Ajisai: A Structure That Matches the Relationship Between Force and Color to Human Perception

Humans find it difficult to perceive visually the level of force exerted on an object by a robot operating with positional control. According to research, humans perceive colors in terms of weight following the order of yellow, green, blue, and red, clockwise on the hue circle. We believe that by developing a structure that changes colors in this specific order, we can achieve visual force transmission that aligns with the relationship between force and color as perceived by humans. In this letter, we used the photoelasticity of an anisotropic transparent material, which changes color depending on the applied force when sandwiched between two polarizing plates. The material is dumbbell shaped, which ensures equalization of the applied force. Based on this, we have developed a structure called Ajisai, which is powered by artificial muscles and whose colors change in response to applied force to match human perception.