In recent years, the field of humanoid robotics has experienced remarkable advancements, largely attributed to breakthroughs in key technologies such as motion control and core componentsThe industry is witnessing rapid development on a global scale, with the commercialization of humanoid robots making significant stridesA crucial element within this paradigm shift is the dexterous hand, which serves as the key execution tool for these sophisticated machinesUnlike conventional end-effectors, dexterous hands have the versatility to interact with a wide range of tools and objects in various human-centric scenarios.

Established in 2016, Jinshihitech has emerged as the first company in China to achieve commercial mass production of dexterous handsThe company has concentrated its efforts on developing humanoid five-fingered hands and their core motion component, the miniature servo actuators

To date, Jinshihitech has released three distinct series of dexterous hand products, catering to diverse application needs across different sectorsWith years of accumulation in productization, commercialization, and process optimization, Jinshihitech has set a benchmark in the industry concerning reliability, standardized mass production capabilities, and cost control.

As the excitement surrounding the dexterous hand market intensifies, divergences have emerged regarding the evaluation criteria for key performance indicators, leaving the public somewhat perplexedA notable point of contention lies in the relationship between the degrees of freedom (DoF) and the number of joints in the dexterous hands.

Traditionally, the degree of freedom in a dexterous hand is dictated by its actuators, which are typically motors or other driving sourcesBased on the relationship between degrees of freedom and the number of actuators, dexterous hands can be classified into two main categories: fully actuated and underactuated

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Fully actuated dexterous hands possess a one-to-one ratio between actuators and joints, enabling each finger joint to be independently controlledConversely, underactuated dexterous hands have more joints than active actuators, resulting in some joints being coupled and moved passivelyJinshihitech’s dexterous hand exemplifies an underactuated design; it utilizes six miniature servo actuators to power twelve joint movements, with four fingers each controlled by one actuator which manages two joints, while the thumb is driven by two actuators controlling four jointsTherefore, we can say that the dexterous hand from Jinshihitech boasts twelve degrees of freedom, composed of six active and six passive degrees of freedom.

The twelve degrees of freedom stem from extensive functional testing conducted during the product definition phase in 2016. This configuration provides superior grasping ability and adaptability, allowing for a greater variety of grasping movements

It is worth mentioning that alternative implementations with only ten or eleven degrees of freedom are also available; however, the lack of critical joints in the thumb significantly restricts the movement capabilities of those designsWhile higher degrees of freedom can undoubtedly enhance flexibility, they also face the downsides of increased costs and potential reliability issues due to complex mechanical designs.

Another key metric that piques public interest regarding dexterous hands is their load-bearing capacityAs society grows increasingly optimistic about the practical applications of humanoid robots, their ability to perform tasks effectively becomes vitalTherefore, dexterous hands must not only exhibit agility in movement but also demonstrate significant load-bearing capabilities; they must be capable of transporting objects and operating various tools.

So, how can one accurately determine load-bearing abilities?

The maximum weight a hand can grasp depends not only on the hand's grip posture but also significantly on the friction between the fingers and the object being held

For instance, Jinshihitech's dexterous hand can easily lift a 10-kilogram dumbbell; however, this does not necessarily imply that its load capacity is solely 10 kilogramsTo address this, Jinshihitech introduced the innovative metric of "finger output force," which measures the maximum force exerted by a single finger pressing against a force gauge, with the entire hand securedThis finger output force can be likened to the strength of human hands; typically, greater hand strength correlates with a higher load-bearing capabilityCurrently, the dexterous hand's finger output force can reach up to 30 Newtons (approximately 3 kilograms), nearly matching human capacity.

It is essential to differentiate between active force and passive load-bearing capacityThe latter, often referred to as passive load capacity, reflects the maximum weight a finger can endure while stationaryThis attribute is closely tied to the structural rigidity of the dexterous hand

In this regard, Jinshihitech’s design excels, with each finger capable of sustaining passive loads exceeding 15 kilograms.

In addition to a robust active force, the ability to implement force control is another critical benchmark for dexterous handsJinshihitech’s dexterous hand employs a force sensor mechanism, achieving a resolution of over 1000 levelsThis advanced force control feature is particularly beneficial for interacting with various materialsFor delicate items such as eggs, strawberries, and tofu—substances that are soft and prone to damage—the dexterous hand's sophisticated force management enables it to perform gentle grasping actions effectivelyIn contrast, traditional control methods typically offer only three force levels, making Jinshihitech's dexterous hand vastly superior in force control capabilities.

Uncovering the "hidden skills" of dexterous hands reveals even more fascinating functionalities

Among these are execution precision and a power-failure self-locking featureThe precision of execution determines the dexterous hand's operational efficiencySimply put, the higher the precision, the more accurate the executionThe core actuator driving this performance—Jinshihitech's miniature servo actuator—boasts an extraordinary positioning accuracy, allowing for a repeat positioning precision of ±0.2 mm.

The power-failure self-locking feature eliminates concerns about power interruptions and maintains the hand's position even during outages, removing the need for recalibration when power is restoredThis capability mitigates potential risks associated with accidental drops during power outages, as well as minimizing interference with hand and arm movements when seeking zero position post-outage.

In contrast to relatively new players in the dexterous hand market, Jinshihitech began its research and development of humanoid five-fingered hands and miniature servo actuators back in 2016, positioning itself as one of the earliest companies to successfully commercialize dexterous hands