Method and system for multi-point force haptic rendering based on a halbach array

Abstract

The application discloses a multi-point force tactile reproduction method and system based on a Halbach array; the method generates a three-dimensional controllable background electromagnetic field by exciting three-dimensional background electromagnets, adjusts the current of three-dimensional orthogonal micro electromagnets of fingertips, and controls the electromagnetic force of the fingertip electromagnets; the three-dimensional controllable background electromagnets are composed of an inner one-dimensional laminated electromagnet and an outer two-dimensional array electromagnet; the one-dimensional laminated electromagnet is composed of a plurality of hollow disc-shaped laminated coils, and the inner cylindrical space is an operation space; the outer two-dimensional array electromagnet is composed of a plurality of two-dimensional coil units and a magnetic medium material wrapped outside the coils, a Halbach electromagnet array is formed by adjusting the current of each coil unit, and a two-dimensional non-uniform electromagnetic field of multiple modes, rotatable, enhanced inside and weakened outside the operation space is generated.

Description

Technical Field

[0001] This invention belongs to the field of force and tactile reproduction technology in human-computer interaction, and particularly relates to a multi-point force and tactile reproduction method and system based on Heilbeck array. Background Technology

[0002] Force-haptic reproduction, as a novel human-computer interaction mode, provides a two-way energy and information exchange channel between humans and the external environment, overcoming the limitations of visual and auditory interaction alone. It significantly increases the realism and immersion of human-computer interaction and is receiving increasing attention. In recent years, with the development of force-haptic reproduction technology, its application scenarios have continued to expand, finding wide application in fields such as medical training, educational simulation, and entertainment games.

[0003] Currently, force-tactile reproduction technology has achieved many results, with various force-tactile reproduction devices of different structures developed, some of which have been commercialized. However, they still fall short compared to real, natural force-tactile interaction. Traditional force-tactile reproduction devices based on mechanical linkages or wearable devices often restrict hand movements, making it difficult for operators to interact realistically with the environment. Furthermore, most commercially available force-tactile reproduction devices are not only expensive but also only provide single-point interaction. To overcome the shortcomings of traditional force-tactile reproduction devices, such as complex structures and restrictions on hand movements, non-contact force-tactile reproduction methods have been proposed, mainly categorized as those based on air pressure, sound radiation force, and electromagnetic force.

[0004] Methods based on air pressure and acoustic radiation can achieve truly natural interaction, offering advantages such as low cost, low power consumption, and controllable force. However, they typically provide only coarse force feedback with low resolution and accuracy, and perform poorly in obstructed environments. Electromagnetic force-based tactile reproduction methods are a promising non-contact approach, offering refined, multi-dimensional, and unconstrained multi-point force-tactile reproduction.

[0005] In the patent "An Electromagnetic Force Feedback Device and Method for Virtual Interventional Surgery Systems" by Yuan Zhiyong et al. (patent number CN 112214931 A), a background magnetic field is generated by four identical electromagnetic coils on the same plane. A surgical instrument consisting of two long cylindrical permanent magnets and a rigid rod-shaped operating lever is used to achieve circumferential rotational force feedback. This device requires a handheld tool, the interaction is not natural, and it can only achieve single-point force feedback.

[0006] Langerak et al. proposed Omni, a force-haptic feedback system based on an omnidirectional spherical electromagnet. The omnidirectional spherical electromagnet consists of an iron core and three orthogonal coils outside the core. By controlling the current in the three interwoven, orthogonal coils within the spherical electromagnet, and using a handheld tool embedded with a permanent magnet, the system can sense radial and tangential attractive and repulsive forces up to 2N. Simultaneously, the device integrates eight Hall effect sensors into the base of the omnidirectional spherical electromagnet to track the three-dimensional position of the permanent magnet. While the system boasts high integration, it suffers from a small operating space and requires a handheld tool for force-haptic feedback reproduction, making the interaction method somewhat unintuitive and unnatural.

[0007] Abler et al. designed Hedgehog, a single-drive spherical pin array device that uses a spherical omnidirectional electromagnet to control the extension and retraction of 86 movable pins made of permanent magnets, achieving a force of 200 mN under maximum load. This device restricts hand movement; the hand can only feel the force when gripping the device. Summary of the Invention

[0008] To address the aforementioned technical problems, the present invention aims to propose a novel force-tactile reproduction device and electromagnetic field control method, which can achieve three-dimensional multi-point force-tactile reproduction with minimal constraints on the hand and natural interaction in a large operating space.

[0009] The multi-point force tactile reproduction method and system based on Heilbeck array provided by this invention consists of a hardware system and a control method. The hardware system includes a three-dimensional background electromagnet module, a background electromagnet driving module, a fingertip micro electromagnet module, a fingertip micro electromagnet driving module, a system central control module, a camera module, etc.

[0010] The three-dimensional background electromagnet module consists of an inner layer of one-dimensional stacked electromagnets and an outer layer of two-dimensional array electromagnets. The one-dimensional stacked electromagnets are composed of multiple coaxial hollow disk-shaped stacked coil units, and their internal cylindrical space is the force and tactile reproduction operation space. The outer layer of two-dimensional array electromagnets is located outside the one-dimensional stacked electromagnets and consists of two-dimensional array coils and magnetic medium material wrapped around the two-dimensional array coils. The magnetic medium material concentrates the magnetic field generated by the two-dimensional coil units to provide a magnetic flux path and enhance the Halebec effect.

