We developed a method of representing carving turn postures of skiers by computer simulation. We assume the following conditions for repeated carving turns. (a) A skier is represented by a wire-frame figure and its posture is fixed by the values of the joint angles. (b) Both skis are always parallel and in contact with the snow surface. (c) The slope of the snow surface is constant everywhere. (d) At the instant of switching the direction of a turn, the skier takes a symmetric posture like straight downhill on a flat plane.
The values of the edging angle of both skis are always the same. Given the values of the edging angle and the distance between the tops of both skis, the form of the lower body of the skier is determined. Subsequently, the form of the whole body of the skier is determined by the angle between the upper body and the left/right femur.
Assuming the range of variation of each joint angle and changing the edging angle synchronously with the movement of the left/right ski along a circular rack on the slope, we can show the animation of a turning skier with skis by computer simulation. The position of the center of gravity of the skier is also shown at each instant.It turns out that a video record of a carving turn played by a skier, chosen arbitrarily, is well reproduced by our computer simulation. The method proposed here is expected to serve as a tool of technical analysis and instruction in skiing technique.

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Snowboarder's motion is seemingly complex. We have made a snowboarding robot which has flexion and extension in an ankle joint. One servomotor was attached to the ankle joint for dorsi-flexion and plantar-flexion.This model leans to the side of the flexed ankle from a basic posture. This posture is an inward-leaning postureof a turn. It is this motion which causes the snowboard to be edged. The edging of the snowboard changesaccording to this movement. To make a toe-side turn, it flexes the ankle (dorsi-flexion) and to make a heel-sideturn, it extends the ankle (plantar-flexion). A carving turn can be performed by using a side-cut snowboard. Thismodel is also capable of achieving a sequential turn. The width of board is found to be significant in maintaininga stable sequential turn. Too narrow a board makes a change of the edged side unstable. It turns out that thewidth of the snowboard plays an important role in allowing the model to make stable repeated turns.

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