---
# System prepended metadata

title: RSS Exam
tags: [RWTH Course, RSS]

---

# RSS Exam
###### tags: `RWTH Course` `RSS`
[ToC]
## Ex 1. View into the future
### 1. Robots can be classified according to the norm ISO 8373:2012.
![](https://i.imgur.com/MNJTN9U.png)

### 2. Explain the main differences between industrial and service robots in terms of application fields.

* Industrial robot: applied in industrial automation applications.
* Service robot: performs useful tasks for humans or equipments excluding industrial automation appications.

### 3. The “Measurement Chain” according to DIN 1319-1:1995
![](https://i.imgur.com/LZx9Ob1.png)
![](https://i.imgur.com/c7HApQd.png)
![](https://i.imgur.com/YC2kSUq.png)

## Ex 2. Control and feedback control systems
### 1. Robot system
![](https://i.imgur.com/spJPhfs.png)

### 2. Specify three technical main characteristics of an industrial robot as its is depicted in the figure above.
![](https://i.imgur.com/fNXdbPQ.png =400x)

### 3. Cascade control
![](https://i.imgur.com/497yhZz.png)
*  position 
*  velocity
*  current
![](https://i.imgur.com/vLly7Y1.png)

### 4. Impact of factors on position error
![](https://i.imgur.com/JO03KxX.jpg =500x)


### 5. Transformation chain
* 注意標法
![](https://i.imgur.com/PeOt1II.png)

## Ex 3. Electromagnetic sensos
### 1. Fundamentals of EM
![](https://i.imgur.com/Nf5nuWZ.png)
* 左邊differential 右邊integral
![](https://i.imgur.com/3BlrYPC.png)

![](https://i.imgur.com/nIoeJEZ.png)
* Functionality: Variable resistors that use the concept of an adjustable voltage divider. Works accoding to Ohm's law. Resistance proportional to rotation angle / absolute distance.
* Purpose: it's a positioning sensor, measuring angle or distance.

![](https://i.imgur.com/NzRPnB8.png =300x)

---
### 2. Odometry
![](https://i.imgur.com/0yGPn0j.png)
* Absolute: 
1. maintains position information when power is removed, and the info is available immediately on applying power
2. System does not need to return to a calibration point

* Incremental:
1. does not report or keep track of absolute position
2. May need to move to a fixed reference point to initialize the position.

---
![](https://i.imgur.com/PesCDff.png)
![](https://i.imgur.com/loWyvkv.png)

![](https://i.imgur.com/UtANM6H.png)

---
![](https://i.imgur.com/YLhN6qp.png)
![](https://i.imgur.com/hfpdNox.png)

### 3. Optical odometry
![](https://i.imgur.com/Rjbzpd3.png)
![](https://i.imgur.com/wTKf353.png)
![](https://i.imgur.com/OTGz6qG.png)

## Ex 4. Capacitive and piezoelectric sensors in robotics
### 1. Capacitive sensor - Capacitance
![](https://i.imgur.com/vcYvLsg.png)

![](https://i.imgur.com/zw5Ku8O.png)

---

![](https://i.imgur.com/iRgBpSp.png)

### 2. Capacitive sensor - plate capacitor
![](https://i.imgur.com/zBdowPR.png)
![](https://i.imgur.com/trBD2id.png)
![](https://i.imgur.com/kHpwXJb.png)


### 3. Piezoelectric sensor - Accelerometer
![](https://i.imgur.com/ZE6WqCx.png)
![](https://i.imgur.com/CVTjlSe.png)




## Ex 5. (L6) Ultrasonic & thermoelectric
### 1. Thermal expansion
![](https://i.imgur.com/7TpjO5s.png)

![](https://i.imgur.com/f6IiWiC.png)

![](https://i.imgur.com/jQQVkxH.png =300x)

### 2. Metallic resistance thermometer (Pt)
![](https://i.imgur.com/M7nnNMc.png)

![](https://i.imgur.com/t0ugmvI.png)

---
![](https://i.imgur.com/R0kpS1C.png)

---
![](https://i.imgur.com/bJSlbEp.png)
* Relatively good linearity (change of resistance almost linear with temperature change)
* Large measuring range

### 3. Thermocouple - Seeback
![](https://i.imgur.com/NUXZQcs.png)

### 4. Ultrasonic
![](https://i.imgur.com/o0T7MTm.png)
![](https://i.imgur.com/1gz64MN.png)
![](https://i.imgur.com/MYo1V4C.png)



## Ex 6. (L7) Machine vision in robotics
### 1. Spatial filtering
![](https://i.imgur.com/EeXVCmi.png)

New value = 188+178+201+197+168

### 2. Hough
![](https://i.imgur.com/jX7afRN.png)
* Classic hough transform can detect edges or lines. It can also detect other structures (ex: circles) if their parametric equation is known.
* Principle: transform edges pixels in image space into parameters space

---
![](https://i.imgur.com/OiKQnU9.png =250x)
![](https://i.imgur.com/lQUMSDz.png)

---
![](https://i.imgur.com/2AnlvnV.png)
![](https://i.imgur.com/0oEjodh.png)

---
### 3. Canny
![](https://i.imgur.com/JVNd6Xc.png)
![](https://i.imgur.com/pDSVa2v.png)


## Ex 7. (L9) Data acquisition
### 1. Position of sensor in data acquisition system
![](https://i.imgur.com/FU1OCOr.png)

### 4. Sampling - Nyquist
![](https://i.imgur.com/ksq6ZMP.png =350x)
* The Nyquist frequency corresponds to half of the sampling frequency and must be greater than the highest frequency occurring in the signal, in order to ensure artifact-free sampling.

