Mechatronic design in computer

Ground loop can occur in a signal recording system where …

grounds of the measurement system and the transducer are different.

A recorded signal has a freq of 100Hz. Determine the correct recording parameters (recording time and sampling freq) to accurately determine its shape (accuracy of 1 Hz):

1s, 10 000 Hz

A recorded signal has a freq of 1000Hz. Determine the correct recording parameters (recording time and sampling freq) to accurately determine its shape (accuracy of 1 Hz):

1s, 10 000 Hz

In which type of network is it necessary to use terminators between wires and their ends?

High-speed CAN (Controller Area Network)

Quantization is defined as:

The process of discretising the signal in the AMPLITUDE domain.

A hall sensor signal has a period of 100ms and is sampled at a frequency of 10 kHz. How many samples should be analysed to determine the signal frequency with a resolution of 0.5Hz using the Fourier transform?

20 000

freq/resolution=10 000/0.5= 20 000

A hall sensor signal has a period of 100ms and is sampled at a frequency of 10 kHz. How many samples should be analysed to determine the signal frequency with a resolution of 2 Hz using the Fourier transform?

5 000

freq=10 000 Hz, resolution=2

10000/2=5000

The dominant level of the signal in the CAN network corresponds to the logical level:

0

Signal sampling is the process of:

Discretising the signal in the TIME domain.

In differential mode, the transducer grounds are connected to:

Inputs of measurement amplifiers.

Calculate the engine speed when the duration of the 2-stroke cycle is 40ms:

1 rev - 40ms=0.04s

2/0.04=x/60

120=0.04x

3000rpm

Spectral leakage can be minimized using:

Measurement windows

For which network do voltage waveforms look like this?

CAN (Controller Area Network)

Designations of CAN network wires:

CAN - High

CAN - Low

Choose a function that the signal conditioning can perform:

Analog-to-digital conversion of the signal

Signal amplification

Galvanic isolation of transducers/cables from the DAQ unit

Recording time (length of the sampled record) determines:

The lowers observable frequency of the signal.

Calculate the engine speed when the duration of the 4-stroke cycle is 40ms:

1 rev - 40ms=0.04s

1/0.04=x/60

1500rpm

Calculate the numer of falling edges after the missing tooth for the start of injection. Impulse wheels: 60-1

The zero drop after the missing tooth is 90 degrees before TDC

Start of injection: 6 degrees before TDC

Injection: 90-6=84 degrees

Injection tooth: 84/6=14

Calculate the angle of shaft rotation during the charging of the fuel injector coil. Charing time of the coil t=1ms, angular velocity n≈6000rpm.

1 rev = 0.01 s

t = 1 ms = 0.001 s

0.001/0.01= 0.1

0.1×360=36 degrees

Calculate the time delay after the last edge after which the start of injection will occur. Engine speed: 4000 rpm Impulse wheel: 60-2 Missing tooth: 60 degrees before TDC (the first edge after the missing tooth is number 0) Start of injection: 15 degrees before TDC

4000 rpm→1rev→ 0.015 s

1 rev→ 60teeth → 1tooth= 0.015/60=0.00025

Injection angle: 60-14=45 degrees

Injection tooth: 45/6=7.5

7.5-7=0.5 (half tooth delay)

Ans. 0.125 ms

Frame identifier field CAN be used to:

Conduct arbitration

The aliasing phenomenon can be prevented by:

Applying low-pass filtering to the signal

The task of the transceiver is to:

Converting logic levels (bits) to voltage levels on the network wires.

Convert voltage levels on the network wires to logic levels (bits).

The components that allow you to build a High-Speed CAN network (for wires up to 40m long) are:

Two terminators, two-pair twisted pair, CAN controllers, CAN transceivers

Select the ISO/OSI model layers that make up the CAN network

Physical layer, data link layer

CAN network cable markings

CAN-High, CAN-Low

The phenomenon of spectral leakage (winda) can be minimized by:

Using measurement windows

The signal from the Hall sensor has a period of 1ms. What sampling frequency should be chosen to measure the times between identical edges with an accuracy of 0.01 ms?

10 kHz

The maximum length of the data field in a CAN frame is:

8 bits

In RSE (Referenced Single Ended) mode, the grounds of the transducers are connected to:

The ground of the measurement system (AI Gnd)

Stray currents can occur in a signal recording system when???

the grounds of the measuring system and the transducer are different

Calculate the numer of the descending slope after the missing, directly after which the injection start to occur. Impulse wheel 60-2. Missing tooth:60 degrees before TDC (the first slope after the missing tooth has a numer 0). Injection start: 15 degrees before TDC

7

Injection angle:60-15=45 degrees

Injection tooth:45/6=7.5=7

The recessive level of the signal in the CAN network corresponds to the level:

1

When does aliasing occur?

The signal contains components above half the sampling frequency.

Without which sensor is it not possible to operate a combustion engine?

Crankshaft position sensor

In which type of CAN network is it not necessary to use terminators between wires and their ends ????

Low-speed CAN

What is the highest frequency that can be read from a signal sampled at frequency fp?

fp/2

The maximum speed of CAN is:

1 Mbit/s