Annularly shaped wearable device and method thereof

Abstract

An annularly shaped wearable device (100) adapted to be worn on a body part (112) of a user, is provided. The wearable device (100) comprises a first touch sensor (104) for detecting a distance covered by a finger (114) touching an outer surface (102) of the wearable device (100) in a sliding motion across the outer surface (102). The wearable device (100) further comprises a rotational sensor (108) for detecting a rotary displacement of the wearable device (100) relative to the body part (112). Further, the wearable device (100) comprises a processing circuitry (124) causing the wearable device (100) to be operative to generate a control signal (206) based on a composite of the distance covered by the finger (114) sliding across the outer surface (102) and the rotary displacement of the wearable device (100) relative to the body part (112).

Description

[0001] ANNULARLY SHAPED WEARABLE DEVICE AND METHOD THEREOF

[0002] Technical field

[0003] The invention relates to an annularly shaped wearable device adapted to be worn on a body part of a user, a method of generating a control signal, a corresponding computer program, a corresponding computer-readable data carrier, and a corresponding data carrier signal.

[0004] The use of wearable devices as a means of controlling connected devices has grown significantly in recent years. This is due in part to the increasing number of connected devices available, such as smart TVs, smartphones, and other smart devices that can be controlled remotely. Wearable devices such as smart rings, wristbands, and watches, offer a convenient way for users to interact with these devices without the need for a separate physical remote control. However, these wearable devices are typically limited in terms of their input capabilities, due to their small size and limited surface area. For example, a smart ring may have only a small touch interface that allows users to interact with the device by tapping or swiping their finger across the surface of the device to control functionality of connected devices. For example, US patent application

[0005] US 2012 / 0075196 A1 discloses a method which includes receiving first and second sensor information of a device that is worn by a user, determining first and second touch inputs indicated by the respective first and second sensor information and causing a respective first and second function to be performed based on the respective first and second touch input.

[0006] Some wearable devices, such as smart rings and bracelets, may receive user inputs from the device’s rotation around a finger or a wrist on which it is worn. For example, US patent US 10,635,173 B2 discloses a smart ring that may be used to control connected devices via rotation of the smart ring.

[0007] Many users using a wearable device such as a smart ring or bracelet may prefer that the ring or bracelet is not too tight. However, a smart ring or bracelet that does not sit tightly on a user’s finger or wrist may result in an unreliable control by the user. Thus, there is a need for improving existing solutions for wearable devices to allow for more reliable control that reflects user intent.

[0008] It is an object of the invention to enable reliable and improved control in wearable devices.

[0009] This object is achieved by the subject matter as defined by the independent claims. Embodiments of the invention are characterized by the dependent claims.

[0010] According to a first aspect of the invention, an annularly shaped wearable device is provided. The wearable device is adapted to be worn on a body part of a user. The wearable device comprises a first touch sensor for detecting a distance covered by a finger touching an outer surface of the wearable device in a sliding motion across the outer surface. The wearable device further comprises a rotational sensor for detecting a rotary displacement of the wearable device relative to the body part. Further, the wearable device comprises a processing circuitry causing the wearable device to be operative to generate a control signal. The control signal is generated based on a composite of the distance covered by the finger sliding across the outer surface and the rotary displacement of the wearable device relative to the body part. According to a second aspect of the invention, a method of generating a control signal is provided. The method is performed by an annularly shaped wearable device worn on a body part of a user. The method comprises detecting a distance covered by a finger touching an outer surface of the wearable device in a sliding motion across the outer surface. The distance covered by the finger sliding across the outer surface is detected by a first touch sensor comprised in the wearable device. The method further comprises detecting a rotary displacement of the wearable device relative to the body part. The rotary displacement of the wearable device is detected by a rotational sensor comprised in the wearable device. The method further comprises generating a control signal. The control signal is generated based on a composite of the distance covered by the finger sliding across the outer surface and the rotary displacement of the wearable device relative to the body part.

[0011] Further features of, and advantages with, the invention will become apparent when studying the following detailed disclosure, the drawings, and the appended claims. Those skilled in the art realize that different features of the invention can be combined to create embodiments other than those described in the following.

