Redundant Robotic Manipulator Posture Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Redundant robotic manipulators with low impedance are difficult to control precisely, leading to uncontrollable drift and potential collisions, as users cannot fully constrain the posture with a single hand, especially when errors in force and torque application occur, making them impractical for industrial use.
Innovation Solution
The system constrains the posture of redundant robotic manipulators by applying computed constraining forces and torques at the joints, modeled as virtual springs, to urge the arm towards a canonical posture, minimizing internal forces and compensating for gravity, allowing single-handed guidance without uncontrollable movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If low impedance is achieved by reducing mass and inertia of moving components, then ease of operation is improved, but load-carrying capability deteriorates
Solution Approach 1:
The system applies active gravitational force compensation through the controller, which calculates and applies counter-forces to balance the weight of robot links. This creates a zero-gravity effect that reduces the apparent weight of the manipulator, enabling easy hand-guiding without physically reducing the actual mass and inertia of the components.
2Ease of operation
If active force compensation is applied at joints to enable free user control, then ease of operation is improved, but system complexity and cost increase
Solution Approach 1:
The robot system performs self-compensation for gravitational forces by using its own sensors and controllers to calculate and apply counter-forces at the joints. This eliminates the need for external complex mechanical counterweights or additional actuation systems, achieving force compensation through the robot's existing components and control capabilities.
3Ease of operation
If gravitational force compensation is precisely implemented, then ease of operation is improved, but any small errors cause uncontrollable drift
Solution Approach 1:
The system dynamically adjusts the gravitational force compensation based on the current configuration of the robot manipulator. The controller continuously recalculates the required counter-forces as the robot moves through different positions and orientations, ensuring that the compensation remains accurate throughout the workspace and preventing drift caused by configuration-dependent gravitational variations.
4Adaptability or versatility
If redundant degrees of freedom are provided for greater dexterity, then adaptability is improved, but controllability and stability deteriorate
Solution Approach 1:
The system changes the control parameters by applying gravitational force compensation specifically to the redundant degrees of freedom. This allows the redundant joints to be controlled with the same precision and stability as the non-redundant joints, enabling stable posture control throughout the entire manipulator while maintaining the dexterity benefits of redundancy.
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 enables easy, single-handed guidance of redundant robotic manipulators by constraining their motion, reducing drift and ensuring stability, while maintaining the flexibility to adjust posture as needed, thus enhancing user control and safety in industrial applications.
Implementation Method 1
the forces applied internally at the joints accurately compensate for the gravitational forces due to the masses of the links constituting the robot's arm
Implementation Method 2
constraining forces and/or torques are internally applied at the robot joints to urge the robot arm towards a particular preferred configuration
Data Source
Figure 1A
Figure 1B
Figure 2
AI summary
Redundant robotic manipulators may be constrained in their motions during operation in a gravity -compensated mode by applying, in addition to gravity -compensating torques, constraining torques to one or more of the joints. The constraining torques may urge the manipulator to a specified canonical posture, and may be modeled by virtual springs attached to the constrained joints.