Position recognition systems are used to determine the position of and track a particular object in 3-dimensions. In robot assisted surgeries, for example, certain objects, such as a surgical instrument, needs to be tracked with a high degree of precision as the instrument is being positioned and moved by a physician.
An infrared signal based position recognition systems use either passive sensors or active sensors. In passive sensors, objects to be tracked such as spherical balls are positioned at strategic locations of the object to be tracked. Infrared transmitters transmit a signal having a predetermined waveform pattern. The spherical balls reflect the signal and the reflected signals are received by infrared signal detectors that are generally located near the transmitters.
In active sensors, the objects to be tracked have their own infrared transmitters and thus generate their own infrared signals in response to the signals transmitted from an infrared transmitter of the position recognition system.
In either active or passive sensors, the responsive infrared signals from the objects to be tracked are received and amplified in a form which is as close to the original infrared signals as possible. The amplified signal is then converted into a digital signal which is usable by a signal processor. The system then geometrically resolves the 3-dimensional position of the spherical balls based on one or more of the converted digital signals, cameras, digital waveform shape of the amplified signals, known locations of the spherical balls, distance, the time it took to receive the responsive signals, or a combination thereof.
One problem is that due to attenuation of infrared signals, the conventional position recognition systems have a relatively limited working range of distance between the system and objects to be tracked. Typically, the working range is limited to about 3-5 meters, at best, before the amplified signal loses sufficient original waveform information to be useful.
Moreover, conventional systems require relatively high bandwidth, high slew rate amplifiers which involve complex and expensive circuits. Therefore there is a need to provide an improved system and method for recognizing the 3-dimensional position of an object, which has a longer working range, is accurate, and is less expensive.