Patent Publication Number: US-2022214741-A1

Title: Human-Machine Interaction Device

Description:
TECHNICAL FIELD 
     The invention relates to a human-machine interaction (HMI) device. 
     BACKGROUND 
     Human-machine interaction generally relates to the communication and interaction between a human and a machine (e.g. electrical device) via a user interface. Traditional user interfaces include buttons, actuators, keyboards, and touch sensitive screens. More-recent user interfaces include voice control interfaces, gesture control interfaces, etc. Ideally, the user interface should enable intuitive control of complex machines or machine operations. 
     SUMMARY 
     In a first aspect, there is provided a human-machine interaction device. The human-machine interaction device comprises: a flexible substrate for mounting to a user; a sensing module arranged to sense deformation of the flexible substrate when the flexible substrate is mounted to the user and in response generate a sensed signal; a controller operably connected with the sensing module and arranged to process the sensed signal to obtain a processed signal; and a communication module arranged to communicate the sensed signal or the processed signal to an external electrical device for controlling operation (e.g., movement) of the external electrical device. The deformation may include stretching, twisting, and/or bending of the flexible substrate. 
     The human-machine interaction device is a wearable device arranged to be worn by the user. The human-machine interaction device may be an epidermal human-machine interaction device. The human-machine interaction device may be in direct skin contact with the user or alternatively indirectly attached to the user. The human-machine interaction device may be mounted to one or more joints of the user. The joint may be knuckle joint, wrist joint, carpometacarpal joint, elbow joint, shoulder joint, leg end joint, knee joint, ankle joint, etc. 
     Optionally, the sensing module comprises one or more sensors arranged to detect change in strain, stress and/or pressure applied to the flexible substrate. The one or more sensors may include strain sensor(s), stress sensor(s), and/or pressure sensor(s). In one example, the sensing module may include two or more strain sensors each arranged to detect change in strain along a respective direction (e.g., respective principal strain axes). 
     Optionally, the sensing module comprises one or more sensors arranged to detect strain, stress and/or pressure applied to the flexible substrate. The one or more sensors may include strain sensor(s), stress sensor(s), and/or pressure sensor(s). In one example, the sensing module may include two or more strain sensors each arranged to detect strain along a respective direction (e.g., respective principal strain axes). 
     Optionally, the sensing module comprises a plurality of sensing channels each comprising a piezoresistive sensor. The voltage across the piezoresistive sensor may change based on the deformation. Each of the plurality of sensing channels may further include, at least, a resistor operably connected, e.g., in series, with the piezoresistive sensor. In one example, the piezoresistive sensors are each arranged to detect change of angle of 0-90 degrees and has a sensitivity of 0.025 to 0.030 per degree, e.g., 0.0274 per degree. 
     Optionally, the sensing module and the controller are in direct, wired connection. The direct, wired connection may be provided by undulating, or wavy, conductor strip(s) or lines(s). 
     Optionally, the flexible substrate is made of polydimethylsiloxane (PDMS) and/or polyimide (PI). For example, the flexible substrate may include multiple PDMS layers arranged to encapsulate, or at least partly enclose, the components of the human-machine interaction device. 
     Optionally, the flexible substrate has a color that matches a color of the skin of the user. 
     Optionally, the controller is arranged to determine, based on the sensed signal, a control command for controlling the external electrical device. The control command may be included in the processed signal. In one example, the controller is arranged to compare the sensed signal with entries in a lookup table to determine the control command corresponding to the sensed signal. The lookup table may include entries of sensed signals and corresponding predetermined control commands (e.g., movement commands). The controller may include a memory and the lookup table may be stored in the memory of the controller. 
     Optionally, the communication module is further arranged to receive feedback signals from the external electrical device; and the human-machine interaction device further comprises a feedback module operably connected with the controller and arranged to provide feedback to the user based on the received feedback signals when the flexible substrate is mounted to the user. 
     Optionally, the feedback module and the controller are in direct, wired connection. The direct, wired connection may be provided by undulating, or wavy, conductor strip(s) or lines(s). 
     Optionally, the feedback module comprises one or more feedback devices arranged to provide haptic feedback to the user. 
     Optionally, the feedback module comprises a plurality of feedback channels each comprising a vibratory actuator. 
     Optionally, the feedback signals received from the external electrical device includes pressure information, and the vibratory actuators are arranged to provide haptic feedback with vibration intensity, duration and/or pattern corresponding to the pressure information included in the feedback signals. In one example, the vibratory actuators are each arranged to provide a vibratory amplitude of 0-0.3 mm and a vibratory frequency of 0-250 Hz. 
     Optionally, each of vibratory actuators include a magnet and a coil controlled to interact with the magnet to induce vibration. 
     Optionally, the communication module comprises a wireless communication module. The wireless communication module may include one or more of: a cellular (e.g., 3G, 4G, 5G, or above, LTE) communication module, a Wi-Fi module, a Bluetooth™ communication module, a ZigBee module, an NFC module, an RFID module, etc. In one example, the wireless communication module is a Bluetooth™ communication module. 
