PROJECTS
These are just a few of very many projects I've tackled in recent years. In each case, I've been responsible for the concept, design, procurement, assembly, integration, and programming of the entire system, and analysis and reporting of data arising.
3-Axis Wind Tunnel Traverse System
Wind tunnel modelling of tall buildings has some unique needs when it comes to probe traversing systems. Conventional fixed-rail Z-axes can't be used, and more unique approaches are required. While 3-joint rotary arms are common in automotive tunnels, they have complex kinematics and are prohibitively expensive.
Inspired in equal parts by scissor lifts, lazy tongs riveters, and clothes airers, the bespoke Z-axis acts as a guided crane, driven through a worm gearbox with independent position feedback via a string encoder. X- and Y-axes are more conventional, built in Minitec structural extrusions and using rack and pinion drive. The Z-axis can, when required "leap tall buildings in a single bound"...
Cellular Remote Motion Monitoring System
Where possible, it's usually preferable to use existing building networking to make connections, internally and externally. In some installations however, their sensitive nature precludes use of the building LAN. In this case, monitoring accelerations of a tall, high-security, structure to assess occupant comfort, required use of a 4G modem for backhaul.
Accelerometers were SENSR CX1 MEMS units remotely mounted direct to building structure, running on POE cabling.
A Mac Mini was chosen for its high reliability, low power consumption and reduced vulnerability to common cyberattacks. The enclosure includes a UPS, to ensure continued reporting during extreme weather events, and a web power switch, to allow manual or automatic rebooting of all system components.
Closed Loop Position Controller for AC Motor
Sometimes you have to "start from where you are"...
In this case, there was a significant existing investment in AC gearmotors and VFDs to position a rotating load. The original bang-bang control system had already been replaced with a proportional control scheme; however, processing had remained host-based, and timing critical. Timing inconsistencies could result in failure to detect wrapping of the absolute encoder, resulting in loss of position.
Replacing the host software with a LabJack T4, with hardware quadrature counting and running an internal Lua script, closed the position loop entirely onboard the equipment, requiring only a setpoint command over ethernet.
Time-resolved Multi-hole Probe Systems
While LDA is the state of the art for time resolved point velocity measurements in the wind tunnel, multi-hole pressure probes are much more convenient to use in a commercial lab, and when complex topology can make optical access impossible.
Starting first with a drilled-elbow 5-hole probe from Aeroprobe, and then with their straight 12-hole "Omniprobe", sensors, software, and transfer function compensation were integrated into a measurement system capable of reporting 3 components of velocity and turbulence. Accuracy is comparable to hotfilm anemometry, but with 3 components.
Acoustic Monitoring and Remediation
Sometimes unique architecture can bring with it unique problems...
In this case, a 40-storey building that "sang" in south-westerly winds, to the point it was uninhabitable! A long-term remote monitoring campaign was conducted in parallel with laboratory simulations, which proved the entire facade of the building was acting as a huge phase-locked planar emitter, radiating frequencies related to the sunshade spacing and depth.
Modelling indicated the optimum percentage of sunshades to remove- initially randomly, but finally in strata- that finally quieted the tones. It was slightly sad to put an end to such a remarkable phenomenon- but it was very loud! (And there are still plenty of singing buildings out there- contact me if yours is one!)