阅读说明：本技术 用于数模混合触觉效果控制器的系统、设备和方法 (Systems, devices, and methods for digital-to-analog hybrid haptic effect controllers ) 是由 J·M·克鲁兹赫尔南德斯 于 2020-02-21 设计创作，主要内容包括：提供了一种包括数模混合控制电路的触觉使能设备。数模控制电路包括模拟控制电路和至少一个处理器,并且被配置为控制振动致动器以产生有限持续时间的触觉效果。数模控制电路接收来自传感器的运动特性反馈信号,并使用运动特性反馈信号对控制振动致动器的命令信号提供连续调整。(A haptic enabled device including a digital-to-analog hybrid control circuit is provided. The digital-to-analog control circuit includes an analog control circuit and at least one processor, and is configured to control the vibration actuator to produce a haptic effect of finite duration. The digital-to-analog control circuit receives the motion characteristic feedback signal from the sensor and uses the motion characteristic feedback signal to provide continuous adjustment to a command signal controlling the vibration actuator.)

1. A haptic enabled device, comprising:

a vibration actuator;

a sensor configured to measure a motion characteristic of the vibration actuator and output a motion characteristic feedback signal;

a digital-to-analog hybrid control circuit comprising an analog control circuit and at least one processor configured to control a vibration actuator to produce a haptic effect of finite duration by:

generating at a processor a reference signal representing a finite duration haptic effect,

an error signal is provided to the analog control circuit,

a command signal is provided by the analog control circuit to the vibration actuator based on the error signal,

sampling the motion characteristic feedback signal, an

Providing, by the processor, a continuous adjustment of the error signal at a sampling frequency based on the motion characteristic feedback signal and the reference signal, causing the analog control circuit to continuously adjust the command signal to minimize an error between the reference signal and the motion characteristic feedback signal.

2. The haptics enabled device of claim 1, wherein providing continuous adjustment of the command signal is performed according to proportional-derivative control.

3. The haptics enabled device of claim 1, wherein providing continuous adjustment of command signals is performed according to lead compensation control.

4. The haptic enabled device of claim 1, wherein the vibration actuator comprises at least one of a linear resonant actuator, a macro-fiber composite actuator, and a piezoceramic actuator.

5. The haptics enabled device of claim 1, wherein the motion characteristic feedback signal is sampled at a sampling frequency of at least 1 kHz.

6. A method of controlling a vibration actuator by a digital-to-analog hybrid control circuit to produce a haptic effect of finite duration, the digital-to-analog hybrid control circuit comprising an analog control circuit and a processor, the method comprising:

generating, by a processor, a reference signal representing a haptic effect of finite duration,

providing, by the processor, an initial error signal to the analog control circuit, causing the analog control circuit to generate a command signal for activating the vibration actuator,

measuring, by a sensor, a motion characteristic of a vibration actuator over time;

outputting, by a sensor, a motion characteristic feedback signal indicative of a motion characteristic; and

controlling a vibration actuator to provide a haptic effect of limited duration by:

sampling the motion characteristic feedback signal by a processor, an

Providing, by the processor, a continuous adjustment of the error signal at a sampling frequency based on the motion characteristic feedback signal and the reference signal, while providing the command signal by the analog control circuit,

Wherein providing continuous adjustment of the error signal causes the analog control circuit to continuously adjust the command signal to minimize the error between the reference signal and the motion characteristic feedback signal.

7. The method of claim 6, wherein providing continuous adjustment of the command signal is performed according to proportional-derivative control.

8. The method of claim 6, wherein providing continuous adjustment of the command signal is performed in accordance with lead compensation control.

9. The method of claim 6, wherein the vibration actuator comprises at least one of a linear resonant actuator, a macro-fiber composite actuator, and a piezoceramic actuator.

10. The method of claim 6, wherein the motion characteristic feedback signal is sampled at a sampling frequency of at least 1 kHz.

Technical Field

The present invention relates to systems, devices and methods for providing limited duration haptic effects. In particular, the present invention is directed to techniques for providing closed-loop feedback control for a vibration actuator using a digital-to-analog hybrid controller to produce well-defined haptic effects of finite duration.

Background

Haptic actuators for generating vibration effects (i.e., vibration actuators such as eccentric rotating masses, linear resonant actuators, piezoelectric-based actuators, etc.) are commonly used in haptic enabled devices to provide vibration effects of moderate to long duration. Such haptic effects are presented to the user as a buzzing or vibrating sensation. Providing a buzz sensation may be accomplished by energizing the vibration actuator to oscillate many times (e.g., tens, hundreds, or even thousands of times). Such vibration effects are achieved by conventional open loop control techniques of vibration actuators. In these cases, precise actuator control over a limited duration is not required, which can introduce unnecessary costs in device manufacture.