     Optionally, the human-machine interaction device further comprises a power source arranged for powering operation of the human-machine interaction device. In one example, the power source comprises a battery (e.g., a Lithium ion battery). 
     Optionally, the power source is a rechargeable power source, and the human-machine interaction device further comprises a charging device for charging the rechargeable power source. The charging device may be a wireless charging device. The charging device may include an antenna with a charging coil (e.g., Copper coil). The charging coil may be formed by undulating, or wavy, conductor strips. 
     Optionally, in plan view, the charging coil is arranged around: the sensing module, the controller, and the communication module, and optionally also the power source and the feedback module. 
     Optionally, the human-machine interaction device further comprises a switch for turning on or off the human-machine interaction device. The switch may be a contact switch or a contactless switch. The switch may take the form of a rotary switch, a slide switch, a toggle switch, etc. 
     Optionally, the human-machine interaction device further comprises an adhesive layer arranged on the flexible substrate to facilitating mounting of the flexible substrate to the user. The adhesive layer may be an adhesive tape. Optionally, the human-machine interaction device further comprises a release liner, the adhesive layer between arranged between the release liner and the flexible substrate. 
     Optionally, the human-machine interaction device is in the form of a single patch arranged to be attached (directly or indirectly) to and worn by the user. 
     Optionally, the sensing module is arranged in or on the flexible substrate. Optionally, the controller is arranged in or on the flexible substrate. Optionally, the communication module is arranged in or on the flexible substrate. Optionally, the communication module is arranged in or on the flexible substrate. Optionally, the feedback module is arranged in or on the flexible substrate. Optionally, the power source is arranged in or on the flexible substrate. Optionally, the charging device is arranged in or on the flexible substrate. 
     In a second aspect, there is provided a human-machine interaction device comprising: a flexible substrate for mounting to a user; a sensing module arranged to sense deformation of the flexible substrate when the flexible substrate is mounted to the user and in response generate a sensed signal; a controller operably connected with the sensing module and arranged to process the sensed signal to obtain a processed signal; a communication module arranged to communicate the sensed signal or the processed signal to an external electrical device for controlling operation (e.g., movement) of the external electrical device and to receive feedback signals from the external electrical device; and a feedback module operably connected with the controller and arranged to provide haptic feedback to the user based on the received feedback signals when the flexible substrate is mounted to the user. The sensing module, the controller, the communication module, and the feedback module are arranged in or on the flexible substrate. The human-machine interaction device may include one or more other features of the human-machine interaction device of the first aspect. 
     In a third aspect, there is provided a system comprising a human-machine interaction device and an external electrical device arranged to be operably connected with and controlled by the human-machine interaction device. The human-machine interaction device is the human-machine interaction device of the first aspect or the human-machine interaction device of the second aspect. The external electrical device may be a moveable device, such as a robot, a vehicle (e.g., unmanned vehicle), an aircraft (e.g., unmanned aircraft), a surgical device or tool, etc. 
     As used herein, the term “machine” in “human-machine interaction” includes machineries and electrical devices such as computers, digital systems, Internet of Things (IoT) devices, vehicles, aircrafts, robots, etc. 
     Other features and aspects of the invention will become apparent by consideration of the detailed description and accompanying drawings. Any feature(s) described herein in relation to one aspect or embodiment may be combined with any other feature(s) described herein in relation to any other aspect or embodiment as appropriate and applicable. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings in which: 
         FIG. 1  is a schematic diagram of a human machine interaction environment in one embodiment of the invention; 
         FIG. 2  is a block diagram of a human-machine interaction device in one embodiment of the invention; 
         FIG. 3  is a circuit diagram of an electrical circuit of a human-machine interaction device in one embodiment of the invention; 
         FIG. 4A  is a photo of a human-machine interaction device in one embodiment of the invention; 
         FIG. 4B  is a schematic diagram of the circuit of the human-machine interaction device of  FIG. 4A ; 
         FIG. 5  is a schematic diagram of a circuit of a human-machine interaction device in one embodiment of the invention; 
         FIG. 6A  is an exploded schematic diagram of a vibratory actuator in one embodiment of the invention; 
         FIG. 6B  is an exploded schematic diagram of a deformation sensor in one embodiment of the invention; 
         FIG. 7A  is a picture showing twisting of a fabricated human-machine interaction device in one embodiment of the invention; 
         FIG. 7B  is a picture showing bending of the human-machine interaction device of  FIG. 7A ; 
         FIG. 7C  is a picture showing stretching of the human-machine interaction device of  FIG. 7A ; 
         FIG. 8A  is a picture showing a fabricated human-machine interaction device in one embodiment of the invention mounted to an arm of a user; 
         FIG. 8B  is a picture showing the fabricated human-machine interaction device mounted to an abdomen of a user; 
         FIG. 8C  is a picture showing the fabricated human-machine interaction device mounted to a leg of a user; 
         FIG. 9A  is a graph showing different transmission signal transmission distances of a fabricated human-machine interaction device placed at different locations relative to its receiver. 
