SmartWalkerFinal Presentation

Group 16Mike Orr

Loc TruongDang Khoa Le

SmartWalker Mechanical

Brake

Camera

Electronics

Interested in robotics and wireless control

To create a useful product◦ Help the elderly and/or disabled

Motivation

Assist in day-to-day activity of user

Durable◦ Battery over-charging protection

Low cost

Goals and Objectives

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)

Specifications

Overall System Block Diagrams

Remote Controller

Remote Controller

2” color display

DPDTSwitches

2.4 GHzVideo

Receiver

433 MHzRF

Transmitter

HT12E4 ChannelEncoder

Receiver

Receiver

Receiver

2.4 GHzVideo

Transmitter

433 MHzRF Receiver

HT12D4 ChannelDecoder

L293DDual H-bridge Motor Driver

M1

M2RemoteController

Task Distribution

Remote Control Schematic

Receiver Schematic

Sub-systems

Motors and Motor Controller

Motor Controller

Left Motor

Right Motor

Using Bridge Motor Drive L293D (16 PIN chip)

Cost : $2.50. Used for DC or Stepper Motor

Motor Controller

L293D with Motors

Forward and Backward Turning left and right

Driving Method

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

Specifications desired for motors

Motor Names

Voltage(V)

Current(A)

Torque(N*m)

RPM Cost(USD/piece)

Electric Gear Motor

12 3-15 11.5 50 59.99

63ZYT01C DC Motor

24 4.5 1.3 2800 18

Leeson M1135246

12 0.23 17.51 83 347

Motor Choices (DC Motor)

ON/OFF switch Momentary switch

Latch Switch

Voltage source 12 V 12 V 12 V

Current rating 15 A 3 A 3 A

Control method On - Off Hold right : turnRelease : stopHold left : turn

opposite directionRelease : stop

Press right : turnPress right : stopPress left : turn

opposite directionPress left : stop

Motor control options :

L293D Motor Driver

Electric Gear

Motor(Left)

Electric Gear

Motor(Right)

Motor Parts

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.

Motor – Wheels connection

433MHz RF ModulesParameters Transmitter Receiver

Operating Voltage 3V-12V 5V (±0.5V)

Operating Current 40mA (12V)9 mA (3V) 5.5mA (5V)

Modulation Mode ASK/OOK OOK/ASK

Frequency 315MHz -433.9 MHz 315MHz-433.9MHz

Transmission Power 25mW (315MHZ at 12V) ---

Operating Range 120ft (clear of obstructions) same

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:o 8 address bitso 4 data bits

• Easily interface with RF Transmitter• Minimal external components

Holtek HT12D DecoderFeature:

• Operating voltage: 2.4V~12V• Low power and high noise immunity

CMOS technology• Low standby current• Capable of decoding 12 bits of

information:o 8 address bits (binary address

setting)o 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

• 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 3 times continuously with the local address given to pin A0 – A7.

• Once confirmed, the data bits are decoded and activates 4 output pins D8-D11.

Encoder/Decoder Operation

Control Switches

Motion

L293D Output Terminals ( Motor Input Terminals)

+ Motor 1 - Motor 1 + Motor 2 - Motor 2

Forward 1 0 0 1

Reverse 0 1 1 0

Left 0 0 0 1

Right 1 0 0 0

Stop 0 0 0 0

• 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

Control Switches

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)

Camera

2.4 GHz Wireless Video/Audio Module◦ 9 Volts◦ Max Current:

180mA (Receiver) 30mA (Transmitter)

◦ Frequency: 2.4 GHz◦ RCA Connectors

Video Transmitter/Receiver

Power System-Block Diagram

UA7805Regulator

9VBattery

Remote Controller Block DiagramPowerControlVideo

DPDTSwitches

2.4 GHzVideo

Receiver

433 MHzRF

Transmitter

HT12E4 ChannelEncoder

2” color display

Power System-Block Diagram

12VBattery

Receiver Block Diagram

Regulator(5V)

PowerControlVideo

2.4 GHzVideo

Transmitter

433 MHzRF Receiver

HT12D4 ChannelDecoder

L293DDual H-bridge Motor Driver

M1

M2

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

Battery

μA7805CKC◦ Internal Thermal-Overload Protection◦ High Power-Dissipation Capability

LM7809◦ Short Circuit Protection◦ Thermal Overload Protection

Regulators

Power ConsumptionDevice Voltage (V) Current (mA) Power (mW)HT12E 5 5 25HT12D 5 5 25

RF Receiver 5 5 25RF Transmitter 5 5 25

L293D (1) - chip 5 0.1 0.5L293D (2) - chip 5 0.1 0.5

Left Motor 12 2400 28800Right Motor 12 2400 28800

Video Transmitter 9 30 270

Video Receiver 9 30 270Camera 12 600 7200

Video Display 9 216 1944

Total Power: 67.385 Watts

Battery Life Calculation

3800----------------------------

5696.2

0.467 Hours*

*calculated for all components running constantly at maximum ratings

Power◦ Constant running motor◦ Varying on/off

Max Weight Supported◦ Driving – 25 pounds◦ Stationary – 200 pounds

Speed (Max vs Avg)◦ Max < 3 MPH◦ Avg = 0.77 MPH

Video – tested at subsystem level

Testing

Thermal Issues◦ Motor Driver reaching thermal 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

Current Issues/Solutions

BudgetItem Unit Price Ordered Price

Video Transmitter/Receiver $32.00 1 $32.00

RF Transmitter/Receiver $4.12 1 $4.12HT12D/HT12E 1 $0.00UA7805CKCS $0.49 1 $0.49LM7809 $0.67 1 $0.67

Pitsco TETRIX 12-Volt Rechargeable NiMH Battery Pack and Charger $84.90 1 $84.90Video Display $42.31 1 $42.31

22 pF capacitor (30pk) $2.43 1 $2.43

QSEE Security Camera FREE 1 $0.00

Wondermotor 12V DC Gear Motor $59.99 2 $119.98L293D $2.50 2 $5.00DPDT Switches $5.00 2 $10.00PCB $48.36 2 $96.72

Miscellaneous (bolts, screws, welding etc) $100.00 1 $100.00

Total $498.62

Questions?