Inverted Two-Wheeled Robot Adaptive Torque Control
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Solution Overview
Problem
Conventional two-wheeled inverted robots face issues with maintaining attitude control and running state when a part of the body comes into contact with the ground or wall, leading to excessive torque application and rapid wheel rotation, which can result in loss of stability and increased user burden.
Innovation Solution
A two-wheeled inverted robot equipped with a body constraint recognizing system that detects inclination and rotation angles, allowing for adaptive control methods to adjust torque distribution and maintain stability by changing running control strategies based on detected constraint conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the robot uses a coaxial two-wheel inverted pendulum model to reduce area and improve turning capability, then the area occupied is reduced and turning circle is improved, but the robot becomes unstable when a part of the body comes into contact with the ground or wall
Solution Approach 1:
The control method dynamically adapts based on the robot's contact state with the ground or wall. When contact is detected through state detection means, the control means switches between different control strategies: using reaction torque from wheel rotation for attitude control during free rotation, and using direct torque application when rotation is constrained by contact. This dynamic adaptation maintains stability across different operational conditions while preserving the compact two-wheel design.
2Stability of the object's composition
If state feedback control is always performed to maintain inverted attitude control, then attitude control is maintained, but excessive torque is applied to the wheels when the body is constrained by contact, causing rapid wheel rotation and loss of stability
Solution Approach 1:
The control system dynamically adjusts the control strategy based on real-time detection of the body's rotation state. When the body can rotate freely, the system uses reaction torque control where wheel rotation naturally provides the necessary counter-torque for attitude control. When contact constraint is detected, the system switches to direct torque control, applying torque directly to the wheels without relying on rotation reaction, thereby preventing excessive torque application and rapid wheel rotation.
Solution Approach 2:
The system employs state detection means to continuously monitor whether the body can rotate or is constrained by contact with the ground or wall. This feedback information is used by the control means to select the appropriate control method. The feedback loop ensures that the control strategy adapts to the current mechanical constraints, preventing the application of excessive torque that would occur if a single fixed control method were used regardless of contact conditions.
3Stability of the object's composition
If the robot maintains inverted attitude control through wheel rotation and reaction torque, then attitude control is achieved, but the robot cannot operate safely when the body comes into contact with obstacles that constrain rotation
Solution Approach 1:
The control method transitions from a static single-strategy approach to a dynamic multi-strategy approach. The system can operate in two distinct modes: reaction torque mode when the body rotates freely, and direct torque mode when constrained by contact. This dynamic capability ensures reliable operation across both free-motion and constrained conditions, eliminating the safety issue that arose when the robot encountered obstacles.
Solution Approach 2:
The control system changes the control parameters and methodology based on the detected contact state. When contact constraint is detected, the system changes from relying on wheel rotation and reaction torque to applying torque directly for attitude control. This parameter change allows the robot to maintain safe operation under constrained conditions while preserving the inverted attitude control capability during free motion.
Data Source
AI summary
A two-wheeled inverted robot includes a body, two wheels coaxially arranged on the body, a drive device for driving each of the wheels, a first state detector for detecting at least one of an inclination angle and an inclination angular speed of the body, a second state detector for detecting at least one of a rotation angle and a rotational angular speed of the wheel, a body constraint recognizing device for detecting whether or not body rotation is constrained, and a controller for determining a command value to the drive device. Based on the detection result by the body constraint recognizing device, the controller determines the command value for changing a ratio of a torque contributing to the body rotation.