Robot Joint Structure with Pneumatic Link Mechanism
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Solution Overview
Problem
Existing robot joint structures are not suitable for small-sized mechanical hand fingers due to lack of sufficient gripping force and rigidity, and are cumbersome due to the need for large motor and reduction mechanisms, as well as the complexity of ball screw mechanisms which increase weight and size.
Innovation Solution
A robot joint structure featuring a metacarpal member with a driving unit that pushes or pulls a movable member in a direction parallel to its surface, connected through a hinge and linear guide devices, allowing for smooth joint motion and improved gripping force, utilizing air-cylinders and link mechanisms for efficient movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a motor and reduction mechanism are used to drive robot arms, then the joint can achieve rotation and swing motion, but the structure becomes large and heavy, making it unsuitable for small-sized mechanical hand fingers
Solution Approach 1:
The patent extracts the heavy motor and reduction mechanism from the joint structure, replacing them with a lightweight air-cylinder driving unit. The air-cylinder (32) is mounted on the metacarpal member (30) and directly drives the proximal member (40) through pneumatic pressure, eliminating the need for complex mechanical reduction gears and heavy rotating motors, thus significantly reducing joint weight while maintaining sufficient gripping force.
Solution Approach 2:
The patent applies pneumatic principles by using an air-cylinder (32) as the driving unit. The air-cylinder converts pneumatic energy into mechanical linear motion, which is then transmitted to the proximal member (40) through a link mechanism. This pneumatic driving approach provides high force output with minimal weight, resolving the contradiction between gripping force and joint structure weight.
2Ease of operation
If a ball screw mechanism is used to achieve swing motion, then precise control is possible, but the structure becomes complex and weight increases
Solution Approach 1:
The patent removes the complex ball screw mechanism from the joint structure. Instead of using a screw-nut pairing for motion conversion, the design directly uses the linear motion of the air-cylinder rod to drive the swing motion through a simplified link mechanism, greatly reducing structural complexity while maintaining controllability.
Solution Approach 2:
The patent substitutes the mechanical ball screw transmission system with a direct pneumatic-driven link mechanism. The air-cylinder's linear motion is directly coupled to the rotational swing motion of the proximal member through a simple link arm, replacing the complex mechanical screw transmission with a more straightforward pneumatic-mechanical coupling system.
3Force
If the metacarpal member is made large to increase gripping force, then gripping performance improves, but the overall finger size increases
Solution Approach 1:
The air-cylinder driving unit provides high force output in a compact form factor. Pneumatic systems can generate substantial force relative to their size, allowing the metacarpal member to maintain a compact volume while achieving sufficient gripping force through the high-pressure pneumatic actuation.
Solution Approach 2:
The patent changes the driving parameter from mechanical torque (motor) or screw mechanical advantage to pneumatic pressure. By using high-pressure pneumatic actuation, the system achieves high force output from a small-volume air-cylinder, allowing compact finger design without sacrificing gripping performance.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The proposed joint structure enables smooth joint motion and enhanced gripping force, suitable for small-sized robot fingers, while maintaining a compact and lightweight design, effectively addressing the limitations of previous technologies.
Implementation Method 1
metacarpal member side driving unit that pushes or pulls a movable member in a direction substantially parallel with a reference surface of the metacarpal member
Implementation Method 2
linear guide device for an MP joint provided with a moving member movable in association with the swing motion of the proximal member
Implementation Method 3
proximal member connected to be swingable to a side end portion of the metacarpal member through a hinge
Data Source
AI summary
A robot joint structure α is composed of a metacarpal member 30 and a proximal member 40 swingably connected through a hinge 31 to a side end portion of the metacarpal member 30. The proximal member 40 includes a linear guide device 44 for an MP joint having a moving member movable in association with a self swing motion thereof, and by connecting a rod 32a and the moving member through a link mechanism 50, a driving force of an air-cylinder 32 is transmitted to the proximal member 40. On the other hand, a second robot joint structure β is also provided with linear guide devices 48, 66, 74 and link mechanisms 69, 75, to which a driving force of the air-cylinder 62 is transmitted through a drive shaft 63 in association with a rod 62a. A robot finger is constructed by the first and second robot joint structures. According to such structures, smooth joint motion can be realized, and the robot joint structure and the robot finger having improved gripping force can be provided.