Chapter 5 CENG Equipment Subsystems

Question 1

Topic 5: Infusion Pump

What is the first option when a patient needs medication or nutrients to be administered on a regular basis?

Answer 1

Option 1:

A nurse would have to come, measure out the volume (or dose), and inject it personally.

Question 2

Topic 5: Infusion Pump

What are the issues over time of asking a nurse to manually infusion a patient rather than using an infusion pump? (3 issues)

Answer 2

1) Boredom due to repetitive work
2) Consistency of dosage delivered
3) It occupies nurses’ time from attending to more critical tasks
4) Overlook the time for medication

Question 3

Topic 5: Infusion Pump

What is the second option when a patient needs medication or nutrients to be administered on a regular basis?

Answer 3

Option 2:

Use an infusion pump where a nurse can program the pump to deliver the medication or nutrients at a specific time, quantity and rate.

This ensures that the patients get what they need while the nurse can also focus on other more crucial tasks.

Question 4

Topic 5: Infusion Pump

What is the infusion pump used for?

Answer 4

It can be used to administer medications or nutrients in a controlled manner to patients that is pre-set by nurses.

Question 5

Topic 5: Infusion Pump

What are the advantages of infusion pump over manual administration of medication? (4 advantages)

Answer 5

1) Can deliver small volumes more accurately
2) Precise programmed flow rates
3) Precise timing intervals
4) Minimize over-infusing and under-infusing patients

This is especially useful in the treatment of very young patients
such as those infants in the neonatal intensive care unit.

Question 6

Topic 5: Infusion Pump

With infusion pumps, what does it allow the doctors to create?

Answer 6

It allow doctors to create a standard drug library that can be administered to patients for similar medical intervention.

Question 7

Topic 5: Infusion Pump

What is the purpose of microprocessor in infusion pump?

Answer 7

It monitors the input components from the buttons, optical sensor block and OEM, and triggers the corresponding output components to switch on and off accordingly.

Question 8

Topic 5: Stepper Motor and Gears

How does a stepper motor work?

Answer 8

It produces rotation through equal angles for each digital pulse supplied to input, via the different pole of the stator and rotor (electromagnet)

Question 9

Topic 5: Stepper Motor and Gears

What does a stepper motor consist of and what can it be used for?

Answer 9

1) It consists of a rotor and stator
2) It can be used for accurate angular positioning

Question 10

Topic 5: Stepper Motor and Gears

What can stepper motors be used in? (2 applications)

Answer 10

1) Medical imaging machines
2) Surgical devices

Question 11

Topic 5: Stepper Motor and Gears

What is the formula to calculate Number of steps, N?

Answer 11

N = number of stator poles x rotor pole pairs

Question 12

Topic 5: Stepper Motor and Gears

How to calculate per step angle of a motor?

Answer 12

Step angle = 360 degrees divided by number of steps (360/N)

Question 13

Topic 5: Stepper Motor and Gears

How do gears work?

Answer 13

It allow variations in the rotational speed and torque to suit the motor and load conditions

Question 14

Topic 5: Stepper Motor and Gears

What is the relationship between turning gear and torque?

Answer 14

Faster turning gear has less torque while slower turning gear has more torque.

Question 15

Topic 5: Stepper Motor and Gears

What are the advantages of a gear system? (2 advantages)

Answer 15

It gives greater accuracy and control for medical professionals.

For example, joysticks in a robotic surgical arm can be used to manoeuvre a delicate tool or an instrument with precision.

Question 16

Topic 5: Stepper Motor and Gears

What is the formula for Gear ratio to calculate number of teeth, speed and torque?

Answer 16

Gear Ratio = NL/NM = wM/wL = TL/TM

NM = number of teeth on the motor side.
NL = number of teeth on the load side.
ωM = speed of motor.
ωL = speed at load.
TM = torque of motor.
TL = torque at load.

Question 17

Topic 5: Stepper Motor and Gears

Figure 2 shows a small motor running at 200 revolution per minute (rpm) drives a paper roller. The gear on the motor has 20 teeth and the gear on the roller has 50 teeth. Calculate how fast is the roller turning?

Answer 17

Gear ratio = NL/NM = WM/WL = TL/TM

Speed at motor (WM) = 200rpm
Teeth on load (NL) = 50 teeth
Teeth on motor (NM) = 20 teeth
Speed at load (WL) = ?

NL/NM = 50/20 = 2.5
2.5 = WM/WL
WM = 200rpm
WL = 200pm/2.5 = 80rpm

Question 18

Topic 5: Stepper Motor and Driver

How does the stepper motor work when common ground red wire is not used?

Answer 18

1) The motor driver will drive current in 2 directions of the 2 magnetic coils and,
2) The first direction will induce the attraction of the rotor towards the electromagnet while,
3) The second direction will induce repulsion of the rotor magnet away from the electromagnet
4) Hence, we get a full 360 degrees rotation with 90 degrees per step

Question 19

Topic 5: Stepper Motor and Driver

What is the purpose of a stepper motor driver? (2 purpose)

Answer 19

1) To isolate the voltage from the Arduino and the stepper motor
2) To provide enough current so that it can drive the stepper motor

Question 20

Topic 5: Stepper Motor and Driver

What is the difference between analogRead() and digitalRead()?

Answer 20

The difference is that analogRead() measures the voltage of a sensor and the values vary from 0 to 1024 while digitalRead() can only read 1 or 0 or HIGH/LOW

Question 21

Topic 5: Stepper Motor and Driver

What is the process of the stepper motor, bipolar mode? (6 steps)

Answer 21

Process

1) Connect the 4 motor pins via L293 driver to 4 UNO IO ports.
2) Set these pins as output.
3) Set only 1 motor pin “HIGH” at a time.
4) Include a time delay.
5) Repeat Steps 3) and 4) until all the 4 motor pins are turned
“HIGH” sequentially.
6) Repeat Steps 3) to 5) until the motor is stopped by the user.