Softy: An Interactive Kit to Revitalize the Plush Toys of Children

Children across the globe experience the phenomenon of quickly losing interest in their toys, leading to the accumulation and wasteful disposal of toys. After conducting research and considering the characteristics of toys along with their potential use cases, we propose Softy, a modular interactive kit designed for plush toys. Corresponding to envisioned application scenarios, we have devised two types of modules and three interaction modes. This paper elucidates the prototype design and development of Softy, delving into the possibilities of rekindling children's interest in toys by incorporating interactive movements into them.


INTRODUCTION
One of the greatest and perhaps most exciting parts of a child's daily life consists of interacting with their toys.Engaging in play with toys is not only fun, but it also constitutes an essential role in the developmental progress of children [5].However, as children explore the world, their interests in toys are also constantly shifting and toys begin to pile up everywhere.The average child's engagement with a toy wanes in just over a month, as their attention shifts, another toy gets banished to the pile [1].Due to this accumulation of toys, parents across the globe face the problem of how to manage their children's toys.Current children's toys sufer from two major drawbacks: relatively fxed characteristics and a predominantly passive nature, leading to a subpar interactive experience.These factors signifcantly contribute to the phenomenon of children growing tired of their toys.There have been some notable works addressing how to transform old toys through interactive design, attempting to rekindle the interest of children.
"Aimoji" enables interaction between children and toys using a display [11]."PINOKY" is a wireless accessory for plush toys that adds dynamic efects to their movements.[14].Both of these designs exhibit characteristics of relatively weak interactivity as they are unable to receive input from users.However, recent research has focused on incorporating user-controlled inputs for interaction.For instance, an acceleration sensor design for estimating the motion of plush toys [10] provides feedback on children's control of plush toy movements through forms such as sound.
Therefore, our objective is to propose a hardware interaction approach capable of reigniting children's interest in playing with old toys, facilitating the reuse and prolongation of the "life span" of previously owned toys.To address this issue, we have designed and developed Softy, a modular kit aimed at revitalizing toys.Comprising various functional modules, including one central core module and multiple skeletal modules, this kit provides a solution.These modules can be afxed to a child's existing toys using Velcro.They possess the ability to perceive the environment, endowing the toy with dynamic movements and ofering children an entirely new interactive play experience.Children also have the autonomy to assemble the skeletal components to ft various forms of plush toys.

DESIGN CONSIDERATION 2.1 Choice of Medium
Children's toys can be broadly categorized into hard toys and soft toys, with plush toys being a prominent subset of soft toys [16].The inherent "softness" of plush toys suggests a potential for manipulability.Interactive play is a crucial component in children's understanding of the world, and toys that are both movable and interactive imbue their world with dynamic and responsive qualities [6].
In the early stages of the preoperational phase (2-4 years old), children are the most attached to soft toys and as children grow older (5-7 years old) they begin to require more challenges and stimulation from their toys [13].Our design takes into account the transitional needs of this stage, providing new stimulation while retaining children's attachment to existing soft toys.
Through integration technology, plush toys can ofer a personalized experience, fostering the development of children's creativity and problem-solving skills.Each child can develop entirely new ways of playing with their old toys.Therefore, we have chosen plush toys as the carrier for Softy.
Embracing Softy's core principles of developmental adaptability, innovative technological integration, and inclusive design, we now delve into the specifc functionalities that bring this visionary concept into the daily lives of children.

