Robotic Arm Passive Grapple Roll Reorientation
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Solution Overview
Problem
Robotic arms for in-space applications face challenges due to high mass, complexity, and limited degrees of freedom, which increase fuel requirements, weight, and cost, while also needing to manage loads and navigate confined spaces effectively.
Innovation Solution
A robotic arm with active and passive orientation and grapple mechanisms, featuring actively driven joints for 3 degrees of freedom, a linear drive system with claws for grasping, and a pressure plate assembly for back-driven roll, along with a passive pitch and yaw mechanism, allowing for efficient payload manipulation and reorientation without active roll and yaw actuators at the end effector.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a robotic arm is designed with 6 degrees of freedom (pitch, roll, yaw) for complete movement capability, then the range of movement is improved, but the mass and complexity increase due to additional actuators and components
Solution Approach 1:
The robotic arm is divided into multiple articulated segments (booms) connected by joints, where each segment performs a specific function. The end effector is separated as a distinct module with its own passive orientation mechanism, allowing the main arm to focus on positioning while the end effector handles orientation, reducing the need for active actuators throughout the entire arm structure.
Solution Approach 2:
Instead of using active actuators at the end effector to provide roll and yaw control, the patent inverts the approach by providing passive pitch and yaw degrees of freedom at the end effector through mechanical compliance, while using the pressure plate assembly and roll post to enable back-driven roll control. This reverses the conventional wisdom of placing all active control at the manipulator end.
2Reliability
If force moment sensors are added to measure forces on the payload, then load management capability is improved, but the mass and complexity of the system increase
Solution Approach 1:
The robotic arm uses its passive orientation mechanism and back-driven roll capability to automatically adapt to payload orientation and force conditions without requiring active sensing and control. The mechanical compliance of the passive joints allows the system to self-adjust to load conditions, eliminating the need for complex sensor-based control systems.
3Volume of moving object
If the robotic arm is designed with stowable articulated segments for space-constrained launch, then the stowability is improved, but the degrees of freedom may be constrained by stowage interfaces
Solution Approach 1:
The articulated segments of the robotic arm are designed to nest within each other during stowage, with smaller segments stored inside larger ones, similar to nested dolls. This minimizes the volume required for stowage while maintaining the full range of motion capabilities when deployed, as the nesting interfaces are designed to preserve the degrees of freedom of each joint.
Data Source
AI summary
Robotic arms with orientation and grapple mechanisms for payload manipulation are provided. A robotic arm includes a mechanical arm assembly having booms connected by actively driven joints to provide pitch and yaw control at the shoulder, elbow and wrist of the arm. To reduce mass and complexity, according to various embodiments, force moment sensors and/or actuators for active roll and/or yaw control at the end of the arm may be omitted. The orienting mechanism provides the grapple mechanism with passive pitch and yaw control to pivot the grapple mechanism to grasp a payload without having to actively position the end effector to align with an axis of the payload. This enables “soft” capture of the payload by the grapple mechanism. Prior to lifting the payload, the grapple fixture is rigidized by fully retracting the grapple mechanism.