[0011] The two-dimensional array coil consists of M1×M2 two-dimensional square coil units. M1 two-dimensional square coil units are wound around the outside of the one-dimensional electromagnet, forming a group of two-dimensional coils. The internal space of this group is a regular prism coaxial with the one-dimensional stacked electromagnet. The M2 groups of two-dimensional coils are arranged sequentially along the axial direction to form the outer two-dimensional array electromagnet. Each two-dimensional square coil unit is composed of two nested orthogonal square coils. The central axis of the outer square coil is tangent to the operating space of the inner cylinder, and is called the tangential coil unit. The inner square coil, orthogonal to it, is called the radial coil unit. The fingertip miniature electromagnet module consists of multiple fingertip miniature electromagnets EM. FTn Composed of miniature electromagnets EM in each fingertip FTn It is composed of three layers of coils with two orthogonal centers arranged in a stacked structure, and is used to provide feedback force to the human finger;

[0012] The three-dimensional controllable background electromagnetic field generated by the three-dimensional background electromagnet is formed by superimposing the one-dimensional electromagnetic field in the X direction generated by the one-dimensional stacked electromagnet and the two-dimensional background electromagnetic field in the YZ direction generated by the outer two-dimensional array electromagnet; the one-dimensional stacked electromagnet controls N coaxial one-dimensional coil units EM Xi (i = 1, 2…N) to realize a one-dimensional electromagnetic field that can be adjusted in multiple local regions;

[0013] For the outer two-dimensional array electromagnet, adjust its tangential coil unit EM Tjk and radial coil unit EM Rjk The current (j=1,2,…,M1; k=1,2,…,M2) controls the direction of the magnetic field generated by each two-dimensional coil unit to be arbitrary in the YZ plane; under the combined action of M1×M2 two-dimensional coil units, various Hellbeck arrays can be constructed, which can enhance the electromagnetic field inside the operating space and weaken the electromagnetic field outside the operating space, while generating magnetic fields of various modes, such as two-pole electromagnetic fields, four-pole electromagnetic fields, and six-pole electromagnetic fields. Furthermore, by regularly rotating the direction of the electromagnetic field generated by each two-dimensional coil unit, the direction of the background electromagnetic field poles can be rotated equivalently.

[0014] The method includes the following steps:

[0015] (1) Build a virtual scene, construct a multi-point force tactile reproduction model of virtual objects and multiple fingertip proxy points in the virtual reality environment;

[0016] (2) Establish a three-dimensional coordinate system A, with the center point of the operating space as the origin of the three-dimensional coordinate system A, and the direction of the central axis of the one-dimensional background electromagnet as the X-axis direction of the three-dimensional coordinate system A. Select the axis direction of any radial coil as the Y-axis direction, and determine the Z-axis according to the right-hand rule; the coordinates of the center point of the one-dimensional coil unit (Px_EM)Xi ,0,0), the center point coordinates of the two-dimensional coil group (Pyz_EM YZk (, 0, 0) and the position of the fingertip electromagnet (Px n Py n Pz n According to the definition of coordinate system A; one-dimensional coil element EM Xi With Px_EM Xi Sort in ascending order, two-dimensional coil group EM YZk With Pyz_EM YZk Sort in ascending order;

[0017] Finger electromagnet EM FTn The center point is used as the local coordinate system B n The origin of coordinate system B is defined by the coordinate axes of coordinate system A. n The coordinate axis direction, the rotation angle (α) of the fingertip electromagnet n ,β n γ n ) are about coordinate system B n The X, Y, and Z axis rotation angles; when different excitation currents are applied to the fingertip electromagnet and the background electromagnet, finite element simulation is performed on the electromagnetic forces acting on the fingertip electromagnet at different positions and angles in the operating space to obtain the EM of the fingertip electromagnet. FTn Offline data of the electromagnetic forces acting on the sample;

[0018] (3) The position of the fingertip is tracked in real time by the camera module, and multiple pose detection units are used to jointly obtain the real-time position and attitude information of multiple fingertip electromagnets;

[0019] (4) Based on the force-tactile reproduction model, calculate and generate the force exerted by the operator’s fingertips when interacting with the virtual object at the current moment, and use it as the target force in the control method;

[0020] (5) The central control module of the system selects to implement a single-point or multi-point force tactile reproduction control method as needed, calculates the excitation signal value required by the background electromagnet module and the fingertip micro electromagnet module, controls the background electromagnet drive module and the fingertip micro electromagnet drive module to output excitation current, generates the required electromagnetic force on the fingertip micro electromagnet module, and forms a single-point or multi-point force tactile reproduction.

[0021] (6) Repeat step 3 or end.

[0022] The specific method for single-point force tactile reproduction control is as follows:

[0023] When the virtual hand comes into contact with the virtual object, the camera module acquires the pose information P(Px, Py, Pz, α, β, γ) of the fingertip electromagnet at that time, where Px, Py and Pz are the three-dimensional coordinate information of the fingertip electromagnet position, and α, β and γ are the rotation angle information of the fingertip electromagnet.

[0024] The excitation method for a one-dimensional background electromagnet is as follows: Adjust the fingertip electromagnet EM FT Drive current (I) FTx I FTy I FTz ) is the maximum safe current I FTmax The maximum safe current of a one-dimensional coil unit is denoted as I. XMAX Based on the X-coordinate Px of the fingertip electromagnet, find the value that makes |Px-Px_EM Xi The smallest one-dimensional coil unit EM Xi Divide other one-dimensional coil units into two parts (such as...) Figure 1 (as shown) (EM) X1 To EM X(i-1) EM X(i+1) To EM XN ).

[0025] First, select the portion with more coil units (setting the current direction of each coil unit to be such that its magnetic moment points in the positive X-axis direction), then select the portion with fewer coil units (setting the current direction of each coil unit to be such that its magnetic moment points in the negative X-axis direction). If the two portions have the same number of coil units, then first select the one-dimensional coil unit EM. X1 To EM X(i-1) (Set the current direction of each coil unit to be such that its magnetic moment points in the positive X-axis direction), and then select a one-dimensional coil unit EM. X(i+1) To EM XN (Set the current direction of each coil unit to be such that its magnetic moment points in the negative X-axis direction), according to |Px-Px_EM Xi The one-dimensional coil elements are numbered in ascending order, denoted as EM. Xi′ (i′ = 1, 2, ..., N-1); Choose N x (1≤N x ≤N-1) one-dimensional coil elements are given an excitation current I Xi′ , where I Xi′ =I XMAX (i′=1,2,…N x -1), and 0<I Xi′ ≤I XMAX (i′=N x This causes the fingertip electromagnet to experience a force F′ in the X direction. xEqual to the target force F x When N x =N-1, and the excitation current of all one-dimensional coil elements is I. XMAX At that time, the amplitude of the force |F′ on the fingertip electromagnet in the X direction is x |Still less than the magnitude of the target force|F x |, output F′ at this point. x As the saturation output value;

