Improved method for synchronous movement of attached self-lifting scaffolds with an optoelectronic sensor array

• We present an improved method for ASLS synchronous movement controlling.
• An optoelectronic sensor array based measuring model is proposed.
• Movement displacement of ASLS can be measured with a resolution of 2.0 mm.
• The agreements of 96.5% and 92.7% with the defined thresholds of 80 mm and 30 mm are obtained.

Synchronous movement of attached self-lifting scaffolds (ASLS) is very important to ensure the safe and economic construction of high-rise buildings. Existing controlling methods for ensuring synchronous movement of ASLS are focused on the measurement of the relative displacement of ASLS modules with simple sensors. It is difficult to acquire the accurate relative module positions. In this article, an improved method is presented for controlling the ASLS synchronous movement based on an optoelectronic sensor array. Firstly, connected pipes were mounted on ASLS modules and the relative liquid level can be detected by the sensor array mounted on the pipe. When the ASLS is lifted or lowered, the relative movement of different ASLS modules leads to the change of the liquid levels, which are then instantly detected and recorded by the sensor array. The relative moving displacements of each ASLS module are obtained which were then compared to the allowable value designated by the construction specifications. Experimental result shows that the proposed model has effectively improved the controlling accuracy with an average agreement of 92.7% and 96.5% with the required allowable relative movement of 30 mm and 80 mm respectively, which leads to the decreased switching on or off of AC (alternating current) contactors and prolongs the service life of AC contactors. Additionally, the movement difference is accurately measured with a resolution of 2.0 mm. The synchronous movement of all ASLS modules is ensured. Finally, statistical data regarding the failure of the AC contactors are collected and it shows that the failure ratio of AC contactor is effectively reduced from 1.18% to 0.69%, indicating a sustainable solution for the synchronous movement control of ASLS.