Ⅰ. Robotic Dexterous Hands: Dexterity+Adaptability
1. Structure and Imitation Function
As an end-effector of robots, the robotic dexterous hand takes the structure and function of the human hand as a model, aiming to play a crucial role in the interaction between the robot and the environment. The robotic dexterous hand has the variability of posture; the higher the variability, the greater the dexterity of the hand.
2. Classification and Characteristics
1) The two-finger gripper is mainly used when a single grasping action is required. Its structure is relatively simple, mainly imitating the grasping action of fingers, and it can successfully grasp and release the target object.
2) Compared to the two-finger gripper, the multi-finger grasping hand performs at a higher level. Generally, it has three or four fingers and achieves the synchronous movement of multiple fingers through a multi-link drive or a cylinder drive. However, it is not precise and flexible enough.
3) Through at least three fingers and nine degrees of freedom, a multi-finger dexterous hand imitates complex operations such as the dexterous grasping, precise pinching, and intermediate grasping of the human hand, and achieves good interaction with the environment.
3. Drive and Transmission Methods
1) Diverse Drive Methods
Motor Drive: As the main drive method for multi-finger dexterous hands, motor drive has significant advantages such as large driving force, high control precision, fast response, modular design, and easy replacement and maintenance.
Hydraulic Drive: The drive system of the hydraulic manipulator realizes driving by a pump to press the liquid into a closed system and moving the piston through the static pressure of the liquid medium. A hydraulic drive can provide a relatively large driving force, but the system is relatively complex and high-cost.
Pneumatic Drive: The dexterous hand based on pneumatic drive is a method relatively close to human muscle drive. It compresses air in a cylinder to generate a pressure difference and uses it as a power source to drive the actuator. It has advantages such as a simple structure, low cost, and fast response speed. However, the control precision of pneumatic drive is relatively low.
Shape Memory Alloy Drive: Shape memory alloys change shape and properties by adjusting temperature. Their drive technology features large displacement and high flexibility, but low energy efficiency and high control difficulty.
2) Exquisite Transmission Methods
Tendon Transmission: Tendon transmission transmits the torque of the drive source to each finger joint through the tendon and the auxiliary device for winding it. This transmission method is suitable for long-distance transmission, which can reduce the load and moment of inertia of the end-effector, and improve the grasping speed and flexibility.
Link Transmission: The link structure has high rigidity and can strongly grasp large objects. In link transmission, the finger's tip, second, and third joints are triangular links. When driving, the link rotates, finger flexes/extends.
Gear/Worm Gear Transmission: Gear drive pulls the spring between the driving device and the finger to drive the finger. Worm gear drive uses the meshing of worm gears to transmit and decelerate motion. It offers a large transmission ratio and a self-locking function to be applied in high torque and precise position control scenarios.
4. Wide Use
1) Industrial Manufacturing: Robotic dexterous hands can perform tasks such as precision assembly, part handling, and quality inspection. For example, in electronics manufacturing, they precisely handle tiny components, and in automotive manufacturing, they assemble parts.
2) Medical: Dexterous hands can be used as prosthetics to restore the hand functions of people with limb disabilities. In terms of surgical assistance, they can assist doctors in performing minimally invasive surgeries, achieving more precise operations.
3) Aerospace: The robotic dexterous hand can be used for tasks such as the maintenance and inspection of spacecraft and sample collection in space exploration missions.
4) Scientific and Education: Dexterous hands offer researchers a platform to study human hand movement, develop control algorithms, and smart robot tech.
Ⅱ. Ball Screws Application in Robotic Dexterous Hands
1. Drive Mechanism: Motor's rotational power reaches the good reversibility ballscrew via transmission devices. Screw shaft rotation makes the nut move axially, allowing the dexterous hand to perform movements.
2. Joint Control: The dexterous hand of Tesla's Optimus Gen3 adopts the transmission scheme of "gearbox + screw + tendon", and realizes the precise control of joints by using high-accuracy micro ball screws.
3. Tendon Transmission: The motor in the forearm drives the high-efficiency ball screw, converting rotation into parallel movement. The tendon wound around the nut pulls the other end of the tendon connected to the finger, causing the finger to rotate around the joint axis.
4. Humanoid Robots Design: These high-rigidity ball screws help robots imitate human walking gaits and perform complex gestures. When the robot adjusts its posture, by precisely controlling the movement of the linear ball screw set, it can ensure that the robot maintains balance and stability during operation.
Ⅲ. Collaborative Development: Opening a New Era of Smart Robots
According to the "In-depth Research Report on the Operation Status and Investment Plan of China's Ball Screw Industry from 2024 to 2029", the global ball screw market was $23.05 billion in 2023 and may reach $42.038 billion by 2029. As robot applications expand from industry to healthcare and services, high-quality ball screw demand will rise. New processing techs like turning and cyclone milling boost efficiency and cut costs, promoting the joint development of precise ball screw and robot industries for a new smart era.