[0026] The excitation method for a two-dimensional background electromagnet is as follows: according to |Px-Pyz-EM YZk The two-dimensional coil groups are numbered in ascending order, denoted as EM. YZk′ (k′=1,2,3), choose N yz (1≤N yz ≤3) two-dimensional coil groups, for their tangential coil units (EM) T1k′ EM T2k′ , ..., EM Tm1k′ ) and radial coil unit (EM) R1k′ EM R2k′ , ..., EM Rm1k′ Apply excitation current I Tjk′ I Rjk′ , when I Tjk′ with I Rjk′ When they are in a certain proportional relationship, a non-uniform two-pole field with the Hale-Becker effect can be generated. The direction of the magnetic poles generated by the two-dimensional coil group can be determined based on the direction of the force exerted on the target by the fingertip electromagnet in the YZ plane. RjkMAX The maximum safe current for the radial coil unit is I. Rjk′ =I RjkMAX (k′=12,…N yz -1), and 0<I Rjk′ ≤I RjkMAX (k′=N yz ), such that F′ y =F y And F′ z =F z When N yz =3, and the excitation current of the radial coil elements of all two-dimensional coil elements is I. RjkMAX At that time, |F′ y |<|F y |or|F′ z |<|F z |, output F′ at this point. y and F′ z As the saturation output value.

[0027] The multi-point force tactile reproduction control method is as follows:

[0028] Acquire pose information P of multiple fingertip electromagnets n (Px n Py n Pz n α n ,β n γ n ) and the target force F n (F xn F yn F zn (n = 1, 2, 3), where Px n Py n and Pz n For the three-dimensional coordinate information of the nth fingertip electromagnet, α n β n and γ n For the rotation angle information of the nth fingertip electromagnet, adjust the EM of each fingertip electromagnet. FTn Drive current (I) FTnx I FTny I FTnz ) is the maximum safe current I FTmax ;

[0029] The excitation method for the one-dimensional background electromagnet is as follows: Based on the X coordinates (Px1, Px2, Px3) of the positions of the three fingertip electromagnets, take Px... MIN =MIN{Px1, Px2, Px3}, Px MAX =MAX{Px1, Px2, Px3}, find the value that makes |Px MIN -Px_EM Xi The smallest one-dimensional coil unit EM Xi1 and make |Px MAX -Px-EM Xi The smallest one-dimensional coil unit EM Xi2 One-dimensional coil unit EM Xi1 With EM Xi2 Divide the one-dimensional electromagnet into three parts, and select two parts located on the two sides (EM). X1 To EM X(i1-1) EM X(i2+1) To EM XN );

[0030] First, select the portion with more coil units (setting the current direction of each coil unit to be such that its magnetic moment points in the positive X-axis direction), then select the portion with fewer coil units (setting the current direction of each coil unit to be such that its magnetic moment points in the negative X-axis direction). If the two portions have the same number of coil units, then first select the one-dimensional coil unit EM. X1 To EM x(i1-1)(Set the current direction of each coil unit to be such that its magnetic moment points in the positive X-axis direction), and then select a one-dimensional coil unit EM. X(i2+1) To EM XN (Assuming the current direction of each coil unit is such that its magnetic moment points in the negative X-axis direction), for a one-dimensional coil unit EM X1 To EM X(i1-1) According to |Px MIN -Px_EM Xi Number the one-dimensional coil units EM in ascending order. X(i2+1) To EM XN According to |Px MAX -Px_EM Xi Number them in ascending order, denoted as EM. Xi′ (i′=1, 2,...,N-i2+i1-2);

[0031] Choose N xn (1≤Nx n ≤N-i2+i1-2) one-dimensional coil elements are given an excitation current I Xi′ , where I Xi′ =I XMAX (i′=1,2,…N xn -1), and 0<I Xi′ ≤I XMAX (i′=N xn This makes the fingertip electromagnet EM FTn Force F′ in the X direction xn Equal to the target force F xn Select N x =MAX{Nx1, Nx2, Nx3}, if there are multiple N... xn equals N x Select the largest As numbered N x The excitation current of the one-dimensional coil unit is adjusted so that the force in the X direction of one fingertip electromagnet is equal to the target force. By adjusting the excitation current of the other fingertip electromagnets, the force in the X direction of the other fingertip electromagnets is also equal to the target force. When N xn =N-i2+i1-2, and the excitation current of all one-dimensional coil units is I. XMAX At that time, the fingertip electromagnet EM FTn The magnitude of the force in the X direction |F′ xn |Still less than the magnitude of the target force|F xn |, output F′ at this point. xn As the saturation output value;

[0032] The excitation method for a two-dimensional background electromagnet is as follows: Find the excitation method that makes |Px MIN-Px_EM YZk The smallest two-dimensional coil group EM YZk1 and make |Px MAX -Px_EM YZk The smallest two-dimensional coil group EM YZk2 EM two-dimensional coil group YZk1 To EM YZk2 This is denoted as a two-dimensional coil group EM. YZk′ (k′=1), then according to |Px MIN -EM YZ(k1-1) |and|Px MAX -PEM YZ(k2+1) Select the two-dimensional coil groups EM in ascending order of size. YZ(k1-1) and EM YZ(k2+1) denoted as EM YZk′ (k′=2,3), choose N YZn (1≤N YZn ≤3) two-dimensional coil groups, with excitation current I applied to their tangential and radial coil units respectively. Tjk′ and I Rjk′ I Tjk′ with I Rjk′ By forming certain proportional relationships, various Heilbeck structures can be constructed, which will generate multi-mode non-uniform magnetic fields with different numbers of magnetic poles and directions. The direction of the magnetic poles generated by the two-dimensional coil group can be determined according to the direction of the force on the target of the fingertip electromagnet in the YZ plane.

[0033] I RjkMAX The maximum safe current for the radial coil unit is I. Rjk′ =I RjkMAX (k′=1,2,…,N YZn -1), and 0<I Rjk′ ≤I RjkMAX (k′=N YZn ), such that F′ yn =F yn And F′ zn =F zn Select N YZ =MAX{N YZ1 N YZ2 N YZ3 If there are multiple N YZn equals N YZ Select the largest As numbered N YZ The excitation current of the radial coil unit is adjusted so that the forces on one of the fingertip electromagnets in the Y and Z directions are equal to the target forces. The excitation currents of the other fingertip electromagnets are adjusted so that the forces on the other fingertip electromagnets in the Y and Z directions are equal to the target forces; when NYZn =k2-k1+2, and the excitation current of the radial coil elements of all two-dimensional coil elements is I. RjkMAX At that time, |F′ yn |<|F yn |or|F′ zn |<|F zn |, output F′ at this point. yn and F′ zn As the saturation output value; repeat the above steps in each mode to find the force on the three fingertip electromagnets under all schemes, and select the scheme with the smallest error with the target force. If there are multiple schemes with the smallest error, check the angle difference between the magnetic induction intensity direction at each fingertip electromagnet position and the overall magnetic moment direction of the fingertip electromagnet in each scheme, and select the current scheme with the smallest angle difference as the final current scheme. If there are multiple schemes with the smallest angle difference, select the scheme with the smallest background electromagnet power.

