Robot Work Area Allocation for Balanced Pick-and-Place Lines
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Solution Overview
Problem
Conventional pick and place systems often experience unbalanced workloads between robots, leading to inefficiencies and potential conveyor stops, due to overlapping and excessive work areas that are not fully utilized, resulting in fluctuations and collisions.
Innovation Solution
Defining and dynamically adjusting the actual work areas of robots by limiting them to A ac < A th - (A ol + A ex), where A ac is the actual work area, A th is the theoretical work area, A ol is the overlapping work area, and A ex is the excessive work area, allowing for a balanced workload by defining pick and place areas that are smaller and further away from conveyors for upstream robots.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If robots are allowed to operate in their full theoretical work areas, then the coverage and potential productivity are maximized, but workload becomes unbalanced and collisions occur between neighboring robots
Solution Approach 1:
The theoretical work area is segmented into actual work areas for each robot by excluding overlapping regions. Each robot is assigned a specific actual work area that does not intersect with neighboring robots' actual work areas, thereby preventing collisions while maintaining adequate productivity through optimized task allocation within these segmented zones.
2Productivity
If robots operate with full theoretical work areas, then more pick and place positions can be accessed, but excessive work areas are created where no tasks are executed
Solution Approach 1:
The excessive work area portions are extracted and removed from each robot's operational zone. By identifying and excluding regions where no pick or place positions exist (such as gaps between conveyors), the system eliminates wasted operational capacity while concentrating robots' efforts in actual work areas where tasks are actually performed, improving energy efficiency and task execution focus.
3Productivity
If upstream robots pick and place items rapidly, then their productivity increases, but downstream robots may not have enough items to process, causing conveyor stops
Solution Approach 1:
Different robots are assigned different actual work area characteristics tailored to their position in the system. Upstream robots may have larger pick areas while downstream robots have optimized place areas, creating local quality variations in workload distribution. This ensures that each robot operates at optimal speed without causing bottlenecks, as the work area allocation compensates for positional differences in the conveyor system.
Data Source
Figure 1a~1e
Figure 2
AI summary
A method for picking and placing items (30) comprises the steps of: providing a picking conveyor (20) transporting items (30) to be picked; providing a placing conveyor (40) to which the items (30) are to be placed; and providing a plurality of robots (50) configured to move the items (30) from pick positions (60) on the picking conveyor (20) to place positions (70) on the placing conveyor (40). For at least one of the plurality of robots (50) there is defined an actual work area Aac (170) that fulfils the condition Aac < Ath — (Aol+ Aex), wherein Ath is a theoretical work area (140), Aol is an overlapping work area (150) and Aex is an excessive work area (160) of the respective robot (50). By limiting the actual work area Aac (170) of the robots (50) more than what is done conventionally, the total workload between the robots (50) in pick and place systems (10) may be balanced.