In some cases, it may be desirable to produce a haptic effect of limited duration, where the vibration actuator experiences only a small number (e.g., less than 10) of oscillations. Such haptic effects may be presented to the user as a click rather than a buzz. For example, it may be desirable for these types of clicks to provide a sensation and satisfaction of the mechanical response to touch screen input. Conventionally, open-loop control techniques and hardware are adapted to provide these short duration clicks by, for example, implementing actuator actuation. Maintaining a high quality well-defined feel with sharp edges by open loop braking may require good actuator characterization. Deviations in the characteristics of the actuator from the open loop control scheme may result in a diminished rather than abrupt ending effect. Thus, for example, a difference from the specified resonant frequency of the linear resonant actuator can result in a limited duration haptic effect degradation. Conventional solutions to this problem include post-manufacturing characterization of the actuator output and adjustment of open-loop control parameters.

The invention described herein provides an improved method of generating haptic effects of limited duration in a haptic enabled device.

Disclosure of Invention

Systems, devices, and methods are provided herein that adapt closed-loop feedback control of a vibration actuator to produce precise haptic vibration effects of limited duration. Closed loop feedback control has not heretofore been applied to vibration actuators because it is believed that conventional vibration effects do not require precise control. Conventional haptic enabled devices also do not include the necessary components for closed loop control, and the introduction of these components is believed to unnecessarily increase the cost of these devices. The digital-to-analog hybrid control system described herein is used to inexpensively provide accurate closed-loop control to a haptic enabled device.

Embodiments of the present invention may include a sensor, control circuitry, and a vibration actuator specifically configured to provide closed-loop control capability to produce a vibration effect of limited duration. Embodiments may also include devices and systems incorporating these components and methods of implementing closed-loop control techniques to provide haptic effects of limited duration.

Embodiments herein include a haptic enabled device. The haptic enabled device includes a vibration actuator; a sensor configured to measure a motion characteristic of the vibration actuator and output a motion characteristic feedback signal; a digital-to-analog hybrid control circuit comprising an analog control circuit and at least one processor configured to control a vibration actuator to produce a haptic effect of finite duration. The digital-analog hybrid controller is configured to control the vibration actuator by: generating, at a processor, a reference signal representative of a finite-duration haptic effect, providing an error signal to an analog control circuit, providing, by the analog control circuit, a command signal to a vibration actuator based on the error signal, sampling a motion characteristic feedback signal, and providing, by the processor, continuous adjustment of the error signal at a sampling frequency as a function of the motion characteristic feedback signal and the reference signal, causing the analog control circuit to continuously adjust the command signal to minimize an error between the reference signal and the motion characteristic feedback signal.

Still further embodiments include a method of controlling a vibration actuator with a digital-to-analog hybrid control circuit including an analog control circuit and a processor to generate a haptic effect of finite duration. The method includes generating, by a processor, a reference signal representing a haptic effect of finite duration. The method also includes providing, by the processor, an initial error signal to the analog control circuit to cause the analog control circuit to generate a command signal for activating the vibration actuator; measuring, by a sensor, a motion characteristic of a vibration actuator over time; outputting, by a sensor, a motion characteristic feedback signal indicative of a motion characteristic; and controlling the vibration actuator to provide the haptic effect for a limited time. Controlling the vibration actuator includes sampling the motion characteristic feedback signal by the processor and providing continuous adjustment of the error signal by the processor at a sampling frequency based on the motion characteristic feedback signal and the reference signal while providing the command signal by the analog control circuit, wherein providing continuous adjustment of the error signal causes the analog control circuit to continuously adjust the command signal to minimize an error between the reference signal and the motion characteristic feedback signal.

Drawings

The foregoing and other features and advantages of the invention will be apparent from the following description of embodiments of the invention, as illustrated in the accompanying drawings. The accompanying drawings, which are incorporated herein and form a part of the specification, further serve to explain the principles of the invention and to enable a person skilled in the pertinent art to make and use the invention. The figures are not drawn to scale.

FIG. 1 is a schematic diagram illustrating aspects of a haptic enabled device according to an embodiment of the invention.

Fig. 2A and 2B are schematic diagrams illustrating a digital-to-analog hybrid control circuit implemented via an integrated circuit, according to an embodiment of the invention.

FIG. 3 is a flow chart of an actuator control process consistent with an embodiment of the present invention.

Fig. 4A and 4B are graphs showing LRA test results consistent with an embodiment of the present invention.

Detailed Description

Specific embodiments of the present invention will now be described with reference to the drawings. The following detailed description is merely exemplary in nature and is not intended to limit the invention or the application and uses of the invention. Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding technical field, background, brief summary or the following detailed description.

Embodiments described herein relate to a haptic enabled device. A haptic enabled device consistent with embodiments herein may be configured as a smartphone, tablet computing device, smart watch, fitness band, haptic enabled wearable device, glasses, Virtual Reality (VR), Augmented Reality (AR), and/or Mixed Reality (MR) headset, handheld gaming device, personal computer (e.g., desktop computer, laptop computer, etc.), television, interactive sign, and/or other device that may be programmed to provide haptic output to a user. A haptic-based device consistent with embodiments of the present invention includes a device having one or more vibratory actuators for delivering vibratory effects to a haptic enabled device. In embodiments of the present invention, the haptic enabled device may further comprise user input elements, e.g. control elements such as triggers, buttons, joysticks, touch screens, touch pads, etc. to allow a user to interact with the computer system. The haptic enabled device may also include a peripheral device configured to enhance the ability of the other device, whether haptic enabled or not.