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

[0035]

[0036] in, This indicates the magnetic torque experienced by the fingertip electromagnet. This represents the magnetic moment experienced by the entire fingertip electromagnet. This represents the magnetic flux density generated by the background magnetic field at the location of the fingertip electromagnet. The magnetic torque on the fingertip electromagnet is minimized when the direction of the magnetic flux density of the background magnetic field is consistent with the direction of the equivalent magnetic moment of the fingertip magnet.

[0037] The calculation of the magnetic moment of the fingertip electromagnet is as follows:

[0038]

[0039] Among them, S xa S represents the area enclosed by the a-th coil along the X-axis of the fingertip electromagnet. yb S represents the area enclosed by the b-th coil along the Y-axis of the fingertip electromagnet. zc Let I represent the area enclosed by the c-th coil along the Z-axis of the fingertip electromagnet, and let nx, ny, and nz represent the number of coils along the X, Y, and Z-axis of the fingertip electromagnet, respectively. FTx I FTy I FTz These represent the magnitudes of the excitation currents of the coils on the fingertip electromagnet along the X, Y, and Z directions, respectively. This indicates the direction of the magnetic moment generated by the coil with its central axis X, relative to the current I. FTxThe direction of flow follows the right-hand screw rule, and the same applies to the Y and Z directions. The overall magnetic moment of the fingertip electromagnet is formed by the superposition of vectors in three orthogonal directions.

[0040] The magnetic field generated by the background electromagnet is specifically as follows:

[0041]

[0042] The magnetic field strength generated by each coil unit at the fingertip position along the X, Y and Z axes is calculated according to the Biot-Savart law. The magnetic field strength generated by each coil unit is vector-superimposed to obtain the magnitude and direction of the magnetic field strength at the fingertip position.

[0043] The calculation of the electromagnetic force on the fingertip electromagnet is as follows:

[0044]

[0045] in, The electromagnetic force experienced by the fingertip electromagnet. As a gradient operator, for the background electromagnet, there is no current flowing inside the fingertip magnet. According to Maxwell's equations, we have... Therefore, the electromagnetic force experienced by the fingertip electromagnet is:

[0046]

[0047] That is, for an ideal magnetic dipole moment, the force it experiences in an external magnetic field is determined by the magnetic flux density gradient and the magnetic moment at its location.

[0048] The relationship between the excitation currents of the tangential coil unit and the radial coil unit is as follows:

[0049] Based on the direction of the target force on the fingertip electromagnet in the YZ plane, the direction of the magnetic poles generated by the two-dimensional coil group is determined. Based on the magnetization direction and distribution of the permanent magnets in the required Halebeck array, the direction of the magnetic field to be generated by each two-dimensional coil unit is determined. The relationship between the excitation current of the tangential coil unit and the radial coil unit is calculated.

[0050]

[0051] Among them, EM Tjk′ and EM Rjk′ The two-dimensional coil unit EMyz jk′ Establish a local two-dimensional coordinate system with the center point as the origin, using the axis of the radial coil as the Y-axis and the axis of the tangential coil as the Z-axis, θ jk′ EMyz, a two-dimensional coil unit jk′ The angle between the direction of the magnetic field to be generated and the Y-axis, L rL is the diameter or side length of the radial coil. t N is the diameter or side length of the tangential coil. r N represents the number of turns of the radial coil. t This represents the number of turns of the tangential coil.

[0052] Compared with the prior art, the present invention, employing the above technical solution, has the following technical effects:

[0053] (1) The peripheral two-dimensional array electromagnet adopts the Heilbeck array structure, which can provide a multi-mode, arbitrary direction and size two-dimensional magnetic field in the YZ plane, while strengthening the magnetic field inside the operating space, weakening the external magnetic field, and reducing power consumption.

[0054] (2) The combination of the outer two-dimensional array of electromagnets and the inner one-dimensional stacked electromagnets can provide multiple locally controllable three-dimensional background magnetic fields.

[0055] (3) The device realizes a natural and intuitive three-dimensional multi-point force tactile reproduction that is precisely adjustable in a large operating space. Attached Figure Description

[0056] Figure 1 This is a schematic diagram of a one-dimensional background electromagnet.

[0057] Figure 2 This is a flowchart of a multi-point force tactile reproduction method based on the Heilbeck array;

[0058] Figure 3 This is a schematic diagram of the hardware system structure of the multi-point force tactile reproduction method based on the Heilbeck array. Detailed Implementation

[0059] This invention provides a multi-point force tactile reproduction method and system based on a Heilbeck array. To make the objectives, control methods, and effects of this invention easier to understand, the invention is further described in detail below with reference to the accompanying drawings and examples. It should be particularly noted that the specific embodiments described herein are only for explaining the invention and are not intended to limit the invention.

[0060] The hardware system of the multi-point force tactile reproduction method based on Heilbeck array involved in this invention is illustrated in the following diagram. Figure 2 As shown. The hardware system includes a 3D background electromagnet module, a background electromagnet driving module, a fingertip miniature electromagnet module, a fingertip miniature electromagnet driving module, a system central control module, a camera module, etc.

[0061] The 3D background electromagnet module consists of an inner layer of one-dimensional stacked electromagnets and an outer layer of two-dimensional array electromagnets. The one-dimensional stacked electromagnets consist of six coaxial hollow disk-shaped stacked coil units, generating a magnetic field in the X direction. Its internal cylindrical space serves as the force-tactile reproduction operating space. The outer layer of two-dimensional array electromagnets, located outside the one-dimensional stacked electromagnets, consists of 12 × 6 two-dimensional coil units and an iron powder core material surrounding each unit. Each two-dimensional coil unit comprises one tangential coil unit and one radial coil unit, capable of generating a magnetic field in any direction on the YZ plane. The fingertip miniature electromagnet module consists of three fingertip miniature electromagnets, each composed of three layers of coils orthogonally aligned to each other along their central axes in a stacked structure.

