Redundant Manipulator Robot Two-Step Fine Positioning Control
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Solution Overview
Problem
Current manipulator robots face limitations in precision and accuracy, particularly in areas requiring repeatability and positioning accuracy below 0.01mm, and struggle with controlling the terminal end near singular configurations due to non-invertible Jacobian matrices, necessitating complex joint structures and additional micrometric devices.
Innovation Solution
A redundant robotic structure with an articulated arm featuring N+1 motorized joints and a computer-controlled two-step positioning process: prepositioning the terminal end into a 'zone of interest' and fine positioning using secondary motorized joints, reducing the number of joints required for precise movements and enabling precise control within a defined volume.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional serial robot structures are used, then the robot can achieve six degrees of freedom for positioning and orientation, but the placement accuracy is limited to ±0.03mm and cannot meet the <0.01mm requirement
Solution Approach 1:
The robot control process is segmented into two distinct phases: a first phase for coarse positioning using all six degrees of freedom to bring the end effector near the target, and a second phase for fine positioning using only three secondary joints. This segmentation allows each phase to be optimized independently, achieving sub-0.01mm accuracy without requiring complex hardware modifications.
Solution Approach 2:
The system dynamically switches between different control modes based on the positioning phase. During the first phase, all six joints are active for gross movement. During the second phase, three joints are locked and only three secondary joints remain active for fine adjustments. This dynamic reconfiguration optimizes precision for the fine positioning task.
2Manufacturing precision
If micrometric devices are added to achieve fine positioning, then positioning precision improves, but the number of joints increases to at least six joints of varying types
Solution Approach 1:
The invention merges the coarse positioning function (performed by all six joints in phase one) with the fine positioning function (performed by three secondary joints in phase two) into a unified two-phase control system. This integration eliminates the need for separate micrometric devices while achieving the same precision goal, reducing the effective number of active joints during fine positioning.
Solution Approach 2:
The first phase performs preliminary coarse positioning to bring the end effector into the vicinity of the target position. This preliminary action reduces the displacement required in the second phase, allowing the three secondary joints to achieve fine positioning with smaller, more precise movements without requiring additional micrometric joints.
3Adaptability or versatility
If the robot operates near singular configurations, then the workspace coverage is improved, but the Jacobian matrix becomes non-invertible causing control problems
Solution Approach 1:
The invention applies different control strategies to different regions of the workspace. In regions far from singularities, the full six-degree-of-freedom model is used. When approaching singular configurations, the system transitions to the three-secondary-joint fine positioning mode, which has better numerical properties. This local adaptation maintains control stability while preserving workspace coverage.
Solution Approach 2:
The three secondary joints act as an intermediary mechanism between the main six-degree-of-freedom robot and the final positioning task. When the robot approaches singular configurations, this intermediary subsystem takes over the fine positioning function, mediating the control transition and maintaining system reliability while allowing the main robot to operate in challenging workspace regions.
Data Source
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AI summary
The invention relates to a robot that has an articulated arm for moving an end in an N-dimensional space comprising at least N+1 motorized articulations, and a computer for controlling the movements of said motorized articulations. Said computer controls a first step of prepositioning the terminal end of the articulated arm and a second step for its fine positioning.