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TUTORIAL: ACTUATORS

Prepared by Dr. Tee Kian Sek

Department of Mechatronics and Robotics Engineering

Faculty of Electrical and Electronic Engineering

UTHM

Date: 30 March 2014

1. A compound gear train consists of the final driven wheel with 15 teeth whcik meshes

with a second wheel with 90 teeth. On the same shaft as the second wheel is a wheel

with 15 teeth. This meshes with a fourth wheel, the first driver, with 60 teeth. What is

the overall gear ratio? (the gear system is illustrated below.)

Source: W. Bolton, 2011. Mechatronics: Electronic control systems in mechanical and electrical

engineering, 5/E, Pearson.

2. Describe how the displacement of the cam follower shown below will vary with the

angle of rotation of the cam.

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Source: W. Bolton, 2011. Mechatronics: Electronic control systems in mechanical and electrical

engineering, 5/E, Pearson.

3. Design a mechanical system which can be used to:

a. Operate a sequence of micro switches in a timed sequence.

b. Move a tool at a steady rate in one direction and then quickly move it back to the

beginning of the path.

c. Transform a rotation into a linear back-and-forth movement with a simple

harmonic motion.

d. Transform a rotation through some angle into a linear displacement.

e. Transform a rotation of a shaft into rotation of another, parallel shaft some

distance away.

f. Transform a rotation of one shaft into rotation of another, close shaft which is at

right angles to it.

Source: W. Bolton, 2011. Mechatronics: Electronic control systems in mechanical and electrical

engineering, 5/E, Pearson.

4. The arm AB rotates at constant rate. B and F are sliders moving along CD and AF.

Describe the behaviours of this mechanism.

Source: W. Bolton, 2011. Mechatronics: Electronic control systems in mechanical and electrical

engineering, 5/E, Pearson.

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5. Design a motorised hoist system as illustrated below. Given:

a. Drum diameter = 0.5m and the load (maximum allowable) = 1000kg, calculate the

torque at the drum. Assume the cable is rigid.

b. If the hoist is operating at constant speed, , calculate the angular

velocity of the drum (in term of rps)

c. If the motor is chosen where its maximum speed is 1500rpm, calculate the

required gear ratio, .

d. Calculate the minimum required torque of the motor when the load is lifted at

constant speed.

e. However, the system is also designed to lift the load from rest to the speed of

in a second.

i. Given the effective moment of inertia of the load as seen by the motor via

the gear.

ii. For the ease of design, we assume the total moment if inertia as seen by

the motor via the gear is about 5 times of (i), calculate the required

accelerating torque.

iii. calculate the maximum torque to lift the load at constant velocity plus that

need to accelerate it to this velocity from the rest in a second.

Adopted from: W. Bolton, 2011. Mechatronics: Electronic control systems in mechanical and electrical

engineering, 5/E, Pearson.

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6. A single axial-motorised system is illustrated below. Given the gear ratio is 10:1, the

pitch of the ball screw is 25mm. If the stepper motor has a step angle of ,

a. Calculate the minimum stepping size (in term of angle).

b. If the table is to move 100mm to the right, calculate the total number of digital

input to the stepper motor.

c. If the worktable is to travel at constant speed, ,

i. Calculate the rate of rotation of the stepper motor,

ii. Calculate the rate of digital input required.

Note to students:

1. Refer to Source: W. Bolton, 2011. Mechatronics: Electronic control systems in

mechanical and electrical engineering, 5/E, Pearson.