Probabilistic latency modeling
View Patent ↗Touchscreen testing techniques are described. In one or more implementations, a piece of conductor (e.g., metal) is positioned as proximal to a touchscreen device and the touchscreen device is tested by simulating a touch of a user. This technique may be utilized to perform a variety of different testing of a touchscreen device, such as to test latency and probabilistic latency. Additional techniques are also described including contact geometry testing techniques.
1. A method implemented by one or more computing devices, the method comprising:
modeling latency of a touchscreen device using parameterized statistics by:
obtaining data describing end-to-end latency measurements of the touchscreen device to recognize a touch input; and
fitting the data to parametric distributions.
2. A method as described in claim 1 , wherein the latency is modeled using a random variable with known distribution.
3. A method as described in claim 1 , wherein the latency is modeled using the following expression:
L=U [0,1 Hardware ] +U [0,1 Bus ] +f INPUT STACK +U [0,1 GRAPHICS ] +f SCREEN
where U [0,1 Hardware ] stands for uniform distribution of hardware latency in range [0,1 Hardware ], U [0,1 Bus ] stands for uniform distribution of bus latency in range [0,1 Bus ], U [0,1 GRAPHICS ] stands for uniform distribution of graphics latency in range [0,1 GRAPHICS ], f INPUT STACK stands for a fixed parameter describing input stack latency, and f SCREEN stands for a fixed parameter describing screen latency.
4. A method as described in claim 3 , wherein U [0,1 Hardware ] describes a scanning rate of the touchscreen device and U [0,1 Bus ] describes latency distribution of a USB connection.
5. A method as described in claim 1 , wherein the obtaining of the data includes:
placing a conductor that is disposed proximal to the touchscreen device in a grounded state;
receiving a report from the touchscreen device indicating a point in time at which the touch input was detected by the touchscreen device; and
computing the time delay by comparing the point in time at which the touch input was detected by the touchscreen device with a point in time at which the conductor was placed in the grounded state.
6. A method as described in claim 5 , wherein the obtaining of the data includes:
placing the conductor that is disposed proximal to the touchscreen device in an ungrounded state;
receiving a report from the touchscreen device indicating a point in time at which a lack of the touch input was detected by the touchscreen device; and
computing the time delay by comparing the point in time at which the lack of the touch input was detected by the touchscreen device with a point in time at which the conductor was placed in the ungrounded state.
7. A method as described in claim 5 , further comprising synchronizing a clock on the one or more computing devices that is utilized to indicate the point in time at which the conductor was placed in the grounded state with a clock of the touchscreen device that is utilized to indicate the point in time at which the touch input was detected by the touchscreen device.
8. A method as described in claim 5 , wherein the placing is performed using an electrical switch driven by the one or more computing devices.
9. A method as described in claim 6 , wherein the placing of the conductor in the grounded state emulates a touch by a user and further comprising placing the conductor in an ungrounded state while the conductor is still disposed proximal to the digitizer to emulate a lack of the touch input on the computing device.
10. A computing device comprising:
One or more modules implemented at least partially in hardware, the one or more modules configured to perform operations comprising:
modeling latency of a touchscreen device using parameterized statistics by:
obtaining data describing end-to-end latency measurements of the touchscreen device to recognize a touch input; and
fitting the data to parametric distributions.
11. A computing device as described in claim 10 , wherein the latency is modeled using a random variable with known distribution.
12. A computing device as described in claim 10 , wherein the latency is modeled using the following expression:
L=U [0,1 Hardware ] +U [0,1 Bus ] +f INPUT STACK +U [0,1 GRAPHICS ] +f SCREEN
where U [0,1 Hardware ] stands for uniform distribution of hardware latency in range [0,1 Hardware ], U [0,1 Bus ] stands for uniform distribution of bus latency in range [0,1 Bus ], U [0,1 GRAPHICS ] stands for uniform distribution of graphics latency in range [0,1 GRAPHICS ], f INPUT STACK stands for a fixed parameter describing input stack latency, and f SCREEN stands for a fixed parameter describing screen latency.
13. A computing device as described in claim 12 , wherein U [0,1 Hardware ] describes a scanning rate of the touchscreen device and U [0,1 Bus ] describes latency distribution of a USB connection.
14. A computing device as described in claim 10 , wherein the obtaining of the data includes:
placing a conductor that is disposed proximal to the touchscreen device in a grounded state;
receiving a report from the touchscreen device indicating a point in time at which the touch input was detected by the touchscreen device; and
computing the time delay by comparing the point in time at which the touch input was detected by the touchscreen device with a point in time at which the conductor was placed in the grounded state.
15. A computing device as described in claim 14 , wherein the obtaining of the data includes:
placing the conductor that is disposed proximal to the touchscreen device in an ungrounded state;
receiving a report from the touchscreen device indicating a point in time at which a lack of the touch input was detected by the touchscreen device; and
computing the time delay by comparing the point in time at which the lack of the touch input was detected by the touchscreen device with a point in time at which the conductor was placed in the ungrounded state.
16. A computing device as described in claim 14 , further comprising a clock and the one or more operations include synchronizing the clock to indicate the point in time at which the conductor was placed in the grounded state with a clock of the touchscreen device that is utilized to indicate the point in time at which the touch input was detected by the touchscreen device.
17. A computing device as described in claim 14 , wherein the placing is performed using an electrical switch driven by the computing device.
18. A computing device as described in claim 15 , wherein the placing of the conductor in the grounded state emulates a touch by a user and further comprising placing the conductor in an ungrounded state while the conductor is still disposed proximal to the digitizer to emulate a lack of the touch input on the computing device.
19. A method comprising:
obtaining data, by one or more computing devices, describing end-to-end latency measurements of a touchscreen device to recognize a touch input;
fitting the data to parametric distributions by the one or more computing devices; and
modeling latency of the touchscreen device using parameterized statistics by the one or more computing devices.
20. A method as described in claim 19 , wherein the latency is modeled using a random variable with known distribution.