[0012] Brief of the

[0013] The above, as well as additional features, and advantages, of the invention, will be better understood through the following illustrative and nonlimiting detailed description of embodiments of the invention, with reference to the appended drawings, in which:

[0014] FIG. 1 is an illustration of an annularly shaped wearable device according to embodiments of the invention.

[0015] FIG. 2 depicts a schematic block diagram of the wearable device according to embodiments of the invention. FIG. 3 illustrates a flowchart of a method of generating a control signal, the method being performed by the annularly shaped wearable device, in accordance with embodiments of the invention.

[0016] All the figures are schematic, not necessarily to scale, and generally only show parts which are necessary in order to elucidate the invention, wherein other parts may be omitted or merely suggested.

[0017] Detailed description

[0018] The invention will now be described more fully hereinafter with reference to the accompanying drawings, in which certain embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided by way of example so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0019] In the present context, a wearable device is an electronic device that can be worn on a body part of a user. Wearable devices may, for example, include smart watches, smart rings, smart bracelets, smart bands, etc. Wearable devices, such as a smart bracelet worn on a wrist or a smart ring worn on a finger, may be equipped with sensors and electronic components that can detect user inputs and hand gestures, allowing them to be used as a remote control for controlling other devices such as smartphones, tablets, TVs, gaming consoles, smart home devices, Head Mounted Display (HMD) devices, In-Vehicle Infotainment (IVI) systems, and other computing devices. For example, a user may use a smart ring worn on a finger to control a smart thermostat to adjust the temperature of a room, or to adjust the volume of music playout. However, there is a risk that the user perceives the control as unreliable in case the smart ring is not correctly fitted to the finger. For example, if the user attempts to provide control commands by touching the ring surface it could be difficult for the user to provide precise control input if the ring has a very loose fit, and the ring could accidentally move, in particular rotate, when the user touches it. Likewise, a very tight fit could also be problematic if the smart ring is designed to receive input from the user by means of rotating the ring around the finger on which it is worn.

[0020] While providing the right fit is important for smart rings according to prior art solutions to work properly, there is also a challenge in that finger diameter will vary over time of day, due to hand-muscle tonus and blood flow, and changes in body and ambient temperature. The same applies for wrist diameter, and accordingly there is also a challenge to provide the ideal size for bracelets and watch bands which are designed to receive user inputs by means of rotation and / or touch. The problem is well known in, e.g., the watch industry, where manufacturers have designed sliding-adjustable clasps to enable wearer to adjust watch band / strap circumference.

[0021] Wearable devices according to embodiments of the present invention aim to reliably reflect the user’s intended control input by generating a control signal based on a composite of sensor information from a touch sensor and sensor information from a rotational sensor. The touch sensor is arranged to detect a distance covered by a finger touching an outer surface of the wearable device. The rotational sensor is arranged to detect a rotary displacement of the wearable device relative to the body part on which the wearable device is worn. Accordingly, the control signal will be based on a combination of sensor information from two different types of sensors which allows for a more reliable control compared to prior art solutions.

[0022] FIG. 1 is an illustration of an annularly shaped wearable device 100, according to embodiments of the invention. The annularly shaped wearable device 100 is adapted to be worn on a body part 112 of a user. For example, the body part 112 may be a finger or a wrist of the user. The wearable device 100 includes a first touch sensor 104, a rotational sensor 108, and a processing circuitry 124. FIG. 2 depicts a schematic block diagram of the wearable device 100 according to embodiments of the invention.

[0023] The first touch sensor 104 is operative to detect a distance covered by a finger 114 touching the outer surface 102 of the wearable device 100 in a sliding motion across the outer surface 102. The first touch sensor 104 may be provided on the outer surface 102. In the present context, the term “outer surface” refers to the part of the wearable device 100 that may be touched by the finger 114 for the purpose of generating a control signal 206 by rotating the wearable device 100 relative to the body part 112 and / or sliding the finger 114 across the outer surface 102, as is described further below. While touch inputs from the user are described as being received from the user’s finger 114, in practice the touch inputs from the user are usually received from the tip of the finger 114.

