The integration error could be removed using nonlinear
relative coordinates. The mouse point could be controlled
intuitively on the basis of both the head rotation angle and
velocity. The optical sensor circuit for detecting mouse events
was designed to reduce the effects of ambient light, and the
number of malfunctions caused by drastic changes in the
ambient light in the environment could be reduced. However,
it is inconvenient to use the proposed mouse since help from
others is required while putting on and taking off the mouse.