By Edward Overton 1 Overview Background Target Behaviour amp BPS Limits Implementation FPGA Software Hardware Calibration amp Testing Plans 2 Background The decision to implement a firmware based BPS system was taken based upon discussionsrecommendations from ISIS staff in August l ID: 589854
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Slide1
The MICE target and the ISIS BPS system
By Edward Overton
1Slide2
Overview
BackgroundTarget Behaviour & BPS Limits
Implementation
FPGA
SoftwareHardwareCalibration & Testing Plans
2Slide3
Background
The decision to implement a firmware based BPS system was taken based upon discussions/recommendations from ISIS staff in August last year.
The firmware based BPS system aims to monitor the trajectory of the target on an actuation by actuation basis by comparing key points in the trajectory to similar key points in a pre-computed reference trajectory.
The comparison between the key values and the actual target trajectory is done in firmware to ensure that the system remains reliable even in the event of a disconnection between the computer and controller.
3Slide4
Set Point 2
Position Set
Flip Acceleration
Begin Actuation
Set Point 1
Flip Acceleration
Record time
Minimum Position
Record position & time
End actuation
Record actuation time
Enter capture mode
(cm)
4Slide5
Set Point 2
Position Set
Flip Acceleration
Begin Actuation
Set Point 1
Flip Acceleration
Record time
Minimum Position
Record position & time
End actuation
Record actuation time
Enter capture mode
Limits on “normal” Actuation, if outside send BPS error
(cm)
5Slide6
FPGA Implementation
8 USB registers set by control software
Provide upper and lower limits for:
FPGA Firmware monitors above position/times and throws an error if they lie outside the limits set in the registers.
The start position and final position are implicitly monitored by the target system. Any deviation from a normal range will throw an error, this has been tied into the BPS system.
"USB_SP1_MAX_TIME"
"USB_SP1_MIN_TIME"
"
USB_MIN_POS_MAX_TIME”
"
USB_MIN_POS_MIN_TIME”
"USB_MIN_POS_MAX_VALUE”
"USB_MIN_POS_MIN_VALUE”
"USB_ACT_MAX_TIME“
"USB_ACT_MIN_TIME“
SP1 TimeActuation Time.
Minimum PositionMinimum Position Time
6Slide7
Calculation of Trajectory
Target acceleration decays exponentially due to decaying power in capacitor bank:
C function calculates trajectory from:
a
0
,
t
RC
, Starting Position, SP1 and SP2.
Fit using C function to analogue data shown as red line =>
Limits can be calculated from the expected trajectory and downloaded to the FPGA registers
(cm)
7
a
0
depends on current and can be calculated for different voltage or temperature coils.
All necessary functions for calculating a
0
and trajectory included in
c++
class.Slide8
Example from Sheffield target
Target warm up
Coolant Temperature
SP1 time
Minimum Position
Minimum Position Time
Coil Temperature
8Slide9
Hardware
FPGA
Relay Driver
Each relay driver is connected to separate FPGA logic pin.
50R Driver
Added a third logical output to give a monitoring signal connected to a BNC
We were asked to provide 2 independent sets of relay contacts for the BPS system itself:
Relay
Rated to 1A 30VDC but PCB tracks limited to about 250mA
BPS Logic
Required to switch 2 relays. 24VDC, 16.8mA total.
9Slide10
Hardware
Row of relays down the RHS of board DC2.
There are 2 spare relays on the circuit board, so if more relays are required then this can be accommodated.
Back panel connectors
Relay Contacts
Available here
50R signal for sending to ISIS CR – If required
10Slide11
Calibration & Testing Plans
Current calibration for outdated test system in Sheffield.
Single minimum position.
Limited data recorded before controller was moved to R78.
New calibration required for ISIS, R78 targets.Multiple minimum positions.
Determination of upper/lower limits to place on actuation.
Thorough testing in R78 required to ensure system is working reliably prior to installation.
11Slide12
Conclusion
FPGA code and Electronics implemented, but requires testing.
Software for estimating parameters is also implemented.
Works well for Sheffield target.
Calibration required for R78 target.upper/lower limits on actuation need setting.
Control software upgrade underway to include BPS functionality.
Thorough testing in R78 required to ensure system is working reliably prior to installation.
12