[0024] The first touch sensor 104 detects the distance covered by the finger 114 sliding across the outer surface 102. The first touch sensor 104 may, for example, be a capacitive touch sensor. A capacitive touch sensor detects changes in electrical field when a conductive object, such as finger 114, comes into contact with the capacitive touch sensor. The first touch sensor 104 may, for example, include a touch-sensitive surface. When the finger 114 touches the touch-sensitive surface of the first touch sensor 104, the capacitive touch sensor detects a change in electrical field. The touch-sensitive surface detects the distance covered by the finger 114 sliding across the outer surface 102. The touch-sensitive surface of the first touch sensor 104 may be made of a conductive material and may include a set of electrodes that can detect the user's finger 114.

[0025] The processing circuitry 124 causes the wearable device 100 to be operative to generate a control signal 206. The control signal 206 is generated based on a composite of the distance covered by the finger 114 sliding across the outer surface 102, and a rotary displacement of the wearable device 100 relative to the body part 112. For example, the processing circuitry 124 may receive a signal which is indicative of the rotary displacement of the wearable device 100 in the form of an angle, which may be measured in degrees or radians, between a start point of rotation 120 and an end point of rotation 122 of the wearable device 100. Similarly, a measure of the distance covered by the finger 114 may be received by the processing circuitry 124 in the form of length a measured between a start point of touch 116 and an end point of touch 118 by the finger 114.

[0026] In one embodiment, the received length a is converted into an angular displacement 0 that corresponds to the length a. The angular displacement 0 can be calculated as follows:

[0027] 0 = a / C * 360° where C is the outer circumference of the wearable device 100. The rotary displacement p of the wearable device 100 and the angular displacement 0 are used to generate the control signal 206.

[0028] In another embodiment, the rotary displacement p of the wearable device 100 is converted into an arc length p, along the outer circumference C of the wearable device 100, which corresponds to the rotary displacement p. The arc length can be calculated as follows: p = p / 360° * C

[0029] The distance a covered by the finger 114 and the arc length p corresponding to the received rotary displacement p of the wearable device 100 are used to generate the control signal 206.

[0030] The wearable device 100 generates the control signal 206 using the distance covered by the finger 114 sliding across the outer surface 102 between the start point of touch 116 and the end point of touch 118, and the rotary displacement of the wearable device 100 relative to the body part 112 between the start point of rotation 120 to the end point of rotation 122. As the finger 114 touches the outer surface 102 at the start point of touch 116 and then slides across the outer surface 102 of the wearable device 100 towards the end point of touch 118, the distance covered by the finger 114 is measured by the first touch sensor 104, in Fig. 1 illustrated as a on the outer circumference of the wearable device 100.

[0031] While sliding from the start point of touch 116 towards the end point of touch 118, the finger 114 may in addition cause a rotary displacement of the wearable device 100 relative to the body part 112. The rotary displacement is measured from the start point of rotation 120 to the end point of rotation 122. The rotary displacement of the wearable device 100 is measured by the rotational sensor 108. The rotary displacement of the wearable device 100 is measured as an angle between the start point of rotation 120 and the end point of rotation 122, in Fig. 1 illustrated as p.

[0032] In an embodiment, the processing circuitry 124 generates the control signal 206 based on the composite of the distance a covered by the finger 114 sliding across the outer surface 102, i.e., the distance a, and the arc length p corresponding to the rotary displacement p of the wearable device 100 relative to the body part 112. The arc length is combined with the distance a covered by the finger 114 sliding across the outer surface 102, to generate the control signal 206. In particular, the control signal 206 may be generated based on a sum of the distance a and the arc length p, i.e., as a+p.

[0033] In another embodiment, the processing circuitry 124 generates the control signal 206 based on the composite of the rotary displacement p of the wearable device 100 relative to the body part 112, i.e., the angle p between the start point of rotation 120 and the end point of rotation 122, and the angular displacement 0 corresponding to the distance a covered by the finger 114 sliding across the outer surface 102. In this embodiment, the distance a covered by the finger 114 sliding across the outer surface 102 is converted into a unit of rotary displacement, i.e., an angular displacement corresponding to the distance a covered by the finger 114 sliding across the outer surface 102. The angular displacement 0 is combined with the angle p to generate the control signal 206. In particular, the control signal 206 may be generated based on a sum of the angular displacement 0 and the angle p i.e., as 0 + p.

