ZeroStick is a joystick that uses strain gauges to measure force applied to it, without the joystick needing to move. The joystick "position" is determined from the force being applied to it, instead of any physical deflection of the stick.
The term "position" is used here to signify the virtual position of the joystick, even though it doesn't physically move. As more force is applied, the virtual position of the joystick is considered to change.
This allows it to be used by people with a limited range of motion, such as from Duchenne muscular dystrophy.
The sensitivity of the joystick can be adjusted in software by changing the scaling of the values detected by the strain gauges.
The position value is measured as % deflection from the zero (central) position, ie: from -100% to +100%. This is equivalent to full effort by the user in each direction.
The force applied to the load cells is measured using a NAU7802 ADC with an I2C interface. The input channels are split so that a single ADC can read both the X and the Y axis load cells sequentially.
You can view more details at:
http://www.superhouse.tv/zerostick
The "Hardware" directory contains the PCB design as an EAGLE project. EAGLE PCB design software is available from Autodesk free for non-commercial use.
The "Firmware" directory contains example firmware as an Arduino project.
The example firmware has three output methods:
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Mouse output. When enabled and plugged into a computer, the ZeroStick will emulate a USB mouse. Buttons on the ZeroStick can also send left and right click events.
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Joystick output. When enabled and plugged into a computer, the ZeroStick will emulate a USB game controller with a joystick.
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I2C digital potentiometer output. External I2C digital potentiometers can be connected, which can then emulate a simple analog joystick when connected to another device such as a wheelchair. This allows the ZeroStick to control wheelchairs that expect to have a normal joystick attached.
- Jonathan Oxer jon@oxer.com.au
- Chris Fryer chris.fryer78@gmail.com
Copyright 2019-2021 SuperHouse Automation Pty Ltd www.superhouse.tv
The hardware portion of this project is licensed under the TAPR Open Hardware License (www.tapr.org/OHL). The "license" folder within this repository contains a copy of this license in plain text format.
The software portion of this project is licensed under the Simplified BSD License. The "licence" folder within this project contains a copy of this license in plain text format.