A haptic enabled device consistent with an embodiment of the present invention may include a processing system. A processing system consistent with the embodiments described herein includes one or more processors (also interchangeably referred to herein as processor(s), for convenience), one or more memory units, audio outputs, user input elements, communication units, and/or other components. The processor may be programmed by one or more computer program instructions to perform the methods described herein. A communication unit consistent with the present invention may include any wired or wireless connection device that may communicate or communicate with a peripheral device.

In embodiments of the present invention, the haptic enabled device may be provided separately from a processing system configured to provide haptic control signals to the haptic enabled device. Such a haptic enabled device includes a vibration actuator and the required control circuitry and a power source to activate the vibration actuator. The haptic enabled device provided separately from the processing system may be, for example, a wearable device intended for communication with a central processing system. Haptic enabled devices according to these embodiments may include wristbands, rings, legbands, finger attachments, gloves, glasses, and other types of devices configured to provide haptic output.

Embodiments of the present invention relate to closed-loop feedback control of a vibration actuator via a digital-to-analog hybrid controller to produce haptic effects of finite duration. A feedback control system consistent with embodiments of the present invention is configured to reduce and/or minimize an error between an intended haptic effect represented by a reference signal and an output haptic effect represented by a motion characteristic signal. The reference signal represents a haptic effect intended to be produced by the vibration actuator. In response to the reference signal, a feedback control system as described herein controls the haptic output, which is measured by a sensor that outputs a motion characteristic signal. The feedback system uses the motion characteristic signal to minimize errors in the haptic output.

As used herein, a "vibratory actuator" refers to an actuator configured to generate a haptic effect by oscillating or vibrating in response to a command signal. A vibration actuator consistent with an embodiment of the present invention can generate a haptic effect by oscillating or vibrating at 1Hz or higher. A haptic effect of finite duration refers to a haptic effect that is less than 100ms in duration. The length of the limited duration haptic effect may vary depending on the frequency of the actuator. For example, one oscillation of a 10Hz actuator requires 100ms, and a haptic effect of finite duration may be 100ms or less. In contrast, at 1,000Hz, only 1ms is required for one oscillation, and a haptic effect of limited duration may include 15 oscillations, requiring approximately 15 ms. In embodiments, the limited-duration haptic effect may have a duration of less than 100ms, less than 50ms, 30ms, less than 25ms, less than 20ms, and/or less than 15 ms. In an embodiment, a limited duration haptic effect may employ a vibration actuator operating between 1Hz and 1000Hz for a duration between 15ms and 50 ms. Selection of a limited duration haptic effect duration may be performed based on the type of actuator used, the magnitude of the force or displacement provided by the vibration actuator, and/or the type of effect sought by the designer. In an embodiment, the duration of the limited-duration haptic effect may be determined according to a representative transient time of a vibration actuator generating the haptic effect. A haptic effect of finite duration may be produced by a vibration actuator that performs from 1 to about 15 oscillations, where the number of oscillations transmitted may be selected according to the frequency of the vibration actuator. Embodiments of the present invention also relate to closed loop feedback control of a vibratory actuator to produce a clear haptic effect of finite duration. As used herein, "clear haptic effect" refers to a haptic effect that has a burst cutoff at the completion of the effect.

In an embodiment, a vibration actuator consistent with an embodiment of the present invention may include a macro-fiber composite actuator capable of producing a vibration effect at a frequency between 1Hz and 10,000 Hz. In further embodiments, vibration actuators consistent with embodiments of the present invention may include piezoelectric material-based vibration actuators, such as piezoceramic actuators, capable of producing vibratory effects at frequencies between about 1Hz and 10,000 Hz. In further embodiments, a vibration actuator consistent with embodiments of the present invention may include an LRA capable of producing a vibratory effect at a frequency between approximately 50Hz and 500 Hz. Embodiments of the present invention may employ other types of vibratory actuators, such as ERM actuators, configured to deliver haptic effects by vibrating a component in the frequency range of 1Hz and 10,000 Hz.

Some vibration actuators consistent with embodiments of the present invention (such as LRAs) are designed to provide a resonant response to a frequency input, and typically have a high Q-factor or narrow bandwidth. Such actuators are configured to minimize damping to provide greater efficiency. Thus, the vibrotactile response is maximized when the command signal is provided at the resonant frequency of the vibratory actuator. To prevent waste of energy, such actuators are configured to minimize friction and other sources of damping. When the command signal to the vibration actuator is stopped, the vibration actuator will still oscillate several times at its resonant frequency. Generating a strong haptic effect requires a correspondingly strong signal, which without damping would cause the vibration actuator to oscillate several times before decelerating to a stop. For conventional use of a vibration actuator, this is an acceptable result because a free oscillation of tens of milliseconds after the command signal ceases does not reduce the haptic effect of a vibration or buzz of hundreds of milliseconds. In contrast, a free oscillation of tens of milliseconds would significantly distort the intended 15 millisecond haptic effect.