[0034] In an embodiment, the first touch sensor 104 may be a fingerprint sensor. While touch sensors are typically used to detect when a finger is touching a screen or button, fingerprint sensors are designed to capture the unique pattern of ridges and valleys on a person's fingertip for identification and authentication purposes. The fingerprint sensor as the first touch sensor 104 may use the fingertip’s pattern moving across the fingerprint sensor to detect the distance covered by the finger 114 sliding across the outer surface 102 of the wearable device 100.

[0035] Optionally, the wearable device 100 may further be operative to identify the specific finger 114 which touches the outer surface 102. In this case, the wearable device 100 may be operative to generate the control signal 206 based on the distance covered by the specific finger 114 identified by the first touch sensor 104. In addition, each finger may be associated with a specific control signal 206 for a specific function. For example, an index finger 114 sliding across the outer surface 102 may cause the wearable device 100 to generate a control signal 206 for scrolling a page, whereas the wearable device 100 may generate a control signal 206 for adjusting a volume in response to detecting a ring finger 114 sliding across the outer surface 102.

[0036] The rotational sensor 108 is operative to detect the rotary displacement of the wearable device 100 relative to the body part 112. The rotational sensor 108 may be provided on an inner surface 106 of the wearable device 100. In the present context, the term “inner surface” refers to the part of the wearable device 100 that faces or abuts the body part 112 when the wearable device 100 is worn on the body part 112. The rotational sensor 108 may be an optical sensor, an inertial measurement unit (IMU), or a second touch sensor. For example, the rotational sensor 108 may be an optical heart rate sensor operative to detect a heart rate of the user. The optical heart rate sensor, in addition to detecting heart rate, may advantageously be used as the rotational sensor 108. The rotational sensor 108 as an IMU sensor may include a set of gyroscopes or accelerometers that can detect the rotary displacement of the wearable device 100. The IMU sensor may optionally include a magnetometer that can detect the magnetic field of the wearable device 100 and provide a reference for the wearable device's 100 orientation.

[0037] The wearable device 100 may, in response to detecting one finger 114 touching the outer surface 102, cause the optical heart rate sensor to detect the rotary displacement of the wearable device 100 relative to the body part 112. The wearable device 100 may be further operative to cause the optical heart rate sensor to stop or pause measuring the heart rate of the user in response to detecting one finger 114 touching the outer surface 102. Advantageously, the heart rate measurement of the user is stopped or paused to ensure accurate detection of the rotary displacement of the wearable device 100 relative to the body part 112. Additionally, the stoppage or pause of the heart rate measurement may save power consumed by the wearable device 100.

[0038] When the finger 114 slides across the outer surface 102, the wearable device 100 may rotate around the body part 112. This may occur during usage due to the user’s loose skin, a sweaty finger or arm, or if the wearable device 100 does not sit tightly on the body part 112. The wearable device 100 generates the control signal 206 based on the composite of the distance covered by the finger 114 sliding across the outer surface 102 and the rotary displacement of the wearable device 100 relative to the body part 112.

[0039] Accordingly, it is an advantage that even if the wearable device 100 has a more loose fit during ordinary conditions and a more tight fit when the user’s finger is swollen, e.g., due to physical activity or increased ambient temperature, the user's intended control command is reliably reflected in the generated control signal 206. When the wearable device 100 has a more loose fit, the contribution from the rotational sensor 108 to the resulting control signal 206 could be larger due to rotation of the wearable device 100 when the user’s finger 114 touches the outer surface 102 of the wearable device 100 to provide a control input. On the other hand, when the wearable device 100 has more tight fit, the contribution from the rotational sensor 108 to the resulting control signal 206 could be smaller due to no or very small rotation of the wearable device 100.

[0040] Advantageously, the same movement of the user’s finger, when attempting to provide a control input to the wearable device 100 by rotating the wearable device 100 and / or sliding the finger 114 across the outer surface 102, will more reliably result in that a control signal 206 is generated which reflects the same composite of the distance covered by the finger 114 sliding across the outer surface 102 and the rotary displacement of the wearable device 100 relative to the body part. This is the case irrespective of whether this corresponds to a small distance covered by the finger 114 sliding across the outer surface 102 in combination with a large rotary displacement of the wearable device 100 relative to the body part 112, or vice versa, i.e. , a large distance covered by the finger 114 sliding across the outer surface 102 in combination with a small rotary displacement of the wearable device 100 relative to the body part 112. In other words, the composite may include a large proportion of the distance covered by the finger 114 sliding across the outer surface 102 and a small proportion of the rotary displacement of the wearable device 100 relative to the body part 112, or vice versa. Thus, the generated control signal 206 reliably and accurately reflects the intention of the user when attempting to provide a control input to the wearable device 100 by rotating the wearable device 100 and / or sliding the finger 114 across the outer surfacel 02 of the wearable device 100.

