Wheel-Legged Robot Base Control for Sphere Balance on Uneven Terrain
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Wheel-legged robots face challenges in balancing spherical objects during transportation due to their unstable floating base and the coupling of under-actuated characteristics, which complicates the control system, especially when moving on uneven terrains.
Innovation Solution
A robot control method incorporating passivity-based control for nonlinear systems, specifically using Interconnection and Damping Assignment-Passivity Based Control (IDA-PBC), is integrated into the whole-body control framework to balance spheres on the wheel-legged robot's base portion, determining control torques for each joint to maintain stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a wheel-legged robot is used to transport spherical objects, then the robot can move on various terrains, but the floating base becomes unstable and control complexity increases
Solution Approach 1:
The control system is segmented into two independent subsystems: sphere balance control and robot balance control. This segmentation allows each subsystem to be optimized separately, reducing the overall control complexity while maintaining the ability to handle various terrains.
Solution Approach 2:
The robot's base posture acts as an intermediary between the sphere balance requirement and the terrain adaptation requirement. By controlling the base posture independently, the system can maintain sphere balance while adapting to different terrains, effectively decoupling the two control objectives.
2Reliability
If sphere balance control is added to the whole-body control framework, then sphere balance is maintained during robot movement, but the control system becomes more complex
Solution Approach 1:
The control framework is divided into independent sphere balance control and robot balance control modules. Each module handles its specific control objective without interfering with the other, maintaining reliability while avoiding the complexity of a fully coupled control system.
Solution Approach 2:
While keeping the control modules independent, the system merges their operations through coordinated base posture control. The base posture adjustments serve both sphere balance and robot balance requirements simultaneously, achieving integration without increasing control framework complexity.
3Adaptability or versatility
If the robot moves on uneven terrains, then terrain adaptability is improved, but sphere balance stability deteriorates due to base shaking
Solution Approach 1:
The system applies preliminary anti-action by proactively adjusting the base posture in response to detected terrain variations before the sphere can be affected by base shaking. This predictive control approach counteracts disturbances before they impact sphere balance.
Solution Approach 2:
The base posture control acts as an intermediary that absorbs and isolates terrain-induced disturbances from the sphere. By independently controlling the base posture, the system filters out vibrations and shocks from uneven terrains, protecting sphere balance stability.
4Adaptability or versatility
If different spheres are balanced on the robot base, then versatility is improved, but control parameter adjustment complexity increases
Solution Approach 1:
The control system utilizes parameter changes by automatically adjusting control parameters based on the detected sphere properties (mass, radius, moment of inertia). This allows the system to handle different sphere types without manual reconfiguration, maintaining versatility while reducing adjustment complexity.
Solution Approach 2:
The control system performs self-service by automatically adapting to different sphere types through parameter identification and automatic parameter adjustment. The system identifies sphere characteristics and configures control parameters autonomously, eliminating the need for manual intervention when changing spheres.
Data Source
AI summary
A control method, executed by a control device, controlling a robot comprising a wheel leg portion and a base portion, the wheel leg portion and the base portion comprising a plurality of joints, the method including obtaining motion information of the robot and motion information of a sphere placed on the base portion of the robot, determining, based on the motion information of the robot and the motion information of the sphere when passivity based control is performed on the sphere and the base portion, base control information for controlling the base portion and balancing the sphere on the base portion, determining, based on the base control information, a control torque for controlling each joint of the plurality of joints, and controlling each joint based on the corresponding control torque.