Closed loop control of a vibration actuator oscillating at high frequency requires high frequency measurement of the motion of such an actuator as well as a high frequency control scheme. An actuator oscillating at 1000Hz cannot be reliably controlled by a control scheme providing commands at 500 Hz. Conventional mobile devices are typically not equipped with digital signal processing circuitry sufficient to implement digital control schemes at high frequencies. While there are processing units that are specifically tailored for high frequency digital control, adding such processing units to mobile devices may mean an unacceptable increase in mobile device expenditures.

Embodiments herein describe the use of a hybrid digital-to-analog control system configured to provide high frequency control through the use of a dedicated analog integrated circuit in conjunction with a digital processing unit. A digital processing unit consistent with an embodiment of the present invention may comprise a central processing unit of a mobile device. Thus, a high frequency closed loop control scheme can be inexpensively added to a haptic enabled device.

FIG. 1 is a schematic diagram illustrating aspects of a haptic enabled device 100 according to an embodiment of the invention. The haptic enabled device 100 includes one or more vibration actuators 105, analog control circuitry 102, one or more motion characteristic sensors 107, and a housing 101. Optionally, the haptic enabled device 100 further comprises a display 106, at least one processor 108, at least one memory unit 120, one or more user input elements 110, one or more audio outputs 109, and one or more communication units 112.

The vibration actuator 105 includes an actuator configured to oscillate or vibrate in response to a command signal. The vibration actuator 105 is configured to produce a haptic effect when oscillating at a frequency in excess of 50 Hz. The vibration actuator 105 may include an actuator configured with a spring-mass oscillation system, such as a Linear Resonant Actuator (LRA) and a voice coil actuator. The vibration actuator 105 consistent with embodiments of the present invention is configured to produce an oscillatory effect ranging between approximately 50Hz and 1000 Hz.

The motion characteristic sensor 107 includes a sensor and a transducer configured to measure motion. The motion characteristic sensor 107 is configured to measure a motion characteristic of the vibration actuator 105 of the haptic enabled device 100. The motion characteristic sensor 107 comprises a sensor configured to determine a motion characteristic of the actuator member. Such motion characteristics may include, for example, vector values such as displacement, force, velocity, momentum, angular velocity, angular momentum, and acceleration, and scalar values such as velocity, distance, and acceleration magnitude. Other motion characteristics may include oscillation characteristics such as frequency, amplitude, and phase. In embodiments, direct measurements of one or more of the above-described motion characteristics may be used to determine values of other motion characteristics. For example, direct measurements of acceleration may be used to indirectly determine velocity and/or displacement. In some examples, system parameters may be stored in memory for use in such determinations. For example, the mass of the system may be stored as a parameter and combined with a measurement of acceleration to allow determination of force. In the example of the motion characteristic sensor 107, the motion characteristic sensor 107 is configured to determine a motion characteristic of a moving mass of the vibration actuator 105. In another example, the motion characteristic sensor 107 is configured to measure the strain of a spring associated with a spring-mass actuator system.

The motion characteristic sensor 107 may be, for example, an accelerometer. The motion characteristic sensor 107 may be implemented as an accelerometer and/or may be a transducer specifically selected to detect motion characteristics of the vibration actuator 105 and/or may be a transducer included within the haptic enabled device 100 for other purposes. For example, haptic enabled device 100 often includes an accelerometer for tilt control or step counting purposes. Such an accelerometer may provide motion characteristics information as does motion characteristics sensor 107. In an alternative embodiment, the motion characteristic sensor 107, implemented as an accelerometer, is oriented to detect motion in the same axis of movement as the vibration actuator 105 is oriented to produce movement.

The analog control circuit 102 for embodiments of the present invention may be a collection of components configured to control the vibration actuator 105. In an embodiment, the control circuit 102 may comprise an integrated circuit containing components dedicated to providing haptic control functionality. For example, the control circuit 102 may include an application specific integrated circuit ("ASIC"), a programmable gate array ("PGA"), a field programmable gate array ("FPGA"), a system on a chip ("SoC"), or other types of integrated circuits. In further embodiments, the control circuit 102 may be implemented entirely in hardware components and may include various electronic components configured to perform the functions discussed herein, such as capacitors, resistors, operational amplifiers, and the like.

Optional components of the haptic enabled device 100 also include a display 106, at least one processor 108, at least one memory unit 120, user input elements 110, an audio output 109, and one or more communication units 112.

Haptic enabled device 100 may include one or more processors 108 and one or more memory units 120. Processor 108 may be programmed by one or more computer program instructions stored in memory unit(s) 120. As described herein, the functions of the processor 108 may be implemented by software stored in the memory unit(s) 120 or another computer-readable or tangible medium, and executed by the processor 108. As used herein, various instructions may be described as performing operations for convenience, but in practice, various instructions program the processor 108 to perform operations.

