Group 16 Karena Stout Ryan Sivek Alex Balogh

1. Group 16 Karena Stout Ryan Sivek Alex Balogh

2. Background • US Army currently uses the Multiple Integrated Laser Engagement System (MILES) for combat training • System is expensive and somewhat inaccurate • Consists of laser emitters attached to rifle barrels and laser receptors on soldiers' helmets and harnesses to simulate combat

3. AEAS In A Nutshell… • A collection of live, inexpensive, and realistic modern combat simulation tools • Will use electronic sensors to pinpoint weapon and user locations as well as monitor weapon orientation • Detected trigger pulls will cause a message to be sent from the weapon to the main server containing position and orientation information • Server will receive these messages and calculate bullet trajectories using simple Newtonian principles • Users detected to be in the path of the simulated bullet will receive indications that they were hit • A web accessible GUI will provide real-time scenario visualization and data

6. Comparison

7. Positioning System Requirements: • Relatively low cost • Minimum virtual bullet accuracy (deviation/distance) of 0.2% • Minimum weapon orientation precision of • Minimum field dimensions: 25m x 25m x 5m

8. Positioning System Compared optical, GPS, and ultrasonic. Optical: cost effective with webcams, but inaccurate at range GPS: best range, but precision is too expensive. Ultrasonic: poor range, but low cost with recorded absolute error of within 3 centimeters* Our Solution: Ultrasonic positioning • Receivers measure time of arrival of signals from pre-positioned beacons to determine distance. *Bjerknes, J. D., Liu, W., Winfield, A. F., and Melhuish, C. (2007). Low Cost Ultrasonic Positioning System for Mobile Robots. In Wilson, M.S., Labrosse, F., Nehmzow, U., Melhuish, C., and Witkowski, M., editors, Proceeding of Towards Autonomous Robotic Systems, pages 107 - 114, Aberystwyth, UK.

9. Ultrasonic Beacons • Maxbotix MB1200 XL-Maxsonar-EZ0 rangefinders attached to raised plastic rods. • Beacon transmission timing will be controlled by the AEAS server directly. • The Maxsonar-EZ0 has the widest beam of any Maxbotix Range Finder. • Maximum range finding depth of approximately 25 ft (7.6 meters).

10. Positioning Subsystems • Murata MA40S4R ultrasonic receivers. • Modules will have a metallic cone attached to the receiving sensor and be positioned upward to be able to accept signals from all directions. • Will use a two stage amplifier to send signals to the weapon and user modules.

11. Trilateration • Subsystems will use trilateration to determine position. • Uses distances from known beacon positions to determine its own position. • Distance From Beacon = Time of Arrival * Speed of Sound.

12. Height Measurement • Although we could compute height using the trilateration data, we can achieve a more accurate calculation by using the distances from two points on the same pole.

13. Beacon Timing

14. Beacon Timing

15. Beacon Timing (Actual Speed)

16. Communication Requirements • In order for the server to collect information from the weapon and body attachments a link must be established • The communication must be wireless to support the users running, twisting, ducking, and jumping

17. Wireless Communication Choices • Bluetooth – too expensive • Wifi – not designed for point-to-point communication • Infrared – Line of Sight is crucial • Zigbee module – relatively slower and shorter range, but well within requirements of the AEAS system

18. Xbee vs. Xbee-Pro • Size – Xbee-Pro is a bit longer • Power Consumption – Xbee-Pro uses more power • Range – Xbee-Pro has a longer range • Cost – Xbee-Pro is more expensive • Size, power, and cost are worth the longer range -> Xbee-Pro!

19. Network Topology

20. Type of Antenna Dipole Chip Antenna Attached Monopole Whip RPSMA U.FL

21. Xbee-Pro circuit design

22. Receiving Base Station

23. User Identification The AEAS system needs a way to track statistics of the users’ shots fired to hit ratio to track progression of training soldiers. • Each user will make an account • Each time trigger sensor is asserted it will be paired with an ID • Server will collect and calculate statistics

24. User Identification Input • Keypad – too bulky • Barcode Scanner – temperamental and over complicated • RFID – user friendly, fast, and light weight -> The AEAS solution is RFID

25. Type of RFID System • Capacitive – (< 1 cm) Smart cards inserted into a reader, too big with card sticking out • Inductive – (1 cm – 1 m) Smart cards held up to a reader • Backscattering – (> 1 m) security systems in stores, WAY too big! -> Inductive RFID system!

26. RFID Reader Voltage is induced by mutual inductance between the reader’s and the card’s induction coil antennas to power the chip, along with an ID query to the chip The load is changed on the coil antenna to rectify the query signal and return its ID

27. Weapon Orientation Attachment Requirements: • Detachable • Minimum battery life: 5 hours • Minimum clock rate: 1MHz • Must be able to do calculations quickly to get a reasonable bullet response. • Maximum weight: 5 lbs 10cm

29. Orientation Measurement • Invensense MPU-6050. • Includes a Digital Motion Processor (DMP) • offloads the computation of motion processing algorithms from the host processor. • Utilizes the I2C communication protocol. • Maximum theoretical precision of approximately 0.008 degrees. 1mm

30. Orientation Calculations To increase accuracy, our implementation will use a weighted average between accelerometer data and the calculated gyroscope measurements to get the final estimated values.

31. Fire Signal Detection • Fire detection will consist of a modified FlexiForce® 25lb pressure sensor placed on the trigger. • When the trigger is pressed to a predetermined pressure threshold, the module will send fire data to the server. 2cm

33. Body Attachment

34. Requirements • Location Determination • Interface with ultrasonic positioning system to retrieve position data • Hit Notification • Activate/Deactivate indicatorclosest to the computed hit location on the user • Communication with Server • Send user position data at regular intervals, receive hit notifications

35. Microcontroller • Requires a large number of available pins • 16MHz clock should be sufficient to perform I/O functions • Analog-to-digital conversion required by positioning system • Support for serial communications with communications subsystem

37. Vibration Motors • Must be small and produce a noticeable response. • 10mm Shaftless Vibration Motor 3.4mm Button Type

38. Vibration Motor Control • Needs to turn on/off a set of 5 vibration motors • Should require as few pins as possible on the MCU • Component must be fast to minimize the delay observed by the user

39. Body Attachment Circuit

40. Server

41. Requirements • Compute bullet trajectories • High-precision floating point computations • Compute intersections between trajectories and user positions • Send hit notifications to body attachments • Provide front-end accessible web GUI • Synchronize timing of positioning system • Compute and store statistics of each user

42. Trajectory Computation • Operating area will have a max bullet travel distance of 35.4 meters • Trajectories can be simplified • At the proposed distance the bullet drop due to gravity is very small (less than one centimeter)

43. Web GUI • To make the system more useful, a visualization of the current state will be included. • Monitor user positions, outgoing trajectories, and hits with minimal delay • Make scenario data available afterward for review

44. GUI Concept Design

45. GUI Implementation • User positions displayed through HTML5 Canvas element (possibly rendered with WebGL) • GUI hosted by Java server client utilizing Java.net classes to perform TCP/IP communications • Server accumulates state information and makes it available via a web interface

46. Server Hardware • Server not required to support a large number of concurrent users • Sophisticated server implementation is not be necessary • Hardware must support floating point operations • Network interface (Ethernet, Wi-Fi) is also required

47. Server Hardware

48. Server Hardware • Raspberry Pi Model B • 700 MHz ARM1176JZF-S • 10/100 Ethernet • GPIO Pins

49. Budget

50. Progress