Transformable Wheel-Leg Assembly for Rough-Terrain Robot Mobility
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Solution Overview
Problem
Existing robots with wheeled locomotion face limitations in traversing rough terrains and obstacles due to size and weight constraints, while legged robots suffer from mechanical complexity and control difficulties, and hybrid systems often require complex actuation and transition mechanisms.
Innovation Solution
A robot with passively transformable wheels that transition from a closed wheel configuration to an open leg configuration based on terrain conditions, using a central gear and leg segments with embedded spring suspension for shock reduction, allowing versatile mobility without increased system complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the wheel size is increased to improve locomotion performance on rough terrains, then the robot's ability to traverse obstacles is improved, but the robot's size and weight increase, limiting accessibility to confined spaces
Solution Approach 1:
The wheel assembly is designed to dynamically transform between a closed wheel configuration for smooth surfaces and an open leg configuration for rough terrains and obstacles. This dynamic reconfiguration allows the robot to adapt its locomotion mode based on terrain conditions without permanently increasing its size or weight, resolving the contradiction between terrain adaptability and compactness.
Solution Approach 2:
The leg segments are nested within the wheel structure when not in use, allowing the wheel assembly to maintain a compact circular form during wheeled locomotion. When legged locomotion is needed, the segments deploy outward to form supporting legs. This nesting approach enables the robot to have large effective dimensions for obstacle traversal only when necessary, maintaining small overall dimensions for confined space accessibility.
2Adaptability or versatility
If a hybrid wheel-leg system is implemented to improve performance on diverse terrains, then locomotion versatility is improved, but the mechanical complexity and control difficulty increase
Solution Approach 1:
The wheel assembly automatically transforms between wheel and leg configurations based on terrain conditions without requiring complex active control systems. The transformation is triggered passively by the interaction between the wheel and the ground surface, eliminating the need for sensors, control algorithms, and actuators that would otherwise be required to detect terrain and initiate mode switching. This self-service approach maintains mechanical simplicity while achieving hybrid locomotion versatility.
Solution Approach 2:
The same wheel assembly structure serves multiple functions: it acts as a rolling wheel for propulsion on smooth surfaces and as a set of supporting legs for traversing obstacles and rough terrains. The central gear and leg segments form a multi-functional mechanism that eliminates the need for separate wheel and leg systems, reducing overall mechanical complexity while maintaining locomotion versatility.
3Measurement precision
If active transformation mechanisms are used to switch between wheel and leg modes, then control precision is improved, but the system complexity and number of actuators increase
Solution Approach 1:
The transformation from wheel to leg mode and vice versa occurs passively through the interaction between the wheel assembly and the ground surface. When the robot encounters an obstacle or rough terrain, the mechanical interaction automatically triggers the leg segments to deploy or retract, eliminating the need for active sensors and control systems to detect terrain conditions and initiate transformation. This passive self-service mechanism maintains simplicity while achieving appropriate mode switching.
Solution Approach 2:
The active control system for transformation is extracted from the wheel assembly itself. Instead of incorporating motors and sensors within the wheel to actively control mode switching, the design removes these active components and relies on passive mechanical triggering. This extraction of the active transformation function simplifies the system while maintaining the essential wheel-leg transformation capability.
4Device complexity
If passive transformation is used to reduce system complexity, then device complexity is reduced, but uncertainty in transition behavior increases
Solution Approach 1:
The central gear and leg segments form a multi-functional mechanism that serves both as the propulsion system during wheeled locomotion and as the transformation mechanism for legged locomotion. The same mechanical components that drive the wheel forward also control the deployment and retraction of the legs, ensuring that the transformation behavior is inherently linked to the propulsion system and thus predictable and reliable.
Solution Approach 2:
The design incorporates mechanical features that ensure smooth and controlled transformation between modes. The leg segments are positioned and constrained within the wheel structure so that their deployment and retraction follow predetermined paths, preventing unpredictable behavior during transition. This beforehand design of the transformation mechanism ensures reliable and repeatable behavior while maintaining passive operation.
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 robot achieves improved mobility on diverse terrains and obstacles with reduced vibrations and shocks, maintaining simplicity in control and operation, and is capable of autonomous navigation and stair climbing, with experimental results consistent with simulation predictions.
Implementation Method 1
embedded spring suspension for shock reduction
Data Source
AI summary
Aspects of the disclosure relate to a robot. The robot includes a body and a wheel assembly coupled to the body. The wheel assembly includes a central hub and a central gear coupled to the central hub. A plurality of legs are coupled to the central hub. The plurality of legs are operatively coupled to the central gear such that the central gear drives the plurality of legs between a closed position and an open position. A motor is coupled to the body and coupled to the wheel. A suspension system is coupled to the wheel assembly. An autonomous guidance system is coupled to the motor.