7.4 - Research Assignment: Sense and Avoid Sensor Selection

DJI Matrice 100 with the "Guidance" Sense and Avoid System

DJI Matrice 100

DJI continues to position itself at the forefront of high-end commercially developed UAVs, and when it comes to sense and avoid, they are clearly ahead of the pack.  In June of this year, DJI rolled out their Matrice 100 drone that comes equipped with a sense and avoid system (Prindle, 2015).  

The sense and avoid system, called “Guidance” by DJI, uses a combination of visual and ultrasonic sensors that are mounted fore, aft, left, right, and below the aircraft.  This provides 360 degrees of sensing at the horizon, as well as directly below the aircraft.  The data from these sensors is fused using DJI’s vision algorithms to perform the sense and avoid function.  This system also helps the aircraft to hover without GPS at altitudes of up to 65 feet (Guidance, n.d.).  I did note the omission of a sixth sensor mounted on top of the system that would provide coverage above the aircraft to keep it from running into the ceiling or other obstructions such as tree limbs, etc.  In all of the various discussions about this system, I couldn’t find a mention of this as being a concern.    

The Guidance System with Five Sensors and Processor

For the theory of operation on this system, as stated above, the system fuses visual (electro-optical or EO) and ultrasonic (sonar) sensors in order to provide the sense and avoid capability.  These sensors can be seen in the image to the below:

Single EO and Ultrasonic Sensor

The two EO cameras closer to the center, and the sonar sensors mounted farther out.  The EO sensors in this system provide a stereo matching in order to provide depth through the parallax effect of objects when viewed from the two cameras, as well as the ability to track motion (Sun, 2013).  The ultrasonic sensors are used to measure the actual distance from the object(s) that are being seen by the cameras (Wu, 2014).  The vision algorithm fuses the two modalities by continuously tracking visual information and updating the overall world model of the system (Tabkhi, 2014).       

Currently, the Matrice 100 is the only DJI airframe that has this capability.  Unlike other DJI aircraft such as the Phantom 3 or Inspire, the Matrice 100 is “developer-friendly” and was built specifically to support experimental research and development (Popper, 2015).  The Matrice 100 is available for around $3,300 from multiple sources online. 

Below is a list of technical specification on the system from DJI’s website (Guidance, n.d.):

Physical Parameters	Dimensions	Guidance Core: 78.5 mm x 53.5 mm x 14 mm
		Guidance Sensor: 170 mm x 20 mm x 16.2 mm
		VBUS Cable: 200mm
	Weight	Guidance Core: 64 g
		Guidance Sensor (single): 43 g
		VBUS Cable (single)：11.6g
Performance Parameters	Velocity Detection Range	0~16 m/s (From the ground 2 m) (The measurement shall prevail)
	Velocity Detection Accuracy	0.04 m/s (From the ground 2 m)
	Positioning Accuracy	0.05 m (From the ground 2 m)
	Effective Sensor Range	0.20 m ~ 20 m
	External Requirements	Good lighting
		Texture-rich surface with clear patterns
Hardware Parameters	Power Consumption	Max. 12 W (with all five Guidance Sensors)
	Input Voltage	11.1 V~25 V
	Operating Temperature	-10°C ~ 40°C
	System Interfaces	VBUS ✕ 5
		CAN ✕ 1
		USB OTG 2.0 ✕ 1
		UART ✕ 1
	UART Level	3.3V

References:

Guidance. (n.d.). Retrieved December 5, 2015, from https://developer.dji.com/guidance/

Popper, B. (2015, June 8). DJI just released the first consumer drone that can see and avoid obstacles. Retrieved December 5, 2015, from http://www.theverge.com/2015/6/8/8745415/dji-guidance-system-matrice-100-sense-avoid

Prindle, D. (2015, June 9). DJI’s new obstacle avoidance tech aims to make drones crash proof. Retrieved December 4, 2015, from http://www.digitaltrends.com/cool-tech/dji-obstacle-avoidance-matrice-100-guidance/

 Sun, H., Zou, H., Zhou, S., Wang, C., & El-Sheimy, N. (2013). Surrounding Moving Obstacle Detection for Autonomous Driving Using Stereo Vision. Int J Adv Robotic Sy International Journal of Advanced Robotic Systems, 1-1.

Tabkhi, H., Sabbagh, M., & Schirner, G. (2014). Power-efficient real-time solution for adaptive vision algorithms. IET Computers & Digital Techniques, 16-26.

Wu, S. (2014). An optimized ultrasonic sensors system. Sensors & Transducers, 182(11), 33-41. Retrieved from http://search.proquest.com.ezproxy.libproxy.db.erau.edu/docview/1635079504?accountid=27203