Robot Arm Compensation on Flexible Booms for Precise Positioning
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Solution Overview
Problem
Existing control systems for end effectors on flexible arms, such as booms, struggle to maintain precise positioning over large areas due to structural deflection and external interference like wind, especially when the boom is mounted on a moving vehicle, leading to errors as the distance from the base increases.
Innovation Solution
A cascading system of positioning devices and measurement systems with dynamic coordinate systems allows for real-time tracking and compensation, enabling the end effector to be programmed in a work coordinate system, accommodating normal CNC coordinate shifts and transformations, and dynamically adjusting for structural deflections and external influences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If a robot arm is mounted on a flexible boom to work over a large area, then the working range is increased, but positioning precision deteriorates due to structural deflection and external interference
Solution Approach 1:
The patent implements a feedback control system where a measurement system continuously monitors the actual position and orientation of the boom and robot arm base, compares it with the programmed position, calculates deviation vectors, and applies compensation to the kinematic chain. This closed-loop feedback mechanism dynamically corrects positioning errors caused by boom deflection and external interference, maintaining precision despite the extended working range.
Solution Approach 2:
The patent replaces purely mechanical rigid positioning with a hybrid system that combines mechanical structure with dynamic computational compensation. Instead of making the boom physically rigid, the system uses real-time measurement data and coordinate transformations to substitute for the mechanical stiffness, allowing the flexible boom to maintain positioning accuracy through software-based correction.
2Length of stationary object
If the boom is made longer to increase working area, then the coverage is improved, but positioning accuracy deteriorates due to increased deflection
Solution Approach 1:
The measurement system continuously monitors the actual position of the robot arm base on the boom, and the control system calculates compensation vectors based on the deviation between actual and programmed positions. This feedback loop dynamically corrects for the increased deflection that occurs with longer boom lengths, maintaining positioning accuracy despite the extended reach.
Solution Approach 2:
The patent transitions from static positioning compensation to dynamic compensation. The system continuously updates the coordinate transformations and compensation vectors in real-time as the boom deflects under different loading conditions and positions. This dynamic adaptation allows the system to maintain accuracy throughout the entire working range of the extended boom.
3Manufacturing precision
If real-time measurement and compensation is implemented, then positioning precision is improved, but system complexity increases
Solution Approach 1:
The measurement system serves multiple functions: it tracks the position and orientation of the boom, determines the actual position of the robot arm base, provides data for compensation calculations, and enables dynamic coordinate transformations. This multi-functionality reduces the need for separate specialized components, managing system complexity while achieving high positioning precision.
Solution Approach 2:
The patent introduces a coordinate transformation system as an intermediary between the measurement data and the robot control. Instead of directly controlling the robot based on raw measurement data, the system uses dynamic coordinate transformations to mediate the information, simplifying the control logic while maintaining positioning accuracy through the transformation of reference frames.
4Manufacturing precision
If dynamic compensation is applied to maintain precision over large areas, then positioning accuracy is improved, but computational requirements and control complexity increase
Solution Approach 1:
The patent divides the compensation task into segments: the measurement system segment that collects data, the coordinate transformation segment that processes the data, and the robot control segment that executes the compensation. This segmentation allows each component to be optimized independently, managing computational complexity while achieving high positioning accuracy through coordinated operation of the segments.
Data Source
AI summary
A control system for a base supporting a boom assembly comprises long telescopic boom and telescopic stick. Mounted to the remote end of the stick is an end effector that supports a robot arm that moves a further end effector to manipulate the items. The robot arm has a robot base, and mounted above the robot base is a first target in the form of a position sensor, that provides position coordinates relative to a fixed ground reference. Mounted on the end of the robot arm immediately above the end effector is a second target that provides position coordinates relative to the fixed around reference. The fixed ground reference tracks the sensors and feeds data to the control system to move the stick with slow dynamic response and to control movement of the robotic arm and end effector with fast dynamic response.