Autonomous Gantry Rebar Tying on Curved Construction Surfaces
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Solution Overview
Problem
Repetitive and physically demanding tasks in construction, such as rebar tying on roadways and bridge decks, remain labor-intensive and unsafe, with limited automation advancements over the past decade, necessitating a more efficient and safer method for performing these tasks.
Innovation Solution
An autonomous assembly system comprising a gantry subassembly, a carrier subassembly, and a tool actuation subassembly, equipped with perception sensors and an autonomous control system, which enables precise motion planning and execution, allowing the system to navigate and tie rebar intersections with minimal human intervention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If manual rebar tying is performed by workers walking along the rebar grid, then the task can be completed with simple tools, but the work is repetitive, time-consuming, and exposes workers to unsafe conditions
Solution Approach 1:
The autonomous assembly is divided into three main subassemblies: gantry subassembly for longitudinal movement, carrier subassembly for lateral movement, and tool actuation subassembly for the tying operation. This segmentation allows each component to perform a specific function, reducing overall system complexity while achieving full automation.
Solution Approach 2:
The patent introduces an autonomous control system as an intermediary that coordinates the gantry drive system, carriage drive system, and tool actuation. This centralized control mediator manages the complex automation tasks, allowing the physical tying mechanism to remain relatively simple while achieving intelligent automation through software coordination.
2Productivity
If automated rebar tying systems are implemented, then productivity increases, but the device complexity and structural requirements increase significantly
Solution Approach 1:
The gantry subassembly serves multiple functions: it provides the longitudinal travel path for the carrier, supports the entire moving assembly, and acts as a bridge spanning the work area. This multi-functionality reduces the need for separate structural components, maintaining productivity while controlling overall system complexity.
Solution Approach 2:
The system adds a lateral dimension to traditional automated tying by introducing the carrier subassembly that moves perpendicular to the gantry's longitudinal movement. This two-dimensional movement capability allows the tool to access all rebar intersections systematically, dramatically increasing productivity compared to linear automated systems.
3Loss of time
If workers manually tie rebar intersections, then equipment cost is low, but the work is physically demanding and time-consuming
Solution Approach 1:
The perception subsystem performs preliminary action by detecting and mapping all rebar intersections before the tying process begins. This advance detection allows the motion planning subsystem to pre-calculate optimal paths and sequences, enabling the autonomous assembly to move efficiently between intersections without delays for real-time decision-making, thus significantly reducing total tying time.
Solution Approach 2:
The autonomous assembly maintains continuous useful action by coordinating the gantry and carrier drive systems to move the tool continuously from one rebar intersection to the next without idle time. The automated system eliminates the repetitive stopping, positioning, and setup time that occurs in manual operations, keeping the tying tool engaged in productive work throughout the process.
Data Source
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AI summary
An autonomous assembly is described herein that includes a gantry subassembly, a carrier subassembly movably mounted on the gantry subassembly, a tool actuation subassembly mounted on the carrier subassembly, and an autonomous control system including a perception subsystem, a motion planning subsystem, and a motion control subsystem. The gantry subassembly includes a bridge member for laterally spanning a selected section of a work site and a gantry drive system for effecting travel of the gantry subassembly along the length of a selected portion of a work site. The carrier subassembly includes a carriage and a carriage drive system for effecting travel of the carriage along the bridge member. The tool actuation subassembly effects linear travel of an end-effector generally perpendicular to the bridge member and the carriage.