Haptic interaction device and method for operating a haptic interaction device

Abstract

Haptic interaction device, with - an adjustment unit designed to adjust a feedback force depending on the penetration depth when a haptic interaction point penetrates a virtual environment, - wherein the penetration takes place during an interaction cycle, wherein the interaction cycle can be divided into a pressure path, in which the haptic interaction point moves towards the virtual environment, and a release path, in which the haptic interaction point moves outwards again, characterized in that the adjustment unit is designed such that a variable, adjustable offset value O(k) is determined to determine the feedback force, wherein the variable, adjustable offset value O(k) at the first interaction cycle during the release path depending on the observed, instantaneous energy E obs(k) is determined for the current interaction cycle, and / or the variable, adjustable offset value O(k) at the second or subsequent interaction cycle during the print path depending on the displayed stiffness K d is determined, where the variable, adjustable offset value O(k) is calculated at the first interaction cycle during the release path as follows: O ( k ) = ( 2 ∗ E obs ( k ) ∗ K v ) − K v ∗ e ( k ) , where E obs (k) is the observed instantaneous energy for the current interaction cycle, where K v is the value of the stiffness of the virtual environment for which the haptic interaction is inherently stable, and e(k) is the penetration depth.

Description

[0001] The invention relates to a haptic interaction device according to claim 1, as well as a method for operating a haptic interaction device according to claim 10.

[0002] Haptic rendering, the generation of forces from the contact of virtual objects, is currently experiencing immense interest, not only in the metaverse. The representation of interaction forces with varying and, in particular, high stiffnesses is also crucial in virtual reality training devices with haptic input devices, for example, for dental surgery. Furthermore, so-called virtual fixtures in augmented telesurgery are expanding the range of applications for haptic rendering algorithms.

[0003] Haptic interaction devices are known that generate a haptic effect for a user controlling the haptic interaction device. The haptic effect includes effects that allow the user to feel a tactile sensation, a force, kinesthetic sensation, and the like. The generation and flow of energy depend on the representation of a virtual environment (VE).

[0004] Haptic interaction devices are known which have an adjustment unit which is designed to adjust a feedback force as a function of the penetration depth when a haptic interaction point penetrates into a virtual environment, wherein the penetration takes place during an interaction cycle, wherein the interaction cycle can be divided into a pressure path in which the haptic interaction point moves towards the virtual environment and a release path in which the haptic interaction point moves outwards again.

[0005] In the prior art, haptic interaction devices and methods for operating the same are known that use a successive force augmentation (SFA) approach for determining the feedback force.

[0006] The disclosure SINGH, Harsimran; RYU, Jee-Hwan: “Circumventing the fundamental tradeoff between stability and performance in haptic rendering - successive force augment approach” discloses a haptic interaction device.

[0007] KR 10 2018 0 007 245 A discloses a method and a system for providing haptic augmented reality through a haptic interaction device.

[0008] DE 10 2020 113 409 A1 relates to a method for controlling a slave system by means of a master system with haptic feedback in the master system originating from the slave system, wherein both systems communicate bidirectionally via a telecommunications channel having time-varying communication delays in at least one direction and generally in both directions. According to the invention, in order to increase transparency in a teleoperation system with time-delayed communication between the master system and the slave system, the current gradient of the delayed force function, which is communicated with a time delay from the slave system to the master system, divided by the current position error (difference between the current master device position and the slave manipulator position), must be inverted if the value of the current gradient is negative.That is, if the position error increases and the force increases at the same time, the gradient used to calculate the force acting on the master device remains unchanged. If the position error increases and the force decreases at the same time, the gradient used to calculate the force acting on the master device remains unchanged. If the position error decreases but the force increases, the gradient used to calculate the force acting on the master device is inverted (i.e., multiplied by -1).

[0009] The object of the present invention is to provide an interaction device and a method for operating a haptic interaction device which further improves the haptic effects for a user.

[0010] The features of claims 1 and 10 serve to solve this problem.

