1120 User Guide: Difference between revisions
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===Measurement Accuracy=== | ===Measurement Accuracy=== | ||
To obtain the most accurate results, it is recommended that the sensor rests on a smooth surface and the object is only on the sensing pad and centered as much as possible. This can be achieved by using a small disc (included) that is just large enough to cover the sensing pad, and then placing the full force on the disc. Without the disc, the object may rest on the surrounding surface and record the force inaccurately. Care must also be taken to avoid jagged or sharp edges on the sensing pad, as it can affect the measurement as well as potentially puncture the pad. The pad at the end of the strip is the only place where force is sensed. Any force along the rest of the strip is ignored. The longer the object rests on the sensing pad, the more the | To obtain the most accurate results, it is recommended that the sensor rests on a smooth surface and the object is only on the sensing pad and centered as much as possible. This can be achieved by using a small disc (included) that is just large enough to cover the sensing pad, and then placing the full force on the disc. Without the disc, the object may rest on the surrounding surface and record the force inaccurately. Care must also be taken to avoid jagged or sharp edges on the sensing pad, as it can affect the measurement as well as potentially puncture the pad. The pad at the end of the strip is the only place where force is sensed. Any force along the rest of the strip is ignored. The longer the object rests on the sensing pad, the more the sensor voltage will drift and vary slowly in value. It is very difficult to compensate for the drift since different constant forces will produce different drift rates. For this reason, the average accuracy of this sensor is approximately 5%. The formula above was determined after the object of known force was resting on the sensing pad for 15 seconds. | ||
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Revision as of 20:47, 17 April 2017
Required Hardware
- A 1120 Flexiforce Adapter
- An InterfaceKit or Hub to read the sensor
- A Phidget cable
- A USB cable
- A computer
- A Flexiforce sensor
Connecting the Pieces
- Connect the Flexiforce adapter to the InterfaceKit or Hub with the Phidget cable.
- Connect the Flexiforce sensor to the adapter. Polarity doesn't matter. See the technical section for details.
- Connect the InterfaceKit or Hub to your computer with the USB cable.
Testing Using Windows
Phidget Control Panel
In order to demonstrate the functionality of the 1018, the Phidget Control Panel running on a Windows machine will be used.
The Phidget Control Panel is available for use on both macOS and Windows machines.
Windows
To open the Phidget Control Panel on Windows, find the 
icon in the taskbar. If it is not there, open up the start menu and search for Phidget Control Panel
macOS
To open the Phidget Control Panel on macOS, open Finder and navigate to the Phidget Control Panel in the Applications list. Double click on the icon to bring up the Phidget Control Panel.
For more information, take a look at the getting started guide for your operating system:
Linux users can follow the getting started with Linux guide and continue reading here for more information about the 1018.
First Look
After plugging the 1018 into your computer and opening the Phidget Control Panel, you will see something like this:
The Phidget Control Panel will list all connected Phidgets and associated objects, as well as the following information:
- Serial number: allows you to differentiate between similar Phidgets.
- Channel: allows you to differentiate between similar objects on a Phidget.
- Version number: corresponds to the firmware version your Phidget is running. If your Phidget is listed in red, your firmware is out of date. Update the firmware by double-clicking the entry.
The Phidget Control Panel can also be used to test your device. Double-clicking on an object will open an example.
Voltage Input
Double-click on a Voltage Input object in order to run the example: [[Image:{{{1}}}_VoltageInputSensor_Example.jpg|center|link=]]
General information about the selected object will be displayed at the top of the window. You can also experiment with the following functionality:
- Modify the change trigger and/or data interval value by dragging the sliders. For more information on these settings, see the data interval/change trigger page.
- If you have an analog sensor connected that you bought from us, you can select it from the Sensor Type drop-down menu. The example will then convert the voltage into a more meaningful value based on your sensor, with units included, and display it beside the Sensor Value label. Converting voltage to a Sensor Value is not specific to this example, it is handled by the Phidget libraries, with functions you have access to when you begin developing!
