System for determining finger coordination and computer program

Abstract

The invention relates to a system (100) for determining finger coordination, comprising at least the following components: - a device (10) with an elastically deformable shell (1) having a plurality of surface portions (2a,2b,2c,2d,2e) for receiving a force from a finger, wherein the shell (1) forms at least a portion of a housing (3) of the device (10), wherein the device (10) comprises, o a plurality of force-sensing resistors (4a,4b,4c,4d,4e), FSR, wherein each sensor (4a,4b,4c,4d,4e) is associated to one of the surface portions (2a,2b,2c,2d,2e) of the shell (1), wherein each sensor (4a,4b,4c,4d,4e) is configured and arranged to detect (and record) a force on the associated surface portion (2a,2b,2c,2d,2e) of the shell (1) and to generate a corresponding FSR-signal, indicative of the detected force, o an inertial measurement unit (5), IMU, configured to detect an orientation and a movement of the device (10) and to generate a corresponding IMU-signal, o a first transmission module (11) configured to receive the FSR-signal of each sensor (4a,4b,4c,4d,4e) and the IMU-signal, wherein the first transmission module (11) is further configured to transmit IMU-data relating to the IMU-signal as well as FSR-data relating to the FSR-signal, wherein the FSR-data is configured such that force information of each surface portion (2a,2b,2c,2d,2e) may be obtained and evaluated separately from the FSR-data. The invention further relates to a computer program.

Description

[0001] ubn107wo

[0002] 1

[0003] System for determining finger coordination and computer program

[0004] Specification

[0005] The invention relates to a system for determining finger coordination, strength and strength control (fine motor skills) and a computer program.

[0006] Hand function, particularly the coordination and dexterity of the fingers, plays a crucial role in the daily lives of all individuals. Impairments in hand function and, more specifically, in finger function lead to a partial loss of motor skills. Reduced finger dexterity and coordination result in difficulties in performing activities of daily living, such as working on a computer, writing, holding cutlery, or dressing. Consequently, many affected individuals find the limitation of fine motor skills highly problematic. Affected individuals include those suffering from neurological diseases such as, but not limited, multiple sclerosis (MS) or Parkinson's, those who have experienced head injuries such as a stroke or traumatic brain injury (tbj), and those who often face dexterity problems following hand or arm injuries. Additionally, people experiencing aging-related issues or suffering from conditions like hand and finger arthritis encounter difficulties. Young individuals, such as children with developmental disorders or Attention-deficit / hyperactivity disorder (ADHD), can also be affected by impaired hand and finger function.

[0007] Regular and intensive training of fine motor skills can lead to improvements in hand and finger functions or, in the case of healthy older adults, can prevent the loss of fine motor skills while also enhancing cognitive abilities. Studies have shown that continuous training promotes neuronal plasticity, thereby contributing to the restoration of motor skills. Therefore, affected individuals often seek help in physiotherapy and occupational therapy. These therapies provide structured and evidence-based approaches to rehabilitation; However, therapy time is often limited and is not sufficient to ensure the regular and intensive training required for optimal rehabilitation, so additional training at home is necessary. This is challenging because primarily manual training tools and methods, such as training balls or coins, are available, which can quickly be perceived as repetitive and boring, leading to a loss of training motivation.

[0008] An object of the present invention is thus to provide a system for determining finger coordination, strength and force control as well as a computer program which ubn107wo

[0009] 2 address the limitations of existing manual training tools by offering a more engaging, effective, and personalized approach to improving or maintaining fine motor skills.

[0010] The object is achieved by a system for determining finger coordination, strength and force control with the features of claim 1 as well as a computer program according to claim 11.

[0011] Advantageous embodiments are described in the corresponding dependent claims as well as in the specification.

[0012] A first aspect of the invention relates to a system for determining finger coordination and dexterity. The system comprises at least the following components: a device with an elastically deformable shell having a plurality of surface portions for receiving a force from a finger, wherein the shell forms at least a portion of a housing of the device, wherein the device comprises, particularly houses, o a plurality of sensors, namely force-sensing resistors, FSR, wherein each sensor is associated to one of the surface portions of the shell, wherein each force-sensing resistor is configured and arranged to detect a force on the associated surface portion of the shell and to generate a corresponding FSR-signal, o an orientation and movement sensor, such as an inertial measurement unit, IMU, wherein the orientation and movement sensor is configured to detect an orientation and a movement of the device and to generate a corresponding signal, the IMU-signal, o a first transmission module configured to receive the FSR-signal of each force-sensing resistor and the IMU-signal, wherein the first transmission module is further configured to transmit IMU-data relating to the IMU-signal as well as FSR-data relating to the FSR- signal, wherein the FSR-data is configured such that force information of each surface portion may be obtained and evaluated separately from the FSR-data.

[0013] It is noted that the term “force-sensing resistor” may be referred to in the art as “force-resisting sensor”. Both expressions refer to the same sensor. Thus, both expressions are used synonymously in the context of the current specification.

[0014] The system according to the invention is applicable for determining finger coordination, strength and strength control (force dosing) of a person. To this end, ubn107wo

[0015] 3 the user can grasp or hold the device in one hand such that at least one finger of the user contacts one of the surface portions of the device in order to apply a force to the force-sensing resistor associated to the respective surface portion. The application of force on the respective surface portion may cause an elastic deformation of the elastically deformable shell in the area of the respective surface portion.

[0016] The FSR-data is configured such that force information of each surface portion may be obtained and evaluated separately from the FSR-data, which advantageously allows determining individual force information associated to each of the surface portions and independently of the other surface portions. For instance, in an example with four surface portions that are arranged and configured to be contacted by an associated finger, the FSR-signals associated to each surface portion - and thus each finger - can be stored separately, e.g. in different columns in the FSR-data, which allows for a determination of associated forces, particularly magnitudes of forces, associated to individual fingers.

[0017] In particular, each of the force-sensing resistors is configured and arranged to detect and to record the force on the associated surface portion of the shell and to generate a corresponding FSR-signal indicative of the detected force.