[0062] A virtual scene is constructed, and a multi-point force haptic reproduction model of virtual objects and multiple fingertip proxy points in the virtual reality environment are built. A three-dimensional coordinate system A is established, with the center point of the operating space as the origin of the three-dimensional coordinate system A, the direction of the central axis of the one-dimensional background electromagnet as the X-axis direction of the three-dimensional coordinate system A, and the direction of the axis of any radial coil as the Y-axis direction. The Z-axis is determined according to the right-hand rule. The coordinates of the center point of the one-dimensional coil unit (Px_EMxi, 0, 0), the coordinates of the center point of the two-dimensional coil group (Pyz_EMyzk, 0, 0), and the position of the fingertip electromagnet (Px n Py n Pz n According to the definition of coordinate system A; one-dimensional coil element EM Xi With Px_EM Xi Sort in ascending order, two-dimensional coil group EM YZk With PyZ_EY YZk Sort in ascending order;

[0063] Finger electromagnet EM FTn The center point is used as the local coordinate system B n The origin of coordinate system B is defined by the coordinate axes of coordinate system A. n The coordinate axis direction, the rotation angle (α) of the fingertip electromagnet n ,β n γ n ) are about coordinate system B n The X, Y, and Z axis rotation angles; finite element simulation of the electromagnetic forces acting on the fingertip electromagnet at different positions and angles in the operating space when different excitation currents are applied to the fingertip electromagnet and the background electromagnet, obtaining the EM value of the fingertip electromagnet. FTn Offline data of the electromagnetic forces acting on the sample;

[0064] The camera module tracks the fingertip position in real time, and multiple pose detection units are used to jointly acquire the real-time position and posture information of multiple fingertip electromagnets. Based on the force tactile reproduction model, the force exerted by the operator's fingertip on the virtual object at the current moment is calculated and generated as the target force in the control method.

[0065] Obtain the pose information P of the three fingertip electromagnets n (Px n Py n Pz n α n ,β n γ n ) and the target force F n (F xn F yn F zn (n = 1, 2, 3), where Px n Py n and Pz n For the three-dimensional coordinate information of the nth fingertip electromagnet, α n β n and γ n For the rotation angle information of the nth fingertip electromagnet, adjust the EM of each fingertip electromagnet. FTn Drive current (I) FTnx I FTny I FTnz ) is the maximum safe current I FTmax ;

[0066] The excitation method for the one-dimensional background electromagnet is as follows: Based on the X coordinates (Px1, Px2, Px3) of the positions of the three fingertip electromagnets, take Px... MIN =MIN{Px1, Px2, Px3}, Px MAX =MAX{Px1, Px2, Px3}, find the value that makes |Px MIN -Px_EM Xi The smallest one-dimensional coil unit EM Xi1 and make |Px MAX -Px_EM Xi The smallest one-dimensional coil unit EM Xi2 One-dimensional coil unit EM Xi1 With EM Xi2 Divide the one-dimensional electromagnet into three parts, and select two parts located on the two sides (EM). X1 To EM X(i1-1) EM X(i2+1) To EM XN );

[0067] First, select the portion with more coil units (setting the current direction of each coil unit to be such that its magnetic moment points in the positive X-axis direction), then select the portion with fewer coil units (setting the current direction of each coil unit to be such that its magnetic moment points in the negative X-axis direction). If the two portions have the same number of coil units, then first select the one-dimensional coil unit EM. X1 To EM X(i1-1) (Set the current direction of each coil unit to be such that its magnetic moment points in the positive X-axis direction), and then select a one-dimensional coil unit EM. X(i2+1) To EM XN (Assuming the current direction of each coil unit is such that its magnetic moment points in the negative X-axis direction), for a one-dimensional coil unit EM X1 To EM X(i1-1) According to |Px MIN -Px_EM Xi Number the one-dimensional coil units EM in ascending order. X(i2+1) To EM XN According to |Px MAX -Px_EM xi Number them in ascending order, denoted as EM. Xi′ (i′=1, 2,...,N-i2+i1-2);

[0068] Choose N xn (1≤Nx n ≤N-i2+i1-2) one-dimensional coil elements are given an excitation current I Xi′ , where I Xi′ =I XMAX (i′=1,2,…N xn -1), and 0<I Xi′ ≤I XMAX (i′=N xn This makes the fingertip electromagnet EM FTn Force F′ in the X direction xn Equal to the target force F xn Select N x =MAX{Nx1, Nx2, Nx3}, if there are multiple N... xn equals N x Select the largest As numbered N x The excitation current of the one-dimensional coil unit is adjusted so that the force in the X direction of one of the fingertip electromagnets is equal to the target force. The excitation current of the other fingertip electromagnets is adjusted so that the force in the X direction of the other fingertip electromagnets is equal to the target force; when N xn =N-i2+i1-2, and the excitation current of all one-dimensional coil units is I. XMAX At that time, the fingertip electromagnet EM FTnThe magnitude of the force in the X direction |F′ xn |Still less than the magnitude of the target force|F xn |, output F′ at this point. xn As the saturation output value;

[0069] The excitation method for a two-dimensional background electromagnet is as follows: Find the excitation method that makes |Px MIN -Px_EM YZk The smallest two-dimensional coil group EM YZk1 and make |Px MAX -Px_EM YZk The smallest two-dimensional coil group EM YZk2 EM two-dimensional coil group YZk1 To EM YZk2 This is denoted as a two-dimensional coil group EM. YZk′ (k′=1), then according to |Px MIN -EM YZ(k1-1) |and|Px MAX -PEM YZ(k2+1) Select the two-dimensional coil groups EM in ascending order of size. YZ(k1-1) and EM YZ(k2+1) denoted as EM YZk′ (k′=2,3), choose N YZn (1≤N YZn ≤3) two-dimensional coil groups, with excitation current I applied to their tangential and radial coil units respectively. Tjk′ and I Rjk′ I Tjk′ with I Rjk′ By forming certain proportional relationships, various Heilbeck structures can be constructed, which will generate multi-mode non-uniform magnetic fields with different numbers of magnetic poles and directions. The direction of the magnetic poles generated by the two-dimensional coil group can be determined according to the direction of the force on the target of the fingertip electromagnet in the YZ plane.

