A CCESSIBLE L OCK O PENER RIT CE Senior Design Jeremy Espenshade Jason Fay

Agenda Domain Introduction Project Overview User Interface Normal Operation Mechanical Design Electrical Design Software Design Power Distribution Operating Conditions Integration and Testing Project Feasibility

Domain Introduction Combination locks are everywhere – Gyms, schools, general purpose lockers, etc The standard Master® lock-style interface is currently difficult or impossible for some people to use – Blind or Visually Impaired – Limited Fine Motor Control Elderly Physically Handicapped Gloved Hands Outside assistance is therefore required, largely defeating the purpose of a private combination.

Project Overview A device must be created that allows combination locks to be accessible without outside assistance. The user will be able to input the combination and the device will dial appropriately. Requirements for normal operation: – No sight required – Reduced need for fine motor control – Time required comparable to unimpeded manual dialing – Portable

User Interaction Handheld, Automated Dialing Device User Story: Pick up the device and turn it on Type in the desired combination on a telephone-style keypad Orient the lock with zero centered at top of lock Position the device on the lock Press the “dial” button and wait for the device to spin the lock appropriately Remove the device and pull on the lock to open it

User Interface Display is 2x16 characters in size Keypad is 2’’ by 2.5’’ Keys take up 1.5’’ by 2’’

User Interface The display has two type of messages Normal messages Error messages Normal messages just state what numbers of the combination have been entered. Ex: Error messages tell the user what they did to cause an error Ex: Invalid number

Normal Operation The user will enter in his or her combination on the keypad The numbers that the user has pressed will be displayed on the LCD screen Each time the user has pressed a button a sound is played There a sound for a valid number being entered And another for an invalid number being entered

Normal Operation (cont) The user has to enter two digits for each number of the combination. So 9 has to be entered as 09 After the user has entered the complete combination they then press the # key to tell the device to physically manipulate the lock. If the user makes a mistake at anytime they can press the * key to reset the device.

Block Diagram

Casing The device casing will be designed so that it is easy to hold. It will be made out of lightweight durable material Aluminum or plastic It will be roughly 7’’ x 6’’ x 2.5’’ in size.

The Dial Connector

Dial Connector Construction Solid aluminum machined with appropriately sized holes Rubber “grip” inserted in large end to hold lock dial Connected to motor shaft with set screw

Electrical Design

The Keypad The keypad has an output pin for each key that is on the board. There is also a common input line. When a key is pressed, it connects the corresponding output pin to the common input. By polling the pins from the keypad, the microcontroller can determine what key(s) are pressed.

The Speaker The Speaker is just a computer speaker It is controlled by the first PWM line of the microcontroller. By changing the frequency scaling factor of the PWM, different tones can be made. There are two different tones: Error tone. This will be a higher pitched sound. Normal tone. This will be a lower pitched sound.

The LCD display It has 4 control pins and 8 data pins. The display consists of two 16 character rows It is used to display the combination and any error that might have occurred. Examples: COMBINATION: INVALIDNUMBER

Stepper Motor Driver Microcontroller supplies clock and direction lines Output current limited by R b Clamp diode suppresses back-EMF

Software Design Freescale Codewarrior IDE HCS12 C-language development Timer Interrupt – Poll the keypad – Send data to the LCD – Generate stepper motor driver control signals 3 operating states

Software Design – Operating States Waiting for Combination – Initial State – Keypad polled for changed input – New key press causes LCD update, tone generation, and error evaluation – May enter invalid combination or turning states Invalid Combination – Error Conditions Formatting: input as 2523 Out of Range: element greater than 39 entered – Error recovery: *-key combination reset and power reset

Software Design – Operating States Turning Motor – Motor resolution = 1.8° and lock resolution = 9° 5 clocks/lock position Clockwise, counterclockwise, and clockwise movements – Clock generated with period twice the timer interrupt period – Clock counts are generated at the beginning and the direction control signal changes before and after counterclockwise movement. – *-key allows manual override to stop the motor from turning – Mechanical problems undetectable

Power Distribution The requirement of portability implies the need for battery power. An RC car battery pack will be used. – 8.4 – 12 volts – 2300 – 4500 mAh Power Requirements: – Microcontroller: 5 volts, 65 mA max 5 volt Voltage Regulator – Stepper Motor: 7.6 – 16.5 volts, mA Battery Life: 4500/(300+65) = 12.4 hours Feedback limiting diode and voltage regulator provide power supply isolation.

Operating Conditions Usable Outdoors Water resistant No exposed wires 0 – 50° C Low-temperature components extremely expensive Portable/Battery Powered Easy access to battery charging Locks supported Standard Master® Lock Similar shaped locks with 40 positions

Integration and Testing The microcontroller software and interface electronics are being developed concurrently with the mechanical elements Electronic portion independently testable Dialing speed determination and accuracy verification can only occur after the dial interface and shaft are completed Battery power to be verified after functionality established Final usability testing to be completed after casing developed

Project Feasibility Lock dial interface and motor shaft Several approaches proved unsuccessful Machined aluminum with rubber hold expected to be far superior (Thanks Josh!!) Unforeseen mechanical problems Secure mounting of motor Ease of lock alignment and steady hold Power Variability Dips and spikes could cause microcontroller reset problems Capacitors and clamping diodes may be used

Questions?