[0011] The invention advantageously provides that the adjustment unit is designed such that a variable, adjustable offset value O(k) is determined to determine the feedback force, wherein the variable, adjustable offset value O(k) at the first interaction cycle during the release path depending on the observed, instantaneous energy E obs (k) is determinable for the current interaction cycle, and / or the variable, adjustable offset value O(k) at the second or subsequent interaction cycle during the printing path depending on the stiffness K d The variable, adjustable offset value O(k) at the first interaction cycle during the release path is calculated as follows: O(k)=(2∗Eobs(k)∗Kv)−Kv∗e(k), where E obs (k) is the observed instantaneous energy for the current interaction cycle, where K vis the value of the stiffness of the virtual environment for which the haptic interaction is inherently stable, and e(k) is the penetration depth.

[0012] The present invention has the advantages that: 1. The first interaction cycle is passive and therefore stable. 2. The decrease in the force jump is not as strong as in the state of the art. 3. The desired stiffness can be achieved more quickly.

[0013] In the present invention, the term "pressure path" is used. Alternatively, the term "releasing path" can also be used.

[0014] The feedback force can be calculated as follows: f(k)=Kv*e(k)+O(k), where f(k) is the feedback force, K vis the value of the stiffness of the virtual environment for which the haptic interaction is inherently stable, e(k) is the penetration depth and O(k) is the offset value.

[0015] The observed instantaneous energy E obs (k) can be calculated as follows: Eobs(k)=Eobs(k−1)+[(f(k−1)*e˙(k))]*ΔT, where f(k-1) is the feedback force of the previous step, ė(k) is the rate of penetration depth (e(k)) and ΔT is the time of the step.

[0016] During the release stroke, due to the value of the stiffness Kv, the energy generated by discretization can be dissipated by the physical damping of the haptic interaction device.

[0017] The adjustment unit can be designed such that the displayed stiffness K d always less than the desired stiffness K de is, where the indicated stiffness K d(k) = [f(k) / e(k)] and e(k) is the penetration depth.

[0018] The value of K d can always be between 0 and K de The value can therefore be neither very large nor negative. This leads to the feedback force and consequently the K d does not fluctuate.

[0019] The indicated stiffness K d can be calculated as follows:

[0020] The adjustment unit can be designed such that the feedback force is increased or decreased stepwise during the second or further interaction cycle during the pressure path, wherein the increase or decrease at each step (sample step) is dependent on the variable, adjustable offset value O(k), which depends on the difference between the displayed stiffness K d and the desired stiffness K de is, where the indicated stiffness K d (k) = [f(k) / e(k)] and e(k) is the penetration depth.

[0021] The adjustment unit can be designed in such a way that the greater the difference between the displayed stiffness K d and the desired stiffness K de is, the greater the increase or decrease at the respective step (sample step).

[0022] The variable, adjustable offset value O(k) can be calculated as follows during the second or subsequent interaction cycle during the printing path: O(k)=O(k−1)±α(k), where α(k)={αmax / (Kde / Kv)}*(Kde / Kd(k−1)), where α max is an adjustable factor and / or is based on a JND (just-noticeable difference) for the maximum stiffness, K de is the desired stiffness, K v is the value of the stiffness of the virtual environment for which the haptic interaction is inherently stable.

[0023] According to the present invention, a method for operating a haptic interaction device can also be provided, in which - an adjustment step is provided in which, when a haptic interaction point penetrates into a virtual environment, a feedback force is adjusted depending on the penetration depth, - wherein the penetration takes place during an interaction cycle, wherein the interaction cycle can be divided into a pressure path, in which the haptic interaction point moves towards the virtual environment, and a release path, in which the haptic interaction point moves outwards again, - where a variable, adjustable offset value O(k) is determined to determine the feedback force, where - the variable, adjustable offset value O(k) at the first interaction cycle during the release path depending on the observed instantaneous energy E obs (k) is determined for the current interaction cycle, and / or - the variable, adjustable offset value O(k) for the second or subsequent interaction cycle during the printing path depending on the displayed stiffness K d is determined.

