Dog curve

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The name dog curve is a common name for various flat curves . The term is derived from the way that an idealized dog describes. The investigation of the so-called dog curves is a sub-area of ​​the pursuit problems .

variants

The path of the dog handler , the leading curve, is in the following a straight line , the x-axis. The dog's movement describes three different curves, depending on the model:

  • Dog on a leash and tree : In the example, the dog handler moves from right to left, i.e. H. from x = 2 to x = 0. There is a tree away from the handler's path . In the example this is in point (0,1) and exactly one line length away from the path. If the dog tries to keep the distance between itself and the tree to a minimum , a conchoid of Nicomedes is created .
  • Dog on a leash : In the example, the dog handler moves from left to right. If the dog is away from the handler's path and is pulled on a leash, trying to minimize its speed , an actual tract is created .
  • Dog without a leash pursues pedestrians : In the example, the dog handler moves at a constant speed from left to right. If the dog is off the path and always runs at a constant speed towards the current position of its handler while the dog is moving, a straight radiodrome is created . Depending on the speed ratio , the dog can reach his master or not.
Comparison between different dog curves. The relevant relevant parameters are 1

aviation

Dog turn when approaching an NDB in cross wind

In aviation, due to the influence of crosswinds during homing, the flight path can correspond to a dog's turn: Without the influence of wind, the flight path between two points describes a straight line. However, when there is a crosswind, the aircraft drifts away from its actual flight path. If the pilot continuously corrects the alignment of the aircraft nose directly to the target, the course line over the ground is not a straight line, but an increasingly narrow curve (radiodrome).

hockey

The term dog curve also describes a certain walking path in hockey . The player starts straight ahead (on the right edge of the field) and then pulls inwards (towards the goal and parallel to the baseline). The counterpart on the left half of the field is called "Katzenkurve", although this term is not very popular.

Motorsport

The term dog curve continues to be used by motor sports enthusiasts to describe progressively tapering road curves (see also the graphic above); that is, the radius becomes smaller as the curve progresses. This type of curve is particularly dangerous for inexperienced drivers in normal road traffic, as it is difficult to predict (it usually occurs on mountain slopes away from the racetracks) and requires a quick correction of the steering angle and possibly the speed while cornering. When riding a motorcycle, it is also necessary to increase the lean angle. Since in most cases the technique would allow a more inclined position, this would actually not be a problem. Inexperienced riders in particular can easily reach the threshold of fear (of larger lean angles) and brake, which - depending on the chassis geometry and tuning - results in the motorcycle straightening up to a greater or lesser extent. This increases the radius driven while the real radius decreases. So there is a risk that the driver “runs out of road”. Even the load change reactions when taking off the accelerator can put the driver in distress.

Sport boat

A dog curve is a course over ground that is not driven as a straight line but as an arc between two points. The angle usually increases with increasing proximity to the target point. The reason for this bow is the displacement of the ship due to currents and / or wind. This can be counteracted by holding up the bow of the ship a little. In other words, depending on the strength of the current or the wind, the bow points at an angle between> 0 ° and <90 ° in the direction of the cause and thus compensates for the offset.

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