Mobile Manipulator Tip-Over Control Using Joint Torque Sensing
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Solution Overview
Problem
Wheeled mobile robots with manipulators are prone to tipping over due to moments exceeding a critical threshold, especially when handling heavy loads or changing directions, which existing systems fail to adequately address.
Innovation Solution
A robot system equipped with a torque sensor to detect moments on the manipulator joints, coupled with a controller that adjusts the manipulator's motion to prevent tipping by controlling speed, acceleration, and orientation to maintain moments below a tipping threshold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the manipulator handles heavy loads or changes direction rapidly, then the productivity and operational capability are improved, but the moment acting on the wheeled platform exceeds the tip-over moment causing instability
Solution Approach 1:
The control device calculates the tip-over moment in advance based on the manipulator's current state and predicted motion, and adjusts the manipulator's acceleration or deceleration before tipping occurs. This preliminary calculation and adjustment prevent tip-over while allowing heavy load handling and rapid direction changes, resolving the contradiction between productivity and stability.
2Speed
If the manipulator operates with high acceleration and speed, then the productivity is improved, but the dynamic moments cause the platform to tip over
Solution Approach 1:
The control device dynamically adjusts the manipulator's acceleration and deceleration rates based on real-time calculation of the tip-over moment. When the manipulator operates at high speed, the control device reduces acceleration to keep the moment below the tip-over threshold, allowing high-speed operation while maintaining platform stability.
3Stability of the object's composition
If the manipulator is controlled to prevent tip-over by limiting moments, then the platform stability is improved, but the manipulator's operational range and productivity are reduced
Solution Approach 1:
The control device changes the parameter of acceleration dynamically based on the manipulator's state and the calculated tip-over moment. By adjusting acceleration rather than simply limiting speed or position, the system maintains platform stability while preserving the manipulator's full operational range and productivity.
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
Prevents wheeled platform tipping by dynamically adjusting manipulator operations, ensuring stable operation even with heavy loads and dynamic changes, thereby enhancing operational safety and reliability.
Implementation Method 1
the manipulator includes a sensor that detects a force or a moment that acts on at least one joint
Data Source
AI summary
A robot system includes a robot and a controller that controls the robot. The robot includes a wheeled platform and a manipulator mounted on the wheeled platform. The manipulator includes a sensor that detects a force or a moment that acts on at least one joint. The controller controls at least one of the manipulator and the wheeled platform on the basis of the force or moment detected by the sensor so that a moment acting on the wheeled platform does not exceed a tip-over moment.