DEEP LEARNING TO STOP FOUL PLAY
One notable feature of PASS is its use of technology to detect and prevent tampering with urine samples.
Attempts to evade detection in drug screening tests usually involve either adulteration or substitution of the urine sample, said DSP Sameeyul.
With manual dipstick tests, supervisees have been known to try various ways of fooling the system, including bringing a prepared urine sample and using a synthetic organ, he said.
HTX lead engineer of the Robotics, Automation & Unmanned Systems Centre of Expertise Tee Wen Kai said that the technological safeguards in PASS include “non-optical sensors” and deep learning to identify a genuine urine sample.
“We train our system to differentiate between real urine freshly procured from the user and one that is pre-prepared and being poured in,” he said.
PASS can also ensure that there is only one person in the cubicle at a time, and alert a prison officer if this is not so.
Any concerns about cross-contamination from other supervisees using the same urinal were also allayed in tests of the flush system.
Mr Tee said that the team prepared a sample containing a concentration of drugs that was 1,000 times above the threshold of the test kit and flushed it down the urinal.
When the residual liquid was collected and tested in a forensic lab, only a negligible amount of substances was detected, he said.
The development of PASS started at the end of 2019. A contactless urinal design was chosen because of concerns about hygiene during the pandemic.
This also means PASS is currently not used for women, as the intention was to concentrate on the majority of supervisees who are male, said DSP Sameeyul.
The design considerations even extended to the entertainment options in the cubicle as supervisees stand waiting for their test results.
Initially, a corporate video from SPS was screened. After feedback, the team procured episodes of British sitcom Mr Bean for supervisees to while away the time.