At a time when robotics seeks to combine performance and accessibility, an educational experiment surprises with its effectiveness. Inspired by work carried out at Pisa/IIT on flexible robotic hands, an anthropomorphic hand built entirely from standard LEGO parts now rivals devices used in academic research. The project, called Educational SoftHand-A, is the result of a collaboration between Jared K. Lepora, a 16-year-old high school student at Bristol Grammar School, and his father, Dr. Nathan F. Lepora, a researcher at the University of Bristol.
Their study, carried out with Haoran Li and Efi Psomopoulou, was published on the arXiv scientific platform and accepted at the IROS 2025 conference, specializing in intelligent robotics. The challenge: to demonstrate that advanced robotic concepts can be taught with consumer equipment, while faithfully reproducing the complex dynamics of human movement.
A robotic hand born from a family challenge
The genesis of the Educational SoftHand-A project therefore dates back to a personal initiative launched by Jared K. Lepora, then aged 14, accompanied by his father, Dr Nathan F. Lepora, a robotics researcher at the University of Bristol. Their ambition: to translate the complex principles of robotic gripping into an accessible construction. They relied solely on parts from LEGO MINDSTORMS kits, without using 3D printing or specialized components. The project is designed from the start with a learning logic in mind. The objective: to allow other young people to explore robotics without technical or financial barriers.
This family approach quickly transformed into a true scientific approach. With the collaboration of Efi Psomopoulou and Haoran Li, also researchers, the team modeled, tested and documented hand performance in a study.
Nathan Lepora's contribution made it possible to adapt the concepts from Pisa/IIT SoftHand to a 100% LEGO version. This is a soft robotic hand model developed in Italy. The challenge was to faithfully reproduce adaptive grasping functions (flexible and automatic grasping of objects). But with material normally used in educational contexts.
The choice of LEGO is not trivial. Its modularity, global distribution and mechanical compatibility offer a prototyping platform that is both stable and reproducible. The project thus becomes a bridge between the domestic world and scientific experimentation. It places in the hands of an adolescent a tool conceptually equivalent to laboratory equipment.
A biomechanical architecture inspired by the human body
The operation of the Educational SoftHand-A is based on simplified biomechanical principles. But nevertheless very close to the real anatomy of the human hand. The device consists of four fingers (index finger, middle finger, little finger and opposable thumb), each with three joints. These twelve joints are driven by a system of antagonistic tendons – one pair per finger – controlled by two LEGO motors.
Concretely, one tendon is used to close the finger (like a flexor), and another to open it (like an extensor). This operation is directly reminiscent of the human musculo-tendinous system, where the muscles always work in pairs to produce a fluid and controlled movement.
The innovation lies in the use of a mechanical differential, made using LEGO ratchet gears. This mechanism distributes the driving force between the fingers. If one of them encounters resistance (like the edge of a cup), the mechanism allows the others to continue their movement. This is the principle of soft synergies, as formalized in the Pisa/IIT SoftHand. It allows automatic adaptation to the shape of objects.
© Jared K. Lepora et al., 2025
Hand action sequence.
The absence of complex electronic sensors is compensated for by this passive mechanical intelligence. It makes the system both robust and simple to operate. The whole thing is controlled by a programmable LEGO module, powerful enough to manage the opening and closing loops in less than a second.
This choice of a highly under-actuated mechanical architecture, where several joints are controlled by a reduced number of motors, allows the LEGO hand to combine simplicity, economy of means, and great efficiency in gestures. It is also a concrete introduction to the principles of energy optimization in robotics.
Performance close to professional robotics
Beyond the technical challenge, the team confronted the project with performance tests. She carried them out in a domestic environment, but according to standards comparable to those of robotics research. The results are notable. The LEGO hand can exert a force of 5 to 6 newtons per finger. This allows you to grip and hold everyday objects—like cups, foam balls, or spools of tape—without slipping or becoming misaligned.
In experiments, the hand was able to complete complete opening and closing cycles in about one second. Sufficient responsiveness for simple interaction scenarios. According to the measurements carried out by the authors, the gripping capacity of the system reaches approximately 90% of that of the 3D printed SoftHand, a benchmark in the field.
The precision of gestures is directly linked to the system of passive synergies. It optimizes the distribution of forces without requiring active sensors. This ability to mechanically adjust to the shape of objects gives the hand a functional versatility that is generally found on much more expensive prototypes.
This efficiency, achieved with inexpensive parts and simplified control, is attracting interest from the robotics community. It demonstrates that certain critical functions — such as automatic adaptation or contact management — can be achieved without complex embedded intelligence, through thoughtful mechanical design alone.
The study also highlights that the reproducibility of the project in no way compromises its performance. It is a rare example of accessibility and efficiency in a field often reserved for experts with industrial resources.
A reproducible and open-source educational approach
One of the most striking aspects of the Educational SoftHand-A project lies in its explicit desire to transmit knowledge. Everything from the construction plan to the control code has been made available in open access at lepora.com/EduSoftHand-A.
This educational approach is part of a logic of learning through practice. As Dr. Nathan F. Lepora explains in a press release from Techexplore. “Learning how a robotic hand works by building it yourself is a particularly effective way to understand the mechanics of adaptive grasping.” By manipulating the parts, young users can concretely grasp the notions of actuation, mechanical transmission and force feedback.
The project also takes on a symbolic value in a particular context. LEGO has announced the end of the MINDSTORMS range, long considered a bridge between play and technical learning. The SoftHand-A becomes one of the last major projects fully exploiting this system, while paying tribute to its educational capacity.
The free distribution of the project is also a response to the challenges of inclusiveness in scientific education. By reducing dependence on expensive or difficult-to-obtain equipment, it becomes possible to integrate robotics into secondary or extracurricular courses.
This robotic hand therefore represents much more than a functional prototype. It embodies a philosophy of accessible, reproducible learning, and anchored in concrete manipulation. She could inspire a new generation of budding engineers. This project shows that technology does not remain a matter of experts, but also of pedagogy and curiosity.
Source: Jared K. Lepora et al., “Educational SoftHand-A: Building an Anthropomorphic Hand with Soft Synergies using LEGO MINDSTORMS”. arXiv (2025).
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