CANHEAD - METU | Aerospace Engineering

CANHEAD

Data acquisition close to the measuring points

Georg Wegener

[email protected]

www.hbm.com

20/03/2008, Folie 2 Hottinger Baldwin Messtechnik GmbH Georg Wegener

CANHEAD

Parts of a measuring chain:

- strain gages and transducers

- DAQ system with amplifiers, filters, A/D converters

- DAQ software

- and...

... cabling


CANHEAD

Example:

DAQ-system

Test articleDistance: 25 m

size: 50 m1.000 strain gages

average cable length per strain gage: > 50 m

Ø more than 50.000 m of transducer cable

Ø Problems: noise, weight and costs

1.000 analog cables


CANHEAD

Typical problem in experimental stress analysis

Stress analysis with many measuring points.- Thick wire harnesses- High weight- No easy identification of

the measuring point - High installation cost in

the surroundings


CANHEAD


CANHEAD

Alternative:

DAQ-system

Distance: 25 m

size: 50 m1.000 strain gages

average cable length per strain gage: 10 m

Ø only 10.000 m of transducer cable

Ø reduction of weight and costs by a factor of 5

digital bus cables Signal conditioningand ADC modules

Test article


CANHEAD

• decentralized measuring and digitizing

• data transfer via digital bus system

DAQ system

Head1 Head2 Head3 Head4 ....

CAN Bus


CANHEAD

Specification:- Operation with standard amplifier system MGCplus

- Modules available for single S/G

- in 3-wire or 4-wire technique

- 120, 350, 700 or 1.000 Ohm

- Easy transducer connection

- 10 channels per head

- 11. channel for temp. compensation- 600 Hz rectangle supply

- Measuring rate: 25 Hz - 300 Hz per channel

- Later on further input modules (family)


CANHEAD

Bus-requirements:

- length > 100 m- Established in the market- Easy connection- Sufficient data rate > 1000 values/s

------->>> CANController Area Network


CANHEAD

Specification CAN-Bus for CanHead:

- Fixed Baud rate = 250 kBd => up to 250 m bus length

- CANOpen => defined protocol

- Wiring with standard DEVICE-Net components

- maximum 12 CAN Heads per bus => max. 120 channels

- Receiving in MGCplus with ML74 => quite normal measuring channels for the software (catman®)


CANHEAD

CAN-HEAD CAN-HEAD CAN-HEAD CAN-HEAD

Idea for CANIdea for CAN--HEADHEAD


CANHEAD

• 120, 350, 700 or 1000 Ohm• accuracy 0.1 % (3-wire technique)

• 600 Hz carrier frequency• integrated bridge completion resistors

• separate A/D-converters for each channel

• simultaneous data acquisition

• shunt calibration

Temperature compensation:• Not compensated

• Temperature - compensation S/G with 11. channel (same lot of foils)

• Mathematical TC-compensation with polynomial calculation


CANHEAD

Measuring ranges: 20 mV/V, 10 mV/V and 4 mV/V at

supply voltage of: 0.5 V, 1 V and 2.5 V

* for quarter bridge circuit wiht k=2

Measuring range in mV/V 20 10 4

Measuring range in µm/m *) 40000 20000 8000

reproducible resolution in µm/m *) 1 0.2 0.1


CANHEAD

Strain gagecable type

AWGcross-

section(mm^2)diameter

(mm) Ohm/mcable

length (m)350 Ohm 20 0.520 0.812 0.033 104.80

24 0.205 0.511 0.084 41.4525 0.163 0.455 0.106 32.8726 0.129 0.405 0.134 26.0732 0.025 0.180 0.540 6.48

Maximum length of S/G connection cableMaximum length of S/G connection cable(at 1% loss of sensitivity)(at 1% loss of sensitivity)


CANHEAD

Speed scalability of one CAN Head bus:

1 head: 10 x 300 MV/s -> 3000 MV/s

2 heads: 20 x 150 MV/s -> 3000 MV/s

..

5 heads: 50 x 60 MV/s -> 3000 MV/s

6 heads: 60 x 50 MV/s -> 3000 MV/s

..

12 heads: 120 x 25 MV/s -> 3000 MV/s

MV = measured value


CANHEADTechnical Concept CANTechnical Concept CAN--HEADHEAD

- Application of 1/4-bridge-S/Gs

- Connection of temperature-compensation-S/G

- Link-up CAN-Bus cable

- Put on cover and fix S/G leads

- Cabling of installation

- Put in integrated electronics module

… ready for measurement !Basic module /Connection board

CAN-HEADelectronic


CANHEAD

Construction (shown without housing)

Amplifier module

Connection area

DeviceNet plug,small form M12


CANHEAD

The CANHEAD Family• Different types of basic modules for

- single strain gages (quarter bridge circuits)- strain gage full- and half bridges, - DC voltage sources

• Standardized amplifier module for all types of base modules


CANHEAD

The CANHEAD Family

CA1030 Amplifier module

• Standardized amplifier module for use in all types of CANHEAD base modules

• Simple plug-in connectionà amplifier can easily be removed when needed elsewhere

• 10 measurement channelsplus 1 additional compensation channel


CANHEAD

CB1015

CB1014

The CANHEAD Family

CB1014 / CB1015 basic module

• Internal completion resistors:different versions for 120, 350, 700, 1000 O

• Internal or external shunt resistor

• Extra channel for compensation of temp. effect on the strain gages

• CB1014 for 3-wire circuitry



CANHEAD

The CANHEAD Family

CB1016 basic module

• Measuring point connection: RJ45 socket

• Internal completion resistors:120 O and 350 O


CB1016


CANHEAD

The CANHEAD Family

CB1010 basic module (for different signal types)

• Basic module for - strain gages half bridges- strain gage full bridges, - DC voltage sources

• Input signal types can be selected individually for each channel

CB1010


CANHEAD

The CANHEAD Family

Master for the CAN bus communication

Communication module ML74(B) / AP74 for MGCplus

• CANHEAD requires MGCpluswhich serves as field bus communication interface

• System can be extended by MGCplus modules toprovide channels for other measurement principles


CANHEAD

Thank you...

... for your attention

Hottinger Baldwin Messtechnik GmbH

Im Tiefen See 45

D-64293 Darmstadt

www.hbm.com

Reiner Schrod

Produkt Manager

Tel. 0 61 51 / 8 03 - 267

[email protected]

Documents

CANHEAD - METU | Aerospace Engineering