[0041] In some embodiments, the wearable device 100 may be operative to detect more than one finger touching the outer surface 102. In one embodiment, the wearable device 100 is operative to generate the control signal 206 using an average of the distances covered by the more than one finger, in response to detecting the more than one finger touching the outer surface 102 in a sliding motion. In another embodiment, the wearable device 100 is operative, in response to detecting more than one finger touching the outer surface 102 in a sliding motion, to generate the control signal 206 using the distance covered by a specific finger 114. The specific finger 114 touching the outer surface 102 may be identified by the fingerprint sensor.

[0042] The wearable device 100 may be operative, in response to detecting more than one finger touching the outer surface 102, with one finger 114 touching the outer surface 102 in a sliding motion and at least one finger fixated on the outer surface 102 of the wearable device 100, to generate the control signal 206 using only the distance covered by the finger 114 sliding across the outer surface 102 in the sliding motion. Advantageously, by fixating the wearable device 100 with one finger, the user may a provide control input solely by sliding the finger 144 across the outer surface 102 of the wearable device 100 without incurring a rotation of the wearable device 100.

[0043] As an alternative, the user may prefer to grip and rotate the wearable device 100, rather than sliding the finger 114 across it’s outer surface 102 to provide control input. In the present context, “gripping” is understood to involve more than one finger touching the outer surface 102 and applying pressure greater than a threshold pressure on the outer surface 102. In practice, the first touch sensor 104 may be operative to detect the fingers 114 gripping the outer surface 102. The wearable device 100 may further be operative, in response to detecting fingers gripping the wearable device 100, to generate the control signal 206 using the rotary displacement of the wearable device 100 relative to the body part 112. In this case, the control signal 206 is not generated based on a detected distance covered by the finger 114 sliding across the outer surface, since the fingers 114 grip the wearable device 100 to rotate it and thereby prevent sliding of the finger 114 across the outer surface 102.

[0044] By measuring the pressure applied by one or more fingers on the outer surface 102, the duration of touch by the fingers on the outer surface 102, and / or the number of fingers on the outer surface 102, the first touch sensor 104 may determine if the fingers are touching, fixating, or gripping, the wearable device 100. For example, a touch gesture may involve a brief contact by at least one finger 114 on the outer surface 102, where the duration of contact is shorter than a threshold time. On the other hand, a fixate gesture may involve at least one finger 114 touching the outer surface 102 for a longer duration which is longer than a threshold time. Furthermore, when at least two fingers 114 apply a pressure on the outer surface 102 that is higher than a threshold pressure, the gesture may be classified as a grip gesture. On the contrary, at least one finger 114 applying a pressure on the outer surface 102 that is less than a threshold pressure may be classified as a touch gesture.

[0045] In an embodiment, the wearable device 100 may transmit the control signal 206 using a wireless communication module 110 comprised in the wearable device 100 to one or more computing devices, e.g., smartphones, tablets, TVs, gaming consoles, smart home devices, and other computing devices. The control signal 206 may be used for controlling various functions in the computing device(s). Examples of such functions include, but are not limited to, scrolling a page, answering phone calls, adjusting a volume, changing a channel, selecting a menu item, changing brightness of a lamp, controlling music playback, adjusting smart home settings, etc. The wireless communication module 110 may transmit the control signal 206 to the one or more computing devices via NFC, Bluetooth, Wi-Fi, ZigBee, Cellular communications such as 4G, 5G, Device-to-Device (D2D) communications, etc.

[0046] The wearable device 100 may include a power source 202. In an embodiment, the power source 202 may be a battery that is used to power the wearable device 100. For example, the battery may be a Lithium-Ion battery. Alternately, the power source 202 may be a capacitor paired with an energy harvesting component, such as a piezoelectric generator or a solar cell. The energy harvesting component converts energy from the environment, such as mechanical energy or light energy, into electrical energy. The electrical energy is then stored in the capacitor for later use. The wearable device 100 may also include a memory 204. The memory 204 may, for example, be a flash memory, RAM, EEPROM, etc. The memory 204 may be used, for example, to store operating system files, user data, and applications.

