2. Passenger/Item Detection System for Vehicles Dec03-05 members Jason Adams Ryan Anderson Jason Bogh Brett Sternberg Acknowledgements Clive Woods – Advisor Heart of Iowa Regional Transportation Agency (HIRTA) – Client

3. Presentation Outline Introductory Materials Assumptions & Limitations Accomplishments Technical Approach System Design Implementation & Testing Resources & Schedules Closing

4. Problem Statement Need to prevent passengers from remaining on the bus after the driver leaves the bus. Need for automatic detection system - Rectifies problem of driver not checking the bus

5. General Solution-Approach Statement Develop initial design Present design to client for approval Order parts Assemble prototype circuits Test prototype circuits Combine circuits into complete detection system Test detection system

6. Operating Environment Transient bus Vibrations - Bus’s engine - Roadways traveled Environmental elements - Dust - Dirt - Moisture Normal temperatures Withstand pressure given off by passengers

7. Intended Users/Uses Users male or female adult commercial driver’s license no discrimination on the basis of sex, ethnic background, physical size, or disability able to operate the commercial vehicle according to the laws of the state. Uses automatically detect remaining passengers and possible items alarm driver of the situation before he or she has fully exited the bus.

8. Assumptions Will be used on a transient bus Occupancy ranges from ten to seventy-five passengers System off while bus is running System starts when bus shuts off Automatic Versatile Pressure sensors cover all seats LED’s attenuation is eight to ten feet Photodiode sensitive to LED only

9. Limitations Cost not to exceed two hundred fifty dollars Power for the system comes from bus’s battery Structure of the bus Response time Self-operational Operating environment Spectrum of LED

10. End Product and Other Deliverables Passenger detection system – Seat pressure system – Floor optical system Technical specifications for parts Installation directions End product design report – Cost analysis report

11. Present Accomplishments Defined problem Determined possible technologies Researched possible technologies Eliminated non-feasible technologies Designed initial circuit designs Presented design to HIRTA Ordered Parts Produced prototype circuits Lab tested prototype circuits

12. Technical Approach Light sensitive resistors Pyrometers Ultra-sonic signature Pressure sensitive resistors Optical counters Photodiode (detector) Weight systems Piezoelectric sensors Magnetic counters Infrared LED (emitter) Analog alarm system Digital display system Alarm System Approaches

13. Technical Approach Results Hybrid system Seats - pressure sensitive resistors Floor - infrared emitters / photodiode detectors

14. Research Activities Phase detection ­ Remove overlapped signals of unwanted emitters ­ Synchronous detection methods allow detectors to accept only wanted signals Seat weight distribution ­ Distribute weight located anywhere on a seat to the force sensor

15. Design Constraints  Physical properties – System should not be restrictive, distracting, or discomforting to the driver and passengers.  Size – System should not interfere with normal bus operations.  Fail-safe – System should never neglect to alert if a passenger is present when the bus is shut off.  Power consumption – Power from the system must come from a 12- volt battery.  Response time – System will need to respond within 3-7 seconds of the bus being shut off.

16. Design Constraints (cont’d) Robust – System may be exposed to the elements and anything tracked on by passengers such as: rain, snow, mud, dust, and dirt. Flexible – Design implementation must be supported for several bus designs. Cost effective – If system cost is over $100, some type of funding must be provided.

17. System Design Part I: Pressure Sensors

18. Purpose: – To detect a left behind passenger and/or item located on the seats. Basic Operation: – If pressure is detected on the sensor then an analog signal is output triggering the alarm. Pressure Sensors

19. Bus Schematic – Pressure Sensors Force Sensitive Resistor Sensors Wiring Buzzer Alarm System

20. Force-to-voltage circuit Rf sets sensitivity of circuit Signaling voltage pre-determined according to Rf Output will signal parallelizing circuit to trigger alarm Pressure Sensing Circuit

21. Initial force-to-voltage circuit design – Removed negative voltage from op-amp – Altered input voltage to incorporate bus battery voltage Short range of linear output voltage – Set alarm trigger voltage within the linear range Size of sensing surface area small – Install a surface to distribute weight from anywhere on the seat to the sensing area Pressure Sensor Implementation

22. Testing output voltage of force-to-voltage circuit (lab) – Variable pressure sensor sensitivities (1 lb, 25 lb, 100 lb) – Variable input voltages – Variable Rf resistance Largest S occurred with 100 lb sensor and Rs = 100 kΩ – Voltage difference = 3 V Pressure Sensor Testing

23. System Design Part II: Optics

24. Optics Purpose: To detect a left behind passenger and/or item located on the floor. To detect a left behind passengers in a wheelchair Basic Operation: Emitted light that is blocked will cause the alarm to be triggered

25. Optics General Layout: Light

26. Optics General Layout: Exhibit A Exhibit B Exhibit A demonstrates a much more efficient configuration among the emitter and detectors!

27. Optics Why Infrared light? To prevent interference from ambient light Optical receiver designed to only recognize infrared light (tinted photodiode) To maintain a failsafe detection system

28. Optics Benefits: Low Cost Small (Will not alter the aesthetics of the bus) Very low maintenance System does not impose any health risk

29. Optics Drawbacks: Tampering with may cause issues Solution: -Enclose in box-type structure -Sheet of plexy-glass over aperture Emitter or Detector

30. Optics Transmitter

31. Optics Receiver

32. Optics Phase Detection (in phase)

33. Optics Phase Detection (90˚ out of phase)

34. Alarm Both the pressure sensors and optics will be able to trigger the alarm Alarm in consideration has the following features: -90 dB buzzer Some other sound levels -Conversation--------------->60 dB -Rock Concert--------------->110 dB

35. Cost Analysis

36. Personal Effort

37. Other Resources’ Cost

38. Final Projected Costs

40. MilestonePercent Completed Project Definition 100 Technologies Considered 100 Ordering of Prototype Parts 100 Construction of Prototype 100 Testing of Prototype 75 Final System Construction 0 Final System Testing 0 Remove Bugs from Final System 0 Project Total75 Project Evaluation

41. Commercialization The cost to produce the product is very difficult to determine - Each system depends on size of bus or vehicle - Each system must be installed during construction of the vehicle Potential market for this product is large - Every large capacity transportation company (bus, airline)

42. Recommendations for Additional Work Detect items in specific locations Timer/Delay Alarm fully on or off Reset/override Digital display

43. Lessons Learned Practical and applicable solution Time constraints and inability to catch up Circuit design Research techniques Application of engineering skills to real world problems Set more strict deadlines Documentation

44. Risk and Risk Management Time consumption of learning the technologies used – Consulting advisor more often than not Complete redesign of optoelectronics – Learn the technology Delay in ordering parts – Ordered parts as soon as possible Unavailability of times for the team to meet – Two smaller teams Reliability of the breadboards used in circuitry – Troubleshoot, troubleshoot Receiving wrong parts – Use replacement parts – Redesign circuitry Small size of the pressure sensing area – Find a surface to distribute weight to the sensor

45. Closing Summary Passenger detection system Hybrid design using two technologies – Floor space : Optoelectronics – Seats : Pressure sensors Automated Eliminates the factors of human error

46. Questions?