Test Bench Automation · Stellar Control

For the test engineer or the manager of environmental test facilities: thermal vacuum, climatic or endurance tests that last days and must run unattended, and stop safely when they must.

Repository: stellar-systems-eu/control-usecase-test-bench-automation · Try it.

The example is a TVAC chamber; temperature regulation, vacuum, instruments, sequences and alarms are the same building blocks for a climatic chamber or an endurance bench.

The bench#

Target	Package	What	Link on the real bench
`chamber-1`	`tvac-chamber`	The chamber through its PLC: safety chain, pumping group (primary and turbo pumps, gate and vent valves, gauge), thermal plate and the thermocouples of the unit under test	Modbus TCP
`psu-1`	`lab-psu`	The supply of the unit under test, through a feedthrough	SCPI
`cam-em-1`	`hsc-100`	The unit under test, the camera of Payload integration	CSP over RS-422 (KISS)

The catalogue of the chamber carries the rules of the bench, checked before each command:

the turbo starts only below 10 Pa;
the gate valve opens only with the turbo running;
venting is hazardous (an operator confirms) and refused while the turbo spins.

The alarm vacuum_leak (pressure above 0.05 Pa for 30 s while pumped at high vacuum) runs the reaction Safe chamber, which closes the gate valve and warms the plate. See Alarms and Alarm Handling.

The TVAC cycle#

packages/tvac-ops, TVAC cycle (inputs hot, cold):

The chamber is ready: door, emergency stop, cooling water, LN2.
Pumpdown: primary pump, turbo, gate valve, down to 10⁻³ Pa.
The unit powered and answering.
Two hot/cold cycles. On each plateau, the procedure waits for the unit to follow the plate, holds, then checks the vacuum and the unit: it answers, has no fault, draws its expected current.
Back to ambient, the turbo spun down, venting confirmed by the operator.

Shell

stellar run --dry runs/tvac-sim.yaml --repository . --report report.html   # about 8 minutes
stellar run runs/tvac-lab.yaml                                             # the real chamber

A leak, at night#

The key moment: a vacuum leak on the first plateau, with nobody in front of the chamber. In a trial environment, switch the fault of the simulated chamber during the cycle:

Shell

stellar sim fault chamber-sim-gw-1 vacuum_leak on

What happens:

The procedure fails on its vacuum check; its if failed switches the unit off.
The alarm raises, and its reaction makes the chamber safe.
The run waits for an operator's decision; its report holds every value and event.

See Questions, Decisions and Control and Test Reports.

Known limits#

The dwell on a plateau is a constant (30 s in the repository): a duration cannot come from an input of the run yet, so the real chamber needs its own value.
A dry run does not schedule faults nor play the alarms and their reactions: the leak is shown in a trial environment, or locally with scripts/leak-demo.sh.