Robotic Load Handler Lifting Drive for Level Container Gripping
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Solution Overview
Problem
Existing robotic load handling devices face issues with the container gripping assembly becoming uneven due to unequal lengths of lifting tethers and slipping timing belts, leading to potential jamming and failure when handling heavy storage containers.
Innovation Solution
A lifting drive mechanism using a single motor with a belt tensioner wheel to control the length of the timing belt under tension, ensuring it forms a serpentine shape over pulleys, reducing strain and minimizing the risk of slipping by redistributing tension to a smaller section of the belt.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single motor and pulley system is used to lift heavy containers, then device complexity is reduced, but the container gripping assembly becomes uneven due to unequal tension in lifting tethers
Solution Approach 1:
A timing belt is introduced as an intermediary component to synchronize the rotation of multiple spools. The timing belt transmits rotational motion from a single motor through a series of pulleys to multiple spools, ensuring they rotate at the same speed and maintain equal tension in the lifting tethers, thus keeping the gripping assembly level.
Solution Approach 2:
The system changes the operational parameters by using a single motor with controlled rotational speed and direction. The motor's rotation parameters are precisely controlled to ensure synchronized operation of all spools through the timing belt mechanism, maintaining equal tension distribution across all lifting tethers.
2Power
If high torque is applied to lift heavy containers with a single motor, then lifting capability is improved, but timing belt slippage occurs on pulleys
Solution Approach 1:
The timing belt is configured to wrap around pulleys in a serpentine pattern, increasing the wrap angle and contact area between the belt and pulleys. This curved path distribution allows the high torque to be transmitted more effectively without slippage, as the force is distributed along the curved contact surface rather than at a single point.
Solution Approach 2:
The timing belt system transitions from a simple linear transmission to a multi-dimensional serpentine configuration. The belt travels through multiple pulleys in different spatial planes, creating a three-dimensional transmission path that increases friction and engagement reliability while maintaining high torque transmission capability.
3Strength
If lifting tethers are made stronger to handle heavy containers, then load capacity is improved, but the gripping assembly becomes more prone to jamming when unevenly tensioned
Solution Approach 1:
The timing belt mechanism provides passive feedback by physically coupling all spools together. When one spool rotates, the timing belt ensures all other spools rotate simultaneously and equally, automatically maintaining balanced tension across all lifting tethers. This mechanical feedback prevents the conditions that lead to jamming.
Solution Approach 2:
The system creates equipotential conditions for tension distribution by using the timing belt to ensure all lifting tethers are subjected to equal tension forces. This equalization of tension potential across all tethers prevents the uneven loading that causes the gripping assembly to tilt and jam.
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
The solution maintains the horizontal orientation of the container gripper assembly and reduces the risk of belt slippage, ensuring smooth operation and preventing container jamming, even when lifting heavy loads.
Implementation Method 1
a belt tensioner wheel arranged between the first timing pulley and the second timing pulley, the belt tensioning wheel being arranged to urge the single timing belt against the first timing pulley
Data Source
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AI summary
A robotic load handling device for lifting and moving storage container stacked in stacks in a grid framework structure comprising a track system comprising a first and second sets of tracks arranged in a grid pattern, the robotic load handling device comprising: a wheel assembly comprising a first and second sets of wheels arranged to engage with the first or second sets of tracks; a wheel positioning mechanism for selectively engaging either the first set of wheels with the first set of tracks or the second set of wheels with the second set of tracks; a container lifting mechanism 251 comprising a container gripper assembly configured to releasbly grip a container and a lifting drive assembly configured to raise and lower the container gripping assembly. The lifting drive assembly comprises a single motor 252 configured to raise the container-gripping assembly in a first rotational direction and lower the container-gripping assembly in a second rotational direction. The container-lifting mechanism 251 further comprises a first set of spools 257, 262 and a second set second of spools 267,268, each spool of the first and second sets of spools carrying a lifting tether 38 having a first end anchored to the container gripping assembly and a second end anchored to its respective spool; a drive pulley 253 connected for rotation with the single motor 252, a plurality of timing pulleys 255, 261, 263, 265 connected for rotation with the first and second set of spools 257, 262, 267, 268 and the drive pulley 253 such that the single motor 252 is configured to rotate the first and second set of spools to raise and lower the container-gripping assembly. The plurality of timing pulleys comprises a first timing pulley 255 and a second timing pulley 261, the first 255 and second 261 timing pulleys are connected for rotation to the drive pulley 253 by a single timing belt 254 forming a closed loop around the first 255 and second 261 timing pulleys and the drive pulley 253 such that the drive pulley 253 drives rotation of the first 255 and second 261 timing pulleys in the same rotational direction; and wherein the first timing pulley 255 is disposed between the drive pulley 253 and the second timing pulley 261 and wherein the lifting drive assembly further comprises a belt tensioner wheel 266a arranged between the first timing pulley 255 and the second timing pulley 261, the belt tensioning wheel 266a being arranged to urge the single timing belt 254 against the first timing pulley 255 such that the tension in a first section T1 of the single timing belt 254 between the first timing pulley 255 and the drive pulley 253, moving in a direction towards the drive pulley, in use, is greater than the tension in a second section t2 of the single timing belt 254 between the first timing pulley 255 and the second timing pulley 261 when the single motor 252 rotates in the first rotational direction.