         FIG. 9B  is a graph showing different transmission signal transmission distances of the human-machine interaction device placed with different orientations relative to its receiver. 
         FIG. 9C  is a graph showing the signal delay time for different distances between the human-machine interaction device and its receiver when they are placed face-to-face; 
         FIG. 9D  is a graph showing the signal communication distance between the human-machine interaction device and its receiver when they are placed face-to-face for different thickness of the PDMS film of the human-machine interaction device; 
         FIG. 9E  is a graph showing the electrical signals of the sensing module of the human-machine interaction device at different bending angles; 
         FIG. 9F  is a graph showing the electrical signals of the sensing module of the external electrical device at different applied pressures; 
         FIG. 9G  is a graph showing the full load operation time of the human-machine interaction device (without tactile feedback) at different initial battery voltages; 
         FIG. 9H  is a graph showing the vibration amplitude of the vibratory actuator as a function of frequency of current applied at a contact voltage 1.67V and duty cycle 10%; 
         FIG. 9I  is a graph showing voltage of the battery as a function of time when the human-machine interaction device is wirelessly charged at a constant power of 41 W and a frequency of 13.56 MHz; 
         FIG. 10A  is a picture showing a set-up with a tele-car arranged to be controlled by a human-machine interaction device in one embodiment of the invention; 
         FIG. 10B  is a picture showing the human-machine interaction device worn on a user arranged to control the tele-car in the set-up of  FIG. 10A ; 
         FIG. 10C  is a picture showing the control of right movement of the tele-car in the set-up of  FIG. 10A  using the human-machine interaction device; 
         FIG. 10D  is a picture showing the control of left movement of the tele-car in the set-up of  FIG. 10A  using the human-machine interaction device; 
         FIG. 10E  is a picture showing the control of forward movement of the tele-car in the set-up of  FIG. 10A  using the human-machine interaction device; 
         FIG. 10F  is a picture showing the control of backward movement of the tele-car in the set-up of  FIG. 10A  using the human-machine interaction device; 
         FIG. 11A  is a picture showing a set-up with a 7-degree of freedom (DOF) robotic arm and a human-machine interaction device worn on a user arranged to control the 7-DOF robotic arm in one embodiment of the invention; 
         FIG. 11B  is a picture showing the control of gesture of the 7-DOF robotic arm using the human-machine interaction device; 
         FIG. 11C  is a picture showing the control of gesture of the 7-DOF robotic arm using the human-machine interaction device; 
         FIG. 11D  is a picture showing the control of gesture of the 7-DOF robotic arm using the human-machine interaction device; 
         FIG. 12A  is a picture showing the wearing of human-machine interaction devices on a user&#39;s body for controlling a 13-DOF robot; 
         FIG. 12B  is a picture showing the control of gesture of the 13-DOF robot using the human-machine interaction device; 
         FIG. 12C  is a picture showing the control of gesture of the 13-DOF robot using the human-machine interaction device; 
         FIG. 12D  is a picture showing the control of gesture of the 13-DOF robot using the human-machine interaction device; and 
         FIG. 12E  is a picture showing the control of gesture of the 13-DOF robot using the human-machine interaction device. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows a human machine interaction environment  10  in one embodiment of the invention. The environment  10  includes a user  12 , an electrical device (“machine”)  14 , and a human-machine interaction device  16  arranged to facilitate interaction of the user  12  with the electrical device  14 . The human-machine interaction device  16  may be arranged to enable one-way interaction from the user  12  to the electrical device  14  or two-way interaction between the user  12  and the electrical device  14 . The human-machine interaction device  16  may receive an input from the user  12 , optionally process it, and then provide it to the electrical device  14  to control operation of the electrical device  14 . The human-machine interaction device  16  may further receive an output signal from the electrical device  14 , optionally process it, and then provide it to the user  12  to provide a feedback to the user  12 . In one example, the human-machine interaction device  16  is arranged to be worn by the user  12 . The electrical device  14  may be a movable device such as a robot, a vehicle, an aircraft, a device, or a tool, suitable for use in commercial, domestic, surgical, biomedical, and/or military applications. 
       FIG. 2  shows various modules of a human-machine interaction device  200 . The human-machine interaction device  200  includes a body arranged to hold various components of the human-machine interaction device. In this embodiment, the body is made of a flexible substrate for mounting to or arranged to be worn by a user. The flexible substrate may be made of at least partly of polydimethylsiloxane (PDMS) and/or polyimide (PI). In one example, the flexible substrate may include multiple PDMS layers arranged to encapsulate, or at least partly enclose, the components of the human-machine interaction device. The flexible substrate may have a color that matches a color of the skin of the user. 
     One component of the human-machine interaction device  200  is a sensing module (or sensing device)  202 . The sensing module  202  is arranged to sense deformation (e.g., stretching, twisting, bending) of the flexible substrate and generate a sensed signal. The sensing module  202  may include one or more sensors arranged to detect strain, stress and/or pressure, or change in strain, stress and/or pressure, applied to or associated with the flexible substrate. The sensing module  202  may include two or more strain sensors each arranged to detect strain or change in strain along a respective direction (e.g., respective principal strain axes). In one embodiment, the sensing module  202  includes multiple sensing channels each having a respective piezoresistive sensor. The voltage across the piezoresistive sensor varies based on the deformation (e.g., its extent) of the flexible substrate. Each of the sensing channels may further include a resistor circuit operably connected with the piezoresistive sensor to facilitate detection of the voltage change, which corresponds to the sensed signal. 
