Three-Dimensional Binocular Range Sensor LSI with Enhanced Correlation Signal

Abstract

We developed a three-dimensional (3D) binocular range sensor LSI with an enhanced correlation signal. The developed LSI chip was produced using a process of 0.35 µm complementary metal oxide semiconductor (CMOS) 1-poly 3-metal and has a die size of 4.20×3.33 mm2. The chip uses a 3.0 V supply voltage and has a power consumption of 280 mW at a clock frequency of 10 MHz. Two image sensors and the circuits for binocular stereo vision are integrated into the sensor. The distance to an object is determined by calculating the correlation between the two photosensors' output differential signals and observing the position of strong correlated values. However, in the previously developed range sensor, the correlation was weak when there was a small differential signal and it was unable to simultaneously detect several objects. In the newly developed range sensor, a circuit that modulates the differential signal was integrated and the correlation process was enhanced. The object detection signals are ten times larger than those of the previous sensor. As a result, we were able to simultaneously detect the 3D position of several objects. All the necessary calculations for 3D detection take 32 µs per frame. However, the output time for one 3D frame is 26 ms. Thus, the frame rate is limited to 38 frames per second.

Binocular range-sensor LSI with improved distance detection precision by coordinated pixel placement

“…We previously developed binocular range-sensor LSIs that solve the above problems [9,10,11]. We realized a small low-cost obstacle recognition system by integrating two image sensors and all the processing circuits on a single chip.…”

“…The APWC circuit can control the logic threshold value through the bias voltage [9,11]. If the bias voltage is changed with time, the output signal inverts when the logic threshold exceeds the input voltage.…”

“…The DIF circuit compares the output of two adjacent APWC circuits [9,11]. The DIF circuit output is determined by the difference between the two pulses.…”

“…The DSWM circuit can remove the small noiselike signal and modulate the input signal pulse width [9]. The ICC circuit removes the correlation response in places where there is no brightness difference [9,11].…”

“…The ICC circuit removes the correlation response in places where there is no brightness difference [9,11]. As a result, the correlation response becomes clear.…”