Robotics and Automation Expert
page 1 page 2 page 3 page 4 page 5

Transaction Logging Improves Robotic System Safety (page 6)

Unfortunately, brownouts and power dips do not always exhibit this characteristic. They can drop in voltage to virtually any level. Proper reset logic depends on moving through the threshold; a voltage that is arbitrarily close to the threshold amplifies noise and creates a poor chip reset.

According to the Data Conversion Handbook by Walter Allan Kester, “The error mechanism is the occasional inability of a comparator to resolve small differential input into a valid logic level.” The brownout pulse can be of small duration and mid-level voltage, which can result in inconsistent operation. The end result is a soft failure in a subsystem, often referred to as a glitch.

Transaction logging can identify this kind of situation as subsystems power up in an unstable way and cause a system malfunction. The ideal solution is to respond to brownout conditions with a system wide discharge of all power to zero volts. In this case, transaction logging detects and captures these unstable situations and leads to a safe and graceful recovery. The secondary result of transaction logs is hard data for post-mortem analysis, followed by effective continuous improvement.

Conclusion - While several different technologies are available from a nonvolatile memory perspective, nvSRAM can offer a highly reliable and robust solution. Fast, on-chip SRAM, combined with auto STORE and RECALL to and from on-chip nonvolatile memory, can keep track of last known position, current known position, sensor data logs, surrounding axis information, and other enhanced functions. In addition, nvSRAM’s superior ability to deal with sudden and unexpected power outages makes It a choice that should be considered for mission-critical robotic control applications where machine safety is of paramount importance..

© copyright SafeMachines, PLLC all rights reserved