[0070] I RjkMAX The maximum safe current for the radial coil unit is I. Rjk′ =I RjkMAX (k′=1,2,…,N YZn -1), and 0<I Rjk′ ≤I RjkMAX (k′=N YZn ), such that F′ yn =F yn And F′ zn =F zn Select N YZ =MAX{N YZ1 N YZ2 N YZ3 If there are multiple N YZn equals NYZ Select the largest As numbered N YZ The excitation current of the radial coil unit is adjusted so that the forces on one of the fingertip electromagnets in the Y and Z directions are equal to the target forces. The excitation currents of the other fingertip electromagnets are adjusted so that the forces on the other fingertip electromagnets in the Y and Z directions are equal to the target forces; when N YZn =3, and the excitation current of the radial coil elements of all two-dimensional coil elements is I. RjkMAX At that time, |F′ yn |<|F yn | or |F′ zn |<|F zn |, output F′ at this point. yn and F′ zn As the saturation output value; repeat the above steps in each mode to find the force on the three fingertip electromagnets under all schemes, and select the scheme with the smallest error with the target force. If there are multiple schemes with the smallest error, check the angle difference between the magnetic induction intensity direction at each fingertip electromagnet position and the overall magnetic moment direction of the fingertip electromagnet in each scheme, and select the current scheme with the smallest angle difference as the final current scheme. If there are multiple schemes with the smallest angle difference, select the scheme with the smallest background electromagnet power.

[0071] According to the determined current scheme, the central control module generates the PWM signal required to drive the background electromagnet through ST's ARM Cortex-M7 processor, and generates the current required to the fingertip electromagnet through the DRV8432 motor driver chip of TI in a voltage regulation manner, so as to generate the required feedback force at the fingertip and realize multi-point force tactile reproduction.

[0072] The multi-point force tactile reproduction method and system based on Hellbeck array involved in this invention generates a three-dimensional locally controllable electromagnetic field by combining an inner layer of one-dimensional stacked electromagnets with an outer layer of two-dimensional array electromagnets. This controls multiple fingertip micro-electromagnet modules to generate three-dimensional controllable electromagnetic forces. The outer two-dimensional array electromagnets innovatively utilize the Hellbeck structure to enhance the magnetic field in the internal operating space and weaken the external magnetic field, achieving low-power, flexible, controllable, and non-contact three-dimensional force tactile reproduction. This provides a more complex and realistic human-computer interaction experience and effectively improves the quality of human-computer interaction.

[0073] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Those skilled in the art can make various modifications and adjustments within the technical scope disclosed in the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A multi-point force-tactile reproduction system based on a Heilbeck array, characterized in that, The multi-point force tactile reproduction system includes a three-dimensional background electromagnet module, a background electromagnet driving module, a fingertip miniature electromagnet module, a fingertip miniature electromagnet driving module, a system central control module, and a camera module. The three-dimensional background electromagnet module is based on a two-dimensional array electromagnet structure using a Heilbeck array. The module consists of an inner one-dimensional stacked electromagnet and an outer two-dimensional array electromagnet. The inner one-dimensional stacked electromagnet comprises multiple coaxial hollow disk-shaped stacked coil units, each containing an inner cylindrical space that serves as the force-tactile feedback reproduction operating space. The outer two-dimensional array electromagnet is located outside the inner one-dimensional stacked electromagnet and includes a two-dimensional array coil and a magnetic medium material located inside the coil. The two-dimensional array coil is composed of M1×M2 two-dimensional square coil units. M1 two-dimensional square coil units are wrapped around the outside of the one-dimensional electromagnet to form a group of two-dimensional coils. The internal space of the coils is a regular prism coaxial with the inner one-dimensional stacked electromagnet. M2 groups of two-dimensional coils are arranged sequentially along the axial direction to form the outer two-dimensional array electromagnet. The two-dimensional square coil unit is composed of two orthogonal nested square coils. The direction of the central axis of the outer square coil is tangent to the operating space of the inner cylinder, and it is called the tangential coil unit. The inner square coil orthogonal to it is called the radial coil unit. The background electromagnet drive module is used to receive control commands from the system's central control module and drive the electromagnets in the three-dimensional background electromagnet module to generate corresponding magnetic fields. The fingertip micro electromagnet module contains multiple fingertip micro electromagnets for providing feedback force to the human finger; The fingertip micro electromagnet driving module is used to drive the fingertip micro electromagnet module to generate the required electromagnetic force. The system's central control module selects and implements a single-point force tactile reproduction or multi-point force tactile reproduction control strategy as needed, calculates the excitation signal values ​​required by the background electromagnet module and the fingertip micro electromagnet module, controls the background electromagnet drive module and the fingertip micro electromagnet drive module to output excitation current, generates the required electromagnetic force on the fingertip micro electromagnet module, and forms a single-point or multi-point force tactile reproduction. The camera module is used to collect fingertip position information in real time and send it to the system's central control module.

2. The multi-point force-tactile reproduction system based on a Heilbeck array according to claim 1, characterized in that, The fingertip miniature electromagnet module consists of multiple fingertip miniature electromagnets. Composed of miniature electromagnets in each fingertip It consists of three layers of coils with their central axes orthogonal to each other, arranged in a stacked structure, and is used to provide feedback force to the human finger.

3. The multi-point force-tactile reproduction system based on a Heilbeck array according to claim 1, characterized in that, The three-dimensional controllable background electromagnetic field generated by the three-dimensional background electromagnet is formed by superimposing the one-dimensional electromagnetic field in the X direction generated by the inner one-dimensional stacked electromagnet and the two-dimensional background electromagnetic field in the YZ direction generated by the outer two-dimensional array electromagnet; the inner one-dimensional stacked electromagnet controls N coaxial one-dimensional coil units. , i=1,2…N, to realize a one-dimensional electromagnetic field that can be adjusted in multiple local regions; For the outer two-dimensional array electromagnet, adjust its tangential coil unit. and radial coil unit The current, j=1, 2, …, M1; k=1, 2, …, M2, controls the direction of the magnetic field generated by each two-dimensional coil unit to be any direction on the YZ plane. Under the combined action of M1×M2 two-dimensional coil units, a variety of Hellbeck arrays are formed, generating a variety of electromagnetic fields. Furthermore, by regularly rotating the direction of the electromagnetic field generated by each two-dimensional coil unit, the magnetic pole direction of the background electromagnetic field is adjusted.

