Optical Shade Controller with Variable Velocity Profile
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Solution Overview
Problem
Motorized roller shades experience jerky motion and often overshoot or undershoot the selected position due to abrupt starting and stopping, and existing methods for positioning are inaccurate due to reliance on constant linear velocity and rotational position measurements, which do not account for fabric thickness variations and gaps.
Innovation Solution
A system that includes an optical sensor to capture images of the shade material's motion and a motor controller using a variable linear velocity profile, such as exponential, ramp, or Gaussian functions, to smoothly move the shade to a selected position, preventing overshooting or undershooting by directly measuring the shade's position and adjusting velocity accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the motorized drive system moves the shade at a constant velocity with abrupt starting and stopping, then the positioning is simpler to control, but the motion becomes jerky and causes overshooting or undershooting the selected position
Solution Approach 1:
The patent applies dynamics by transitioning from constant velocity to variable velocity control. The motorized drive system dynamically adjusts the shade's velocity during movement, accelerating smoothly from rest and decelerating before reaching the target position. This dynamic velocity adjustment eliminates jerky motion and prevents overshooting, while maintaining relatively simple control through automated velocity profiling.
2Device complexity
If the linear velocity is estimated by multiplying RPM by the changing distance from the last outer layer of fabric to the tube center, then the control system is simpler, but the positioning accuracy is limited by motor rotational position measurement accuracy and fabric variations
Solution Approach 1:
The patent replaces the indirect mechanical estimation method (RPM × changing radius) with direct optical measurement. An optical sensor system captures images of the shade fabric at multiple linear positions, directly measuring the shade's actual position without relying on motor rotational measurements. This substitution eliminates errors from fabric thickness variations and layer gaps, achieving high positioning accuracy while keeping the control system manageable through automated image processing.
3Stability of the object's composition
If multiple shades are controlled to arrive at desired positions simultaneously, then the coordination between shades is improved, but the control system complexity increases due to varying velocity requirements
Solution Approach 1:
The patent implements feedback control for coordinating multiple shades. The optical sensor system continuously monitors the position of each shade, and the controller adjusts the velocity of each motorized drive system based on real-time position information. This feedback mechanism ensures all shades arrive at their desired positions simultaneously, maintaining synchronization stability. The complexity is managed through automated feedback loops that independently control each shade while achieving coordinated arrival.
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 system ensures smooth and accurate positioning of roller shades by directly measuring motion and adjusting velocity, preventing jerky motion and ensuring the shade arrives at the desired position without overshooting or undershooting, allowing multiple shades to synchronize at varying velocities.
Implementation Method 1
an optical sensor configured for capturing an image frame of the flexible shade material at a plurality of linear positions along the flexible shade material
Data Source
AI summary
Presented is a system for controlling a roller shade. The system includes a flexible shade material having a lower end, a roller tube windingly receiving the flexible shade material, and a reversible motor for rotating the roller tube to move the lower end of the shade material between a first and second position. The system further includes an optical sensor for capturing an image frame of the shade material at a plurality of linear positions as the lower end of the flexible shade material moves from the first position to the second position. The system further includes a motor controller for controlling the reversible motor to move the lower end of the shade material from the first position to the second position using a variable linear velocity profile in response to position information obtained from the plurality of captured image frames.