Video 1: Gerhard flying a quadcopter (RC Logger EYE One Extreme) with the 4D Joystick

Video 2: David teaches Gerhard how to fly a Miniprop Magnum Reloaded.
4D-Joystick and a Spektrum DX8 are connected and in trainer mode.
David takes control in critical situations.

Video 3: Gerhard controling a RC Car.
Since the car needs just two control-channels, just the X- and Z-Axis of the 4D-Joystick are used.

4D-Joystick Features


Playing with toys is much more than amusement and the right to play is specified in the "Convention on the Rights of the Child" by the United Nations. Playing with other children fosters social skills and can be used to teach children important things for their lives. All these benefits are hardly accessible for people with severe physical disabilities, because there are only very few off-the-shelf toys that they can use. One type of toys are remote controlled (RC) models like cars, boats, helicopters and airplanes. These devices are controlled with non-accessible radio transmitters using the 2.4 GHz band. The advantage of RC-toys is that the control unit can be replaced by an accessible one without the need to modify the original product and therefore the customer does not loose warranty.

Implementation Details of the 4D-Joystick

The prototype of the 4D-Joystick, see Figure 1, was developed for and with a user with severe physical disabilities (tetraplegia) who is only able to move his head and to raise his left forearm. The arm could only be used to trigger a switch but not to control complex systems. Therefore the possibilities with available chin and mouth controls were evaluated. The problem was that most RC-models like helicopters or airplanes need at least four accurate input modalities to control all possible movements and throttle of the vehicle.

Picture of the actual 4D-Joystick prototype

Figure 1: Prototype of the 4D-Joystick

On the market there are no suitable joysticks for people with severe physical disabilities available and therefore a new type of joystick was developed. The 4D-Joystick allows to control up to eight channels (input modalities) concurrently:

The 4D-Joystick sensors are: a joystick, a slide potentiometer, a sipp/puff sensor and two digital switches. These data is processed by an Arduino and sent to the RC-transmitter

Figure 2: System overview

Configuration Software and Firmware

The joystick allows to create and to store up to six different profiles for RC models which can be edited and stored on the joystick using a terminal program on a Computer or the touchscreen at the right side of the 4D Joystick. The terminal programm communicates with the Joystick via USB (RS232) and lets the user’s assistant set, load and store parameters for all channels of an RC model.

Picture of the touch display of the 4D-joystick showing the status monitor with live sensor data visualized by bar charts.

Figure 4: User interface of the 4D-Joystick

The firmware supports dual rates, expo and inverting of each channel. To compensate mechanically caused drifts of an RC model trimming on each channel is supported. Additionally two methods were implemented for adapting the behaviour of the joystick to fit the requirements of people with physical disabilities. The first method is to limit a channel to a maximum value (e.g. half throttle) and interpolate this smaller range to the same joystick movement. This allows a much smoother control of a channel and the possibility to oversteer an RC model decreases drastically. The only downside when limiting the value too much is that the RC model cannot do fast movements anymore. To support users with a tremor or who cannot move the stick very accurately, a dead zone can be set for each channel, which filters control inputs around the centre of a channel. For first impressions on how accurate the user can move the stick the touchscreen can display graphical feedback for each channel in real-time, which visualises the set parameters and how they affect the actual output signals. This helps to optimise the control input for different user requirements, see Fig. 4.


Modellbaumesse Wels 2014

Photo: Gerhard controls a Walkera Scorpion Multicopter with the 4D-Joystick
Gerhard controls a Walkera Scorpion Multicopter with the 4D-Joystick (Photo by Mark Höllerbauer, 2014)

Photo: Gerhard controls a Remote Controlled Car with the 4D-Joystick
Gerhard controls an XciteRC SandStorm car with the 4D-Joystick (Photo by Mark Höllerbauer, 2014)

Ars Electronica Center, Science Days, 28. und 29.06.2014

Photo: Gerhard controls a RC Logger Eye One Extreme Quadrocopter with the 4D-Joystick
Gerhard controls an RC Logger Eye One Extreme Quadrocopter with the 4D-Joystick (Photo by Reinhard Pühringer, 2014)

Ars Electronica Festival 2014

Photo: Gerhard controls a Walkera Ladybird Quadrocopter with the 4D-Joystick
Gerhard controls a Walkera Ladybird Quadrocopter with the 4D-Joystick (Photo by Tom Mesic, 2014)

Related Work


Informationstechnologie zur Förderung der
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