[0024] The variable, adjustable offset value O(k) at the first interaction cycle is calculated during the release path as follows: O(k)=(2∗Eobs(k)∗Kv)−Kv∗e(k), where E obs (k) is the observed instantaneous energy for the current interaction cycle, where K v is the value of the stiffness of the virtual environment for which the haptic interaction is inherently stable, and e(k) is the penetration depth.

[0025] The feedback force can be calculated as follows: f(k)=Kv*e(k)+O(k), where f(k) is the feedback force, K v is the value of the stiffness of the virtual environment for which the haptic interaction is inherently stable, e(k) is the penetration depth and O(k) is the offset value.

[0026] The observed instantaneous energy E obs (k) can be calculated as follows: Eobs(k)=Eobs(k−1)+[(f(k−1)*e˙(k))]*ΔT, where f(k-1) is the feedback force of the previous step (sample step), ė(k) is the rate of penetration depth (e(k)) and ΔT is the time of the step (sample step).

[0027] During the release path, the value of stiffness K v be adjusted in such a way that the energy generated by discretization is dissipated by the physical damping of the haptic interaction device.

[0028] The indicated stiffness K d can always be less than a desired stiffness K de be, where the indicated stiffness K d (k) = [f(k) / e(k)] and e(k) is the penetration depth.

[0029] The indicated stiffness K d can be calculated as follows:

[0030] The adjustment unit can be designed such that the feedback force is increased or decreased stepwise during the second or further interaction cycle during the pressure path, wherein the increase or decrease at each step (sample step) is dependent on the variable, adjustable offset value O(k), which depends on the difference between the displayed stiffness K d and the desired stiffness K de is, where the indicated stiffness K d (k) = [f(k) / e(k)] and e(k) is the penetration depth.

[0031] The greater the difference between the indicated stiffness K d and the desired stiffness K de is, the greater the increase or decrease in the respective step (sample step).

[0032] The variable, adjustable offset value O(k) can be calculated at the second or subsequent interaction cycle during the print path as follows: O(k)=O(k−1)±a(k), where a(k)={amax / (Kde / Kv)}*(Kde / Kd(k−1)), where α max is an adjustable factor and / or is based on a JND (just-noticeable difference) for the maximum stiffness, K de is the desired stiffness, K v is the value of the stiffness of the virtual environment for which the haptic interaction is inherently stable.

[0033] In the following, embodiments of the present invention are explained in more detail with reference to the drawings.

[0034] They show schematically: Fig. 1 shows a position-force diagram, Fig. 2 shows the energy used for the pressure path, Fig. 3 shows the releasing path of the first interaction cycle (releasing path #1), Fig. 4 shows the output energy, Fig. 5 shows an interaction cycle, Fig. 6 shows that the indicated stiffness K d always less than the desired stiffness K de can be, Fig. 7 - Fig. 11 show the variable, adjustable offset value O(k) depending on the difference between displayed stiffness K d and the desired stiffness K de .

[0035] According to the present invention, a haptic interaction device is provided which has an adjustment unit which is designed to adjust a feedback force as a function of the penetration depth when a haptic interaction point penetrates into a virtual environment, wherein the penetration takes place during an interaction cycle, wherein the interaction cycle can be divided into a pressure path in which the haptic interaction point moves towards the virtual environment and a release path in which the haptic interaction point moves outwards again.

[0036] This will now be done using Fig. 1 will be explained. Fig. Figure 1 shows a position-force diagram. The feedback force, referred to as force (f), is plotted on the y-axis. The penetration depth, also referred to as e or error, is plotted on the x-axis. The virtual wall of the virtual environment (VE boundary) is located at the point on the x-axis where the y-axis meets the x-axis.

[0037] Also shown is the pressure path of the first interaction cycle (pressing path #1). The feedback force is gradually increased. Furthermore, the desired stiffness K de shown.

[0038] In Fig. Figure 2 shows the input energy for the pressure path, which corresponds to the area below the pressure path. The input energy is positive.