[0018] Likewise, the orientation and movement sensor, e.g., the inertial measurement unit can be configured and arranged to detect, indicate and record the orientation and movement of the device and to generate a corresponding signal, the IMU-signal. The IMU-signal is particularly indicative of the detected movement and orientation of the device. The IMU-signal may be generated by the orientation and movement sensor, and not necessarily by an IMU. In particular, the IMU-signal can be used to track the spatial orientation of the device during fine motor exercises, wherein the device, particularly the egg-shaped handheld device, is manipulated around different rotational axes within the user's hand. Due to the device's compact, particularly egg- shaped geometry that can be fully enclosed in one hand, such manipulation requires coordinated engagement of different fingers, thereby training fine motor skills. The combination of the device and the I MU-based orientation tracking enables the system to monitor and assess complex finger-based rotational movements that are characteristic of fine motor dexterity exercises. The term “IMU signal” (as well as “IMU data”) is used for the purpose of differentiation from the FSR signal (and “FSR data”) in the context of the current specification.

[0019] The orientation and movement sensor may comprise a device selected from one or more of the following list: ubn107wo

[0020] 4

[0021] - an IMU, an accelerometer, a gyroscope, a magnetometer, a barometer, an optical sensor, an electric charge variation sensor configured to detect a user holding the device.

[0022] The IMU may comprise one or more devices from the list, such as the accelerometer, the gyroscope, the magnetometer, the barometer.

[0023] In particular, the IMU comprising the electric charge variation sensor allows to switch from a standby mode of operation to a fully powered mode of operation. Such electrostatic sensors are for example known as QVAR sensors, wherein QVAR stands for electric charge (= Q) variation (= var). It is an electrical potential sensing channel configured to measure the quasi-electrostatic potential changes on the shell of the device.

[0024] The expression “movement” in the orientation and movement sensor, particularly refers to an acceleration that may be detected and recorded by the sensor.

[0025] The recording via said orientation and movement device particularly includes acquiring and saving time-series of the detected forces and / or detected orientation, as well as movement of the device.

[0026] The surface portions can be formed as indentations on the outside of the shell. Particularly, the indentations are spaced apart on the outside of the shell, and particularly separated from each other, such that a user can place multiple fingers on the indentations at the same time, wherein each finger is arranged in or on a respective indentation.

[0027] Particularly, the FSR-signal can be indicative of a magnitude of the detected force. As such, the FSR-signal can provide precise information about the magnitude of force exerted for instance by a single finger on the associated surface portion of the shell, rather than for example a binary representation that merely indicates the presence or absence of a force based on a predefined force threshold. Instead, the FSR-signal can deliver information indicative of the magnitude of the detected force by means of an absolute force value, for instance on a Newton-scale. ubn107wo

[0028] 5

[0029] Besides for determining finger coordination, the system can be used for training and monitoring of finger coordination and single finger strength, as well as force dosage of individual fingers.

[0030] According to an embodiment of the system according to the invention, the housing of the device consists of the shell. As such, the components of the device with the FSR, the IMU and the first transmission module can be entirely enclosed by the shell forming the housing, which simplifies the handling of the device and protects its components.

[0031] In another embodiment of the system according to the invention, the device comprises a rigid core portion, on which that plurality of force-sensing resistors is arranged, wherein the force-sensing resistors are arranged on a first side of the rigid core portion, such that the device is configured to separately detect forces exerted by one or more fingers of a hand, wherein the fingers are selected from the group consisting of: an index finger, a middle finger, a ring finger, a little finger. Particularly, the rigid core portion is arranged on an inside of the elastically deformable shell that faces away from the surface portions that form an outside of the elastically deformable shell. For example, if the housing of the device consists of the shell, the rigid core portion is fully enclosed by the elastically deformable shell. The core portion may by entirely comprised in the elastically deformable shell except a data transfer and / or charging socket, such as a USB-port. The data port may be used to upload firmware and updates to the electronics comprised by the core portion. Further, the port may be utilized to charge a battery comprised by the core portion. The battery may be arranged and configured to power the electronic components of the core portion.

[0032] Alternatively, the electronics in the core portion and the core housing, may be configured to wirelessly receive firmware and firmware updates via the first transmission module. For updating the firmware, a microprocessor may be arranged in the core portion. Similarly, according to one embodiment of the invention, the core portion comprises a wireless charging device, that is arranged and configured to wirelessly charge the battery in the core portion. The wireless charging device may comprise a flat coil. The coil may be arranged on a side of the core housing that is opposite the side comprising the one or more openings.

[0033] According to another embodiment of the invention, the force-sensing resistors are comprised entirely in the core portion. ubn107wo

[0034] 6

[0035] In particular, the rigid core portion of the device comprises a higher hardness than its elastically deformable shell. The “hardness” in this context denotes a resistance of the respective material against plastic deformation under application of mechanical forces.

[0036] According to another embodiment of the system according to the invention, the rigid core portion has a second side opposite the first side, wherein one more forcesensing resistor(s) of that plurality of force-sensing resistors is arranged on said second side, such that the device is configured to separately detect forces exerted by a thumb of a hand. For example, four force-sensing resistors are arranged on the first side of the rigid core portion for detecting forces exerted by the index finger, the middle finger, the ring finger and the little finger and one force-sensing resistor is arranged on the second side of the rigid core portion for detecting forces exerted by the thumb. This example allows determining finger coordination of all five fingers of a hand, particularly a human hand.

[0037] In an embodiment of the system according to the invention, the rigid core portion comprises a printed-circuit board, PCB, wherein the plurality of force-sensing resistors is electrically contacted with the PCB. The I MU and / or the first transmission module can likewise be arranged on the PCB.

[0038] In particular, the force-sensing resistors may be fixedly arranged on the PCB.

[0039] According to another embodiment of the invention, the core portion may comprise a rigid core housing that encloses the force-sensing resistors, and in particular the PCB. The core housing itself may be entirely enclosed by the shell, particularly with the exception of a data and / or a charging port, such as a USB port. The shell may comprise a flexible cover that covers the USB from dirt and / or moisture. The cover may be removable or foldable to access the port.

[0040] In one embodiment the core housing comprises the force-sensing resistors an comprises a data port arranged at a housing wall that allows connecting the data port to a processor, microcontroller or the like.

[0041] The core housing comprises a housing wall enclosing the force-sensing resistors.

