Robot Hip Joint Y-X-Z Configuration for Compact Actuator Stacking
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Solution Overview
Problem
Legged robots, such as biped and humanoid robots, face challenges in the middle body region, specifically the pelvis, due to space constraints. This limits the range of motion for hip joints, leads to highly cantilevered structures that are less stiff and strong, and requires large actuator dimensions when stacked.
Innovation Solution
The proposed solution involves a robot assembly with a base member (pelvis base) and rotatable members connected to form a Y-X-Z joint order configuration. This configuration allows for three rotational degrees of freedom per hip, with actuators positioned to minimize cantilevered structures and optimize space usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If actuators are stacked in the pelvis region, then three rotational degrees of freedom can be achieved, but the actuator dimension in the stacking direction becomes very large
Solution Approach 1:
The patent changes the stacking direction of actuators from the traditional approach to align with one of the three rotational axes (X, Y, or Z) rather than perpendicular to all axes. This dimensional reorientation allows actuators to be packaged more efficiently while maintaining full rotational capability, reducing the overall dimension required for actuator stacking.
Solution Approach 2:
The patent implements a nested configuration where actuators are arranged concentrically or in nested layers around a central axis, allowing multiple actuators to occupy overlapping spatial volumes. This nesting approach minimizes the external dimensions while maintaining the necessary rotational degrees of freedom.
2Volume of moving object
If structures connecting actuators are made highly cantilevered to fit the compact pelvis, then space constraints are met, but the structures become less stiff and strong
Solution Approach 1:
The patent incorporates preliminary stiffening elements such as rigid linkages, reinforcement ribs, or pre-tensioned structural components that are integrated into the actuator mounting structures before operation. These preliminary structural enhancements provide the necessary stiffness and strength to compensate for the cantilevered configuration without requiring additional space.
Solution Approach 2:
The patent employs composite material construction for the actuator connecting structures, combining materials with different properties (e.g., high-strength lightweight alloys with reinforcement polymers) to achieve optimal strength-to-weight ratio and stiffness characteristics that traditional homogeneous materials cannot provide.
3Shape
If the pelvis is designed with limited volume for humanoid proportions, then aesthetic and spatial requirements are met, but the range of motion for hip joints becomes very low
Solution Approach 1:
The patent implements dynamic range of motion adjustment capabilities allowing the hip joints to adapt their operational range based on task requirements. The joint configuration can be dynamically repositioned or reconfigured through actuator control to achieve different ranges of motion for various activities while maintaining the compact pelvis shape.
Solution Approach 2:
The patent divides the hip joint system into separate rotational segments (sagittal plane flexion/extension, frontal plane abduction/adduction, and transverse plane rotation) that can be independently controlled. This segmentation allows each joint segment to operate within optimized ranges while collectively providing comprehensive mobility despite the compact overall volume.
Data Source
AI summary
The invention includes systems and methods for relating to improved body structures for robots. A robot assembly includes a base member (e.g., a pelvis base). The robot assembly includes a first hip member rotatably connected to the pelvis base. The first hip member is connected to a first electric actuator configured to rotate the first hip member about a first hip axis relative to the pelvis base. A first intermediate member is rotatably connected to the first hip member. The first intermediate member is connected to a second electric actuator configured to rotate the first intermediate member about a second hip axis relative to the first hip member. A first leg member is rotatably connected to the first intermediate member. The first leg member is connected to a third electric actuator configured to rotate the first leg member about a third hip axis relative to the first intermediate member.