p10002 dynamic keyboard
DESCRIPTION
P10002 Dynamic Keyboard. Alexander Moulton Marie Hammer Xingwang Gao Andrew Robertson Team Lead Mechanical Engineer Electrical Engineer Electrical Engineer. Project Goals. The purpose of this project is to capture key-strike dynamics for integration into a full keyboard - PowerPoint PPT PresentationTRANSCRIPT
P10002 Dynamic Keyboard
Alexander MoultonMarie HammerXingwang GaoAndrew Robertson
Team LeadMechanical EngineerElectrical EngineerElectrical Engineer
Project GoalsThe purpose of this project is to capture key-
strike dynamics for integration into a full keyboard
Enhance text based communication by providing an analog signal in parallel with binary keystroke data
Accurate differentiation of typing forces appliedEncapsulate typing forces with keystroke data
and communicate with a PCCharacterize human typing forces for future
projects
Revised Project GoalsOriginal project goal:
capture emotion while typingComplications:
Keyboards are binary devices Users are not trained to pay attention to how
they typeRevisions:
No association between emotion and typing patterns
Conscious user input expected
Customer Needs and SpecificationsNeed Specification Metric Ideal Value
Enhance text based communication
Establish a voltage output linearly proportional to force applied while typing
Linear relationship between force and voltage output
Couple analog data with keystroke character
Character data transmitted with analog data (Boolean)
True
System is able to measure a large range of input force
Range of force (N) 0 to 10N
Differentiate user input accurately
Users are able to establish up to 8 distinct outputs while typing
Number of output partitions 8
Use sensors with static output Variation in output voltage under static load (dV/dt)
dV/dt = 0
Output is independent of simultaneous keystrokes
Variation in output voltage with and without concurrent loads on multiple keys (V)
Compatible with modern PC/Laptop
USB protocol used for communication USB communication (Boolean) True
Output is readable by PC software
Applications able to monitor USB port can be programmed to interpret and display the data received
Pass/fail ofCommunication (Boolean)
True
2
20
d V
dF
0V
Design Concept - ElectricalAnalog data acquisition is independent of the original
keyboard designFour stages:
Thin film pressure sensitive device acts as a variable resistor in a voltage divider
Conditioning circuitryAnalog to digital conversionCommunication
Micro Controller
Conditioning Circuitry
Design Concept - MechanicalKeys: scissor switch, buckling, dome springMaterials: ABS plastic, silicone, foamMethods of Manufacturing: re-fabrication of current keyboard, rapid prototyping with ABS plastic, injection molding, machining raw material
Test Plan Sensors have a static output (i.e. no capacitive loads)
Load a sensor with a static weight and measure any variation in the output over time Establish a voltage output linearly proportional to force applied while typing
Calibrate device output (Voltage vs. Force) using weights ranging from 100g (~1N) to 2kg (~20N) A linear best-fit line should be possible
Force transmitted through the key to the sensor matches the force applied at the top of the key within ±10%.
Calibrate the device output with and without the key and spring Output of key strikes must be independent of simultaneous key strikes
A test key is loaded with a static force while a second key is fully depressed The variation in output voltage with and without the second key being pressed is
measured Characterize human typing force
Objective is to establish a baseline of normal typing force for future reference Result are compared with results from previous studies in typing force (1N to
2N) to ensure device accuracy determine the resolution of human typing force
Objective is to determine the minimum amount of force a user can consistently increment Tap key with successively increasing force average difference between keystrokes is measured
Test Data
Force (N) ΔV (mV)
1 0
5 0
10 31
Variation in output voltage for 1, 5, and 10N test forces with a second key fully depressed
Modified: y = 0.002701 - 0.046Unmodified: y = 0.002477 + 0.148%errorm = (0.002701 – 0.002477)/0.002477 * 100% = 9.04%
ΔV << Vmax/(# of output partitions)31mV << 3.7V/8 = 462mV
Test Data (cont.)Average typing force among users
User Trial 1 Trial 2 Trial 3 Trial 4 Trial 5Alex (N) 1.73 1.79 1.68 1.68 1.74Marie (N) 1.70 1.74 1.76 1.80 1.69Xingwang (N) 1.81 1.69 1.84 1.75 1.72Andrew (N) 1.69 1.78 1.75 1.72 1.80
Number of distinct partitions without feedbackUser Trial 1 Trial 2 Trial 3 Trial 4 Trial 5
Alex 6 6 7 5 7Marie 7 5 7 6 6Xingwang 6 7 6 6 6Andrew 6 6 7 7 6
Number of distinct partitions with feedbackUser Trial 1 Trial 2 Trial 3 Trial 4 Trial 5
Alex 8 7 8 7 6Marie 6 8 7 5 7Xingwang 8 7 6 8 7Andrew 8 8 7 8 8
Meeting SpecificationsEstablish a voltage output linearly proportional to force
applied while typing - PASSCouple analog data with keystroke character - PASSSystem is able to measure a large range of input force -
PASS (0 to 13N)Users are able to establish up to 8 distinct outputs while
typing – Not met, only 6 levels were achievedUse sensors with static output - PASSOutput is independent of simultaneous keystrokes – PASSUSB protocol used for communication - PASSApplications able to monitor USB port can be programmed
to interpret and display the data received - PASS
Future Project RecommendationsPrinting Force Sensitive Resistors in a matrix
underneath the keys for future keyboardsDesigning modified keyboard to hold more
circuitry as an alternative to modifying the keyboard.