[0039] In Fig. Figure 3 shows the release path of the first interaction cycle (releasing path #1). During the release path, the feedback force also decreases gradually.

[0040] The offset value is also shown, which is explained in more detail in the following figures.

[0041] In Fig. Figure 4 shows the output energy. This corresponds to the area below the release path. The output energy is negative.

[0042] As long as the input energy plus the output energy is greater than zero, the system is passive and thus stable. This is Fig. 5 shown.

[0043] According to the present invention, the adjustment unit is designed such that a variable, adjustable offset value O(k) is determined to determine the feedback force, wherein the variable, adjustable offset value O(k) at the first interaction cycle during the release path depending on the observed, instantaneous energy E obs (k) is determinable for the current interaction cycle, and / or the variable, adjustable offset value O(k) at the second or subsequent interaction cycle during the print path depending on the displayed stiffness K d can be determined.

[0044] In Fig. 3, the variable, adjustable offset value O(k) during the first interaction cycle is denoted by O1. O1 has a value greater than zero at a penetration depth of zero. This ensures that there is no significant force drop and thus no distortion of the haptic perception.

[0045] The present invention has the advantages that: 1. The first interaction cycle is passive and therefore stable. 2. The decrease in the force jump is not as strong as in the state of the art. 3. The desired stiffness can be achieved more quickly.

[0046] The feedback force can be calculated as follows: f(k)=Kv*e(k)+O(k), where f(k) is the feedback force that Fig. 3 is shown on the y-axis K v is the value of the stiffness of the virtual environment for which the haptic interaction is inherently stable, e(k) is the penetration depth and O(k) is the offset value.

[0047] The variable, adjustable offset value O(k) at the first interaction cycle during the release path can be calculated as follows: O(k)=(2∗Eobs(k)∗Kv)−Kv∗e(k), where E obs (k) is the observed instantaneous energy for the current interaction cycle, K vis the value of the stiffness of the virtual environment for which the haptic interaction is inherently stable, and e(k) is the penetration depth.

[0048] The observed instantaneous energy E obs (k) can be calculated as follows: Eobs(k)=Eobs(k−1)+[(f(k−1)*e˙(k))]*ΔT, where f(k-1) is the feedback force of the previous step (sample step), é(k) is the rate of penetration depth (e(k)). ΔT is the time of the step (sample step).

[0049] The discretization (stair-shaped line of the releasing path) during the releasing path preferably has no influence on the energy calculation, since the value of K v is chosen so that the energy generated by the discretization is dissipated by the physical damping of the haptic device.

[0050] The adjustment unit can be designed such that the displayed stiffness K dalways less than the desired stiffness K de can be. This is in Fig. 6 shown. where the indicated stiffness K d (k) = [f(k) / e(k)] and e(k) is the penetration depth.

[0051] If K d is greater than K de and closer to the VE limit, its value would increase exponentially to very high values ​​due to e→0. This would lead to undesirable force jumps.

[0052] K d is therefore preferably selected according to the invention so that its value is always smaller than K de remains. Fig. Figure 6 shows that the haptic interaction point (HIP) after the end of a release path is at (e 1 , f 1 ). To calculate the new K d therefore the point (e 1 , f 1 ) by exactly the same distance to the right of K de postponed (e 2 , f 1 ), see Fig. 6.

[0053] The value of K d can always be between 0 and K de The value can therefore be neither very large nor negative. This leads to the feedback force and consequently K d does not fluctuate.

[0054] The indicated stiffness K d can be calculated as follows:

[0055] The adjustment unit can be designed such that the feedback force f is increased or decreased stepwise during the second or further interaction cycle during the pressure path, wherein the increase or decrease at each step (sample step) is dependent on the variable, adjustable offset value O(k), which depends on the difference between the displayed stiffness K d and the desired stiffness K de is, where the indicated stiffness K d (k) = [f(k) / e(k)] and e(k) is the penetration depth.

[0056] The greater the difference between the indicated stiffness K d and the desired stiffness K de is, the greater the increase or decrease in the respective step (sample step).