[0047] FIG. 3 illustrates a flowchart of a method 300 of generating a control signal 206, the method 300 being performed by the annularly shaped wearable device 100 worn on a body part 112 of the user, in accordance with embodiments of the invention. The method 300 comprises detecting 304 a distance covered by a finger 114 touching an outer surface 102 of the wearable device 100 in a sliding motion across the outer surface 102. The distance covered by the finger 114 touching the outer surface 102 is detected 304 by the first touch sensor 104 comprised in the wearable device 100. The method 300 further comprises detecting 306 a rotary displacement of the wearable device 100 relative to the body part 112. The rotary displacement of the wearable device 100 is detected 306 by the rotational sensor 108 comprised in the wearable device 100. The method 300 further comprises generating 308 a control signal 206 based on a composite of the distance covered by the finger 114 sliding across the outer surface 102 and the rotary displacement of the wearable device 100 relative to the body part 112. It will be appreciated that the method 300 may comprise additional, alternative, or modified, steps in accordance with what is described throughout this disclosure, in particular in relation to embodiments described in respect of the first aspect of the invention.

[0048] The control signal 206 may be generated 308 based on the composite of the distance covered by the finger 114 sliding across the outer surface 102 and an arc length corresponding to the rotary displacement of the wearable device 100 relative to the body part 112.

[0049] The control signal 206 may be generated 308 based on the composite of the rotary displacement of the wearable device 100 relative to the body part 112 and an angular displacement corresponding to the distance covered by the finger 114 sliding across the outer surface 102.

[0050] The control signal 206 may be generated 308 based on the composite of the distance covered by the finger 114 sliding across the outer surface 102 and the rotary displacement of the wearable device 100 relative to the body part 112 in response to detecting 302 one finger touching the outer surface 102. Optionally, in response to detecting 310 more than one finger 114 touching the outer surface 102 in a sliding motion, the control signal 206 may be generated 312 using an average of the distances covered by the more than one finger 114. Alternatively, in response to identifying a specific finger 114 touching the outer surface 102 by the fingerprint sensor, the control signal 206 may be generated 314 based on the distance covered by the specific finger 114.

[0051] Further, in response to detecting 316 more than one finger 114 gripping the wearable device 100, the control signal 206 may be generated 318 using the rotary displacement of the wearable device 100 relative to the body part 112. As a further alternative, in response to detecting 320 one finger touching the outer surface 102 in a sliding motion and at least one finger fixated on the outer surface 102 of the wearable device 100, the control signal 206 may be generated 322 using the distance covered by the finger 114 touching the outer surface 102 in the sliding motion.

[0052] The method 300 may further comprise transmitting the generated control signal 206 to one or more computing devices using the wireless communication module 110 comprised in the wearable device 100.

[0053] The method 300 may further comprise, if the rotational sensor 108 is an optical heart rate sensor operative to detect a heart rate of the user, to cause the optical heart rate sensor to detect the rotary displacement of the wearable device 100 relative to the body part 112 in response to detecting one finger 114 touching the outer surface 102. Optionally, the method 300 may further comprise, in response to detecting one finger 114 touching the outer surface 102, causing the optical heart rate sensor to stop or pause measuring the heart rate of the user.

[0054] Advantageously, the wearable device 100 enables controlling one or more computing devices using the control signal 206, that is generated based on the composite of the distance covered by the finger 114 sliding across the outer surface 102 and the rotary displacement of the wearable device 100 relative to the body part 112.

[0055] Even though advantages of the invention have in some cases been described with reference to some embodiments of the invention, corresponding reasoning applies to other embodiments of the invention as well.

[0056] The person skilled in the art realizes that the invention by no means is limited to the embodiments described above. On the contrary, many modifications and variations are possible within the scope of the appended claims.

