A well-designed chair is ideally an armchair where you can sit smoothly and get up with a minimum of effort.
Decomposition of movement
Our center of gravity is at our navel. To be balanced this center of gravity must be vertical of the sustening polygon that draws the perimeter of our feet in support of th
e ground. To get up from an armchair, you start by rolling your feet under the seat so that they are vertically from our navel. We can then push with the thighs to lift our body.
We also have the arms to help us. We will be able to lean on the armrests of the chair to get up.
Effort to produce
It depends on the weight to be lifted and the distance to travel. This distance is equal to the difference in height between the navel in a sitting position and standing position.
In addition, the more the legs are bent the harder you have to push harder.
It is therefore important if you want to get up easily to have a higher seat and more inclined forward.
But if the seat is too high and/or leaning forward too much, there is a risk of slipping and falling.
How to build a classic chair to get up effortlessly
In relation to the movement and effort required to get up from an arm
chair: – the underside of the seat must be cleared so that the fe
et can be recoiled – the armrests must offer a fairly high and advanced grip area (b
ut not too advanced) – the seat should be as high as possible without the fe
et being de-glued from the ground – the
tilt of the seat should be close to 0-A chair made to measure specifications.
The electric lift chair
The principle is to use an engine to lift the seat so that it lifts the user. The difficulty is to keep the seat in contact with the user during the climb because otherwise it could slip and fall.
This requires the seat to rotate around an axis at the knee.
Be careful that the dimensions of the chair are well adapted to the user. Otherwise it is preferable, for reasons of safety and preservation of autonomy, to have an armchair manufactured to its measurements.