[0057] The variable, adjustable offset value O(k) can be calculated at the second or subsequent interaction cycle during the print path as follows: O(k)=O(k−1)±a(k), where α(k)={αmax / (Kde / Kv)}*(Kde / Kd(k−1)), where α max is an adjustable factor and / or is based on a JND (just-noticeable difference) for the maximum stiffness, K de is the desired stiffness, K v is the value of the stiffness of the virtual environment for which the haptic interaction is inherently stable.

[0058] In the Fig. 7 to Fig. 11 shows that the variable, adjustable offset value O(k) depends on the difference between the displayed stiffness K d and the desired stiffness K de is. At the Fig. 7-10 is calculated based on the difference between the indicated stiffness K d and the desired stiffness K de the feedback force f is gradually reduced during the second or subsequent interaction cycle during the pressure path until K d smaller than K de Then, as in Fig. 11 the feedback force is increased, whereby the increase also depends on the difference between the displayed stiffness K d and the desired stiffness K de This makes it possible to provide variable, adjustable offset values ​​that result in K d can rise very quickly.

Claims

[1] Haptic interaction device, with - an adjustment unit designed to adjust a feedback force depending on the penetration depth when a haptic interaction point penetrates a virtual environment, - wherein the penetration takes place during an interaction cycle, wherein the interaction cycle can be divided into a pressure path, in which the haptic interaction point moves towards the virtual environment, and a release path, in which the haptic interaction point moves outwards again, characterized by , that the adjustment unit is designed such that a variable, adjustable offset value O(k) is determined to determine the feedback force, wherein the variable, adjustable offset value O(k) at the first interaction cycle during the release path depending on the observed, instantaneous energy E obs(k) is determined for the current interaction cycle, and / or the variable, adjustable offset value O(k) at the second or subsequent interaction cycle during the print path depending on the displayed stiffness K d is determined, where the variable, adjustable offset value O(k) is calculated at the first interaction cycle during the release path as follows: O(k)=(2∗Eobs(k)∗Kv)−Kv∗e(k), where E obs (k) is the observed instantaneous energy for the current interaction cycle, where K v is the value of the stiffness of the virtual environment for which the haptic interaction is inherently stable, and e(k) is the penetration depth. [2] Interaction device according to claim 1, characterized by that the feedback force can be calculated as follows: f(k)=Kv*e(k)+O(k), where f(k) is the feedback force, K vis the value of the stiffness of the virtual environment for which the haptic interaction is inherently stable, e(k) is the penetration depth and O(k) is the offset value. [3] Interaction device according to claim 1, characterized by that the observed instantaneous energy E obs (k) is calculated as follows: Eobs(k)=Eobs(k−1)+[(f(k−1)*e˙(k))]*ΔT, where f(k-1) is the feedback force of the previous step (sample step), ė(k) is the rate of penetration depth (e(k)) and ΔT is the time of the step (sample step). [4] Interaction device according to one of claims 1 to 3, characterized by that during the release path, due to the value of the stiffness Kv, the energy generated by discretization can be dissipated by the physical damping of the haptic interaction device. [5] Interaction device according to one of claims 1 to 4, characterized bythat the adjustment unit is designed in such a way that the displayed stiffness K d always less than a desired stiffness K de is, where the indicated stiffness K d (k) = [f(k) / e(k)] and e(k) is the penetration depth. [6] Interaction device according to claim 5, characterized by that the indicated stiffness K d can be calculated as follows: [7] Interaction device according to one of claims 1 to 6, characterized by that the adjustment unit is designed such that the feedback force is increased or decreased step by step during the second or further interaction cycle during the pressure path, wherein the increase or decrease at each step (sample step) is dependent on the variable, adjustable offset value O(k), which depends on the difference between the displayed stiffness K d and the desired stiffness K de is, where the indicated stiffness K d (k) = [f(k) / e(k)] and e(k) is the penetration depth. [8] Interaction device according to claim 7, characterized by that the adjustment unit is designed in such a way that the greater the difference between