generated by the background electromagnet is specifically:

[0038]

[0039] According to the Biot-Savart law, the magnetic induction intensity generated by each coil unit at the fingertip position along the X, Y and Z axes is calculated respectively, and the magnetic induction intensity generated by each coil unit is vector-superimposed to obtain the magnitude and direction of the magnetic induction intensity at the fingertip position;

[0040] The calculation of the electromagnetic force on the fingertip electromagnet is specifically as follows:

[0041]

[0042] in, is the electromagnetic force on the electromagnet at the fingertip, is the gradient operator. For the background electromagnet, there is no current flowing inside the fingertip magnet. According to Maxwell's equations, Therefore, the electromagnetic force on the fingertip electromagnet is:

[0043]

[0044] That is, for an ideal magnetic dipole moment, the force it experiences in an external magnetic field is determined by the magnetic induction intensity gradient and magnetic moment at its location.

[0045] The force is transmitted to the central control module of the system. After the control strategy selects the best current excitation scheme, it drives the three-dimensional background electromagnet to generate electromagnetic force on the fingertip electromagnet to achieve force tactile feedback.

[0046] Repeat until step 2 or end.

[0047] Compared with the prior art, the present invention adopts the above technical solution and has the following technical effects:

[0048] (1) The universal rotating structure can rotate at any angle, eliminating the possible influence of the magnetic field torque, so that the magnetic moment of the electromagnet always coincides with the direction of the magnetic field to provide electromagnetic attraction, and can provide multi-directional non-contact force tactile feedback, realize precise control of force tactile feedback, improve the user's operating efficiency, and enhance the user's immersion and interactive experience;

[0049] (2) The finite element simulation of the three-dimensional background electromagnetic field can obtain an adjustable magnetic field strength. The algorithm for obtaining the excitation scheme is simple and can provide large-space, continuously adjustable force tactile feedback;

[0050] (3) The force tactile device designed by this method can achieve more precise and multi-point force tactile perception, enhancing the experiencer's sense of reality and immersion. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure (1) is a system diagram of a magnetic force tactile reproduction method based on a universal rotating mechanism;

[0052] Figure (2) is a structural diagram of a universal rotating mechanism of a magnetic force tactile reproduction method based on a universal rotating mechanism;

[0053] Figure (3) is a structural diagram of fingertip force tactile feedback based on a magnetic force tactile reproduction method of a universal rotating mechanism. DETAILED DESCRIPTION

[0054] The present invention provides a magnetic force tactile reproduction method based on a universal rotating mechanism. In order to make the stated purpose, control method and effect easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and examples.

[0055] The magnetic force tactile reproduction system and reproduction method based on the universal rotating structure involved in the present invention has a flow chart as shown in FIG. Figure 2 As shown, Example 1 is as Figure 3 shown.

[0056] Embodiment 1:

[0057] This embodiment is a magnetic force tactile reproduction system based on a universal rotating structure, the system comprises a three-dimensional background electromagnet module, a universal rotating structure, a fingertip magnet module, a system central control module and a position detection module; wherein,

[0058] The universal rotating structure comprises three layers of ring frames, namely, inner, middle and outer layers, and mutually perpendicular rotation axes. The inner ring frame rotates around the rotation axis fixed to the middle ring frame, and the middle ring frame rotates around the rotation axis fixed to the outer ring frame. A fingertip magnet module is placed on the inner ring frame of the universal rotating structure, allowing the fingertip magnet module to rotate at any angle.

[0059] The three-dimensional background electromagnet module is composed of multiple coils, and generates the required three-dimensional controllable background electromagnetic field through the current excitation signal sent by the system central control module;

[0060] The fingertip magnet module is composed of a permanent magnet or an electromagnet.

[0061] When a permanent magnet is used as the fingertip magnet, the fingertip magnet has a fixed magnetic moment; when an electromagnet is used as the fingertip magnet, the magnetic moment of the fingertip magnet is adjustable, and the strength and direction of the magnetic field are adjusted by changing the current passing through the coil.

[0062] Embodiment 2:

[0063] Based on the above magnetic force tactile reproduction system based on the universal rotating structure, the present application also provides a corresponding reproduction method, which includes the following steps:

[0064] Establish the mapping relationship between the operation space and the virtual space. First, use the finite element method to simulate the three-dimensional controllable background electromagnetic field distribution generated by the three-dimensional background electromagnet in the operation space under various excitations, and determine the optimal excitation scheme data for each point. Establish a virtual scene including a virtual hand and a virtual object model, and establish the spatial mapping relationship between the real operation space inside the background electromagnet module and the virtual scene, as well as the three-dimensional position mapping relationship between the human hand and the virtual hand. Establish a multi-point force tactile reproduction model of the virtual object and multiple fingertip proxy points in the virtual reality environment:

[0065] The excitation scheme is as follows: establish a three-dimensional background electromagnet simulation model, set the spatial finite element simulation step size according to the accuracy requirements and traverse each group of excitation currents to determine the magnitude of the magnetic field force in the space, and the magnetic field force at any position (x, y, z) in the space

[0066] The specific relationship with the excitation current is as follows:

[0067] F=A1

[0068]

[0069] in is the ratio of the force produced by each coil to the current at a given position, is the coil driving current vector.