     Another component of the human-machine interaction device  200  is a controller  204 . The controller  204  is arranged to process the sensed signal sensed by the sensing module  202  to provide or obtain a processed signal. The controller  204  includes a processor and optionally a memory (storage). The processor may be formed by one or more of: CPU, MCU, controllers, logic circuits, Raspberry Pi chip, digital signal processor (DSP), application-specific integrated circuit (ASIC), Field-Programmable Gate Array (FPGA), or any other digital or analog circuitry configured to interpret and/or to execute program instructions and/or to process signals and/or information and/or data. The memory may include one or more volatile memory (such as RAM, DRAM, SRAM), one or more non-volatile memory (such as ROM, PROM, EPROM, EEPROM, FRAM, MRAM, FLASH, SSD, NAND, and NVDIMM), or any of their combinations. Appropriate computer instructions, commands, codes, information and/or data may be stored in the memory. In one embodiment, the controller  204  is arranged to determine, based on the sensed signal, a control command to be provided to an external electrical device for controlling the external electrical device. The control command (e.g., movement command) may be included in the processed signal. The controller  204  may compare the sensed signal with entries in a lookup table that stores entries of sensed signals and corresponding predetermined control commands to determine the control command corresponding to the sensed signal. In some embodiments in which the controller  204  includes a memory, the lookup table may be stored in the memory of the controller  204 . 
     Another component of the human-machine interaction device  200  is a communication module (or communication device)  206 . The communication module  206  is arranged to communicate the sensed signal sensed by the sensing module  202  or the processed signal provided by the controller  204  to an external electrical device for controlling operation (e.g., movement) of the external electrical device. In some embodiments, the communication module  206  communicates the sensed signal sensed by the sensing module  202  to the external electrical device for further processing. In some embodiments, the communication module  206  communicates the processed signal provided by the controller  204  to the external electrical device for further processing. The communication module  206  may establish one or more communication links with the external electrical device. The communication module  206  may include one or more of: a modem, a Network Interface Card (NIC), an integrated network interface, a NFC transceiver, a ZigBee transceiver, a Wi-Fi transceiver, a Bluetooth™ transceiver, a radio frequency transceiver, an optical port, an infrared port, a USB connection port, or other wired or wireless communication interface(s). The transceiver may be implemented by one or more devices (integrated transmitter(s) and receiver(s), separate transmitter(s) and receiver(s), etc.). The communication link(s) may be wired or wireless for communicating commands, instructions, information, and/or data. In one embodiment, the communication module  206  is a wireless communication module that includes one or more of: a cellular (e.g., 3G, 4G, 5G, or above, LTE) communication module, a Wi-Fi module, a Bluetooth™ communication module, a ZigBee module, an NFC module, an RFID module, etc. The communication module  206  may be further arranged to receive feedback signals from the external electrical device. 
     Another component of the human-machine interaction device  200  is a power source  208 . The power source  208  is arranged to provide power for powering operation of the components of the human-machine interaction device  200 . The power source  208  can be a DC power source (e.g., battery) or an AC power source (e.g., AC mains). The power source  208  may include be a recharge battery that can be charged through wires or wirelessly. In one example, the rechargeable battery includes a Lithium (Li) ion battery. 
     Another component of the human-machine interaction device  200  is a feedback module (or feedback device)  210 . The feedback module  210  is arranged to provide feedback to the user based on the feedback signals received from the external electrical device by the communication module  206 . The feedback module  210  may include one or more feedback devices arranged to provide haptic feedback to the user. In one embodiment, the feedback module  210  includes multiple feedback channels each having a vibratory actuator. In one embodiment, the vibratory actuators can provide tactile feedback of variable vibration intensity, duration and/or pattern to the user. For example, if the feedback signals received from the external electrical device includes pressure or force information, the vibratory actuators can provide haptic feedback with vibration intensity, duration and/or pattern corresponding to the pressure or force information included in the feedback signals. In another example, the controller  204  may analyze the feedback signals or compare the feedback signals with entries in a lookup table that stores entries of feedback signals and corresponding predetermined haptic feedback (vibration intensity, duration and/or pattern) to determine the control signal to be provided to the vibratory actuators. In some embodiments in which the controller  204  includes a memory, the lookup table may be stored in the memory of the controller  204 . 
     The sensing module  202 , the controller  204 , the communication module  206 , the power source  208 , and the feedback module  210 , are arranged to be in data and/or power connection with each other. For example, these components may be connected with each other through one or more conductors or buses. The conductors or buses may be undulating, or wavy, to adapt to the deformation of the flexible substrate without breaking. One or more or all of the sensing module  202 , the controller  204 , the communication module  206 , the power source  208 , and the feedback module  210  may be arranged in or on the flexible substrate. In one implementation, the sensing module  202 , the controller  204 , and the feedback module  210  are hard-wired together. For example, each of the sensing module  202  and the feedback module  210  are in direct wired connection with the controller  204 . 
