« PreviousContinue »
CONTROLLING HAPTIC SENSATIONS FOR
VIBROTACTILE FEEDBACK INTERFACE
CROSS REFERENCE TO RELATED
 This application claims the benefit of and is a continuation of patent application Ser. No. 09/669,029, which is incorporated herein by reference for all purposes. In addition, this application claims the benefit of Provisional Patent Application No. 60/156,354, filed Sep. 28, 1999 by Goldenberg et al., entitled, "Controlling Force Sensations for Vibrotactile Feedback Interface Devices," and which is incorporated herein by reference for all purposes.
 The present invention relates generally to control techniques for human-computer interface devices, and more specifically to controlling vibrotactile haptic sensations from a vibrotactile feedback device.
SUMMARY OF THE INVENTION
 The present invention is directed to mapping kinesthetic force sensations to vibrotactile sensations output by a vibrotactile feedback device connected to a computer. Sophisticated vibrations can be output from a haptic feedback device that includes driver electronics driving a rotating mass in one direction, and allowing the magnitude and frequency of the resulting vibrations to be controlled independently. Other kinesthetic force effects can be mapped to other vibrations and motor control methods.
 More specifically, one aspect of the present invention relates to a method for controlling a vibrotactile interface device, such as a gamepad, mouse, etc., from a host microprocessor. A desired haptic effect to be output by the vibrotactile interface device to a user is determined, and effect information is provided to the vibrotactile device, the information describing a magnitude and a frequency that are independent of each other. Aperiodic control signal based on the effect information drives a rotary motor of the vibrotactile device to cause a mass to rotate, where the rotation of the mass causes a vibration having the magnitude and frequency to be output to the user. The magnitude of the vibration is based on a duty cycle of the control signal, and the frequency of the vibration is based on a frequency of the control signal. In one embodiment, the control signal can be either on or off, where the control signal is turned on for an on-time for each period of the vibration, which determines the magnitude of the vibration. The provided information can include a higher level command and at least one parameter that is parsed by the device, or the information can be substantially equivalent to the control signal. The control signal may drive the motor in only one direction.
 In another aspect of the present invention, a method for providing a vibration for a haptic feedback device coupled to a host microprocessor includes providing an actuator for the haptic feedback device, the actuator including a rotatable mass, and receiving information at the haptic feedback device which causes a control signal to be produced. The control signal controls the actuator to rotate the mass about an axis of rotation such that the mass rotation induces a vibration in the device, where a magnitude and a
frequency of the vibration can be adjusted independently of each other by adjusting the control signal. A magnitude of the vibration is based on a duty cycle of the control signal and a frequency of the vibration is based on a frequency of the control signal. The control signal can be applied at a predetermined point in time of every period of the vibration. An on-time of the control signal can be determined as a percentage of a period of the vibration, or as a predetermined amount of time for each period. Methods can be used to ensure the mass is rotating, such as sending an initial control signal to said actuator to start the mass rotating before the vibration is output. A haptic feedback device including similar features is also disclosed. Some embodiments can cause the mass to move bidirectionally.
 In another aspect of the present invention, a method for allowing kinesthetic haptic effects to be output on a vibrotactile interface device includes receiving a command describing a kinesthetic haptic effect that is intended to cause forces to be output in at least one degree of freedom of a manipulandum of a kinesthetic haptic feedback device that is manipulated by a user. The kinesthetic haptic effect is mapped to a vibrotactile haptic effect that is intended to cause vibrotactile forces to be output to a user contacting the vibrotactile device. The vibrotactile haptic effect is provided to be output by the vibrotactile interface device. The kinesthetic haptic effect can be a periodic effect having a specified magnitude and frequency, where the mapped vibrotactile haptic effect is a vibration having an equivalent magnitude and frequency. The kinesthetic haptic effect can also be a nonperiodic effect, such as a spring, damper, obstruction, or vector force, and the mapped vibrotactile haptic effect can be a vibration having a magnitude based on a magnitude of the nonperiodic effect.
 The present invention advantageously provides methods for outputting more sophisticated force effects on a vibrotactile interface device. A vibrotactile feedback device of the present invention can independently control and specify the magnitude and frequency of vibrations output by a eccentric rotating mass motor using duty cycle and frequency of a control signal and can use low-cost uni-directional amplifiers and control circuitry. Techniques for mapping kinesthetic force effects to vibrotactile effects allow software designed to control kinesthetic force feedback devices to control haptic effects for vibrotactile devices. Less-expensive vibrotactile devices thus are a viable alternative to a purchaser to experience compelling haptic feedback in a variety of existing computer applications.
 These and other advantages of the present invention will become apparent to those skilled in the art upon a reading of the following specification of the invention and a study of the several figures of the drawing.
BRIEF DESCRIPTION OF THE DRAWINGS  FIGS. 1 and 2 are perspective views of gamepad vibrotactile interface devices which can be used with the present invention;
 FIG. 3 is a top view of an interior of the gamepad device of FIG. 1;
 FIG. 4 is a block diagram of a vibrotactile interface device suitable for use with the present invention;
 FIG. 5 is a graph illustrating a control signal of the present invention and resulting output vibration;
 FIG. 6 is a graph illustrating a control signal of the present invention modified from FIG. 5 and resulting output vibration;
 FIGS. 7, 8 and 9 are graphs illustrating control signals of different frequencies and the resulting vibrations; and
 FIGS. 10a and lOfc are force profiles illustrating a kinesthetic spring force and a vibrotactile sensation mapped to the kinesthetic spring force, respectively.
