Since the okiagari-koboshi is a self-righting doll and would not topple over, the centre of gravity has to be as low as possible in the model. According to the concepts of centre of gravity, to make an object have a lower centre of gravity, the object has to have a heavier base and have a larger base area. Thus, these concepts were implemented into the process of making the model. It has a heavy base in comparison to the model's body, and has a large base area.* Principle Two: StabilityOne of the key properties of the okiagari-koboshi is that it does not topple or fall down no matter how one pushes it. The okiagari-koboshi would rock back up to its original state and position.
To fulfill this requirement, the object has to remain at a stable equilibrium at all times, regardless if it is being pushed. To keep the model at a stable equilibrium, the centre of gravity must be as low as possible and the base area as large as possible, so as to keep the model at its maximum stability. The weight of the model should also be concentrated at the base of it. When constructing the model, as mentioned above, a heavier base was made for the okiagari-koboshi and a larger base area than the top of the model.
Also, we concentrated the weight of the model at the base of the okiagari-koboshi.* Principle three: Turning effects of forcesAs explained earlier, the okiagari-koboshi needs to maintain a stable equilibrium for it to work. In a stable equilibrium, the object returns back into its equilibrium position after being pushed. This is due to the turning effects of forces, also known as moments. When the okiagari-koboshi is tilted to one side, the centre of gravity of it is raised, placing it in a less stable position. Being in a less stable position, the okiagari-koboshi creates a turning force, or moment from its weight, that leans it back to its more stable, original position that has a lower centre of gravity.
Without this turning effect, the okiagari-koboshi would topple over.Thus, to make the okiagari-koboshi work, the model has to have as low a centre of gravity as possible, so that it would be much more likely that the centre of gravity would shift upwards, than downwards, when pushed. If the centre of gravity is lowered when pushed, the model, in a more stable position, would topple over from the moment caused by the model's weight. This is to allow the model to remain in the more stable position with a lower centre of gravity. So, when making the model, it had to have all the aspects as mentioned under "Principle Two: Stability": a heavy and large base.
ConclusionTo make the okiagari-koboshi with it being functional, there are two key factors to consider when making it: 1. it must have a heavy base heavier than its body, and 2. it must have a large base area bigger than its body.