     The human-machine interaction device  200  may include other components. In some embodiments in which the power source is rechargeable, the human-machine interaction device  200  further includes a charging device for charging the rechargeable power source. The charging device may include an antenna with a charging coil arranged to wirelessly receive charging power from an external charger to charge or power the power source. The charging coil may be arranged to surround the components of the human-machine interaction device  200  for improved charging efficiency. Additionally or alternatively, the human-machine interaction device  200  may include an on/off switch. Additionally or alternatively, the human-machine interaction device  200  further comprises an adhesive layer (e.g., adhesive type, gel, etc.) arranged on the flexible substrate to facilitating mounting of the flexible substrate to the user, and a release liner that protects or hides the adhesive layer prior to use of the human-machine interaction device  200  (the adhesive layer is arranged between the flexible substrate and the release liner). 
     In one implementation, the human-machine interaction device  200  is a wearable device, in the form of a patch, arranged to be worn by the user. The human-machine interaction device  200  may be an epidermal human-machine interaction device, which may be arranged to be in direct skin contact with the user or otherwise indirectly attached to the user. The human-machine interaction device  200  may be mounted to a joint of the user (e.g., knuckle joint, wrist joint, carpometacarpal joint, elbow joint, shoulder joint, leg end joint, knee joint, ankle joint, etc.) to detect the user&#39;s movement. The external electrical device controlled by the human-machine interaction device  200  may be a moveable device, such as a robot, a vehicle (e.g., unmanned vehicle), an aircraft (e.g., unmanned aircraft), a surgical device or tool. 
       FIG. 3  shows an electrical circuit  300  of a human-machine interaction device in one embodiment of the invention. The electrical circuit  300  may be at least partly arranged in or on a flexible substrate, such as one made by PDMS and/or PI. As shown in  FIG. 3 , the electrical circuit  300  includes a power management circuit  302 , a sensor circuit  304 , a data processing circuit  306 , a feedback circuit  308 , and a communication circuit  310 . 
     The power management circuit  302  includes a battery  302 B, an antenna  302 A, and a rectifier circuit  302 R (e.g., diode bridge) arranged between the antenna  302 A and the battery  302 B. The battery  302 B is a Li-ion battery arranged to provide power to the sensor circuit  304 , the data processing circuit  306 , the feedback circuit  308 , and the communication circuit  310  to power their operation. The antenna is provided by a coil and is arranged to operate as a wireless charging interface for receiving power from an external wireless charger to charge or power the battery. The power management circuit  302  also includes a capacitor  302 C connected in series with the rectifier circuit  302 R, with the capacitor  302 C and the rectifier circuit  302 R connected across the antenna  302 A. The capacitor  302 C is arranged to affect a resonant frequency of the antenna. In this example, the antenna  302 A has a resonant frequency of 13.56 MHz, which is compatible with cellphone communication. The power management circuit  302  may further include an on/off switch connected in series with the battery  302 B. 
     The sensor circuit  304  includes 7 sensing channels connected between the battery  302 B and the data processing circuit  306 . The 7 sensing channels are arranged in parallel. Each of the sensing channel includes a piezoresistive sensor  304 S and a resistor  304 R connected in series with the piezoresistive sensor  304 S. The piezoresistive sensor  304 S and the resistor  304 R are connected across the high potential and low potential power lines. The piezoresistive sensors  304 S may be mounted onto joints of the human body (e.g., the user&#39;s body) to sense human body motion hence deformation of the flexible substrate and to convert the sensed deformation into electrical signals. The resistor  304 R facilitates reading out of a voltage change across the piezoresistive sensor  304 S, e.g., induced by deformation of the flexible substrate. The piezoresistive sensors  304 S may operate as strain or pressure sensors. In each sensing channel, between the piezoresistive sensors  304 S and the resistor  304 R is a node for connection with the data processing circuit  306 . The piezoresistive sensors  304 S are in direct wired connection with the data processing circuit  306 . 
     The data processing circuit  306  includes an MCU  306 C. In this embodiment, the MCU  306 C includes a processor and a memory, and is arranged to operate as a controller controlling operation of the circuit  300 . The MCU  306 C is in direct wired connection with the piezoresistive sensors  304 S and is in direct wired connection with the feedback circuit  308 , 
     The feedback circuit  308  includes 5 feedback channels connected between the MCU  306 C and the communication circuit  310 . The 5 feedback channels are arranged in parallel. Each of the feedback channel includes a vibratory actuator  308 A arranged to provide tactile or haptic feedback to the user. The intensity, duration, and/or pattern of vibrations provided by the actuators  308 A are controlled by the MCU  306 C. 
     The communication circuit  310  includes a Bluetooth™ communication module  310 B arranged to communicate with an external electrical device using Bluetooth™ communication link(s). The Bluetooth™ communication module  310 B is arranged to be directly connected to the MCU  306 C. 