[0042] The core housing, in particular the housing wall, comprises one or more openings that are arranged to allow contacting of the force-sensing resistors, e.g. by means of a structural element that is configured to reach into the opening to contact the forcesensing resistor to transmit a force applied to the associated surface portion. ubn107wo

[0043] 7

[0044] The one or more openings are thus arranged along an imaginary line extending between the surface portion associated with the respective force-sensing resistor, more precisely with an active surface of the force-sensing resistor. The openings and thus the housing wall may have a distance to the force-sensing resistor in the range of several millimeters, e.g. 0.25 mm to 20 mm., particularly in the range of 0.5 mm to 10 mm. Any structural element may be formed and made such that it may reach into the opening deep enough to contact the force-sensing resistor. The structural element advantageously comprises a stiffness that allows it to transmit the force from the shell to the force-sensing resistor without bending or nicking away. The structural element may be formed from the same material than the shell. In particular, the structural elements are monolithically formed with the shell.

[0045] The core housing, and particularly in connection with the force-sensing resistors being arranged on the PCB, allows for increased robustness of the device and allows wireless sensor integration. The absence of cables or wires provides a device free of sources of error due to cable breaks or loose connections.

[0046] The core housing further allows for stable mechanics, as the force-sensing resistors are arranged precisely in core housing opening(s), which in turn allows for precise, reproducible force transmission.

[0047] As all force-sensing resistors are located inside the core housing, direct contact with the shell is avoided, which in turn reduces wear and tear.

[0048] According to another embodiment of the invention, the core housing comprises a plurality of openings, each opening being associated with one of the force-resisting sensors. That is, in particular, the number of openings and the number of forcesensing resistors are identical. For example, in case the device comprises four forcesensing resistors, the core housing comprises four openings, each associated with one of the force-sensing resistors. Further, each opening is arranged on an imaginary line, particularly an imaginary straight line extending between the surface portion and the force-sensing resistor. This allows for suitable structural elements to reach into the opening and to transmit a force from the shell to the force-sensing resistor.

[0049] Alternatively the core housing may comprise five openings and five force-sensing resistors. ubn107wo

[0050] 8

[0051] Particularly one opening if arranged on an opposite side of the housing wall such as to allow contacting a force-sensing resistor that faces in an opposite direction than the remaining force-sensing resistors.

[0052] The core housing allows protecting other components arranged in the core portion, such as the orientation and movement sensor and / or the first transmission module. This embodiment allows for a particularly robust device.

[0053] The core housing may be made of a rigid material such as metal and / or a polymer.

[0054] In yet another embodiment of the system according to the invention, each resistive force sensor is devoid of moving parts. In other words, each resistive force sensor maintains its shape during operation, particularly in case forces are applied to the respective resistive force sensor. This measure improves the handling of the device since the resistive force sensors maintain their shape within the device, particularly during the application of forces.

[0055] In an embodiment of the system according to the invention, a detected force on any one of the surface portions is transmitted in the FSR data with a bit depth of more than 1 bit, such that a digital representation of an external force may be evaluated in a non-binary fashion.

[0056] Particularly, a detected force on any one of the surface portions is transmitted in the FSR data with a bit depth of more than 2 bits, particularly with a bit depth of more than 6 bits or 7 bits.

[0057] According to another embodiment of the system according to the invention, on a side of the shell facing toward the force-sensing resistors, at each surface portion, the shell comprises an associated protruding structural element, wherein each structural element mechanically contacts the shell with the force-resistive sensor associated with the respective surface portion, or wherein each structural element is arranged such that a gap between the associated force-resistive sensor and the structural element is formed, such that upon exposure to a force, movement of the respective surface portion may be evoked particularly solely by compressing a shell material of the shell.

[0058] According to another embodiment of the invention, on a side of the shell facing toward the force-sensing resistors, at each surface portion, the shell comprises an associated protruding structural element. This protruding structural element may be stiff. ubn107wo

[0059] 9

[0060] According to another embodiment of the invention, each structural element mechanically contacts the shell with the force-resistive sensor associated with the respective surface portion.

[0061] According to another embodiment of the invention, each structural element is arranged to form a gap between the associated force-resistive sensor and the structural element, wherein upon exposure of one or more of the surface portions to a force, movement of the respective surface portion toward the rigid core narrows the gap between the protruding structural element and the associated force-sensing resistor.

[0062] This embodiment allows for a first mode of operation during which the force-sensing resistors do not record a FSR signal, but the system allows for plastic deformation that reverses once the force ceases. This allows for general strength development of the fingers.

[0063] According to another embodiment of the invention, the system, particularly the device, is configured to operate in a first mode of operation, wherein in the first mode of operation, upon exposure of one or more of the surface portions to a force, the shell deforms and the gap between the structural element associated with the respective surface portion and the force-sensing resistor narrows.

[0064] According to another embodiment of the invention, the system, particularly the device, is configured to operate in a second mode of operation, wherein in the second mode of operation the force on the one or more surface portions is so high that the gap between the structural element associated with the respective surface portion and the force-sensing resistor is closed and the respective structural element is in contact with the respective force-sensing resistor, and a force on the forcesensing resistor is determined.

[0065] This embodiment allows for training the fine motor skills of a person, while deformation of the shell in the second mode of operation is negligible.

[0066] According to another embodiment of the invention, the device comprises a rigid core housing enclosed inside the shell, wherein the core housing comprises one or more openings that allow the protruding structural element to reach into the opening.

[0067] This allows for a more robust device, as will be elaborated in subsequent paragraphs.

[0068] According to another embodiment of the invention, the core housing is fixed to the shell by a discrete fixing structure, wherein a volume comprised by the shell is hollow ubn107wo

[0069] 10 to allow deformation of the shell, particularly a deformation indenting the shell deeper than 0.5 cm to 2 cm.

[0070] In particular, each structural element may reach into the opening of the core housing. The resulting structure avoids any misguiding of the structural element with regard to the associated force-sensing resistor.

[0071] The gap between the structural element and the force-sensing resistor may be located in the housing, i.e. between the opening and the force-sensing resistor. This allows a robust and fail-safe operation of the device.

[0072] The protruding structural element points inward to the shell, i.e. toward the forcesensing resistors. The protruding structural elements may be monolithically formed with the shell, wherein each protruding structural element may be located at one of the surface portions. In case the surface portion is deformed toward the core portion, the associated structural element of this surface portion may move closer to the associated force-sensing resistor. Once the gap between the structural element and the force-sensing resistor (i.e. its active area) is closed, the structural element contacts the force-sensing resistor and transmits the force to the force-sensing resistor. Any force applied in addition leads to an increased force exerted on the force-sensing resistor. Once the force is released, the surface portion may return to its original state, which is referred to as the resting state. In the resting state, the gap is recovered, and no force is exerted on the force-sensing resistor.