4. A multi-point force-tactile reproduction method based on Heilbeck array, characterized in that, The method is implemented based on the multi-point force tactile reproduction system as described in claim 1, and the method includes the following steps: (1) Build a virtual scene, construct a multi-point force tactile reproduction model of virtual objects and multiple fingertip proxy points in the virtual reality environment; (2) Establish a three-dimensional coordinate system A in the operating space; (3) In the three-dimensional coordinate system A, the fingertip position is tracked in real time by the camera module, and multiple pose detection units are used to jointly obtain the real-time position and attitude information of multiple fingertip electromagnets; (4) Based on the force-tactile reproduction model, calculate and generate the force exerted by the operator's fingertips on the virtual object at the current moment, which is used as the target force in the control method; (5) The central control module of the system selects to implement single-point force tactile or multi-point force tactile reproduction control method as needed, calculates the excitation signal value required by the background electromagnet module and the fingertip micro electromagnet module, controls the background electromagnet drive module and the fingertip micro electromagnet drive module to output excitation current, generates the required electromagnetic force on the fingertip micro electromagnet module, and forms single-point or multi-point force tactile reproduction.

5. The multi-point force-tactile reproduction method based on Heilbeck array according to claim 4, characterized in that, The establishment of the three-dimensional coordinate system A in the operation space specifically includes: Taking the center point of the operating space as the origin of the three-dimensional coordinate system A, and the direction of the central axis of the one-dimensional background electromagnet as the X-axis of the three-dimensional coordinate system A, the direction of the axis of any radial coil is selected as the Y-axis, and the Z-axis is determined according to the right-hand rule; the coordinates of the center point of the one-dimensional coil unit are... Coordinates of the center point of the two-dimensional coil group and the position of the fingertip electromagnet According to the definition of coordinate system A; one-dimensional coil element by Sort in ascending order, two-dimensional coil group by Sort in ascending order; fingertip electromagnet The center point is used as the local coordinate system The origin of the coordinate system is defined by the coordinate axes of coordinate system A as the three-dimensional coordinate system. The coordinate axis direction, the rotation angle of the fingertip electromagnet Respectively around the coordinate system The X, Y, and Z axis rotation angles; when different excitation currents are applied to the fingertip electromagnet and the background electromagnet, finite element simulation is performed on the electromagnetic forces acting on the fingertip electromagnet at different positions and angles in the operating space to obtain the values ​​of the fingertip electromagnet. Offline data on the electromagnetic forces acting upon the object.

6. The multi-point force-tactile reproduction method based on Heilbeck array according to claim 4, characterized in that, The specific method for single-point force tactile reproduction control is as follows: When the virtual hand comes into contact with a virtual object, the camera module captures the pose information of the fingertip electromagnet at that moment. ,in , and This provides the three-dimensional coordinate information of the fingertip electromagnet's position. , and The rotation angle information of the fingertip electromagnet; based on the pose information, simultaneously excite both a one-dimensional background electromagnet and a two-dimensional background electromagnet: The excitation method for the one-dimensional background electromagnet is as follows: Adjusting the fingertip electromagnet The drive current is the maximum safe current. The maximum safe current of a one-dimensional coil unit is denoted as... According to the X coordinate of the fingertip electromagnet , find to make | - The smallest one-dimensional coil unit The other one-dimensional coil units are divided into two parts. to , to ; First, select the portion with more coil units, and set the current direction of each coil unit to be such that its magnetic moment points in the positive X-axis direction. Then, select the portion with fewer coil units, and set the current direction of each coil unit to be such that its magnetic moment points in the negative X-axis direction. If the two portions have the same number of coil units, then select the one-dimensional coil unit first. to The current direction of each coil unit is set to be such that its magnetic moment points to the positive X-axis. Then, a one-dimensional coil unit is selected. to The current direction of each coil unit is set to be such that its magnetic moment points in the negative X-axis direction, according to | - The one-dimensional coil elements are numbered in ascending order, denoted as... , =1,2,…, ;choose An excitation current is applied to each one-dimensional coil unit. ,in , ,and ( This causes the fingertip electromagnet to experience a force in the X direction. Equal to the target force ;when And the excitation current of all one-dimensional coil units is At that time, the amplitude of the force on the fingertip electromagnet in the X direction Still less than the magnitude of the target force Output the current value As the saturation output value; The excitation method for a two-dimensional background electromagnet is as follows: according to | - The two-dimensional coil groups are numbered in ascending order, denoted as... ,choose A two-dimensional coil group, to which excitation current is applied to the tangential coil unit and the radial coil unit. , ,when and When the ratio is set, a non-uniform two-pole field with the Halebeck effect is generated. The direction of the magnetic poles generated by the two-dimensional coil group is determined according to the direction of the force on the target of the fingertip electromagnet in the YZ plane. The maximum safe current for the radial coil unit is denoted as . ,and , , making = and = ;when And the excitation current of the radial coil units of all two-dimensional coil units is hour, < or < Output the current value and As the saturation output value.