     In operation, when the flexible substrate on or in which the circuit  300  is arranged is mechanically deformed (stretched, twisted, bent), voltage across respective piezoresistive sensors  304 S of the sensor circuit  304  change, and this voltage change is detected and processed by the MCU  306 C. The MCU  306 C detects the sensed signals, processes them, and transmits the processed signals to the Bluetooth™ communication module  310 B for communicating the processed signals to the external electrical device to control its operation. In one example, the MCU  306 C processes the sensed signals by comparing the sensed signal with entries in a lookup table to determine a control command corresponding to the sensed signal, and incorporates the control command into the processed signal to be sent to the external electrical device. In some embodiments, the external electrical device may provide feedback signals to the Bluetooth™ communication module  310 B, in which case the feedback signals will be processed by the MCU  306 C. The MCU  306 C then provides control signals to the vibratory actuators  308 A to actuate them, so as to provide some feedback to the user. In one example, the MCU  306 C compares the feedback signals with entries in a lookup table that stores entries of feedback signals and corresponding predetermined haptic feedback (vibration intensity, duration and/or pattern) to determine the control signal to be provided to the vibratory actuators. 
       FIG. 4A  is a prototype of a human-machine interaction device  400  in one embodiment of the invention. In this illustration, the human-machine interaction device  400  includes a flexible substrate and a circuit  300  of  FIG. 3  mounted to the flexible substrate. As shown in  FIG. 4A , in plan view, the antenna coil  402 A is generally arranged around the other components of the human-machine interaction device  400 . 
       FIG. 4B  shows the circuit connections of the human-machine interaction device  400 . The circuit connections include conductor strips or lines. The conductor strips or lines are undulating or wavy such that they can withstand a certain degree of deformation (as the flexible substrate is mechanically deformed). 
       FIG. 5  shows a modelled circuit  500  of a human-machine interaction device substantially the same as the human-machine interaction device  400  of  FIG. 4 . The enlarged views of two portions of the modelled circuit  500  show part of the antenna coil (left) and the MCU (right). 
       FIG. 6A  shows a vibratory actuator  600 A in one embodiment of the invention. The vibratory actuator  600 A can be used as the vibratory actuator (feedback device) in the embodiments of  FIGS. 2 to 5 , among other embodiments. The vibratory actuator  600 A operates based on electromagnet effect. The vibratory actuator  600 A includes an annular ring member  606 A with the top annular surface attached to a polyethylene terephthalate (PET) layer  602 A and the bottom annular surface attached to a PDMS layer  610 A. The annular ring member  606 A may be non-conductive. The bottom surface of the PDMS layer  610 A (opposite the surface attached to the ring) includes an adhesive layer  612 A arranged to be attached to a user or an object. In this example the annular ring member  606 A, the terephthalate (PET) layer  602 A, the PDMS layer  6 ioA, and the adhesive layer  612 A are coaxial with respect to axis X. A coil  608 A and a magnet  604 A is arranged in the central hole of the annular ring member. The coil  608 A may be connected with a controller through conductor wires or lines. The controller may control the current to the coil  608 A to control the vibration generated by the magnet  604 A due to electromagnetic interaction between the coil  608 A and the magnet  604 A. In one example, the controller may provide pulsed current with variable frequencies ranging from 0 Hz to 250 Hz to the coil  608 A to control vibration intensity of the magnet  604 A. In one embodiment, the vibratory actuator  600 A has an overall size of 7 mm diameter and 1.9 mm thickness. In one embodiment the vibration amplitude can increase from 0 mm to 0.3 mm when the frequency increases from 0 Hz to 250 Hz. 
       FIG. 6B  shows a deformation sensor  600 B in one embodiment of the invention. The strain sensor  600 B can be used as the sensor in the embodiments of  FIGS. 2 to 5 , among other embodiments, to detect deformation of the flexible substrate. The deformation sensor  600 B may also be mounted onto an external electrical device (a robot) and operate as a pressure sensor to provide feedback information. The deformation sensor  600 B includes top and bottom PDMS layers  602 B,  608 B, with a piezoresistive element  604  and a PI layer  606 B arranged between the top and bottom PDMS layers  602 B,  608 B. In one embodiment, the deformation sensor  600 B has a length of 30 mm, a width of 10 mm, and a thickness of 1.8 mm. The deformation sensor  600 B may be mounted onto human joints, including knuckle, wrist, elbow, shoulder, leg end, knee, ankle joints, to detect deformation or movement associated with these joints. In one example, the deformation sensor  600 B can be used to detect bending, to support a wide detection angle range from o degree to 90 degrees with a high sensitivity of 0.0274 per degrees. 
