post plant

Graduation project, 2020
Industrial design, Interaction design, Mechanical design, HRI research, Creative direction

Collaborated with
Electrical engineering: Jaeyeon Park, Taeyun Li
Film directing: Minkyeong Song
CG: Yejin Choi  

Post Plant is a plant-like robot which communicates nonverbally through physical movement. Until now, robots have in most cases communicated with us by mimicking human speech and human/animal expressions and gestures. Post Plant takes a radically different approach by assuming a form inspired by plants; responding to touch instead of language, it nonverbally conveys simple emotions and information feedback. With Post Plant as a starting point, robots of the future will communicate with us in their own way, without having to mimic human behavior.

postplant sends you a message with its movements instead of words, expressions, gaze, and hand gestures. Feel the delicate signals they deliver.
Film Credit
Director: Song Minkyeong
Director of Photography: Lee Siyoung
Cast: Lee Seungmin

pp-1 is a tree-like robot. Its message is delivered in a way that the upper and lower axes contract and release through the twisting movement. We can easily see that it is negative by looking at the twisted shape of pp-1. If you approach it and touch the upper part or sweep the stem, pp-1 can return to a healthy state.

pp-2 is a flower-like robot. Its message is delivered through a sense of rhythm from the speed and direction of rotation. If pp-2 is frozen, touch it slightly. It will naturally move in the direction you touch and respond. Even when pp-2 is moving unstable, it will be fine if you touch it once.

Why robots?

How can we communicate with robots without face, arms, legs?

Most of the Robots in Sci-Fi movies are humanoids. They communicate with voice, gestures, and facial expressions. However in reality, most of the industrial robots have no face, some of them only have arms or legs. In the future, we need to figure out a new way to communicate with robots even witout face, legs, arms, whatever that look like human or animals.
There are two main reasons for this. With the current technology, robots with physical shapes cannot communicate on the same level as humans. This is not something that can be achieved when a single technology is completed, but human-like interaction is applied to robots for a very long period of time, so it is difficult to communicate at the same level as humans at the moment.
  Second, and more important than this, is the meaning. If you make a robot that resembles a human, it represents a human being. If you make a robot that mimics the physical characteristics of a specific gender, for example, a woman, the robot is not a robot but a female representation. Likewise, when a robot is made with a cute and weak object such as a puppy or a child as a model, the robot does not exist only as a robot, but becomes an entity representing something represented. For example, beating a dog robot is not only violence against the robot, but also violence against the underlying dog. For this reason, a robot must have a robot-like ‘new’ shape, and a new communication method that can communicate only with ‘movement’ must be found.
image credit: SONY, GQ

Why plants?

CG credit: Yejin Choi

Plant-looking post plant

So, why do postplants resemble plants? Plants sometimes appear dead because they move much slower than humans. But as you know, the world of plants is fierce. It's just slow. They interact with each other and compete with each other. Postplant uses plants as motifs to transform perceptions by representing plants that are not recognized as dynamic subjects by people, and to make unfamiliar and familiar feelings coexist.



  First, in order to define the communication method of non-humanoid robots, literature studies were conducted on non-verbal communication methods of robots. Based on theories of Laban, psychologists James A. Russell, David Chalmers, Daniel Dennett, etc. I concluded that humans read emotions and information from movement. In particular, the roboticist Cynthia Breazeal's AVS theory, that is, Arousal (awareness level), Valence (positive or negative), and Stance (open attitude or closed attitude), influenced how I mapped the shape and movement of the postplant into emotional expressions.
  The movement of postplant, even a very simple expression, was made based on these philosophical and engineering theories. Therefore, people can instinctively read the movement of the postplant without learning. Also, by arranging various theories about movement, I started to observe objects based on the degree of freedom of movement by using the four characteristics of freedom and movement: direction, speed (tempo, speed, acceleration), and volume (size, kinisphere). I

I found hints from the shape and movement of objects and organized them into the concept of ‘motion affordance’.

‘Motion affordance’ refers to the implied motion of the shape of an object. The rightmost shape in the image is taken from the swing. The shape of swing includes two strings spanning while holding the mass in place, allowing it to move back and forth. However, if you make a gap in the upper cylinder so that it can move from right to left like the image in the middle, this structure will have one more degree of freedom than the previous swing. Similarly, when the shape, not the structure, is changed, the movement is different. The rotating mass inserted into the circular rail on the left implies a different movement than the two on the right. Combining numerous degrees of freedom and numerous shapes and structures in this way can produce infinite motion affordances.

However, if this process is carried out arbitrarily, the structure may be far from reality. Therefore, it is necessary to observe and analyze things in reality.

Most of the objects seen in daily life were observed and recorded, and various observations were made in addition to the objects and movements in the images described above. In order to classify these objects and movements, a rough idea of the taxonomy was first needed, so I brought the concept of 'information element' that can increase the resolution of information according to 'posture' and 'sight' among the non-verbal communication elements of the robot. The information element refers to the 'unitary characteristics' of each thing. For example, in the case of the physical structure of a sunflower, petals can be used as an information element, and in the case of an abacus, the abacus egg has the potential to be used as an information element. In other words, if a structure of the same shape exists repeatedly, it can be used to create a pattern, which means that it can serve as a platform that can transmit information.

Structural analysis1. Classification based on degree of freedom type

Structural analysis2. Classification by number of information elements

After completing structural and theoretical analysis of movement and information expression, the most appropriate plan was selected among the narrowed structures.

initial working prototypes for testing interactions

Soft mock-ups

Material and shape prototyping

Mechanical / PCB design

PCB iterations
Engineering credit: Jaeyeon Park, Taeyun Li

Interaction testing
Engineering credit: Jaeyeon Park, Taeyun Li

Concept backgrounds
CG credit: Yejin Choi

Final design exploded render

Laser cutting / assembly testing process

CNC machining process

CNC machined aluminium parts

Final parts

Assembly process

Final Images

Photography credit: Minkyeong Song
Model: Seungmin Lee




Graduation Exhibition

Special Thanks to

Electrical engineering: Jaeyeon Park, Taeyun Li
Film production: Minkyeong Song, Lee Siyoung, Lee Seungmin
Photograph: Minkyeong Song
CG: Yejin Choi
Assistance: Yuri Lim, Yongjun Yu, Gaeun Kim
Advice: Junhwan Lee, Euichul Jung, Seona Lim, Juhong Park  

*This project is funded by Undergraduate Research Program and Student Directed Education course from Faculty of Liberal Education, Seoul National University