Mobile Robot Maneuvering via Dynamic Center of Mass Shifting
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Solution Overview
Problem
Mobile robots face instability and balance issues when performing tasks that involve lifting and handling heavy objects due to shifts in center of mass and changes in momentum, particularly during turning maneuvers, which can lead to tipping over.
Innovation Solution
The method involves shifting the center of mass of the robot toward the turning direction by moving a counter-balance body relative to the inverted pendulum body or altering the height of the legs, allowing the drive wheels to lean into the turn and maintain balance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a robot uses a large stationary or moveable base to maintain an upright position while lifting and handling heavy objects, then stability is improved, but mobility and maneuverability deteriorate due to heavy weight and cumbersome structure
Solution Approach 1:
The robot employs dynamic balance control by continuously adjusting the position of a counter-balance body relative to the inverted pendulum body during turning maneuvers. The system transitions from a static large base design to a dynamic control system that actively manages center of mass position, allowing the robot to maintain stability while being more maneuverable. The counter-balance body can move along the longitudinal axis to dynamically compensate for centrifugal forces during turns.
Solution Approach 2:
The robot incorporates a counter-balance body that acts as a movable counterweight to offset the effects of centrifugal force during turning. By positioning the counter-balance body toward the outside of the turn, the system creates a balancing moment that counteracts the tipping moment caused by the turn, effectively using counterweight principles to maintain stability during dynamic operations.
2Ease of operation
If a robot uses a smaller and lighter base or mobility platform to improve maneuverability, then mobility is improved, but stability deteriorates due to instabilities from shifts in center of mass and changes in momentum when carrying heavy objects
Solution Approach 1:
The system uses dynamic control to adjust the counter-balance body position in real-time during turning maneuvers. By continuously monitoring turn parameters and calculating the required counter-balance position, the system dynamically compensates for center of mass shifts and momentum changes, maintaining stability despite the lighter, more maneuverable platform.
Solution Approach 2:
The control system receives feedback about turn parameters (turn rate, yaw angle) and robot state (center of mass position, momentum), then adjusts the counter-balance body position accordingly. This closed-loop feedback control enables the lighter platform to maintain stability by actively responding to changes in the robot's dynamic state during operations involving heavy objects.
3Speed
If a robot turns by conventional methods without shifting center of mass, then turning capability is achieved, but stability deteriorates due to centrifugal forces causing the robot to tip over
Solution Approach 1:
The system applies preliminary anti-action by shifting the counter-balance body toward the outside of the intended turn before and during the turning maneuver. This preemptive positioning creates a counter-moment that opposes the centrifugal force-induced tipping moment, preventing the robot from tipping over while maintaining turning capability. The control system calculates the required counter-balance position based on predicted turn parameters.
Solution Approach 2:
During turning, the counter-balance body functions as a dynamic counterweight positioned toward the outside of the turn to balance the centrifugal forces. By creating an opposing moment through strategic counterweight placement, the system enables stable turning without tipping, resolving the contradiction between turning speed and stability.
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
This approach enhances the robot's maneuverability and stability during turns by canceling out centripetal forces with gravity moments, maintaining momentum and handling turns efficiently.
Implementation Method 1
turning the robot by shifting a center of mass of the robot toward a turning direction, thereby leaning the robot into the turning direction
Implementation Method 2
altering a height of the at least one leg with respect to the surface, causing the right and left drive wheels to lean into the turning direction
Implementation Method 3
enhances the robot's maneuverability and stability during turns by canceling out centripetal forces with gravity moments
Implementation Method 4
enhances the robot's maneuverability and stability during turns by canceling out centripetal forces with gravity moments
Data Source
AI summary
A method of maneuvering a robot includes driving the robot across a surface and turning the robot by shifting a center of mass of the robot toward a turn direction, thereby leaning the robot into the turning direction. The robot includes an inverted pendulum body, a counter-balance body disposed on the inverted pendulum body and configured to move relative to the inverted pendulum body, at least one leg prismatically coupled to the inverted pendulum body, and a drive wheel rotatably coupled to the at least one leg. The inverted pendulum body has first and second end portions and defines a forward drive direction. The method also includes turning the robot by at least one of moving the counter-balance body relative to the inverted pendulum body or altering a height of the at least one leg with respect to the surface.