     A human-machine interaction device in accordance with the above designs in  FIGS. 3 to 5  was fabricated. The fabricated human-machine interaction device, with the communication module of the electrical circuit  300  of  FIG. 3  mounted at/near its top surface, when mounted to a user&#39;s tummy, can communicate with an external electrical device with the same type of Bluetooth™ communication module mounted at/near its corresponding top surface, with a transmission distance of 4 m. It is found that the transmission distance decreased to 2 m when the human-machine interaction device and the corresponding receiver (of the external electrical device) are placed side-by-side with the top surface of the human-machine interaction device and the top surface of the external electrical device both facing upwards. The delay time between the transmitter and receiver (the two communication modules) can be decreased to 2 μs, which is beyond the human perception. The communication module of the human-machine interaction device may be in communication with a computer, or like information handling system, to extend the data transmission range of the human-machine interaction device. It was also found that the thickness of the encapsulation layer (PDMS) enclosing the Bluetooth™ communication module of the human-machine interaction device affects the communication performance. By optimizing the thickness of the PDMS layer on the top of the Bluetooth communication module of the human-machine interaction device, the transmission distance between human-machine interaction device and the correspond receiver (of the external electrical device) was extended from 1.32 m to 2.96 m (with the human-machine interaction device mounted onto a human arm in a face-to-face arrangement with the external electrical device). The electrical characteristics of the battery, including its operation time, stand-by time, and wireless charging time, were studied. It was found that the human-machine interaction device could continuously operate for over 240 minutes (without operating the actuators), and can operate over  20  minutes for the full load operation. The battery can maintain a stable voltage, which varies from 4.081 V to 4.062 V in 334 h. The wireless charging means can charge the battery from 3V to 4V in about 35 mins as the coupled coil (diameter of 2 cm; 10 cycles; 1Ω resistance) can provide high power (41 W) with a frequency of 13.56 MHz. The encapsulation layer is made as a skin-color encapsulation layer which makes the device visually less prominent (and perhaps more aesthetically pleasing) when worn by the user. 
       FIGS. 7A to 7C  illustrate deformation of the fabricated human-machine interaction device. The fabricated human-machine interaction device is based on the device  400  in  FIG. 4  but includes an additional encapsulation layer (e.g., PDMS layer) arranged on the device  400  to enclose or encapsulate the device components. In this example the fabricated human-machine interaction device has a length of 70 mm, a width of 50 mm, and a thickness of 2 mm.  FIG. 7A  shows the fabricated human-machine interaction device being twisted.  FIG. 7B  shows the fabricated human-machine interaction device being bent.  FIG. 7C  shows the fabricated human-machine interaction device being stretched. In these three cases, the fabricated human-machine interaction device can operate normally under the deformation. 
       FIGS. 8A to 8C  illustrate the mounting of the fabricated human-machine interaction device to the user&#39;s arm ( FIG. 8A ), the user&#39;s abdomen ( FIG. 8B ), and the user&#39;s leg ( FIG. 8C ) respective. 
       FIG. 9A  shows different transmission signal transmission distances of the fabricated human-machine interaction device placed at different locations relative to its receiver (of the external electrical device). In all of A 1  to A 5 , the human-machine interaction device and the receiver are placed face-to-face (i.e., the communication module near/at the top surface of the human-machine interaction device directly facing the communication module/receiver near/at the top surface of the external electrical device). In A 1 , the human-machine interaction device is arranged far away from human body, and the average transmission distance is above 10 m. In A 2 , the human-machine interaction device is mounted to the back of a hand of a user. In A 3 , the human-machine interaction device is mounted to the forearm of the user. In A 4 , the human-machine interaction device is mounted to the tummy of the user. In A 5 , the human-machine interaction device is mounted to a knee of the user. In A 2  to A 5 , the average transmission distance is about 2.5 m to 5 m. 
       FIG. 9B  shows different transmission signal transmission distances of the human-machine interaction device placed with different orientations relative to its receiver (of the external electrical device). In all of B 1  to B 4 , the human-machine interaction device is mounted to a forearm of a user. In B 1 , the human-machine interaction device and the receiver are mounted face-to-face (i.e., the communication module near/at the top surface of the human-machine interaction device directly facing the communication module/receiver near/at the top surface of the external electrical device). In B 2 , the human-machine interaction device and the receiver are mounted side-by-side (i.e., the communication module near/at the top surface of the human-machine interaction device and the communication module/receiver near/at the top surface of the external electrical device both face upwards towards the ceiling/sky). In B 3 , the human-machine interaction device and the receiver are mounted face-to-back (i.e., the communication module near/at the top surface of the human-machine interaction device directly facing the bottom surface of the external electrical device). In B 4 , the human-machine interaction device and the receiver are mounted back-to-back. (i.e., the bottom surface of the human-machine interaction device directly facing the bottom surface of the external electrical device). The average transmission distances in B 1  to B 4  is in the range of about 2 m to about 4 m, with the average transmission distances in B 2  and B 4  lower than average transmission distances in B 1  and B 3 . 
       FIG. 9C  shows the signal delay time for different distances between the human-machine interaction device and its receiver (of the external electrical device) when they are placed face-to-face. As seen from  FIG. 9C , the average delay time for 1 m to 5 m in the range of about 2 μs to about 3.5 μs. 