[0073] The gap may be an air gap. The gap may be in the range of 0.25 mm to 20 mm, particularly in the range of 1 mm to 15 mm.

[0074] AS indicated previously, the gap allows for a first mode of operation of the device in which a user needs to overcome a minimum force to deform the shell to the extent that the gap is closed. The first mode of operation allows for a haptic experience of the device and a general strength development of the fingers of the user, while a feedback (a deformation of the shell) is provided. The quantitative force measurement by the force-sensing resistors may take place only when the gap is closed. When the gap is closed, the device essentially switches into the second mode of operation: once the gap is closed, deforming the shell further becomes difficult as the experienced stiffness of the surface portion increases rapidly due to the stiff protruding structural element being in contact with the non-moving forcesensing resistor. ubn107wo

[0075] 11

[0076] The second mode of operation offers a quantitative force measurement that is facilitated by the force-sensing resistors and allows, for example, for interactive control of a digital object (e.g. displayed on a screen). The second mode allows for training some aspects of the fine motor skills to a greater extent than the first mode of operation, as minute changes of the force may be recorded and a feedback via the control of the digital object may be provided. The second mode of operation allows for general strength development and fine motor skill training.

[0077] According to another embodiment of the invention, the device is configured to operate in a first mode and a second mode, wherein in the first mode, deformation of the surface portion does not lead to a recorded force by the associated force-sensing resistor, particularly wherein in the first mode of operation, the gap between the protruding structural element and the force-sensing resistor is present, such that a deformation of the surface portion solely narrows the gap but does not close the gap.

[0078] According to another embodiment of the invention, the second mode of operation comprises transmitting a force from the surface portion to the associated forcesensing resistor by way of the protruding structural element, wherein the gap between the structural element and the force-sensing resistor is closed during the second mode of operation. The advantages of the first and the second mode of operation have been elaborated in one of the previous paragraphs.

[0079] According to another embodiment of the invention, the device comprises five forcesensing resistors, wherein four of the sensors are arranged on a first side of the PCB and wherein the fifth sensor of the five force-sensing resistors is arranged in or on a wall portion, particularly a bottom wall portion of the core housing that faces in an opposite direction than the four force sensing resistors on the PCB. The fifth sensor may be configured to sense within a different force range than the other four sensors, namely in a higher force range than the four remaining sensors.

[0080] This embodiment allows arranging the fifth sensor such that it does not interfere with a positioning of a battery in the core housing.

[0081] In yet another embodiment of the system according to the invention, the shell is egg- shaped, particularly wherein the housing consists of the shell. Such an egg shape is particularly comfortable and easy to handle by a hand such as a human hand. The shape further allows for an advantageous space management of the surface portions of the shell as well as the rigid core portion. ubn107wo

[0082] 12

[0083] In another embodiment of the system according to the invention, the system comprises a computer arranged outside the shell of the device, wherein the computer is connected to or comprises a second transmission module, wherein the second transmission module is configured to transmit control data to the device and to receive FSR-data and IMU-data from the first transmission module, wherein the first transmission module is configured to receive control data from the second transmission module. Particularly, the first and the second transmission module are configured for wireless communication between each other. Arranging the computer outside the shell of the device allows for a remote analysis of FSR- or IMU-data obtained from the device, particularly in real time.

[0084] According to another embodiment of the invention, the system is configured to automatically determine, whether the device is held in the right or in the left hand of the user during operation.

[0085] For this purpose, the device may comprise an additional orientation sensor, such as a magnetometer that is configured to determine an orientation of the device, wherein the device comprises a marker on the shell configured to indicate an initial position an orientation so that the system, upon initialization of a training program or the like, may determine in which hand the device is held.

[0086] Alternatively, or additionally, the system may be configured to determine a range of orientations in which the device is moved by a hand of the user, wherein by evaluating the determined orientations, the system determines the hand in which the device is held. This embodiment makes use of the fact that each hand, due to the restrictions in human joint-mechanics, may access or perform only a limited range of rotations and motions depending on whether it is the right or left hand.

[0087] According to another embodiment of the invention, the system is alternatively or additionally configured to receive a user input indicative in which hand the user holds the device.

[0088] In another embodiment of the system according to the invention, the system comprises two devices according to the invention, such that a user may grasp or hold one device in each hand for determining finger coordination of both hands simultaneously.

[0089] In yet another embodiment of the system according to the invention, the system comprises at least two devices according to the invention. This embodiment allows multiple users, i.e. more than one user, to use the system according to the invention ubn107wo

[0090] 13 at the same time. For example, each user can use one device according to the invention. Alternatively, each user may use two devices according to the invention, with one device associated to one hand of each user, respectively. FSR- or IMU-data obtained from different devices controlled by different users can be evaluated and / or processed centrally on said computer.

[0091] A second aspect of the invention relates to a computer program comprising computer program code that, when executed on the system according to the first aspect of the invention comprising said computer and said second transmission module, causes the computer to execute the following steps: from the FSR-data and the IMU-data received from the first transmission module, determining: o a force on at least one surface portion of the shell and / or o an orientation and a movement of the device.

[0092] For example, the computer forms or is part of one of the following: a notebook, a mobile phone, or a mobile computerized device, a tablet, a website, a smart TV.

[0093] The computer may be the computer comprised by the system.

[0094] According to another embodiment of the invention, the computer program causes the computer to issue a feedback to the user in accordance with the inputs, via a user interface such as a display or the device (e.g. by a vibration signal).

[0095] The display or screen may be preferably arranged externally of the device and may be controlled by the computer.

[0096] In an embodiment of the computer program according to the invention, the computer program code, when executed on the system according to the first aspect of the invention comprising said computer and said second transmission module, causes the computer to determine a magnitude of the force, particularly respective magnitudes of the forces associated to the respective surface portions of the shell. For example, for a device comprising four or more surface portions with at least four force-sensing resistors arranged on the first side of the rigid core portion for detecting forces exerted by the index finger, the middle finger, the ring finger and the little finger and one surface portion with one force-sensing resistor arranged on the second side of the rigid core portion for detecting forces exerted by the thumb, the computer can determine respective magnitudes of the forces associated to the different five surface portions and the associated fingers. ubn107wo

[0097] 14

[0098] In another embodiment of the computer program according to the invention, the computer program code, when executed on the system according to the first aspect of the invention comprising said computer and said second transmission module, causes the computer to generate control data for controlling an analogue or digital object, particularly in real-time, based on the FSR-data and the I Mil-data. An analogue object can be an object in real space, for example a robot or components of a robot. A digital object may be an object on displayed on a screen, said object being encoded by a computer. The digital object may take the form and appearance of a spaceship on the screen that can be controlled in a digital environment on a screen. Hence, FSR- and IMU-data obtained for one or more users can be used to control said object, for instance in terms of movements and orientation of the object in real-space or a digital environment.

