The winners of the PneuDrive Challenge 2008 competition were the Stellenbosch University. Their project was titled - A~DOT – The Automated Dart Throwing Robot.

The student team were made up of:

* B. de Lange

* P. Grobbelaar

* P. van Deventer

* W.J.L. van Schalkwyk.

A~Dot is presented as a mechatronic system, consisting of four main subsystems, that is:

* The Magazine,
* The Reloading Arm
* The Aiming Subsystem
* The Throwing Subsystem.

1. Intention and Rationale

A~Dot’s purpose is to autonomously execute the aiming and throwing of a dart as specified by a user and then automatically reload itself. All subsystems are bolted onto the base plate which is welded onto a supporting structure.

The aim of the design was not to invent a new household appliance, but to impress potential customers at trade exhibitions with the "off-the shelf" potential of SEW Eurodrive and FESTO components.

Two ideas that have fascinated engineers for centuries are flight and weapons. The winning team felt that by by designing an interactive dart-thrower for exhibitions, that it would be possible to capture the attention of passing visitors. The design team proposed to develop a mechanism that would combine the use of accurate position control (aiming and launching a dart) with elaborate movements to enhance viewing pleasure. The idea further proposed the possibility of including an automated re-loader that could demonstrate the use of additional product ranges.

2. Primary design considerations

A number of primary considerations were kept in mind during the design process. The main concerns were technical accuracy, level of practicality, creativity and budgeting. The business acumen and level of difficulty were considered as supplementary to the design.

3. Engineering Specifications

3.1. Adherence to standards -  According to international standards, the distance between the thrower and the dartboard must be 2.37 meters. This is this first engineering specification.
Secondly, the design should use conventional darts and throw at a conventional dart board.

3.2. Throwing specifications - Appropriate inputs and their ranges  An A~Dot user has three parameters to specify upon throwing: throwing speed, horizontal throwing angle and vertical throwing angle.

3.2.1. Throwing speed and vertical throwing angle  Vertical accuracy, in other words the difference in vertical position between the point where the dart is released and where it hits the dart board is influenced by gravity, the vertical throwing angle and the throwing speed. It was decided that, in order to make the game challenging, the player must throw with an arc, rather than with a straight line.

3.2.2. Horizontal throwing angle  The horizontal throwing angle is not affected by gravity forces and is thus solely affected by the dart board radius and the distance from the board. Since both of these quantities are already constrained by international conventions, the horizontal throwing angle range is automatically constrained. It was decided to make the horizontal throwing angle range such that it is possible to just miss the board when throwing at the limiting angles. This angle was determined by trigonometry as being ± 5º.

3.2.3. Repeatability  In order for the trail-and-error principle to function, a good degree of repeatability is necessary. It was decided that a there should be a throwing speed tolerance of ± 0.5 m.s-1, which translates to ± 6.5 % on the average throwing speed. Also, aiming tolerance was to be limited to less than ± 0.1º, which translates to about a 4 mm tolerance radius on the dart board.