       FIG. 9D  shows the signal communication distance between the human-machine interaction device and its receiver (of the external electrical device) when they are placed face-to-face for different thickness of the PDMS film of the human-machine interaction device. As seen from  FIG. 9D , the thicker the film the shorter the communication distance. 
       FIG. 9E  shows the electrical signals of the sensing module of the human-machine interaction device at different bending angles (e.g., when the human-machine interaction device, or its sensing module, is bent). The signals are at a substantially constant frequency of 1 kHz. 
       FIG. 9F  shows the electrical signals of the sensing module of the external electrical device at different applied pressures (e.g., when the external electrical device, or its sensing module, is subjected to pressure change). The signals are at a substantially constant frequency of 1 kHz. 
       FIG. 9G  shows the full load operation time of the human-machine interaction device (without tactile feedback) at different initial battery voltages. As shown in  FIG. 9G , at 4.2V initial battery voltage, the operation time can be over 240 minutes. The lower the initial battery voltage, the shorter the operation time. 
       FIG. 9H  shows the vibration amplitude of the vibratory actuator of the human-machine interaction device as a function of frequency of current applied to the coil of the vibratory actuator, at a contact voltage 1.67V and duty cycle 10%. The resonance frequency is about 250 Hz, with a vibration amplitude of 0.3 mm. 
       FIG. 9I  shows voltage of the battery as a function of time when the human-machine interaction device is wirelessly charged at a constant power of 41 W and a frequency of 13.56 MHz. 
     Further human-machine interaction devices in accordance with the above designs were fabricated and applied in human-machine interaction applications. 
       FIG. 10A  is a set-up with a track and a tele-car arranged in the track and arranged to be controlled by a human-machine interaction device in one embodiment of the invention.  FIG. 10B  shows two human-machine interaction devices each worn on a respective hand of the user.  FIG. 10C  illustrates the movement required by the user controlling the human-machine interaction device to move the tele-car to the right.  FIG. 10D  illustrates the movement required by the user controlling the human-machine interaction device to move the tele-car to the left.  FIG. 10E  illustrates the movement required by the user controlling the human-machine interaction device to move the tele-car forward.  FIG. 10F  illustrates the movement required by the user controlling the human-machine interaction device to move the tele-car backward. 
       FIG. 11A  is a set-up with a 7-degree of freedom (DOF) robotic arm and a human-machine interaction device worn on a user arranged to control the 7-DOF robotic arm in one embodiment of the invention.  FIG. 11B  shows movement of the 7-DOF robotic arm in accordance with movement of the user&#39;s finger.  FIG. 11C  shows movement of the 7-DOF robotic arm in accordance with the user clinching his/her fist.  FIG. 11D  shows movement of the 7-DOF robotic arm in accordance with the user&#39;s movement to facilitate oral sampling. 
       FIG. 12A  shows the wearing of human-machine interaction devices on a user&#39;s body for controlling a 13-DOF robot.  FIGS. 12B to 12E  illustrate various controls of gesture of the 13-DOF robot by the user wearing the human-machine interaction devices. 
     The invention has provided a human-machine interaction device is particularly suitable for (but not limited to) use as interface between human users and movable electrical devices (e.g., movable machines, robots, vehicles, aircrafts, etc.). The human-machine interaction device enables users to remotely manipulate various movable or robotic devices, including but not limited to driverless vehicles, complicated robots, etc. Some embodiments of the human-machine interaction device further offers a tactile (force) feedback to enhance the interactivity between the human user and electrical device. The human-machine interaction device can be mounted onto human skin without causing irritation to the skin, hence is easy and intuitive to carry and manipulate for controlling an external “machine”. 
     The human-machine interaction devices of the embodiments of the invention can be used in various applications such as in the commercial, biomedical, and military fields. In one commercial application, the human-machine interaction device can be used to control movement of an unmanned car even when the user is away from the vehicle. In another commercial application, the human-machine interaction device can be used by pilots to control movement of aircrafts. The human-machine interaction device could be used by injured or disabled user. For example, a user with hand disability or injury can remotely manipulate a robot to carry heavy goods through the human-machine interaction device. In one biomedical engineering application, the human-machine interaction device could be worn or otherwise carried by doctors to remotely control a surgical or therapeutic robot to perform surgery or therapy. In another biomedical engineering application, the human-machine interaction device could be worn or otherwise carried by medical workers to perform nasal and throat swabs, with the medical workers away from the potentially infected patients or persons. In one military application, the human-machine interaction device could be used to remotely control a device to defuse a bomb. 
     It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the invention as shown in the specific embodiments to provide other embodiments of the invention. The feature(s) of the human-machine interaction device  200  and the feature(s) of the circuit  300  may be selectively combined, or modified, to provide other human-machine interaction device embodiments. The described embodiments of the invention should therefore be considered in all respects as illustrative and not restrictive. 
     For example, the human-machine interaction device may be arranged in a distributive manner such that different electronic components are arranged on two or more different devices operably connected with each other. In some embodiments, the human-machine  30  interaction device may include no feedback module, no charging circuit, no integrated power source, etc. The feedback module may provide visual and/or audible feedback, in place of or in addition to tactile feedback.