Robot Arm Orientation Linkage for Constant Tilt Across Large Workspaces
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Solution Overview
Problem
Existing industrial robot arms face challenges in achieving a lightweight, high-speed design with a large workspace and constant tilt angles without adding weight or complexity, particularly in applications requiring precise movements and safety features like human-robot collaboration.
Innovation Solution
A robot arm design featuring a combination of kinematic chains and gearing mechanisms that allow for six degrees of freedom without actuators in the arm structure, using a first actuator to rotate an inner arm-assemblage, a second actuator to pivot an outer arm-linkage, and a third actuator to rotate a shaft, along with orientation linkages and transmissions to maintain constant tilt angles and rotation capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If a parallel kinematic robot (Delta robot) is used to achieve light weight structure, 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 robot arm is divided into modular components: a base unit with actuators, and multiple arm units that can be connected in series. Each arm unit contains its own actuator, allowing distributed actuation that reduces overall arm weight while maintaining a larger workspace compared to parallel kinematic structures.
Solution Approach 2:
The patent transitions from parallel kinematic architecture to a serial-like arrangement with distributed actuators, effectively changing the dimensional organization of the system. This allows the robot to achieve both light weight and extended workspace by distributing mass and actuation across multiple segments rather than concentrating them in a parallel structure.
2Adaptability or versatility
If actuators are mounted on the arm structure to enable six degrees of freedom, then the robot can achieve complex movements, but the arm weight increases substantially
Solution Approach 1:
The six degrees of freedom are distributed across multiple arm units, with each unit containing one or more actuators. This segmentation allows the robot to achieve complex movements while keeping each individual arm unit lightweight, as the total mass is distributed rather than concentrated in a single heavy structure.
Solution Approach 2:
The robot arm uses a dynamic configuration where arm units can be selectively activated based on task requirements. Not all actuators need to be fully engaged simultaneously, allowing the system to achieve six degrees of freedom adaptively while maintaining lower effective arm weight during specific operations.
3Length of moving object
If a slim robot structure is used to reduce space occupation, then the robot arm becomes more compact, but maintaining constant tilt angles becomes difficult without additional actuators
Solution Approach 1:
The arm units are designed with intrinsic geometric properties that enable them to maintain constant tilt angles through their own structure and motion characteristics. The spherical joints and arm geometry are configured so that the tilt angle is naturally maintained during rotation, eliminating the need for additional actuators or complex control mechanisms.
Solution Approach 2:
The patent employs composite structural designs in the arm units that combine different materials and geometric configurations to achieve both slim dimensions and precise angle maintenance. The composite structure provides the necessary stiffness and geometric constraints to maintain constant tilt angles without adding significant weight or length.
4Manufacturing precision
If wrist actuators are added to maintain constant tilt angles, then the robot can achieve precise orientation control, but the arm weight increases and cabling is required
Solution Approach 1:
The patent extracts the tilt angle control function from dedicated wrist actuators and integrates it into the arm unit geometry and joint configuration. By taking out the need for separate tilt control actuators, the design eliminates their weight and associated cabling requirements while maintaining precise orientation control through the inherent properties of the arm structure.
Data Source
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.