---

### 5. Sampling - Nyquist
![](https://i.imgur.com/kwQcZ2I.png)

---

### 6. Quantization error


![](https://i.imgur.com/j8uBCIs.png)
![](https://i.imgur.com/HgHJQEQ.png =200x)

---

### 7. DAC - binray weighted resistor
![](https://i.imgur.com/qywciB0.png)

![](https://i.imgur.com/ewIKAIg.png =500x)

---

### 8. Sensor fusion - Motivation
![](https://i.imgur.com/O2o67Bq.png)

* Sensor deprivation: breakdown of a senso element --> loss of perception on the desired object
* Limited spatial coverage: usually an individual sensor only covers a restricted region
* Limited temporal coverage: some sensors need a particular set-up time to perform & transmit measurement --> limiting the maxiimum freq of measurements
* Imprecision: the precision of a single sensor is limited
* Uncertainty: due to the sensor's limited view of the object.

---

### 9. Sensor fusion - Types
![](https://i.imgur.com/yRrwchk.png)
![](https://i.imgur.com/PsxNJKT.png)


## Ex 8. (L8) Data preprocessing - filtering & noise removal
### 1. Signal Filtering
 
![](https://i.imgur.com/zNSfuuv.png)![](https://i.imgur.com/AMeClUc.png)

---
![](https://i.imgur.com/XBHquia.png)
![](https://i.imgur.com/5sI6jwC.png)

---
![](https://i.imgur.com/O7pxQKR.png)
![](https://i.imgur.com/8UviaOu.png)

---
![](https://i.imgur.com/bTkYPFf.png)
![](https://i.imgur.com/VJ6k1QA.png)

---
![](https://i.imgur.com/Wu5C009.png =1000x)
* pros: 
1. better frequency response (narrower transition band & better attenuation, thus better approx. to ideal filter)
2. greater design flexibility 

* cons:
1. Larger phase shift
2. More complex design
3. Higher costs (and longer development time)

### 2. Noise and signal extraction

![](https://i.imgur.com/hf8f6Dk.png)
* White noise: 
:arrow_right: has a constant power spectral density (i.e., constant power spectrum). (i.e., equal amount of energy per frequency band). 
:arrow_right: Amplitude does not necessarily distributed according to a Gaussian distribution (ex: maybe uniform, or some other non-Gaussian) Could be generated using a random number generator.
* Gaussian noise: 
:arrow_right: Does not always have a constant power spectrum.
:arrow_right: the probability distribution of noise amplitude follows a Gaussian distribution.
* White Gaussian noise
has a flat power spectrum and also a Gaussian probability distribution.
![](https://i.imgur.com/vaOha2v.png =250x)

--- 
![](https://i.imgur.com/j0312HK.png)
![](https://i.imgur.com/CEALN9D.png)

---
![](https://i.imgur.com/CxbXkZn.png)
For specific types of noises:
![](https://i.imgur.com/oix5YUb.png)
In general:
* Apply filters (ex: bandpass filtering)
* lock-in amplification could improve SNR. (but require prior knowledge of the signal and its characteristics)
---

![](https://i.imgur.com/0HrQzq9.png)
:::danger

![](https://i.imgur.com/5GwOjr4.png)

:::

## Ex 9. (L10) Signal transmission

### 1. Modulation - Motivation
![](https://i.imgur.com/L2OKXOP.png)
* to adapt physical properties of msg signal optimally to the transmission channel, but without implications for the transmitted msg.

### 2. AM
![](https://i.imgur.com/Z2nTbEH.png)

---

![](https://i.imgur.com/zEd5yH4.png)

---

![](https://i.imgur.com/tqTQiPp.png)
* Synchronous modulation requires transmitter and receiver to be synchronous in phase all the time. However, it is challenging (ex: carrier signal may phase shift over time). If mismatch occurs, then the demodulated signal would be distorted.
* Solution: use asynchronous demodulation, which avoids this necessity. It simply uses envelope detector that connects the peaks of the signal and is a good approximation of the original signal.

---

![](https://i.imgur.com/JI7JsX2.png)

![](https://i.imgur.com/6pfIJlt.png =250x)

![](https://i.imgur.com/6p5Zvbn.png =300x)
![](https://i.imgur.com/iXHLHdG.png =300x)

