Various instructions described herein may be stored in memory unit 120, and memory unit 120 may include Random Access Memory (RAM), Read Only Memory (ROM), flash memory, and/or any other memory suitable for storing software instructions. Memory unit(s) 120 may store computer program instructions (e.g., the foregoing instructions) to be executed by processor 108, as well as data that may be manipulated by processor 108.

The processor 108 is configured to operate in conjunction with the analog circuit 102 to provide closed-loop control of the vibration actuator 105 as a digital-to-analog hybrid controller, as discussed in more detail below.

User input elements 110 used with embodiments herein may include any elements suitable for accepting user input. These elements may include buttons, switches, dials, levers, touch screens, touch pads, and the like. The user input elements 110 may also include peripheral connected devices such as a mouse, joystick, game controller, keyboard, and the like. User input elements 110 may also include cameras, radar devices, lidar devices, ultrasound devices, and other devices configured to remotely capture user gestures.

The communication unit 112 according to an embodiment of the present invention may include one or more devices or components configured for external communication. The communication unit may include a wired communication port, such as a USB port, an HDMI port, an a/V port, a fiber optic cable port, and any other component or device configured to receive or transmit information in a wired manner. The communication unit may also include a wireless communication device, such as BluetoothAn antenna,Antennas, cellular antennas, infrared sensors, optical sensors, and any other device configured to wirelessly receive and/or transmit information. In further embodiments, the communication unit 112 may include an ultrasonic speaker and microphone configured to communicate information via ultrasonic waves.

The display 106 used with embodiments of the present invention may be a screen for providing visual output to a user. The display 106 may include touch screen capabilities (and thus also serve as user input elements 110). The display 106 may be of any size, shape, or configuration to accommodate the needs of the haptic enabled device 100. In some embodiments of the haptic enabled device 100, such as a wearable device configured to deliver haptic effects, the display 106 is not required. In embodiments, the display 106 may comprise a head mounted display, such as a VR, AR, or MR headset, goggles, and/or other VR/AR/MR display device. In embodiments, the display 106 may be projected onto a surface or used for display in the air.

Audio output 109 comprises a device configured to provide audio output to a user. The audio output 109 may include a speaker and an audio output port, such as a headphone jack, configured to transmit audio signals to the speaker or headphones. The audio output 109 may also include any hardware and/or antenna required for wireless transmission of audio signals (e.g., via bluetooth protocol).

Fig. 2A and 2B illustrate a digital-to-analog hybrid control system consistent with an embodiment of the present invention. Fig. 2A illustrates a digital-to-analog hybrid control system 111 consistent with an embodiment of the present invention. The digital-to-analog hybrid control system 111 includes an analog control circuit 102 and a digital control circuit 208. The digital control circuit 208 includes at least the processor 108 and the memory unit 120. The digital-to-analog hybrid control system 111 further includes an analog-to-digital converter (ADC)121 and a digital-to-analog converter (DAC) 122. As shown in fig. 2A, the ADC 121 and DAC 122 may be part of a digital control circuit 208. The ADC 121 and DAC 122 may be separate components and/or their functionality may be included as part of the processor 108. In further embodiments, the ADC 121 and DAC 122 may be part of the analog control circuit 102 and/or may not be included in the analog control circuit 102 or the digital control circuit 208. Analog control circuit 102 and digital control circuit 208 cooperate to provide high frequency control of vibration actuator 105 to produce a haptic effect of finite duration.

The analog control circuit 102 is implemented as an integrated circuit in fig. 2A. As shown in fig. 2A, the analog control circuit 102 is an integrated circuit configured as a PID controller. The illustrated embodiment of the analog control circuit 102 is by way of example only, and additional or different analog circuit components and controller schemes may be used without departing from the invention.

The processor 108 receives or generates a reference signal. The reference signal represents a desired haptic output. The reference signal is a time varying signal representing the expected value of the motion characteristic measured over time. The reference signal may be a time varying signal of any motion characteristic, including each of those discussed herein. For example, the reference signal may be an acceleration over time. The reference signal may represent a desired motion characteristic of the vibration actuator 105. In an embodiment, the reference signal may represent desired motion characteristics of different components of the haptic enabled device 100 coupled to the vibration actuator 105. The reference signal may be generated by the processor 108 of the haptic enabled device 100, received from the at least one memory unit 120, and/or may be received from a source external to the haptic enabled device 100. For example, where the haptic enabled device 100 is implemented as a wearable device (such as a bracelet) for providing haptic effects, the reference signal may be communicated from a processor of a larger system with which the wearable device is associated to the processor 108. In an embodiment, the reference signal may track the same parameter as the motion characteristic sensor 107, e.g. when the motion characteristic sensor 107 is an accelerometer, the reference signal may indicate a desired acceleration over time. In still other embodiments, the reference signal may track a different parameter than the motion characteristic sensor 107. For example, when the motion characteristic sensor 107 is an accelerometer, the reference signal may indicate a desired velocity over time.

