SmartWalker

1. SmartWalker Final Presentation Group 16 Mike Orr Loc Truong Dang Khoa Le

2. SmartWalker Mechanical Brake Camera Electronics

3. Motivation • Interested in robotics and wireless control • To create a useful product • Help the elderly and/or disabled

4. Goals and Objectives • Assist in day-to-day activity of user • Durable • Battery over-charging protection • Low cost

5. Specifications • Weight less than 50 pounds • Be able to support up to 200 pounds of weight (manual) • Travel no faster than 3 miles per hour • Have no more than a 2 second delay in video streaming and control • Be able sustain functionality up to 40 meters away from the walker • Be able to sustain functionality for up to 2 hours without recharging (non-continuous use)

6. Overall System Block Diagrams

7. Remote Controller Remote Controller 2” color display DPDT Switches 2.4 GHz Video Receiver Receiver HT12E 4 Channel Encoder 433 MHz RF Transmitter

8. Receiver Receiver M1 Remote Controller 2.4 GHz Video Transmitter L293D Dual H-bridge Motor Driver M2 433 MHz RF Receiver HT12D 4 Channel Decoder

9. Task Distribution

10. Remote Control Schematic

11. Receiver Schematic

12. Sub-systems

13. Motors and Motor Controller

14. Motor Controller • Using Bridge Motor Drive L293D (16 PIN chip) • Cost : $2.50. Used for DC or Stepper Motor

15. L293D with Motors

16. Driving Method • Forward and Backward • Turning left and right

17. Specifications desired for motors • Produce high torque • Have reasonable turn speed • Require 12V DC (to be compatible with system voltage supplier) • Generates low current to reduce heat • Low cost

18. Motor Choices (DC Motor)

19. Motor control options :

20. Motor Parts

21. Motor – Wheels connection • Motors connect to small discs. • Pulleys connects to the fixed-wheels using low-tension belts. • Small pins are used switch from remote control to manual use. • When using remote, the pins will connect the motors to the plastic pulleys.

22. 433MHz RF Modules

23. Holtek HT12E Encoder • Feature: • Operating voltage 2.4V-12V • Built-in oscillator needs only small value external resistor • Low power and high noise immunity CMOS technology • Low standby current: 0.1µA (typical) at VDD=5V • Capable of encoding and transmit 12 bit of information: • 8 address bits • 4 data bits • Easily interface with RF Transmitter • Minimal external components

24. Holtek HT12D Decoder • Feature: • Operating voltage: 2.4V~12V • Low power and high noise immunity CMOS technology • Low standby current • Capable of decoding 12 bits of information: • 8 address bits (binary address setting) • 4 data bits • Built-in oscillator needs only 5% resistor • Received codes are checked 3 times • Easy interface with an RF receiver • Minimal external components

25. Encoder/Decoder Operation • HT12D decoder will be in standby mode initially. Oscillator is disabled at this point • When the decoder receive data from the encoder through the RF receiver, Din goes high and it activates the oscillator. • The device starts decoding the input data, which consists of 8 address bits and 4 data bits • The decoder matches the received address 3times continuously with the local address given to pin A0 – A7. • Once confirmed, the data bits are decoded and activates 4 output pins D8-D11.

26. Control Switches • Rotation of the motor changes by switching its polarity • To switch/control the polarity of the motors from the remote controller, 2 DPDT switches are used

27. Control Switches

28. Camera • Foscam FI9821W • HD Quality, 1280x 720 Resolution • High Cost • TENVIS JPT3815W • Lesser Quality • Good Pricing • Q-SEE Security Camera • Good Quality • RCA Compatible • Free of Charge (Loc)

29. Video Transmitter/Receiver • 2.4 GHz Wireless Video/Audio Module • 9 Volts • Max Current: • 180mA (Receiver) • 30mA (Transmitter) • Frequency: 2.4 GHz • RCA Connectors

30. Power System-Block Diagram Power Control Video Remote Controller Block Diagram 2” color display 9V Battery 2.4 GHz Video Receiver UA7805 Regulator DPDT Switches HT12E 4 Channel Encoder 433 MHz RF Transmitter

31. Power System-Block Diagram Power Control Video Receiver Block Diagram 12V Battery 433 MHz RF Receiver HT12D 4 Channel Decoder M1 Regulator (5V) L293D Dual H-bridge Motor Driver M2 2.4 GHz Video Transmitter

32. Battery • 3 options: • HitLights Rechargeable 3800mAh Lithium Ion Battery Pack • Pitsco TETRIX 12-Volt Rechargeable NiMH Battery Pack and Charger • NiMH Battery Pack: Customize 12V 5000mAh

33. Regulators • μA7805CKC • Internal Thermal-Overload Protection • High Power-Dissipation Capability • LM7809 • Short Circuit Protection • Thermal Overload Protection

34. Power Consumption

35. Battery Life Calculation 3800 ---------------------------- 5696.2 0.467 Hours* *calculated for all components running constantly at maximum ratings

36. Testing • Power • Constant running motor • Varying on/off • Max Weight Supported • Driving – 25 pounds • Stationary – 200 pounds • Speed (Max vsAvg) • Max < 3 MPH • Avg = 0.77 MPH • Video – tested at subsystem level

37. Current Issues/Solutions • Thermal Issues • Motor Driver reachingthermal threshold • Use 12V relays to drive motors • Mechanical Issues • Platform causes stability issues • Wheel drive limits weight support capability • Redo platform • Antenna • Limits transmission range • Need longer antenna

38. Budget

39. Questions?