In the evolving landscape of robotic innovation, dexterous hands stand out as a noteworthy standard for human-like robot interaction with the world. Since the early days of robotics, replicating the human hand has held fascination for researchers and enterprises alike. The technology itself captures the imagination, and also carries self-evident practical uses, with the ability to perform teleoperated tasks that require complex dexterous movement. In this article, we explore the history of dexterous robotic hands, the technologies involved, as well as ongoing research. Additionally, we discuss several practical applications for dexterous hand technology that are in use today.
At the forefront of dexterous hand innovation is the Shadow Robot Company. The company behind the Shadow Robot Dexterous Hand has paved the way for advanced haptic systems, AI-driven control, and material innovations that have created new possibilities for real solutions using human-like dexterity. This article presents the Shadow Dexterous hand as the culmination of technological advancements and dexterous hand history.
Early research and development into dexterous robotic hands emerged in response to the apparent utility of robots capable of performing tasks that require fine motor skills and adaptability. The Stanford/JPL Hand, considered the first dexterous robotic hand, was developed in the early 1980s to investigate fine robotic manipulation. The Stanford/JPL Hand has three independently controlled fingers and is equipped with force feedback for more natural interaction with objects than previous industrial gripper hands. Soon after, the Utah/MIT Dextrous Hand made breakthroughs in human-like articulation, robotic dexterity, and sensing, becoming the foundation for future dexterous hand design. Here is a timeline of the key milestones and breakthroughs in dexterous hand design:
The engineering of dexterous robotic hands has both benefited from and informed the research and development of a wide range of key technologies, including actuators, sensors, haptics, artificial intelligence, machine learning, and materials science. The sections below look at each of these areas of development as they relate to dexterous hands.
Actuators are the components that deliver movement in the fingers, wrist, and other joints of a dexterous robotic hand. Actuator movement is directed by a teleoperated controller and by sensors on the hand itself. Various types of actuators are used in robotic hands, depending on the power, size, precision, and application.
Actuators are also responsible for the degrees of freedom in a robotic hand, which are the number of independent axes on which a robotic hand can move. Each axis requires an actuator to bend. Actuators drive the grasping pattern and level of dexterity of the robot hand.
An important advancement for dexterous robotic hands was the development of underactuated mechanisms. Underactuated robotic hands have fewer actuators than the number of degrees of freedom. This is achieved by breaking down finger movements into modular units controlled by a single actuator, meaning that the hand can perform agile movements with reduced complexity of controls.
Sensors integrate with actuators to enable a dexterous robot hand to interact with the environment and perform various tasks. Sensors gather data about the properties of an object in the environment and about the state and position of the hand itself. This data is shared with other parts of the system resulting in precise control at individual points of contact.
Data from sensors is incorporated into actuator movement for a more human-like response to an object’s weight, fragility, temperature, and other qualities. Hands with advanced sensory systems are capable of delicate and precise grasping and contact pressure sensing. Sensors also detect the position of each joint in relation to other joints and the entire hand itself, resulting in a complete system of sensing and movement that operates like a human hand.
The following are some examples of advanced sensor technology used in dexterous robotic hands:
Sensor data can be relayed to a human operator in the form of haptic feedback. Haptics provide the operator with tactile feedback so that the operator can remotely sense the properties of an object that the robotic hand is interacting with. The operator can receive this feedback through hand-held controllers, gloves or other types of wearables. Advancements in haptic capabilities may also improve object recognition and handling for dexterous robotic hands. Some examples of haptic capabilities are:
Artificial intelligence and machine learning play important roles in the advancing capabilities of dexterous robotic hands. Algorithms are applied to data from sensors to improve perception and recognition of objects in the hands environment. These technologies also enhance robotic grasping and manipulation, and with machine learning algorithms, the robotic hand can learn from data and improve how it handles different objects, materials, and what to anticipate in different environments.
Artificial intelligence and machine learning algorithms are also applied to operator controls for enhanced human-robot interaction. The robotic hand can learn to recognize gestures, spoken commands, and other input, and it can provide more effective haptic feedback in return. These advancements contribute to the research and development of versatile and intuitive robotic hands.
Materials science is another critical area of research that influences the design, functionality, and performance of dexterous robotic hands. The choice of materials impacts the hand’s durability, performance, and adaptability. These are some key considerations of materials science in the development of robotic hands:
Dexterous robotic hands are a valuable field of research and will continue to be because their development has significant implications across diverse industries, including manufacturing, healthcare, exploration, and more.
Today, one of the most notable contributors to dexterous robotic hand research and development is the Shadow Robot Company. Shadow Robot aims to create custom advanced dexterous robotic systems that solve real problems and provide meaningful scientific advancement. The company’s “robots for good” policy guides the direction of innovation and partnerships, with a firm stance to never sell technology for military use.
The Shadow Robot Company began with a post on an internet hobbyist forum in 1997. The first hand was a wooden model, and the post caught the attention of a university. Around 2004, the company introduced the next generation of the hand with air muscles—the company’s flagship product until about 2010, when the Shadow Dexterous Hand introduced internal motors instead of air muscles. Since then, the hand has undergone countless improvements that build on the motorized concept.
The innovations at Shadow Robot have been put to practical use in a range of industries including research, health and medicine, space exploration, manufacturing, and entertainment. The company offers a range of dexterous hand products. Their current flagship Shadow Dexterous Hand has 20 degrees of freedom across 24 joints, and is equipped with 129 sensors and 20 DC motors for remarkable dexterity and precision.
The Shadow Hand has been used by organizations like Open AI to explore machine learning and dexterity, while its teloperated system has the potential to improve safety and efficiency for workers in hazardous settings. The hand can be controlled with a haptic glove for intuitive operation and real-time control. The company has also developed technology to perform intricate tasks in sterile environments, like the manufacture of vaccines and pharmaceuticals. Shadow Robot continues to advance dexterous hand technology with effective innovations that solve practical problems.
The applications and science of dexterous robotic hands continue to inspire both innovation and imagination. From precise surgical procedures to harsh and hazardous environments, the capabilities of dexterous robotic hands open new possibilities for industries as well as scientific fields. The field of robotics has greatly benefited from dexterous hand innovation, which has led to the development of underactuated technology, sensors that can detect increasingly subtle properties, haptics with human-like response, as well as the exploration of artificial intelligence as it relates to dexterity.
The Shadow Robot Dexterous Hand, a benchmark in this field, has pushed the limits further with cutting-edge technologies and applications that redefine robotic capabilities. Part 2 of this series will present a deep-dive into the dexterous hand series from Shadow Robot, and Part 3 will introduce dexterous hand and glove technology, and the lightweight Shadow Glove.
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