The processor is configured to receive a motion characteristic feedback signal 222 from the motion characteristic sensor 107. The motion characteristic feedback signal 222 is converted from an analog signal to a digital signal by the ADC 121. The motion characteristic sensor 107 is configured to detect, measure and/or determine at least one motion characteristic of the vibration actuator 103 and to communicate a motion characteristic feedback signal 222 based on the motion characteristic to the processor 108. As discussed above, the motion characteristic sensor 107 may deliver a motion characteristic feedback signal 222 based on a directly measured motion characteristic (e.g., acceleration measured by an accelerometer), and/or may deliver a motion characteristic feedback signal 222 derived from a measured motion characteristic, e.g., a velocity signal derived from acceleration measured by an accelerometer. The motion characteristic feedback signal 222 may also be based on a motion measurement of a portion of the haptic enabled device 100 coupled to the vibration actuator 105. Once received, the motion characteristic feedback signal 222 is converted from an analog signal to a digital signal for processing by the processor 108.

The processor 108 receives (or generates) the reference signal and receives the motion characteristic feedback signal 222 and outputs an error signal 223 to the analog control circuit 102. The processor 108 compares the reference signal to the motion characteristic feedback signal 222 to determine an error therebetween. Based on the error, the processor 108 generates a digital error signal that is converted to an analog error signal 223 by the DAC122, which is then passed to the analog control circuit 102.

The analog control circuit 102 receives the error signal 223. The control portion 104 of the analog control circuit 102 acts as a PID controller for the error signal 223 to produce the unamplified command signal 224. The unamplified command signal 224 of the control section 104 is amplified by the amplifier section 103 to generate the command signal 221.

The command signal 221 is output to the vibration actuator 105 to cause a haptic output. When the vibration actuator 105 is driven by the command signal 221, the haptic output of the vibration actuator 105 is measured by the motion characteristic sensor 107.

The processor 108 receives the motion characteristics feedback signal 222 and compares it to the reference signal to continuously adjust the error signal 223 to continuously adjust the command signal 221 output to the vibration actuator 105 to minimize the error between the reference signal and the motion characteristics feedback signal 222.

As used herein, continuously adjusting means that the signal output by the processor 108 (e.g., the error signal 223) is continuously adjusted during the output of the signal to adjust the haptic effect or output. For digital applications, it is understood that continuous adjustment includes repeated discrete adjustments. As used herein, continuous adjustment does not include parameter adjustment using measurements of haptic output for future haptic effects, even if performed periodically. In an embodiment, the continuous adjustment may be performed digitally at frequencies above 500Hz, above 1k Hz, 5k Hz, 10k Hz and 20k Hz. In an embodiment, the motion characteristic feedback signal 222 is sampled at a frequency equal to or exceeding the continuous adjustment frequency. In an embodiment, the motion characteristic feedback signal 222 is sampled at a frequency that is at least twice the continuous adjustment frequency. These definitions of "continuously adjusting" apply to all embodiments discussed herein and the use of that term.

In the digital-to-analog hybrid control system 111, the processor 108 performs a simple calculation based on the reference signal and the motion characteristic feedback signal 222 to generate the error signal 223. These relatively simple calculations (e.g., as compared to calculations performed by PID control of the analog control circuit 102) can be performed by a central processing unit in a conventional mobile device without the need for a dedicated and specialized digital signal processor. The analog control circuit 102 performs more complex calculations of a PID control scheme or any other suitable control scheme. The hardwired analog nature of the analog control circuit 102 allows the analog control circuit 102 to perform control calculations more efficiently and in a cheaper package than a digital version.

In an embodiment, the processor 108 is further configured to receive or generate an adjusted reference signal during or immediately following the execution of the haptic effect. The desired haptic output may be determined based on user interaction with the haptic enabled device 100, and such requirements may change continuously. The processor 108, which may operate as a central processing unit of the haptic enabled device 100, may update or adjust the reference signal as needed.

In an embodiment, the processor 108 is further configured to adjust a characteristic of the analog control circuit 102. The analog control circuit 102 may be implemented as an integrated circuit, such as an FPGA, with adjustable parameters. The processor 108 may be configured to adjust parameters of the FPGA to adjust parameters of the control scheme implemented by the analog control circuit 102. In an embodiment, the processor 108 may be configured to adjust parameters of the FPGA to correspond to one of a plurality of predefined control schemes to be implemented by the analog control circuit 102. For example, multiple potential FPGA programmed control scheme parameters may be adjusted to produce different control results, e.g., different gains or different damping. In an embodiment, multiple FPGA programming may be configured for optimal performance of driving the vibration actuator 105 at different frequencies. The processor 108 can switch between the multiple FPGA programming to select the preferred analog control circuit 102 based on the reference signal (and the desired haptic effect).

