In the search for the perfect haptic experience, GRIFFWERK tested a wide variety of profiles in several studies. Finally, several criteria could be defined that are relevant for a "perfect" gripping experience:
The "perfect" profile corresponds to the hollow space,of the closing hand. This is three-sided for anatomical reasons and not round or rectangular
During operation, the angle of the closed hand is changed, as well as the position of the user in space. The closed hand is therefore "moved" on the door handle. It does not remain static. The edges must therefore be softly rounded to allow for movement play.
Most pressure is exerted on the upper contact surface. This is also the largest contact surface between the door handle and the hand. It therefore plays the most important role for the grip feeling. It is particularly pleasant if it is kept very wide, as is the case with TRI.
The upper contact surface should also be inclined towards the door. An angle that slopes gently towards the door corresponds to the natural posture of the wrist when operating a door handle. Thanks to the inclined angle, the wrist is not hyperextended when pressing the handle (as would be the case with a horizontal surface).
Door handle TRI 134 was developed based on these criteria.