Interaction Design
When contemplating Softy's response mechanisms to interaction modes, we integrated aspects of common actions associated with ordinary plush toys such as hugging, swinging, and playing with its limbs.Corresponding to these actions, Softy is capable of making plush toys hug, dance, and raise their hands.Such physical gesture responses in robots enhance human-robot interaction and generally improve user experience [3].It's worth mentioning that gestures such as waving and hugging are fundamental in day-to-day social interactions and they carry positive connotations, possibly providing comfort to children [8].
In the development of interaction modes, our primary focus was to maintain low learning complexity while implementing interactivity.We also kept in mind that cause-and-efect experiences are vital in interactive toys [9].Our approach involves designing responsive interactions that mirror the natural behaviors children exhibit with standard plush toys.These behaviors, or 'causes,' include actions such as hugging, moving around, talking to, and squeezing the toys.The 'efect' is manifested in how Softy, our interactive toy, responds to these actions.This design strategy enables Softy to react in a meaningful way to the child's engagement, thereby enriching the interactive experience.Movement Detection Mode Physical interactions with plush toys are often one-sided.While this gives children total control, double-sided gestures of afection may increase feelings of companionship [17].So, we wanted Softy to be able to reciprocate afectionate movements from children.To achieve this, we included an infrared sensor that can detect proximity.When children approach their toy, the servos drive the skeletal structure to make a small-range oscillation, initiating movement in their toy.
Hands-on Mode Considering that ordinary toys give children complete control, we also wanted to maintain this element as much as possible.Particularly, the aforementioned group of children in the preoperational phase primarily engage in pretend play and imaginative play [12].Taking inspiration from this, we wanted children to be able to take control of their own play experiences and also aid in their development of fne motor skills by using a button [4].Children can manipulate Softy's skeletal modules through a button switch.In the prototype design, pressing the button switch causes the servos to drive the skeletal structure, switching between diferent angles.
Interactive Sound Mode As previously mentioned, children often talk to their toys.We believe interactive elements will boost these actions as children who are still developing their speech skills feel more encouraged to talk when they have feedback [7].We envision Softy moving and dancing when there is sound.This can also engage children in interactive musical experiences and foster their rhythm skills through imitation [2].To fulfll this, we added a microphone.Based on the strength and frequency of the sound captured by the microphone, Softy controls the skeletal structure to induce movement in the attached toy varying in amplitude and frequency.
The above features were designed to create more dynamic, interactive, and educational play experiences with Softy.

Modular design
The use of a modular design in Softy is a key feature that enhances its adaptability and versatility.This design allows for the integration of a core module and multiple skeletal modules, enabling the drive of every movable part on the plush toy [15].The core module integrates the main board and necessary sensors for core control.The skeletal modules include servos and buttons for controlling individual servos, enabling fexible control of each skeletal module.
The primary purpose of this modular design is to adapt to the diverse shapes of plush toys while maintaining certain degrees of freedom.For instance, a bear toy may have four limbs, a rabbit toy might have long ears, and a snake toy could possess only a cylindrical body.By partitioning the modules according to our design, we can attach skeletal modules to the core module in various positions and quantities.This enables the movement of every possible part of the plush toy.This design strategy provides a robust foundation for Softy's versatility and adaptability, allowing it to accommodate a wide range of toy structures.To facilitate the simple assembly of our core module and skeletal components, we have utilized LEGO bricks to construct the shell of the core module and the physical interface section of the skeletal modules.This design allows for a swift connection between the core and skeletal modules using LEGO bricks.Children also have the fexibility to modify the color and shape of these bricks using their own LEGO pieces.By planning the interface direction of the LEGO bricks, children can achieve diferent degrees of freedom in various directions when using Softy.This signifcantly enhances the playability of the toy.
Moreover, the highly integrated modular design makes Softy even more user-friendly.Children or parents simply need to attach diferent skeletal modules at any position on the core module, allowing them to animate their beloved toys in various forms.This design simplifes the learning curve for children, reducing the likelihood of impatience when faced with complex operations.

Results
Considering the above factors, we have conceptualized and developed Softy, a modular prototype robot.The name "Softy" was inspired by the enchanting idea of toys springing to life, reminiscent of Woody, the beloved main character from the iconic children's movie, "Toy Story".

Figure 5: Modules of Softy
Softy comprises multiple modules.Through straightforward assembly, children or parents can afx it to various soft accessories (Figure 1).For instance, dressing a teddy bear in clothing equipped with Softy or attaching Softy to a plush tail.Once Softy is attached to the toy, children can engage in novel interactions with their "new" old toys.

