Industrial Robot Arm Kinematics for Large Workspace and Low Moving Mass
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Solution Overview
Problem
Existing robot arm designs face challenges in achieving a lightweight, high-speed, and high-safety configuration with a large workspace, as they either require significant space or compromise on workspace size due to limitations in kinematic chain design and actuator placement.
Innovation Solution
The robot arm design incorporates a combination of kinematic chains with actuators mounted on a fixed stand, utilizing parallel links and gearing mechanisms to provide six degrees of freedom without any actuators in the arm structure, allowing for constant tilt and rotation angles across a large workspace.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If actuators are mounted on the robot arm structure, then the robot can achieve high positioning precision and control, but the robot arm weight increases and speed decreases
Solution Approach 1:
The patent extracts all actuators from the moving robot arm structure and mounts them on a fixed base structure. The robot arm consists only of passive kinematic chains (links and joints) that transmit motion without containing actuators, thereby minimizing moving mass and maximizing acceleration and speed while maintaining positioning precision through the kinematic chain design.
Solution Approach 2:
Instead of the conventional approach where actuators are mounted on moving parts of the robot arm, the patent inverts this arrangement by mounting all actuators on a fixed base structure. The actuators drive the kinematic chains from the base, allowing the robot arm itself to be purely passive and lightweight, thus resolving the contradiction between positioning precision and weight.
2Weight of moving object
If a parallel kinematic structure is used, then the robot arm weight is reduced, but the workspace becomes very small in relation to the space needed for the arm system
Solution Approach 1:
The patent employs a parallel kinematic structure with multiple kinematic chains (at least two chains) that operate in different spatial dimensions or configurations. This allows the robot arm to achieve a large workspace volume while keeping the physical footprint of the arm system compact, as the chains can be arranged to exploit three-dimensional space efficiently.
Solution Approach 2:
The patent implements a nested configuration where inner kinematic chains are positioned within or alongside outer kinematic chains. This nested arrangement allows multiple chains to occupy overlapping or adjacent spatial volumes, maximizing the workspace available to the end effector while minimizing the overall space required for the robot arm structure.
3Area of stationary object
If the robot arm structure is made slim to reduce space, then the workspace increases, but the arm system requires substantial weight for structural integrity
Solution Approach 1:
The patent utilizes composite materials for the kinematic chains and structural components to achieve high strength-to-weight ratios. This allows the robot arm to be made slim and compact while maintaining the structural integrity and load-bearing capacity needed for precise motion control, thereby increasing workspace without proportionally increasing weight.
Solution Approach 2:
The patent divides the robot arm into multiple separate kinematic chains (at least two chains), each responsible for specific degrees of freedom or motion tasks. This segmentation allows each chain to be optimized independently for minimal weight and compact dimensions, while the collective system provides the required structural strength and workspace.
4Speed
If actuators are placed on the fixed stand, then the robot arm becomes lightweight for high speed, but the kinematic chain design becomes more complex
Solution Approach 1:
The patent designs the kinematic chains with universal joints and links that can accommodate multiple functions and degrees of freedom within a single chain structure. This multi-functionality reduces the total number of separate components needed, simplifying the overall design while enabling the actuators on the fixed stand to control the lightweight robot arm effectively for high-speed operations.
Data Source
Figure 1
Figure 2A~2B
Figure 3A~3D
AI summary
A robot arm (500) for end-effector motion. The robot arm comprises a first actuator (4) and a first kinematic chain from the first actuator to an end-effector platform, which gives a first degree of freedom for positioning the end-effector platform. The robot arm also comprises a second actuator (5; 5b) and a second kinematic chain from the second actuator to the end-effector platform, which gives a second degree of freedom for positioning the end-effector platform. The robot arm further comprises a third actuator (6; 6b, 512) and a third kinematic chain from the third actuator (6; 6b) to the end-effector platform, which gives a third degree of freedom for positioning the end-effector platform. The robot arm also comprises a fourth actuator (50; 150) and a fourth kinematic chain configured to transmit a movement of the fourth actuator to a corresponding orientation axis (65) for an end-effector (28). The fourth kinematic chain comprises an orientation linkage (52, 57, 59; 202, 204, 207, 209; 284, 286; 251, 256, 258) mounted to the inner arm-assemblage via at least one bearing (53, 55; 206), and an orientation transmission (64B, 64A, 216; 64C, 64D, 64E; 100, 64A; 281, 279, 275; 260, 262, 264, 266, 271, 270) mounted to the end-effector platform, wherein the orientation linkage comprises an end-effector rotation link (59; 209; 258; 281) and joints (58, 60; 208, 210; 257, 259; 257, 259; 282, 280) that provide at least two degrees of freedom for each end joint of the end-effector rotation link.