the displayed stiffness K d and the desired stiffness K de is, the greater the increase or decrease in each step. [9] Interaction device according to one of claims 1 to 8, characterized by that the variable, adjustable offset value O(k) for the second or subsequent interaction cycle during the printing path can be calculated as follows: O(k)=O(k−1)±α(k), where α(k)={αmax / (Kde / Kv)}*(Kde / Kd(k−1)), where α max is an adjustable factor and / or is based on a JND (just-noticeable difference) for the maximum stiffness, K deis the desired stiffness, K v is the value of the stiffness of the virtual environment for which the haptic interaction is inherently stable. [10] Method for operating a haptic interaction device, in which - an adjustment step is provided in which, when a haptic interaction point penetrates into a virtual environment, a feedback force is adjusted depending on the penetration depth, - wherein the penetration takes place during an interaction cycle, wherein the interaction cycle can be divided into a pressure path, in which the haptic interaction point moves towards the virtual environment, and a release path, in which the haptic interaction point moves outwards again, characterized by , that a variable, adjustable offset value O(k) is determined to determine the feedback force, where the variable, adjustable offset value O(k) at the first interaction cycle during the release path depending on the observed, instantaneous energy E obs (k) is determined for the current interaction cycle, and / or the variable, adjustable offset value O(k) at the second or subsequent interaction cycle during the print path depending on the displayed stiffness K d is determined, where the variable, adjustable offset value O(k) is calculated at the first interaction cycle during the release path as follows: O(k)=(2∗Eobs(k)∗Kv)−Kv∗e(k), where E obs (k) is the observed instantaneous energy for the current interaction cycle, where K v is the value of the stiffness of the virtual environment for which the haptic interaction is inherently stable, and e(k) is the penetration depth. [11] Method according to claim 10, characterized bythat the feedback force is calculated as follows: f(k)=Kv*e(k)+O(k), where f(k) is the feedback force, K v is the value of the stiffness of the virtual environment for which the haptic interaction is inherently stable, e(k) is the penetration depth and O(k) is the offset value. [12] Method according to claim 10 or 11, characterized by that the observed instantaneous energy E obs (k) is calculated as follows: Eobs(k)=Eobs(k−1)+[(f(k−1)*e˙(k))]*ΔT, where f(k-1) is the feedback force of the previous step (sample step), ė(k) is the rate of penetration depth (e(k)) and ΔT is the time of the step (sample step). [13] Method according to one of claims 10 to 12, characterized by that during the release path due to the value of the stiffness K vthe energy generated by discretization can be dissipated by the physical damping of the haptic interaction device. [14] Method according to one of claims 10 to 13, characterized by that the indicated stiffness K d always less than a desired stiffness K de is, where the indicated stiffness K d (k) = [f(k) / e(k)] and e(k) is the penetration depth. [15] Method according to claim 14, characterized by that the indicated stiffness K d is calculated as follows: [16] Method according to one of claims 10 to 15, characterized bythat the adjustment unit is designed such that the feedback force is increased or decreased step by step during the second or further interaction cycle during the pressure path, wherein the increase or decrease at each step (sample step) is dependent on the variable, adjustable offset value O(k), which depends on the difference between the displayed stiffness K d and the desired stiffness K de is, where the indicated stiffness K d (k) = [f(k) / e(k)] and e(k) is the penetration depth. [17] Method according to claim 16, characterized by that the greater the difference between indicated stiffness K d and the desired stiffness K de is, the greater the increase or decrease at the respective step (sample step). [18] Method according to one of claims 10 to 17, characterized bythat the variable, adjustable offset value O(k) is calculated at the second or subsequent interaction cycle during the print path as follows: O(k)=O(k−1)±α, where α={αmax / (Kde / Kv)}*(Kde / Kd), where α max is an adjustable factor and / or is based on a JND (just-noticeable difference) for the maximum stiffness, K de is the desired stiffness, K v is the value of the stiffness of the virtual environment for which the haptic interaction is inherently stable.

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