This WPI Capstone Engineering Experience course was in collaboration with Otis Elevator Co. The goal of the project was to improve the safety of high-rise, high-speed elevators which are vulnerable to rope sway caused by periodic building sway as a result of wind loading on tall buildings.

There were 3 defined teams tasked with certain major areas of focus; Development of a Test  Rig, Characterization of Sensors, and Development of a method to process data from sensors. I was a part of the Characterization of Sensors team. We started the project by researching various sensors that could be used to measure rope sway. After a thorough analysis, we decided to use Lidar sensors as they provide high-precision, real-time data, and are well-suited for dynamic environments.

We then further analyzed 3 different types of lidar systems; Time of Flight (TOF), Phase Difference, and Triagnulation. Time of Flight (TOF) lidar uses a laser to emit pulses of light that bounce off objects and return to the sensor. The time it takes for the light to return to the sensor is used to calculate the distance to the object. Phase Difference lidar uses two laser beams that are emitted simultaneously and are offset in phase by a known amount. The phase difference between the two beams is used to determine the distance to the object. Triangulation lidar uses a laser beam and a camera to measure the distance between objects. The laser is projected onto the object, and the camera is used to capture the image of the laser dot. The position of the dot on the image is used to calculate the distance to the object.

The team then developed a smaller, manual test rig system that could measure these types of lidar systems to accuracy of rope sway detection in real-time. We put elevator ropes through various simulated conditions to validate their accuracy and reliability.

We determined triangulation lidar technology is the most accurate method of the three lidar methods but requires a high degree of calibration. We recommended that OTIS look further into this type of lidar technology as it is a reliable solution for measuring rope sway in high-rise elevators.

As much as I would like to share our results, those at OTIS made our final report confidential to protect any company information we worked with.