A team of researchers from Polytechnic University of Madrid developed new design concepts to integrate mechanics and electronics in the hand of a humanoid robot, which allows a friendlier communication with humans and favors their social interaction.
ManoPla is a hand robot whose purpose is gestural communication. It was conceived and developed by researchers from the Center for Automation and Robotics (CHARACTERS), a joint research center of the Polytechnic University of Madrid (UPM) and the Superior Council for Scientific Research (CSIC).
Its design is inspired by a real hand and is lightweight. With this objective, creative and original solutions have been adopted in its development. ManoPla will allow guide or assistance robots to convey, in a more natural way, emphasis, certain feelings and emotions, thus enriching human-robot communication.
It is a working prototype with 17 controllable joints plus four passive ones.
In social robotics, a friendly and natural interaction with humans is particularly sought. In a conversation with another person, gestural communication can be as rich and even more eloquent than verbal communication. For this reason, in the last decade, there are many developments and investigations that focus on this robot’s interactive capability.
For example, at the Superior Technical School of Engineering and Industrial Design (ETSIDI) at UPM, a humanoid social robot Hidalgo was developed and, for it, it was decided to design a robotic hand as close as possible to the human hand in terms of mobility.
The impact, mobility and grip tests carried out have aroused interest in the field of social robotics, so part of their development was published in the International Journal of Social Robotics.
Each element has its function
The result of this research, carried out by researchers from the Robotics and Cybernetics group at CAR-UPM-CSIC, is a functional prototype with 17 controllable joints plus four passive ones.
The four finger joints are driven by three motors (following the model proposed by the humanoid astronaut robonaut). The thumb, due to its uniqueness, controls the four joints with which it was modeled. In addition, the palm can bend, managing to exceptionally emulate human morphology and movements.
Given that the ManoPLA is totally autonomous, both for the actuation systems and for the control (it has its own microcontroller to regulate all the movements and measure and serve the information), the most relevant physical problem that arises is the limitation of space. offered by the device.
The external appearance of the hand is not merely decorative: each of its parts, both the fingers and the palm, are part of some internal mechanism.
The use of mechatronic design methods that bring together the three fields covered —mechanics, electronics and programming— allowed the development of the fully functional final prototype. In this project everything is used. This means that the electronic board is structural, and still has all possible sensors integrated, adapting the mechanics of the fingers and sensors to make this possible. In addition, specific solutions have been developed to obtain elastic actuations with optical joint transducers of new and specific configuration and design.
All these solutions make the hand a meticulous engineering project, with its own identity, which has constantly sought alternative solutions for difficult problems. The software design has been studied in detail to achieve absolute control in the robotic hand. Thanks to the low-level programming of the microcontroller, it was possible to optimize the execution cycles and control the processing frequencies of each of the elements.
The external appearance of the hand is not merely decorative either. Each of the pieces, both the fingers and the palm, are part of some internal mechanism, so the final appearance is completely linked to functionality.
In total, the ManoPLA weighs only 250 grams, integrates 17 motors and 17 sensors, and has 22 articulations, with their respective power electronics and control system. The only thing it does not include is a battery, as it is considered that it will always have to be supported by a robotic arm through which the energy needed for its operation arrives.
REFERENCE:
M. Hernando et al. “Mechatronic design of an independent skilled robotic hand for gestural communication”. International Journal of Social Robotics (2023).