Force feedback joystick with digital signal processor controlled by host

Abstract

A force feedback joystick unit connected to the serial port of a personal computer applies a variety of force effects to the joystick handle in response to commands from the executing personal computer program. Forces are applied to the joystick, which is mounted on a gimbal support for movement in two degrees of freedom, by a pair of drive motors which operate under the control of a digital signal processor (DSP). The DSP is programmed to respond to predetermined commands issued by a program executing on the personal computer to produce basic force effects including a constant force, a spring force proportional to the displacement of the joystick handle from a reference, a damping force proportional to the velocity of the joystick, and a time varying force effect having a selectable waveform, magnitude and period. More complex forces effects are produced by combining the basic effects. Custom force effects can be defined by the executing application program, the definitions being downloadable from the personal computer into the DSP which thereafter produces the defined custom force effect upon subsequent command from the personal computer. Multiple force effects, including both basic predefined effects and complex custom effects can be simultaneously operative and can be independently initiated and terminated by commands from the personal computer.