Mobile Robot Suspension with Compliant Caster for Irregular Surfaces
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Solution Overview
Problem
Mobile robots face challenges in maintaining traction and level navigation on irregular surfaces, which affects the consistency of sensor scans and navigation precision, especially when equipped with rigid wheels that fail to absorb surface irregularities.
Innovation Solution
A suspension system incorporating rigid drive wheels and a passive caster wheel with a compliant member, such as a torque spring, to absorb surface irregularities while maintaining the robot's levelness and ensuring continuous contact with the surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If rigid drive wheels and rigid caster assemblies are used, then the robot maintains structural stability and sensor levelness, but the robot cannot absorb surface irregularities and loses traction
Solution Approach 1:
The suspension system divides the robot's wheel assembly into independent segments: rigid drive wheels for propulsion, a rigid front caster for stability, and a compliant rear caster for shock absorption. Each segment handles specific functions, allowing the system to maintain both structural integrity and surface adaptability without requiring complete redesign of the entire wheel system.
Solution Approach 2:
Different parts of the robot have different rigidity characteristics tailored to their functions. The drive wheels and front caster use rigid connections for stable propulsion and steering, while the rear caster employs a compliant member (torque spring) to absorb surface irregularities. This localized differentiation resolves the contradiction by applying rigidity where needed and compliance where beneficial.
2Reliability
If a compliant member is added to the rear caster assembly, then surface irregularities are absorbed and traction is maintained, but the device complexity increases
Solution Approach 1:
The torque spring in the rear caster assembly automatically adjusts to surface irregularities without requiring external control systems. The compliant member passively absorbs shocks and maintains wheel contact through its elastic properties, eliminating the need for sensors, actuators, or control algorithms that would increase system complexity.
Solution Approach 2:
The compliant member uses a simple torque spring instead of complex active suspension systems. This inexpensive, passive component provides sufficient shock absorption for the application, avoiding the need for expensive sensors, motors, and control systems while maintaining reliability on irregular surfaces.
3Measurement precision
If rigid interconnection is used between chassis and wheels, then sensor scan plane consistency is maintained, but surface irregularities cause uneven robot movement
Solution Approach 1:
The robot's support system is segmented into rigid and compliant sections. The front caster and drive wheels use rigid connections to maintain sensor levelness, while the rear caster's compliant member isolates surface irregularities. This segmentation allows the sensor platform to remain stable while the compliant section absorbs terrain variations.
Solution Approach 2:
The compliant member acts as an intermediary between the chassis and the rear caster wheel. It transmits necessary support forces to the chassis while filtering out surface irregularities, thereby maintaining scan plane consistency without compromising navigation smoothness. The torque spring mediates between the rigid chassis and the variable terrain.
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 solution allows mobile robots to maintain traction and level navigation on uneven surfaces, ensuring consistent sensor scans and improved navigation accuracy by absorbing surface irregularities without compromising the levelness required for precise navigation.
Implementation Method 1
a compliant interconnection member to rotate about a second swivel axis. When the at least one motor propels the first and second drive wheels, thereby causing the mobile robot to drive on the surface, the compliant interconnection member of the second caster assembly absorbing the irregularities in the surface
Data Source
AI summary
A mobile robot configured to drive on a surface with irregularities, comprising: a chassis having a front end facing a forward direction of travel, a back end, a first side, and a second side. There is a first drive wheel rigidly affixed to the chassis proximate the first side and interconnected to a motor to propel it. There is a second drive wheel rigidly affixed to the chassis proximate the second side and interconnected to a motor to propel it. A first caster assembly is rigidly affixed to the chassis proximate the front end and includes a first caster wheel configured to rotate about a first swivel axis. A second caster assembly is rigidly affixed to the chassis proximate the back end and includes a second caster wheel configured to rotate about a second swivel axis and it includes a compliant member to absorb the irregularities.