Melexis utilizes time-of-flight technology for collision avoidance system

September 12, 2011 //By Christoph Hammerschmidt
Chipmaker Melexis has licensed SoftKinectic's DepthSense range-sensing technology and plans to use it to implement a collision avoidance system. The versatile system will also be used for other automotive systems in the future.

DepthSense was invented by Belgian software company SoftKinetic which has significant expertise in processing 3D optical information. Subsequent advances and developments have been the result of close cooperation between SoftKinetic and Melexis. Melexis said in a release it plans to integrate DepthSense in solutions which enable next-generation comfort and safety systems for the automotive industry. Besides collision avoidance, other possible applications include gesture detection and parking assistance.

The system aims at detecting and avoiding collisions with obstacles around the vehicle. Towards this end, Melexis develops camera sensors with Time Of Flight pixels that allow 3-dimensional imaging with high resolution and accuracy. The sensor technology is developed in standard CMOS, allowing systems to achieve very high integration levels at low cost.

An optical Time-Of-Flight (TOF) range sensor is a system that measures the time for light to travel between 2 points in space. As the speed of light is constant it allows measurement of the distance between those 2 points. Several well-known methods exist to perform this type of measurement.

The principle of operation is described as follows:

  • A light source illuminates the scene with modulated NIR (near infrared) light.
  • The NIR light source and the sensor typically operate in sync at modulation frequencies of 20 MHz.
  • The time delay of the light traveling from the light source to objects in the scene and back to the sensor results in a phase delay of the detected light with respect to the reference signal.
  • The sensor detects the reflected NIR light, both in amplitude and in phase.
  • The sensor translates this phase delay into an electrical output signal for each pixel.

SoftKinetic'S DepthSense technology represents the heart of Melexis' optical Time Of Flight. According to Melexis, the principal advantage of DepthSense compared to other range sensor technologies is the combination of high sensitivity and low noise.

The solution will be demonstrated at the International Motor Show in Frankfurt.