[0070] By solving:

[0071] A -1 F=I

[0072] The virtual interaction force can be determined to determine the current excitation I required to generate the corresponding magnetic field force.

[0073] Acquire the three-dimensional position information of the human hand in real time, and transmit the three-dimensional position information of the human hand to the virtual hand in the virtual scene in (1);

[0074] The control strategy is as follows:

[0075] The camera module obtains the 3D position information of the human hand in real time and converts it into the coordinates of the human hand in the virtual environment. When the operator's fingertips interact with the virtual object, the interpolation method is used to select the spatial discrete point x closest to the current interaction point among the n points in the excitation scheme. m ,y m , z m , and determine the optimal excitation scheme current combination value (I1, I2, I3...I m )

[0076] Finally, electromagnetic force The permanent magnet is rotated by the universal rotating structure to maximize the electromagnetic force and complete the force tactile feedback.

[0077] The camera module is used to obtain the fingertip position information P(P x , P y , P z , α, β, γ), where P x , P y and P z is the three-dimensional coordinate information of the fingertip electromagnet, and α, β and γ are the rotation angle information of the fingertip electromagnet.

[0078] Step 3: According to the force tactile reproduction model, the force exerted on the operator's fingertips when interacting with the virtual object at the current moment is calculated and generated as the target force in the control method. The calculation of the magnetic torque of the fingertip electromagnet is specifically as follows:

[0079]

[0080] in, It represents the magnetic torque of the electromagnet at the fingertip. It represents the magnetic moment of the fingertip electromagnet as a whole. It indicates the magnetic induction intensity generated by the background magnetic field at the fingertip electromagnet position; when the direction of the magnetic induction intensity of the background magnetic field is consistent with the direction of the equivalent magnetic moment of the fingertip magnet, the magnetic moment of the fingertip electromagnet is the smallest;

[0081] The calculation of the magnetic moment of the fingertip electromagnet is specifically as follows:

[0082]

[0083] Among them, S xa It represents the area enclosed by the ath coil on the fingertip electromagnet whose central axis is in the X direction.

[0084] S yb S represents the area enclosed by the bth coil on the fingertip electromagnet with the central axis in the Y direction. zc represents the area enclosed by the cth coil whose central axis is in the Z direction on the fingertip electromagnet, nx, ny, nz are the numbers of coils whose central axis is in the X, Y, and Z directions on the fingertip electromagnet, respectively, FTx ,I FTy ,I FTz They respectively represent the magnitude of the excitation current of the coils with the central axis in the X, Y, and Z directions on the fingertip electromagnet; Indicates the direction of the magnetic moment generated by the coil with the central axis X, which is related to the current I FTx The flow direction obeys the right-hand screw rule, and the same can be said for the Y and Z directions. The overall magnetic moment of the fingertip electromagnet is formed by the superposition of vectors in three orthogonal directions.

[0085] The magnetic field generated by the background electromagnet is specifically:

[0086]

[0087] According to the Biot-Savart law, the magnetic induction intensity generated by each coil unit at the fingertip position along the X, Y and Z axes is calculated respectively, and the magnetic induction intensity generated by each coil unit is vector-superimposed to obtain the magnitude and direction of the magnetic induction intensity at the fingertip position;

[0088] The calculation of the electromagnetic force on the fingertip electromagnet is specifically as follows:

[0089]

[0090] in, is the electromagnetic force on the electromagnet at the fingertip, is the gradient operator. For the background electromagnet, there is no current flowing inside the fingertip magnet. According to Maxwell's equations, Therefore, the electromagnetic force on the fingertip electromagnet is:

[0091]

[0092] That is, for an ideal magnetic dipole moment, the force it experiences in an external magnetic field is determined by the magnetic induction intensity gradient and magnetic moment at its location.

[0093] The force is transmitted to the central control module of the system. After the control strategy selects the best current excitation scheme, it drives the three-dimensional background electromagnet to generate electromagnetic attraction to the fingertip electromagnet to achieve force tactile feedback.

[0094] Repeat the above steps until finished.