In an embodiment, the digital-to-analog hybrid control system 111 may include a plurality of analog control circuits 102. Each analog control circuit 102 may differ in control scheme parameters. For example, the control scheme parameters of the plurality of analog control circuits 102 may be adjusted to produce different control results, e.g., different gains or different damping. In an embodiment, the plurality of analog control circuits 102 may be configured for optimal performance of driving the vibration actuator 105 at different frequencies. The processor 108 may switch between the plurality of analog control circuits 102 to select a preferred analog control circuit 102 based on the reference signal (and the desired haptic effect).

In an additional embodiment, as shown in FIG. 2B, the digital-to-analog hybrid control system 311 may employ a switch 301 to allow switching between open-loop and closed-loop control. The digital-to-analog hybrid control system 311 may include each of the same elements as the digital-to-analog control system 111, including the analog control circuit 102, the digital control circuit 208, the vibration actuator 105, and the one or more motion characteristic sensors 107. The digital-to-analog hybrid control system 311 also includes a switch 301 and a summing circuit 302.

The digital-to-analog hybrid control system 311 may operate as follows. During open loop operation, switch 301 may be in position a. During open loop operation, switch 301 provides a direct control path between digital control circuit 208 and vibration actuator 105. The digital control circuit 208 outputs a reference signal 224. During open loop operation, the reference signal 224 is the same as the command signal 221, which is received by the vibration actuator to control its output.

During closed loop operation, the switch 301 may be in position B. During closed loop operation, switch 301 provides a path between digital control circuit 208 and summing circuit 302. The digital control circuit 208 provides a reference signal 224 for closed loop operation of the analog control circuit 102. The summing circuit 302 receives the reference signal 224 and the motion characteristic signal 222 from the digital control circuit 208 and outputs an error signal 223 as a difference between the reference signal 224 and the motion characteristic signal 222.

Thus, according to the digital-to-analog hybrid control system 311, the vibration actuator 105 may be controlled alternatively by open-loop or closed-loop control according to the requirements of the haptic enabled device 101.

In embodiments, analog control circuitry 102 may implement any suitable control scheme. For example, the analog control circuit 102 may implement a lead compensation controller. When implemented with an LRA, lead compensation control may be advantageous due to lag of the LRA system at the resonant frequency. When the LRA is excited at the resonant frequency, the initial frequency response exhibits a phase lag relative to the input signal. Lead compensation control may be used to counteract this lag and reduce the error between the reference signal and the motion characteristic feedback signal 222. In other examples, the analog control circuit 102 may implement a proportional controller, a proportional-derivative (PD) controller, a proportional-integral-derivative (PID) controller, a proportional-integral (PI) controller, a lead-lag compensation controller, and/or any other suitable controller.

The digital-to-analog hybrid control system 111 is advantageous when applied to produce haptic effects of limited duration, i.e., effects having a duration less than 100 ms. In an embodiment, the limited duration haptic effect may be between 5 and 50ms and use between 1 and 10 oscillations of the vibration actuator 105. Due to the limited duration of the haptic effect produced by embodiments of the present invention, the digital-to-analog hybrid control system 111 operates to provide continuous adjustment of the command signal 221. This continuous adjustment means that the command signal 221 is adjusted multiple times based on the motion characteristic feedback signal 222 even during very short haptic effects. In an embodiment, the motion characteristic feedback signal 222 may capture motion of the vibration actuator 105 at a sampling frequency in excess of 500Hz, in excess of 1kHz, in excess of 5kHz, in excess of 10kHz, and/or in excess of 20 kHz. The processor 108 may perform updates to the error signal 223 at the same rate as the sampling frequency of the motion characteristic feedback signal 222.

In further embodiments, different portions of the digital-to-analog hybrid controller may be implemented in digital or analog form. For example, in an embodiment, the entire control loop including the error signal may be implemented in analog circuitry, where the digital processor provides the reference signal only to the analog portion of the control loop. In still other embodiments, the digital processor may process a larger portion of the control loop. For example, in a control system employing a PID control scheme, the digital processor may perform the steps required for the P (proportional control) aspect of the control scheme, while the analog circuitry is configured to perform the steps required for I (integral control) and D (derivative control). In such embodiments, the digital processor is configured to transmit the proportional control signal and one or both of the error signal and the reference signal to the analog control circuit. Still further embodiments may include a digital processor and an analog circuit, each performing any aspect of the implemented control scheme.

FIG. 3 depicts a flow chart showing a process 400 of providing closed-loop feedback control of a vibration actuator. Process 400 may be performed by digital-to-analog hybrid control system 111 as discussed herein. As discussed further herein, any portion of a controller suitable for implementing process 400 may be implemented digitally and any portion may be implemented in analog. The closed-loop feedback control implemented by process 400 may be understood to provide close tracking of the desired reference signal, which may include abrupt or abrupt starts and stops. For example, process 400 may provide controlled damping to a controlled system to provide a sharp cut-off or abrupt stop for haptic effects. As discussed above, closed-loop feedback control may be used for only a portion of the haptic effect delivered, e.g., to eliminate excessive vibration at the end of the haptic effect. Such an embodiment is consistent with process 400 discussed below.