For more information about Voltage Inputs, check out the Voltage Input Primer.
Testing Using Mac OS X
- Go to the Quick Downloads section on the Mac OS X page.
- Download and run the Phidget OS X Installer
- Click on System Preferences >> Phidgets (under Other) to activate the Preference Pane
- Make sure your device is properly attached
- Double click on your device's objects in the listing to open them. The Preference Pane and examples will function very similarly to the ones described above in the Windows section.
Testing Using Linux
For a general step-by-step guide on getting Phidgets running on Linux, see the Linux page.
Using a Remote OS
We recommend testing your Phidget on a desktop OS before moving on to remote OS. Once you've tested your Phidget, you can go to the PhidgetSBC, or iOS pages to learn how to proceed.
Technical Details
Formulas
The FlexiForce Force sensor is a piezoresistor that has a very large resistance when it is not loaded (in the range of MegaOhms). The resistance decreases as more and more force is applied to it. Tekscan offers sensors with standard force ranges, such as 0-1 lb, 0-25 lbs, and 0-100 lbs. The same adapter board can be used for all three ranges. Because the expected part-to-part variance between FlexiForce sensors is as high as 40%, it is imperative that you calibrate your sensor and determine the specific formula which applies to your sensor. For information on how to calibrate your sensor, refer to the FlexiForce User Manual from Tekscan.
FlexiForce Sensors
The FlexiForce sensors are easy to interface to the adapter board. They can be plugged into the Interface cable that is included. The other end of the cable has been stripped and tinned so that they can be easily inserted into the terminal block. This is useful if a longer cable is needed, as wires can be soldered to the stripped ends. The polarity of the FlexiForce sensors does not matter. If a larger force range is desired, a resistor on the Adapter board can be replaced. This resistor is designated as RGAIN on the board and has a default value of 15 kiloOhms. When the RGAIN resistor value is reduced, the sensor becomes less sensitive and more force can be applied before saturating the output. Conversely, if the RGAIN value is increased, the sensitivity increases and the output saturates at a lower applied force. If RGAIN is changed, calibration with known forces will have to be done to determine the proper formula. Based on limited testing, RGAIN=5 kilo-ohms will give enough range to measure up to 1000 lbs with the 100 lb. Flexiforce sensor. Changing the gain by much larger amounts can cause sensor instability and is not recommended. Also note that adjusting the gain is not a substitute for calibrating and conditioning the sensor. You should look at the manual for the sensor you are using and follow all calibration procedures contained therein before resorting to adjusting the gain value to achieve accurate results.
Measurement Accuracy
To obtain the most accurate results, it is recommended that the sensor rests on a smooth surface and the object is only on the sensing pad and centered as much as possible. This can be achieved by using a small disc (included) that is just large enough to cover the sensing pad, and then placing the full force on the disc. Without the disc, the object may rest on the surrounding surface and record the force inaccurately. Care must also be taken to avoid jagged or sharp edges on the sensing pad, as it can affect the measurement as well as potentially puncture the pad. The pad at the end of the strip is the only place where force is sensed. Any force along the rest of the strip is ignored. The longer the object rests on the sensing pad, the more the sensor voltage will drift and vary slowly in value. It is very difficult to compensate for the drift since different constant forces will produce different drift rates. For this reason, the average accuracy of this sensor is approximately 5%. The formula above was determined after the object of known force was resting on the sensing pad for 15 seconds.
Phidget Cable
The Phidget Cable is a 3-pin, 0.100 inch pitch locking connector. Pictured here is a plug with the connections labelled. The connectors are commonly available - refer to the Analog Input Primer for manufacturer part numbers.
What to do Next
- Programming Languages - Find your preferred programming language here and learn how to write your own code with Phidgets!
- Phidget Programming Basics - Once you have set up Phidgets to work with your programming environment, we recommend you read our page on to learn the fundamentals of programming with Phidgets.
