A method and apparatus for providing safe and low-cost force feedback
peripherals for consumer applications. A device microprocessor local to
an interface device is coupled to the host by a first interface bus. The
microprocessor receives host commands from the host computer on the first
interface bus, such as an RS-232 interface, and commands an actuator to
apply a force to a user object, such as a joystick, in response to host
commands. A sensor detects positions of the user object and output
signals to the host on a second interface bus, such as a PC game port
bus, separate from the first bus. In a "recoil" embodiment, a user
initiates force feedback by pressing a button on the joystick, which
sends an activation signal to the actuator. In other recoil embodiments,
the host computer can transmit one or more enable signals and/or
activation signals to the actuator to enable or command forces. A safety
switch of the present invention disables the actuator when the interface
device is not in use and enables the actuator when an amount of weight
over a predetermined amount is placed on the joystick created by a user
grasping the joystick a circuit of the present invention includes a
capacitor for storing power provided by an input signal and supplied to
the actuator when forces are to be output.