DETAILED DESCRIPTION  This application describes techniques for controlling a vibrotactile interface controller, such as a haptic feedback gamepad, using more sophisticated force effects, as well as techniques for enhancing the vibrotactile feedback output by such vibrotactile controllers. Herein, the term "vibrotactile device" or "vibrotactile feedback device" is intended to refer to any controller or interface device that outputs vibrations to the user of the device, and can include gamepads, handheld steering wheels, fishing-type controllers, joysticks, mice, trackballs, adult devices, grips, remote controls, handheld game devices, flat screens, styluses, etc. In contrast, the term "kinesthetic device" or similar term is intended to refer to devices that provide forces along the axes or degrees of freedom of motion of a manipulandum of the device.
 FIG. 4 is a block diagram illustrating a haptic system 100 suitable for use with the present invention. System 100 includes a host computer 102 and a vibrotactile device 104.
 Host computer 102 is any of a variety of computing or electronic devices. In one preferred embodiment, computer 102 is a personal computer, game console, or workstation, such as a PC compatible computer or Macintosh personal computer, or game console system from Nintendo Corp., Sega Corp., Sony Corp., or Microsoft Corp. In other embodiments, host computer 102 can be a "set top box" which can be used, for example, to provide interactive television functions to users, or a "network-" or "internetcomputer" which allows users to interact with a local or global network using standard connections and protocols such as used for the Internet and World Wide Web. Some embodiments may provide a host computer 102 within the same casing or housing as the interface device or manipulandum that is held or contacted by the user, e.g. hand-held video game units, portable computers, arcade game machines, etc. Host computer preferably includes a host microprocessor, random access memory (RAM), read only memory (ROM), input/output (I/O) circuitry, an audio output device, and other components of computers well-known to those skilled in the art. Other types of peripherals can also be coupled to host computer 102, such as storage devices (hard disk drive, CD ROM drive, floppy disk drive, etc.), printers, and other input and output devices.
 A display device 106 is preferably connected or part of the computer 102 and displays images of a graphical environment, such as a game environment, operating system application, simulation, etc. Display device 106 can be any of a variety of types of devices, such as LCD displays, LED displays, CRT's, flat panel screens, display goggles, etc.
 Host computer 102 preferably implements a host application program with which a user is interacting via the
interface device 104 and other peripherals, if appropriate. For example, the host application program can be a video game, word processor or spreadsheet, Web page or browser that implements HTML or VRML instructions, scientific analysis program, virtual reality training program or application, or other application program that utilizes input of device 104 and outputs haptic feedback commands to the device 104 (or a different layer can output such commands, such as an API or driver program on the host). The host program checks for input signals received from the electronics and sensors of device 104, and outputs force values and/or commands to be converted into forces output for device 104. Suitable software drivers which interface such simulation software with computer input/output (I/O) devices are available from Immersion Corporation of San Jose, Calif.
 Several different layers of programs can be running on the host computer 102. For example, at an application layer, one or more application programs can be running, such as a game program, word processing program, etc. Several sub-layers can also be provided, such as an Application Programming Interface (API) layer (e.g. used in Windows from Microsoft Corp.), and different driver layers. The application program can command forces directly, or a driver program can monitor interactions within an application program and command haptic effects when predetermined conditions are met. In one embodiment, a haptic feedback driver program can receive kinesthetic haptic commands from an application program and can map the commands to vibrotactile commands and effects, and then send the necessary information to the interface device 104.
 Vibrotactile interface device 104 is coupled to host computer 102 by a bi-directional bus 108. The bidirectional bus sends signals in either direction between host computer 102 and the interface device. For example, bus 108 can be a serial interface bus, such as an RS232 serial interface, RS-422, Universal Serial Bus (USB), MIDI, or other protocols well known to those skilled in the art; or a parallel bus or wireless link. For example, the USB standard provides a relatively high speed interface that can also provide power to actuators of device 104.
 Vibrotactile device 104 can, in many embodiments, include a local microprocessor 110. Local microprocessor 110 can optionally be included within the housing of device 104 to allow efficient communication with other components of the device. Processor 110 is considered local to device 104, where "local" herein refers to processor 110 being a separate microprocessor from any processors in host computer 102. "Local" also preferably refers to processor 110 being dedicated to haptic feedback and sensor I/O of device 104. Microprocessor 110 can be provided with software instructions to wait for commands or requests from host 102, decode or parse the command or request, and handle/control input and output signals according to the command or request. In some embodiments, processor 110 can operate independently of host computer 102 by reading sensor signals and calculating appropriate forces from those sensor signals, time signals, and stored or relayed instructions selected in accordance with a high level host command. Suitable microprocessors for use as local microprocessor 110 include the MC68HC711E9 by Motorola, the PIC16C74 by Microchip, and the 82930AXby Intel Corp., for example, as well as more sophisticated force feedback processors such