7. The multi-point force-tactile reproduction method based on Heilbeck array according to claim 5, characterized in that, The multi-point force tactile reproduction control method is as follows: Acquire pose information of multiple fingertip electromagnets Force acting on the target , =1,2,3, where , and This provides the three-dimensional coordinate information for the nth fingertip electromagnet. , and For the rotation angle information of the nth fingertip electromagnet, adjust each fingertip electromagnet. drive current ( (This refers to the maximum safe current) ; A one-dimensional background electromagnet and a two-dimensional background electromagnet are simultaneously excited. The excitation method for the one-dimensional background electromagnet is as follows: based on the X coordinates of the positions of the three fingertip electromagnets... , , ,Pick , , find to make | - The smallest one-dimensional coil unit and make| - The smallest one-dimensional coil unit One-dimensional coil unit and Divide the one-dimensional electromagnet into three parts, and select the two parts located on the two sides. to , to ; First, select the portion with more coil units, and set the current direction of each coil unit to be such that its magnetic moment points in the positive X-axis direction. Then, select the portion with fewer coil units, and set the current direction of each coil unit to be such that its magnetic moment points in the negative X-axis direction. If the two portions have the same number of coil units, then select the one-dimensional coil unit first. to The current direction of each coil unit is set to be such that its magnetic moment points to the positive X-axis. Then, a one-dimensional coil unit is selected. to Assume that the current direction of each coil unit is such that its magnetic moment points in the negative X-axis direction. For a one-dimensional coil unit... to According to | - Numbering is done in ascending order for one-dimensional coil units. to according to - Number them in ascending order, and denote them as follows: ; choose An excitation current is applied to each one-dimensional coil unit. ,in , ,and , This makes the fingertip electromagnet Force in the X direction Equal to the target force Select If there are multiple equal Select the largest As numbered The excitation current of a one-dimensional coil unit is adjusted so that the force in the X direction of one fingertip electromagnet is equal to the target force. The excitation current of the other fingertip electromagnets is adjusted so that the force in the X direction of the other fingertip electromagnets is equal to the target force. And the excitation current of all one-dimensional coil units is At that time, the fingertip electromagnet The magnitude of the force in the X direction Still less than the magnitude of the target force Output the current value As the saturation output value; The excitation method for a two-dimensional background electromagnet is as follows: Find the method that excites | - The smallest two-dimensional coil group and make| - The smallest two-dimensional coil group , two-dimensional coil group to This is denoted as a two-dimensional coil group. , =1, then according to | - |and| - Select two-dimensional coil groups in ascending order of size. and , recorded as , =2,3, select A two-dimensional coil group, with excitation current applied to its tangential coil unit and radial coil unit respectively. and , and By forming a certain proportional relationship, various Heilbeck structures are constructed, which generate multi-mode non-uniform magnetic fields with different numbers of magnetic poles and directions. The direction of the magnetic poles generated by the two-dimensional coil group is determined according to the direction of the force on the target of the fingertip electromagnet in the YZ plane. The maximum safe current for the radial coil unit is denoted as . ,and , making = and = Select If there are multiple equal Select the largest As numbered The excitation current of the radial coil unit is adjusted so that the forces on one of the fingertip electromagnets in the Y and Z directions are equal to the target forces. The excitation currents of the other fingertip electromagnets are adjusted so that the forces on the other fingertip electromagnets in the Y and Z directions are equal to the target forces. And the excitation current of the radial coil units of all two-dimensional coil units is hour, < or < Output the current value and As the saturation output value; repeat the above steps in each mode to find the force on the three fingertip electromagnets under all schemes, and select the scheme with the smallest error with the target force. If there are multiple schemes with the smallest error, check the angle difference between the magnetic induction intensity direction at each fingertip electromagnet position and the overall magnetic moment direction of the fingertip electromagnet in each scheme, and select the current scheme with the smallest angle difference as the final current scheme. If there are multiple schemes with the smallest angle difference, select the scheme with the smallest background electromagnet power.

8. The multi-point force-tactile reproduction method based on Heilbeck array according to claim 5, characterized in that, The calculation of the magnetic torque of the fingertip electromagnet is as follows: ； in, This indicates the magnetic torque experienced by the fingertip electromagnet. This represents the magnetic moment experienced by the entire fingertip electromagnet. This represents the magnetic flux density generated by the background magnetic field at the location of the fingertip electromagnet. The magnetic torque on the fingertip electromagnet is minimized when the direction of the magnetic flux density of the background magnetic field is consistent with the direction of the equivalent magnetic moment of the fingertip magnet. The calculation of the magnetic moment of the fingertip electromagnet is as follows: ； in, This indicates the first [unclear] on the fingertip electromagnet with the central axis in the X direction. The area enclosed by each coil, This indicates the first fingertip electromagnet with its central axis in the Y direction. The area enclosed by each coil, This indicates the first [unclear] on the fingertip electromagnet with its central axis in the Z direction. The area enclosed by each coil, , , These represent the number of coils on the fingertip electromagnet along the X, Y, and Z directions, respectively. , , These represent the magnitudes of the excitation currents of the coils on the fingertip electromagnet along the X, Y, and Z directions, respectively. This indicates the direction of the magnetic moment generated by the coil with its central axis X, relative to the current. The direction of flow follows the right-hand screw rule, and the same applies to the Y and Z directions. The overall magnetic moment of the fingertip electromagnet is formed by the superposition of vectors in three orthogonal directions. The magnetic field generated by the background electromagnet is specifically as follows: ； The magnetic field strength generated by each coil unit at the fingertip position along the X, Y and Z axes is calculated according to the Biot-Savart law. The magnetic field strength generated by each coil unit is vector-superimposed to obtain the magnitude and direction of the magnetic field strength at the fingertip position. The calculation of the electromagnetic force on the fingertip electromagnet is as follows: ； in, The electromagnetic force experienced by the fingertip electromagnet. As a gradient operator, for the background electromagnet, there is no current flowing inside the fingertip magnet. According to Maxwell's equations, we have... Therefore, the electromagnetic force experienced by the fingertip electromagnet is: ； That is, for an ideal magnetic dipole moment, the force it experiences in an external magnetic field is determined by the magnetic flux density gradient and the magnetic moment at its location.

9. The multi-point force-tactile reproduction method based on Heilbeck array according to claim 5, characterized in that, The relationship between the excitation currents of the tangential coil unit and the radial coil unit is as follows: Based on the direction of the target force on the fingertip electromagnet in the YZ plane, the direction of the magnetic poles generated by the two-dimensional coil group is determined. Based on the magnetization direction and distribution of the permanent magnets in the required Halebeck array, the direction of the magnetic field to be generated by each two-dimensional coil unit is determined. The relationship between the excitation current of the tangential coil unit and the radial coil unit is calculated. ； Among them, with and Composed of two-dimensional coil units Establish a local two-dimensional coordinate system with the center point as the origin, using the axis of the radial coil as the Y-axis and the axis of the tangential coil as the Z-axis. Two-dimensional coil unit The angle between the direction of the magnetic field to be generated and the Y-axis. The diameter or side length of the radial coil. The diameter or side length of the tangential coil. The number of turns of the radial coil. This represents the number of turns of the tangential coil.

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