[0099] In yet another embodiment of the computer program according to the invention, the computer program code, when executed on the system according to the first aspect of the invention comprising said computer and said second transmission module, causes the computer to generate a user feedback signal for a user, based on the forces on the at least one surface portion and / or the orientation and movement of the device caused by the user and determined by the computer.

[0100] Particularly, the feedback aims at improving a user performance regarding finger force control and comprises instructions or information relating to said performance.

[0101] For example, the feedback can be haptic, visual, auditory or a combination of the three. In case of a haptic feedback, the feedback can be returned to a user by means of a vibration of the device caused by a vibration motor or by a change of temperature of the device. In case of a visual feedback, the feedback can be returned to a user by means of a light source such as an LED integrated in the device. Alternatively, visual feedback can also be returned to the user via a screen of the computer of the system located outside the device. Likewise, auditory feedback can be returned to the user via a speaker of said computer.

[0102] In another embodiment of the computer program according to the invention, the computer program code, when executed on the system according to the first aspect of the invention comprising said computer and said second transmission module, causes the computer to generate a user interface for interaction between the system and the user. For example, the user interface can be displayed on a screen, particularly on a touchscreen. The user interface can be configured to provide outputs of the system to the user, for example by means of visual information on said ubn107wo

[0103] 15 screen, for instance with respect to information regarding past and / or future training programs, game performance or similar. The user interface can be configured for the input of inputs by a user, such as the selection of a specific training program, game, or similar.

[0104] In other embodiments of the computer program according to the invention, the computer program is used in a system according to the first aspect of the invention comprising said computer, said second transmission module as well as a plurality of devices according to the invention. As such, each device of the invention is configured to communicate with the second transmission module of the computer by means of its respective first transmission module. This measure allows for the determination of respective forces and / or orientations and movements of multiple devices, particularly simultaneously, which may be caused by a plurality of users. Particularly, each user can operate one device with one hand or two devices with one device per hand.

[0105] According to one of these embodiments, such a computer program comprises computer program code that when executed on such a system causes the computer to determine respective forces on at least one surface portion of the shell and / or respective orientations and movements of the respective device, for said plurality of devices of the system.

[0106] In another one of these embodiments, such a computer program comprises computer program code that, when executed on such a system, causes the computer to generate respective control data for controlling an analog or digital object, based on the FSR-data and the I Mil-data, for said plurality of devices of the system.

[0107] According to another embodiment of the invention, the computer program is configured to generate a sound output indicative of the FSR-signal.

[0108] According to another embodiment of the invention, the computer program, when executed on the computer, executes a training program for the user. The training program may have the form of a computer game and / or a rehabilitation program.

[0109] The training program comprises displaying a graphical user interface, comprising one or more digital objects, wherein the digital objects each are associated to one of the surface portions, displaying target objects associated to the digital objects, ubn107wo

[0110] 16 instructing a user to adjust a force of one or more fingers in the surface portion(s), such as to match a position and / or an orientation of the digital object(s) with the target object(s), receiving and analyzing the FSR-data and IMU-data by the computer program, adjusting a position and or an orientation of the digital objects on the display based on the FSR-data and IMU-data, generating visual, tactile and / or auditory feedback to the user, with regard to a mismatch of the digital objects and the target objects.

[0111] Further, at an end of the training program, the training program may evaluate and output a user performance with regard to movement, position and orientation of the digital objects in response to the instructions.

[0112] This embodiment allows for a gamification of a rehabilitation or medical training. It may be that the target object(s) change(s) position, e.g. that they are moving, during the training program, such that the user needs to adjust the forces accordingly to match the position and / or orientation of the digital objects.

[0113] Further, the user performance may comprise information on reaction times, accuracy, and errors in controlling the digital objects.

[0114] Particularly, when conducting the training program, at least two main elements appear on the display or screen. First, a training guide that can be presented through videos, text, images, sounds, or simulations, and a feedback box where specific feedback on the training program is displayed. When starting the training, the FSR- and / or IMU-data is evaluated. The evaluated data is displayed in a graphical feedback box. Additionally, the feedback can also comprise tactile or auditory feedback. Evaluated data may include the orientation of the device (at least 6 Degrees of Freedom), accelerations, and pressure force (Force) of the individual fingers (at least index finger, middle finger, ring finger, and little finger) or the entire hand, or both.

[0115] The orientation may be determined by the orientation and movement sensor.

[0116] In an embodiment of this invention, the results of the training program are transferred to a server, wherein the server may be configured to aggregate said results with other data from the user such that a progression of the training over multiple sessions can be determined, as well as other useful statistical data. ubn107wo

[0117] 17

[0118] In an embodiment of this invention, processing of the sensor data of the device is executed by the device and particularly with components, e.g., a microprocessor comprised by the device.

[0119] Further, the device may be configured to provide user feedback (vibration, sound, visual) in response to the processed sensor data. Alternatively, the external computer may cause the device to activate an actuator (e.g. a vibration element).

[0120] According to a further aspect, the invention relates to a use of the system in a rehabilitation program or for gaming.

[0121] Figures and Examples

[0122] Particularly, exemplary embodiments are described below in conjunction with the Figures. The Figures are appended to the claims and are accompanied by text explaining individual features of the shown embodiments and aspects of the present invention. Each individual feature shown in the Figures and / or mentioned in said text of the Figures may be incorporated (also in an isolated fashion) into a claim relating to the device according to the present invention.

[0123] Fig. 1 shows an embodiment of a system for determining finger coordination according to the present invention;

[0124] Fig. 2 shows a device of the system according to the invention, according to another embodiment;

[0125] Fig. 3 shows an embodiment of the system with a rigid core housing;

[0126] Fig. 4 shows an embodiment of the rigid core housing;

[0127] Fig. 5 shows a top view of an embodiment of the core housing;

[0128] Fig. 6 shows a bottom view of an embodiment of the core housing; and

[0129] Fig. 7 shows an embodiment of the device in the assembled state.