PROTOTYPE DEVELOPMENT
The prototype of Softy (Figure 1) is composed of numerous skeletal modules and a central core module, employing pre-owned teddy bears produced by IKEA as demonstrative entities afxed to the robot.It is imperative to note that all components integrated into our design are fundamental parts and sensors readily available for purchase online.
We have developed attachable and modular skeletal modules designed for fexible objects.This module is propelled by servo motors to induce limb oscillation.The module is comprised of extendable plastic frameworks, servo motors, and button switches.Further, it features physical interfaces, power interfaces, and signal interfaces, facilitating utilization by connecting to the core module.
The core module functions as the control unit of the robot and incorporates a distance sensor, a mic, and an ARDUINO UNO.It features multiple interfaces designed for the insertion of skeletal modules.In our prototype, we have provisioned four interfaces for connecting skeletal modules, each corresponding to distinct parts of the plush toy, such as the arms, legs, ears, and tail.

USE CASE
As previously mentioned, we would like Softy to become a companion for children by responding to them interactively.In alignment with this goal, three main application scenarios for children using plush toys attached to Softy are envisioned: "Companion" Scenario (Figure 6-1): When a child approaches the plush toy, Softy will prompt it to gently shake its body in response.Softy can also contract the arms of a toy and perform a hugging action as a response.This kind of interaction can provide a sense of companionship.
"Pretend play" Scenario (Figure 6-2): A child is pretending to be a teacher and wants their plush toy to play the role of a student.Softy can prompt the toy to mimic the actions of a student, raising its hand by pressing a limb button.This can help children thrive in their imaginations and creative world.Further, sharing such interactions can encourage social interactions between children and their peers.
"Dance Party" Scenario (Figure 6-3): When a child wishes to listen to music with someone, Softy will pick up the surrounding sounds and prompt the toy to move around and dance.This can encourage children to move along and thus take part in fostering their rhythm skills.

Future work
In the future, Softy Kit will shift from "play toys" to "play everything," with the nature of play defned by the children themselves.Currently, we are eagerly exploring the integration of modular input and output components into large language models.Our goal is to transfer data from these components through a computational module for processing within the language model.This approach is designed to enable the language model to merge with various old toys, augmented by our kit and the creative assemblies of children.Such integration has immense potential to automate and transform any old toy.This aligns them with the interactive modes anticipated by children and thereby introduces new dimensions of engagement and interactions.Furthermore, our design incorporates inclusive features for children with special needs.The tactile feedback provided by the augmented toys opens up new possibilities for interactive experiences for these children.For instance, A child with hearing impairments might receive motion feedback from a toy, allowing them to be aware of and engage with distant peers, thus fostering friendships.In this context, toys become more than mere playthings; they serve as essential tools for children to explore and interact with the world, acting as their eyes and ears.

Limitations
Our kit currently ofers a relatively singular form of interaction, primarily limited to feedback in the form of movements.Popular toys in the market often incorporate various playful features such as sound efects, lighting, and more.Additionally, Softy currently lacks communication functionalities, which means it cannot facilitate interaction between two toys or with other terminals.

CONCLUSION
We have observed that as children grow older, their toys often become neglected or accumulated due to a lack of engaging interactive experiences.Based on this observation, our study focused on designing and developing a modular, movable robot kit named Softy.This kit can be fexibly attached to any soft, plush toy, animating it and facilitating both active and passive interactions for children.Through Softy, we aim to repurpose old toys, reinvigorating them with new life.Moreover, by incorporating Softy into plush toys, we enable children to experience emotional support, enhanced imagination, creativity, and social skills during their play.

Figure 3 :
Figure 3: Skeleton modules can be assembled with multiple degrees of freedom through Lego bricks.

Figure 4 :
Figure 4: Softy can have various degrees of freedom.

Figure 6 :
Figure 6: Three main application scenarios for children using plush toys attached to Softy.