Robotic mm Wave Collision Avoidance and Imaging Sensors

The mm Wave Radar Sensor (MWRS) provides collision avoidance and imaging capabilities for planetary exploration rovers of the "Sojourner" type. The design is based on the use of the Integrated Phased Array (IPA), developed by Beltran that allows electrical scanning in azimuth plane sectors without any moving mechanical parts. The traveling wave IPA has a low profile design and a simple beam controlled by changing the ferrite's magnetization.

The continuous mode of operation includes linear frequency modulation and special synchronization of frequency and control magnetization changes. As a result there is a set of 50 unmovable beams in the azimuth plane and during the scan the beam direction jumps from one angle position to another.

The working frequency of MWRS is 34 GHz, the scanning sector is 90 degree, the angle resolution in 2.5 degrees, and the range resolution is approximately 0.2 m. The maximum range at which the large obstacles can be detected is 30 m. For ranges greater than 15 m, new areas of operation were explored. For instance, we could determine the distance to a large boulder in the field of view, and thereby determine the position in which large features are visible. The peak power consumption is less than 10 W. If we take into account small sensor speed of approximately 0.1 m/s and long range applications, the average power consumption may be less than 1 W. The sensor's dimensions are 290x120x104 mm.

The MWRS provides information about the distances to possible obstacles and their angular position . The wedge shape screen is created on the computer monitor. This screen represents the set of antenna beams obtained after beam azimuth scanning. Each beam is represented by a sector on the computer screen. Within each sector the weakest reflections are marked in the color black and the strongest in red, with blue, cyan. green and yellow colors in between the black and red.

The Frequency Modulated Continuous Wave  (FMSW) sensor is a complex electronic system that includes millimeter wave components (transmitting and receiving antennas, oscillator, amplifiers and switches), low-frequency components as well as low frequency amplifiers,  filters, digital control, and signal processing circuits. The software for signal processing and the visualization tools are also an integral part of the sensor.

The configuration of the sensor can easily be customized without a total redesign. The radar sensor for planetary exploration is a good prototype for radar collision avoidance sensors used in small airplanes , helicopters and cars. The information obtained estimates the time before a potential collision and gives a map of the obstacles, which shows the least dangerous way to avoid the collision and can be very helpful for navigation under difficult conditions, for example, at night, in fog etc.

Three targets spread on the floor

Radar image of the empty floor

Radar image showing three images on the floor