[0130] Fig. 1 shows an embodiment for a system 100 for determining finger coordination according to the present invention. The system 100 comprises a device 10 with a first transmission module 11 and a computer 8 with a second transmission module 12. The device 10 is shown in a cut-representation through the device 10. The device 10 comprises an elastically deformable shell 1 with a plurality of surface portions 2a, 2b, 2c, 2d, 2e. Each of the surface portions 2a, 2b, 2c, 2d, 2e is arranged opposite an associated force-sensing resistor 4a,4b,4c,4d,4e (FSR), wherein between the ubn107wo

[0131] 18 surface portions and the associated sensor there may be a small air gap 8a, 8b,8c,8d,8e, typically below 1 cm, in the range of 0.5 mm to 9. mm. When a force is applied to one of the surface portions 2a, 2b, 2c, 2d, 2e, a movement of the respective surface portion 2a, 2b, 2c, 2d, 2e can be evoked solely by compression the shell material of the shell 1 or by a local deformation of the shell, wherein the force causes the gap to close and the shell to contact the associated sensor, such that he force exerted on the surface portion is transmitted to the associated FSR. Some embodiments each or some contact portions 2a- 2e may have a respective structural element 7a,7b,7c,7d,7e arranged on the inside of the shell, such as to allow the gap to be in a predetermined range, and for flexible design and placement of the FSRs inside the shell. Each of the force-sensing resistors 4a,4b,4c,4d,4e is configured and arranged to detect the force on the associated surface portion 2a, 2b, 2c, 2d, 2e. For example, a force applied to a first surface portion 2a by an index finger of a user can be detected by a first force-sensing resistor 4a and a force applied by a middle finger of a user to a second surface portion 2b can be detected by a second force-sensing resistor 4b. Each of the force-sensing resistors 4a,4b,4c,4d,4e is configured to generate a corresponding FSR-signal that is indicative of the force acting on the respective associated surface portion 2a, 2b, 2c, 2d, 2e.

[0132] The device 10 further comprises an inertial measurement unit 4 (IMU) configured to detect an orientation and a movement of the device 10 as well as to generate a corresponding IMU-signal. Both the force-sensing resistors 4a,4b,4c,4d,4e and the inertial measurement unit 4 are in the present embodiment arranged on a printed circuit board 9 (PCB) within a rigid core portion 6 that is enclosed by the elastically deformable shell 1 of the device 10. The rigid core portion 6 is harder than the elastically deformable shell 1 of the device 10. Particularly, each force-sensing resistor 4a,4b,4c,4d,4e is devoid of moving parts such that it maintains its shape within the rigid core portion 6, even under compression of the elastically deformable shell 1 of the device 10, for instance in case one or more fingers apply forces to one or more of the surface portions 2a, 2b, 2c, 2d, 2e.

[0133] Four of the five surface portions 2a, 2b, 2c, 2d are arranged on a first side of the rigid core portion 6 and one of the five surface portions 2e is arranged on a second side of the first rigid core portion 6 opposite to the first side. A first surface portion 2a is particularly configured for being contacted by an index finger, a second surface portion 2b is particularly configured for being contacted by a middle finger, a third surface portion 2c is particularly configured for being contacted by a ring finger, a ubn107wo

[0134] 19 fourth surface portion 2d is particularly configured for being contacted by a little finger and a fifth surface portion 2e is particularly configured for being contacted by a thumb. As such, the device 10 can be handheld and grasped by one hand while FSR signals are detected for each finger individually.

[0135] As can further be seen in Fig. 1, the shell 1 forms a housing 3 of the device 10 that houses its components, wherein the shell 1 or housing 3 is egg-shaped. Such an egg shape is particularly comfortable and easy to handle by a hand such as a human hand. The shape further allows for an advantageous space management of the surface portions of the shell 1 as well as the rigid core portion 6 with the printed circuit board 9 and its components.

[0136] The first transmission module 11 of the device 10 is likewise arranged on the printed circuit board 9 and configured to communicate with the second transmission module 12 of the system 100, which is part of a computer 8 located outside the device 10 defined by its shell 1. In particular, the communication is a wireless communication, which further simplifies the handling of the device 10. The first transmission module 11 is configured to receive the FSR-signal of each force-sensing resistor 4a,4b,4c,4d,4e and the IMU-signal, and to transmit IMU-data relating to the IMU- signal as well as FSR-data relating to the FSR-signal to the second transmission module 12 of the computer 8. The FSR-data is configured such that force information of each surface portion 2a, 2b, 2c, 2d, 2e may be obtained and evaluated separately from the FSR-data by means of the computer 8.

[0137] Fig. 2 depicts schematically a device 10 of the system 100 according to the invention, according to another embodiment. This device 10 comprises, besides its shell 1 with said plurality of surface portions 2a, 2b, 2c, 2d, 2e (not shown), the following components that may be arranged on a printed circuit board 9:

[0138] Four force-sensing resistors 4a, 4b, 4c, 4d, wherein each force-sensing resistor 4a, 4b, 4c, 4d is associated to one of the surface portions 2a, 2b, 2c, 2d of the shell 1, for detecting force on the associated surface portion 2a, 2b, 2c, 2d of the shell and to generate a corresponding FSR- signal indicative of the detected force.

[0139] - An inertial measurement unit 5 configured to detect an orientation and a movement of the device 10 and to generate a corresponding IMU-signal.

[0140] - A first transmission module 11 which is in the present embodiment formed as a transceiver 205 configured to receive the FSR-signals and the IMU- signal as well as to transmit IMU-data relating to the IMU-signal as well as ubn107wo

[0141] 20

[0142] FSR-data relating to the FSR-signal, particularly by means of wireless communication.

[0143] - A memory 206 for saving recorded FSR- and / or IMU-data.

[0144] - A reset button 207 for resetting the device electronics.

[0145] - An on / off function 208 for switching the device on and off.

[0146] - A light source 209, particularly an LED, for returning visual feedback to a user using the device 10, based on forces on the at least one surface portion 2a, 2b, 2c, 2d and / or the orientation and movement of the device 10 caused by the user and determined by the computer 8 of the system 100.

[0147] - A battery 210 for powering the components of the device 10.

[0148] - A charging unit 211 for charging the battery 210.

[0149] - A coil charger 212 for charging a coil of an induction charging mechanism.

[0150] - A vibration motor 213 for returning haptic feedback to a user using the device 10, based on forces on the at least one surface portion 2a, 2b, 2c, 2d and / or the orientation and movement of the device 10 caused by the user and determined by the computer 8 of the system 100

[0151] - A magnetometer 214m, e.g. for determining an absolute orientation in space and to correct gyroscope drift, enabling more precise and stable positioning.

