A joint angle indication system provides information related to an angular relationship
between a first body part and a second body part that are pivotally coupled at
a joint. The system includes a first arm member attached to the first body part,
and a second arm member attached to the second body part. One end of the second
arm member is pivotally coupled to one end of the first arm member. The system
includes one or more joint angle variation sensors that provide one or more electrical
characteristics that vary based on variation in the joint angle between the first
and second arm members. The joint angle is variable over an angular range that
includes a first angle and a second angle. A biofeedback circuit generates a first
feedback signal when the joint angle is less than or equal to the first angle,
generates a second feedback signal when the joint angle is greater than or equal
to the second angle, and generates no feedback signal when the joint angle is less
than the second angle and greater than the first angle. Preferably, the first and
second feedback signals are audio signals, and the second feedback signal has a
different frequency from the first feedback signal. The system also includes an
angle display circuit that is electrically coupled to the one or more joint angle
variation sensors. The angle display circuit visually displays a joint angle value
based on the one or more electrical characteristics.