In operation 402, the process 400 includes receiving (or generating) a reference signal. The reference signal represents a haptic effect that the haptic enabled device is attempting to produce. The goal of process 400 is to reduce the error between the measured haptic effect (i.e., measured by the motion characteristic feedback signal) and the haptic effect intended to be produced by the reference signal. The embodiments discussed herein are well suited for generating clear haptic effects of less than 50ms, less than 30ms, less than 20ms, less than 15ms, and less than 10 ms.

In operation 404, the process 400 includes providing an initial error signal to the analog control circuit to generate a command signal to cause the vibration actuator to deliver a haptic effect of finite duration. An initial value of the error signal is selected to initiate movement of the vibration actuator and cause a haptic effect of finite duration. The initial value of the error signal is determined from the reference signal and known characteristics of a feedback system that includes at least the vibration actuator, the component to which it is coupled, and the sensor. While feedback from the sensor will be used to minimize the error between the reference signal and the motion characteristic signal (i.e., the measured haptic effect), selecting an initial error signal value close to that needed to achieve the desired output serves to minimize the error in the early portion of the haptic effect.

In operation 406, the process 400 includes measuring, by a sensor, one or more motion characteristics of a haptic activation component of a haptic enabled device. In an embodiment, the sensor is a motion characteristic sensor as discussed herein. The motion characteristics may include vector values such as displacement, velocity, momentum, angular velocity, angular momentum, and acceleration, and scalar values such as velocity, distance, and acceleration magnitude. The motion characteristic may be directly measured or may be derived from directly measured values. The motion characteristic sensor may be directly or indirectly vibrationally coupled to the vibration actuator.

In operation 408, the process 400 includes outputting, by the sensor, a motion characteristic feedback signal indicative of a motion characteristic for feedback control of the vibration actuator.

In operation 410, the process 400 includes providing the updated error signal to the analog control circuit. The updated error signal is based on a difference between the motion characteristic feedback signal and the reference signal.

In operation 412, the process 400 includes providing, by the processor, a continuous adjustment of the error signal based on the motion characteristic feedback signal and the reference signal while the command signal is continuously provided by the analog control circuit. The continuous adjustment of the error signal minimizes the error between the reference signal and the motion characteristic feedback signal. The motion characteristic feedback signal measures the output haptic effect, and thus the continuous adjustment is used to control the vibration actuator to control the output haptic effect. The feedback system reduces and/or minimizes an error between the intended haptic effect represented by the reference signal and the output haptic effect represented by the motion characteristic signal. In an embodiment, the rate at which the continuous adjustment of the command signal is performed is equal to the rate at which the motion characteristic feedback signal is sampled.

An illustrative flow of an example process 400 of providing closed-loop control of a vibratory actuator to produce a haptic effect of finite duration in accordance with embodiments described herein is described above. The process shown in fig. 3 is merely exemplary, and variations exist without departing from the scope of the embodiments disclosed herein. The steps may be performed in a different order than described, additional steps may be performed, and/or fewer steps may be performed.

Systems and methods consistent with the closed-loop control schemes described herein may allow for the use of actuators having wider characteristic variations than conventional. As discussed above, accurate open-loop control of the actuator requires that the actuator characteristics fall within a narrow range. Characteristics outside this range will cause abnormal behavior of the actuator. However, the use of closed-loop controllers consistent with those described herein allows an actuator with out-of-specification characteristics to perform as an in-specification actuator. This broader acceptance allows the use of less expensive actuators.

Experiments were performed on 20 LRAs, 10 of which were within specification, 10 of which failed quality control. Fig. 4A shows the resonant frequencies of 20 LRAs, illustrating that 10 are within specification and 10 are outside specification. Fig. 4B shows the accelerated response of 5 LRAs within the specification and 5 LRAs outside the specification when producing a clear finite duration haptic effect. These LRAs are controlled via a closed-loop control scheme consistent with embodiments of the present invention. As shown in fig. 4B, the LRAs both within and outside the specification show excellent finite-duration responsiveness. Accordingly, systems, devices, and methods are provided that provide accurate control of a vibration actuator during limited duration haptic effects using a digital-to-analog hybrid closed-loop control system. The precise control methods implemented by embodiments herein allow for the generation of haptic effects with a limited duration of clear or burst completion. While various embodiments in accordance with the present invention have been described above, it should be understood that they have been presented by way of illustration and example only, and not limitation. It will be apparent to persons skilled in the relevant art that various changes in form and detail can be made therein without departing from the spirit and scope of the invention. It will also be understood that each feature of each embodiment discussed herein, and of each reference cited herein, can be used in combination with the features of any other embodiment. In other words, aspects of the above-described methods of rendering haptic effects may be used in any combination with other methods described herein, or these methods may be used alone. The following paragraphs describe additional aspects and embodiments of the invention.