[0152] Fig. 3 shows an exemplary schematic embodiment of the device similar to Fig. 1. In addition to the device 10 of Fig. 1, the core is comprised in a rigid core housing that encloses the PCB 9 with all electronic components. The core housing comprises several openings 13a, 13e that are each associated with one of the force-sensing resistors 4a-4e, wherein the protruding structural elements 7a-7e extend through the openings, 13a, 13e, such that the gaps 8a-8e are formed within the core housing 14. This embodiment allows for various advantages, as elaborated in the previous sections of the specification. Elements with the same reference numerals as in Fig. 1 have the same function as elaborated in the context of Fig. 1 and are not elaborated in duplicate for Fig. 3 to avoid wordiness.

[0153] Fig. 4 shows a detailed exploded view drawing of core portion and the core housing 14. The core housing 14 comprises a housing wall 14a, 14b, wherein a lateral wall portion 14a is formed to allow a top portion of the wall 14b to form fit in corresponding recesses.

[0154] The top portion 14b of the core housing 14 comprises four openings 13a- 13d, each arranged on top of a corresponding force-sensing resistor 4a-4d. The top portion ubn107wo

[0155] 21 further comprises openings 18 that, in the assembled state of the core housing 14, serve for screws to fix the top portion 14b to the lateral wall portion 14a.

[0156] The force-sensing resistors 4a-4d are fixedly arranged and wirelessly connected to the PCB 9 that is entirely enclosed in the core housing 14. The force-sensing resistors are arranged to allow a compact build of the core by arranging the middle ones in alternating orientation on the PCB.

[0157] The PCB comprises a connector port 16, in this case a data and charging port in form of a USB socket, that is configured to serve as a data port that may be connected to upload firmware and / or firmware updates. At the same time the port 16 may be configured to charge a battery comprised in the core portion (not shown).

[0158] Further, on a side opposite the top wall portion 14b the core housing comprises a bottom wall portion that comprises a charging coil for wireless charging of the battery (not shown).

[0159] In one embodiment charging is facilitated by the charging coil; firmware and firmware updates may be facilitated by wireless data transfer via the first transmission module.

[0160] This embodiment allows for a water-tight monolithic shell, that entirely encloses the core portion.

[0161] Electric wires 17 for a vibration motor (not shown) comprised by the PCB inside the core housing are shown as well.

[0162] Fig. 5 and 6 show a top view and a bottom view of the core housing 14 in the assembled state. The core housing 6 has cut edges to make it fit into an egg-shaped shell. In Fig. 5 a top view of the core housing 14 is shown. The top portion of the wall 14b has four openings 13-13e that allows access and contacting of the force-sensing resistors. The top wall portion 14b is fixed with four screws 19 to the lateral wall portion 14a through the fixing holes. The core housing 14 is rigid and robust to protect the electronics in the core housing. On the side the data port 16 is visible.

[0163] Fig. 6 shows a bottom view of the core housing 14. Here, the charging coil 20 with the two connection wires 17 is visible. The charging coil 20 is configured to charge the battery 22 in the core housing 14 and is arranged on the bottom wall portion 14c opposite the top wall portion 14b. The battery 22 allows driving all electronic components as well as the vibration motor for haptic feedback. With regard to Fig. 6 it is noted that an embodiment comprising a fifth force-sensing resistor (not shown) may be realized by arranging the fifth sensor on the bottom wall 14c next to the charging coil 20 (or by removing the charging coil), wherein the fifth sensor may then ubn107wo

[0164] 22 be arranged on the bottom wall portion or in a recess on said bottom wall portion 14c. This allows to place the battery securely on a bottom side of the core housing next to the bottom wall portion 14c.

[0165] Fig. 7 shows one exemplary embodiment of the device 10 in the assembled state. The device 10 fits in a single hand and can be easily grabbed and held in the hand.

[0166] The dimensions of the device 10 are selected so it can be held with a pincher grip by two fingers, thumb and index finger, of a single hand.

[0167] The elastically deformable shell 1 that surrounds the core housing has a minute opening 21 on a side of the device 10 facing in a different direction than the side comprising the surface portions in order to avoid interference with the intended function and use of the device 10. In the shell opening 21 the data and charging port 16 is located to allow charging and data transfer to and from the device 10.

[0168] Alternatively, the shell may not comprise an opening (not shown in Fig. 7) and the data part is located inside the shell (and may be used only during assembly of the device).

[0169] ubn107wo

[0170] 23

[0171] List reference numerals

[0172] 1 shell

[0173] 2 surface portion

[0174] 3 housing

[0175] 4a-4e force-sensing resistor

[0176] 5 orientation and movement sensor

[0177] 6 rigid core portion

[0178] 7a-7e protruding structural element

[0179] 8a-8e gap

[0180] 9 PCB

[0181] 10 device

[0182] 11 first transmission module

[0183] 12 second transmission module

[0184] 13a-13e core housing opening

[0185] 14 core housing

[0186] 14a lateral wall

[0187] 14b top portion

[0188] 14c bottom wall portion

[0189] 15 fixing structure

[0190] 16 data and charging port

[0191] 17 wires for the vibration motor

[0192] 18 fixing openings

[0193] 19 srews

[0194] 20 charging coil

[0195] 21 shell openining

[0196] 22 battery

[0197] 80 computer

[0198] 100 system

[0199] 201 micro-controller

[0200] 205 transceiver

[0201] 206 non-transitory memory ubn107wo

[0202] 24

[0203] 207 reset button

[0204] 208 on / off switch

[0205] 209 light source

[0206] 210 energy source 211 charging unit

[0207] 212 coil charger

[0208] 213 vibration motor

[0209] 214 magnetometer

[0210] *****

Claims

ubn107wo25Claims1. A system (100) for determining finger coordination, comprising at least the following components: a device (10) with an elastically deformable shell (1) having a plurality of surface portions (2a, 2b, 2c, 2d, 2e) for receiving a force from a finger, wherein the shell (1) forms at least a portion of a housing (3) of the device (10), wherein the device (10) comprises, o a plurality of sensors, namely force-sensing resistors (4a,4b,4c,4d,4e), FSR, wherein each sensor (4a,4b,4c,4d,4e) is associated to one of the surface portions (2a, 2b, 2c, 2d, 2e) of the shell (1), wherein each sensor (4a,4b,4c,4d,4e) is configured and arranged to detect a force on the associated surface portion (2a, 2b, 2c, 2d, 2e) of the shell (1) and to generate a corresponding FSR-signal, indicative of the detected force, o an orientation and movement sensor, such as an inertial measurement unit (5), IMU, wherein the orientation and movement sensor is configured to detect an orientation and a movement of the device (10) and to generate a corresponding -signal, the IMU-signal o a first transmission module (11) configured to receive the FSR- signal of each force-sensing resistor (4a,4b,4c,4d,4e) and the IMU- signal, wherein the first transmission module (11) is further configured to transmit IMU-data relating to the IMU-signal as well as FSR-data relating to the FSR-signal, wherein the FSR-data is configured such that force information of each surface portion (2a, 2b, 2c, 2d, 2e) may be obtained and evaluated separately from the FSR-data.