[0095] The magnetic force tactile reproduction method of the universal rotating mechanism involved in the present invention constructs a fingertip magnet module based on the universal rotating structure, and controls the strength and direction of the three-dimensional controllable background electromagnetic field by adjusting the excitation of the three-dimensional background electromagnet, so as to realize the regulation of the electromagnetic force of the electromagnet at the universal rotating structure. The three-dimensional controllable background electromagnet is composed of multiple coils and can generate the required three-dimensional controllable background electromagnetic field. The optimal electromagnetic excitation scheme is determined according to the current finger posture detection result. The algorithm of the magnetic force tactile reproduction method based on the universal rotating structure is simple to implement, and the non-contact multi-point force tactile feedback is continuously adjustable and has obvious effect, which can provide a more complex and realistic human-computer interaction experience and effectively improve the quality of human-computer interaction.

Claims

1. A magnetic force tactile reproduction system based on a universal rotating structure, characterized in that: The system includes a three-dimensional background electromagnet module, a universal rotating structure, a fingertip magnet module, a system central control module and a position detection module; wherein, The universal rotating structure comprises three layers of ring frames, namely, inner, middle and outer layers, and mutually perpendicular rotation axes. The inner ring frame rotates around the rotation axis fixed to the middle ring frame, and the middle ring frame rotates around the rotation axis fixed to the outer ring frame. A fingertip magnet module is placed on the inner ring frame of the universal rotating structure, allowing the fingertip magnet module to rotate at any angle. The three-dimensional background electromagnet module is composed of multiple coils, and generates the required three-dimensional controllable background electromagnetic field through the current excitation signal sent by the system central control module; The fingertip magnet module is composed of a permanent magnet or an electromagnet.

2. The magnetic force tactile reproduction system based on a universal rotating structure according to claim 1, characterized in that: When a permanent magnet is used as the fingertip magnet, the fingertip magnet has a fixed magnetic moment; when an electromagnet is used as the fingertip magnet, the magnetic moment of the fingertip magnet is adjustable, and the strength and direction of the magnetic field are adjusted by changing the current passing through the coil.

3. The reproduction method of the magnetic force tactile reproduction system based on the universal rotating structure according to claim 1, characterized in that: The method comprises the following steps: S1, simulate the three-dimensional controllable background electromagnetic field distribution generated by the three-dimensional background electromagnet in the operation space under various excitations through the finite element method, and obtain the optimal excitation scheme data for each point; establish a virtual scene including a virtual hand and a virtual object model, and establish a spatial mapping relationship between the real operation space inside the background electromagnet module and the virtual scene, as well as a three-dimensional position mapping relationship between the human hand and the virtual hand, and establish a multi-point force tactile reproduction model of the virtual object and multiple fingertip proxy points in the virtual reality environment; S2, real-time acquisition of the three-dimensional position information of the human hand, converting it into the coordinates of the human hand in the virtual environment, and transmitting the three-dimensional position information of the human hand to the virtual hand in the virtual scene in S1; S3, calculating and generating the force exerted on the operator's fingertips when interacting with the virtual object at the current moment according to the force tactile reproduction model, as the target force in the control method; S4, transmitting the target force to the central control module of the system, determining the current three-dimensional position of the human hand, selecting the best current excitation scheme formed in S1 according to the control strategy, driving the three-dimensional background electromagnet to generate electromagnetic attraction to the fingertip electromagnet, and the universal rotating structure rotates the permanent magnet so that the magnetic moment of the electromagnet always coincides with the direction of the magnetic field, thereby realizing force tactile feedback; Repeat to step S2.

4. The reproduction method according to claim 3, characterized in that: The incentive scheme includes: Establish a three-dimensional background electromagnet simulation model, set the spatial finite element simulation step size according to the accuracy requirements, and traverse each set of excitation currents to determine the magnitude of the magnetic field force in space, and the magnetic field force at any position (x, y, z) in space The specific relationship with the excitation current is as follows: F=AI Among them, the excitation matrix A=[f j1 , f j2 , f j3 ], is the ratio of the force produced by each coil to the current at a given position, is the coil driving current vector.

5. The reproduction method according to claim 3, characterized in that: The control strategy is as follows: the camera module obtains the three-dimensional position information of the human hand in real time and converts it into the coordinates of the human hand in the virtual environment. When the operator's fingertips interact with the virtual object, the interpolation method is used to select the spatial discrete point x closest to the current interaction point among the n points in the excitation scheme. m ,y m , z m , and determine the optimal excitation scheme current combination value (I1, I2, I3...I m ) Finally, electromagnetic force is realized The permanent magnet is rotated by the universal rotating structure so that the magnetic moment of the electromagnet always coincides with the direction of the magnetic field, thus completing the force tactile feedback.

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