Transfer Functions

Discussion in 'Homework Help' started by kwbake01, Jun 29, 2011.

1. kwbake01 Thread Starter New Member

Jun 29, 2011
4
0
How do I get the transfer functions of the following block diagrams

a) [K(s+a)/(s+1)]--->[1/s(s+2)(s+3)]
........BLOCK 1.............BLOCK 2

b) [4+(40/s)]--->[s^2/(s+100)(4s^2+5s+4)]
.....BLOCK 1..................BLOCK 2

c) [a+(B/s)]---->[1/(s+1)]
.....BLOCK 1........BLOCK 2

2. kevinarms New Member

Jun 29, 2011
6
2
If the blocks are simply in series (one directly after the other with no feedback), then the answer is really simple: all you have to do is multiply the blocks.

For example, if your block diagram looks like:

R --> | G | --> | H | --> Y

where R is the input, Y is the output and G and H are blocks (with corresponding transfer functions), then all you do to get the signal at each point is multiply the previous signals/blocks: so Y = H*G*R, so your transfer function is output/input = Y/R = H*G.

3. kwbake01 Thread Starter New Member

Jun 29, 2011
4
0
yes they are all in series with no feedback, b) was asked for the open loop. Is that any different

4. Georacer Moderator

Nov 25, 2009
5,150
1,271
It's exactly the case kevinarms described.