2. The system (100) according to claim 1, wherein the housing (3) of the device (10) consists of the shell (1).

3. The system (100) according to claim 1 or 2, wherein the device (10) comprises a rigid core portion (6), on which that plurality of force-sensing resistors (4a,4b,4c,4d,4e) is arranged, wherein the force-sensing resistors (4a, 4b, 4c, 4d) are arranged on a first side of the rigid core portion (6), such that the deviceubn107wo26(10) is configured to separately detect forces exerted by one or more fingers of a hand, wherein the fingers are selected from the group consisting of an index finger, a middle finger, a ring finger, a little finger.

4. The system (100) according to claim 3, wherein the rigid core portion (6) has a second side opposite the first side, wherein one more force-sensing resistor (4e) of that plurality of force-sensing resistors (4a,4b,4c,4d,4e) is arranged on said second side, such that the device (10) is configured to separately detect forces exerted by a thumb of a hand.

5. The system (100) according to claim 3 or 4, wherein the rigid core portion (6) comprises a printed-circuit board, PCB, wherein the plurality of force-sensing resistors (4a,4b,4c,4d,4e) is electrically contacted with the PCB.

6. The system (100) according to one of the preceding claims, wherein each resistive force sensor (4a,4b,4c,4d,4e) is devoid of moving parts.

7. The system (100) according to one of the preceding claims, wherein a detected force on any one of the surface portions (2a, 2b, 2c, 2d, 2e) is transmitted in the FSR data with a bit depth of more than 1 bit, such that a digital representation of an external force may be evaluated in a non-binary fashion.

8. The system (100) according to one of the preceding claims, wherein on a side of the shell (1) facing toward the force-sensing resistors (4a,4b,4c,4d,4e), at each surface portion (2a, 2b, 2c, 2d, 2e), the shell (1) comprises an associated protruding structural element (7a,7b,7c,7d,7e).

9. The system according to claim 8, wherein each structural element (7a,7b,7c,7d,7e) mechanically contacts the shell (1) with the force resistive sensor (4a,4b,4c,4d,4e) associated to the respective surface portion (2a, 2b, 2c, 2d, 2e).ubn107wo2710. The system according to one of the claim 8, wherein each structural element (7a,7b,7c,7d,7e) is arranged to form a gap (8a,8b,8c,8d,8e) between the associated force-resistive sensor (4a,4b,4c,4d,4e) and the structural element, wherein upon exposure of one or more of the surface portions to a force, movement of the respective surface portion (2a, 2b, 2c, 2d, 2e) toward the rigid core (6) narrows the gap between the protruding structural element and the associated force-sensing resistor.

11. The system according to claim 10, wherein the system (100) is configured to operate in a first mode of operation, wherein in the first mode of operation, upon exposure of one or more of the surface portions (2a-2e) to a force, the shell (1) deforms and the gap (8a-8e) between the surface portion (2a-2e) and the force-sensing resistor (4a-4e) narrows.

12. The system according to claim 10 or 11, wherein the system is configured to operate in a second mode of operation, wherein in the second mode of operation, a force on one or more of the surface portions (2a-2e) is so high that the gap (8a-8e) associated to the surface portion is closed and the structural element (7a-7e) is in contact with the force-sensing resistor (4a-4e), and a force on the force-sensing resistor (4a-4e) is determined.

13. The system (100) according to one of the claims 8 to 12, wherein the device (10) comprises a rigid core housing (14) enclosed inside the shell (1), wherein the core housing (14) comprises one or more openings (13a-13e) that allow the protruding structural element to reach into the opening to contact the forcesensing resistors comprised by the core housing.

14. The system (100) according to claim 13, wherein the core housing (14) is fixed to the shell (1) by a discrete fixing structure (15), wherein a volume comprised by the shell (1) is hollow to allow deformation of the shell (1), particularly a deformation indenting the shell deeper than 1 cm.

15. The system (100) according to one of the preceding claims, wherein the shell (1) is egg-shaped.ubn107wo2816. The system (100) according to one of the preceding claims, wherein the system (100) comprises a computer (80) arranged outside the shell (1) of the device (10), wherein the computer (80) is connected to or comprises a second transmission module (12), wherein the second transmission module (12) is configured to transmit control data to the device (10) and to receive FSR-data and IMU-data from the first transmission module (11), wherein the first transmission module (11) is configured to receive control data from the second transmission module (12).

17. A computer program comprising computer program code that when executed on the system (100) according to claim 16, causes the computer (80) to execute the following steps: from the FSR-data and the IMU-data received from the first transmission module (11), determining: o a force on at least one surface portion (2a, 2b, 2c, 2d, 2e) of the shell (1) and / or o an orientation and a movement of the device (10).

18. The computer program according to claim 17, wherein computer program causes the computer (80) to execute the step of issuing a user-feedback on a user interface.

19. The computer program according to claim 17 or 18, wherein the computer program code, when executed on the system (100) according to claim 16, causes the computer (80) to determine a magnitude of the force associated to the surface portions (2a, 2b, 2c, 2d, 2e) of the shell (1).

20. The computer program according to one of the claims 17 to 19, wherein the computer program code, when executed on the system (100) according to claim 10, causes the computer (80) to generate control data for controlling an analogue or digital object, based on the FSR-data and the IMU-data.

21. The computer program according to one of the claims 17 to 20, wherein the computer program code, when executed on the system (100) according to claim 16, causes the computer (80) to generate a user feedback signal for a user, based on the forces on the at least one surface portion (2a, 2b, 2c, 2d, 2e)

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