Claims

CLAIMS1 . An annularly shaped wearable device (100) adapted to be worn on a body part (112) of a user, comprising:- a first touch sensor (104) for detecting a distance covered by a finger (114) touching an outer surface (102) of the wearable device (100) in a sliding motion across the outer surface (102);- a rotational sensor (108) for detecting a rotary displacement of the wearable device (100) relative to the body part (112); and- a processing circuitry (124) causing the wearable device (100) to be operative to generate a control signal (206) based on a composite of the distance covered by the finger (114) sliding across the outer surface (102) and the rotary displacement of the wearable device (100) relative to the body part (112).

2. The wearable device (100) of claim 1 , being a ring adapted to be worn on a finger, or a bracelet adapted to be worn on an arm or a wrist, of the user.

3. The wearable device (100) of claim 1 or 2, wherein the first touch sensor (104) is a fingerprint sensor.

4. The wearable device (100) of claim 3, being operative, in response to identifying a specific finger touching the outer surface (102) by the fingerprint sensor, to generate the control signal (206) based on the distance covered by the specific finger.

5. The wearable device (100) of any one of claims 1-3, wherein the rotational sensor (108) is an optical sensor, an inertial measurement unit, I MU, or a second touch sensor.

6. The wearable device (100) of any one of claims 1-3, wherein the rotational sensor (108) is an optical heart rate sensor operative to detect a heart rate of the user.

7. The wearable device (100) of claim 6, further operative, in response to detecting one finger (114) touching the outer surface (102), to cause the optical heart rate sensor to detect the rotary displacement of the wearable device (100) relative to the body part (112).

8. The wearable device (100) of claim 7, further operative, in response to detecting one finger (114) touching the outer surface (102), to cause the optical heart rate sensor to stop or pause measuring the heart rate of the user.

9. The wearable device (100) of any one of claims 1-8, wherein the control signal (206) is generated based on the composite of the distance covered by the finger (114) sliding across the outer surface (102) and an arc length corresponding to the rotary displacement of the wearable device (100) relative to the body part (112).

10. The wearable device (100) of any one of claims 1-9, wherein the control signal (206) is generated based on the composite of the rotary displacement of the wearable device (100) relative to the body part (112) and an angular displacement corresponding to the distance covered by the finger (114) sliding across the outer surface (102).11 . The wearable device (100) of any one of claims 1-10, being operative to generate the control signal (206) based on the composite of the distancecovered by the finger (114) sliding across the outer surface (102) and the rotary displacement of the wearable device (100) relative to the body part (112) in response to detecting one finger touching the outer surface (102).

12. The wearable device (100) of claim 11 , being further operative, in response to detecting more than one finger touching the outer surface (102) in a sliding motion, to generate the control signal (206) using an average of the distances covered by the more than one finger.

13. The wearable device (100) of claim 11 , being further operative, in response to detecting more than one finger gripping the wearable device (100), to generate the control signal (206) using the rotary displacement of the wearable device (100) relative to the body part (112).

14. The wearable device (100) of claim 11 , being further operative, in response to detecting more than one finger touching the outer surface (102), with one finger touching the outer surface (102) in a sliding motion and at least one finger fixated on the outer surface (102) of the wearable device (100), to generate the control signal (206) using the distance covered by the finger (114) touching the outer surface (102) in the sliding motion.

15. The wearable device (100) of any one of claims 1-15, further comprising a wireless communication module (110), the wearable device (100) being further operative to transmit the generated control signal (206) to one or more computing devices using the wireless communication module (110).

16. A method (300) of generating a control signal (206), the method being performed by an annularly shaped wearable device (100) worn on a body part (112) of a user, the method comprising:- detecting (304), by a first touch sensor (104) comprised in the wearable device (100), a distance covered by a finger (114) touching an outer surface (102) of the wearable device (100) in a sliding motion across the outer surface (102);- detecting (306), by a rotational sensor (108) comprised in the wearable device (100), a rotary displacement of the wearable device (100) relative to the body part (112); and- generating (308) a control signal (206) based on a composite of the distance covered by the finger (114) sliding across the outer surface (102) and the rotary displacement of the wearable device (100) relative to the body part (112).

17. The method (300) of claim 17, further comprising performing operations of any of claims 2 to 16.

18. A computer program comprising instructions which, when the computer program is executed by an annularly shaped wearable device (100), causes the wearable device (100) to carry out the method (300) according to any one of claims 16 to 17.

19. A computer-readable data carrier having stored thereon the computer program according to claim 18.

20. A data carrier signal carrying the computer program according to claim 18.

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