Specialized Concentrated Focused
Servo Motor
「
21
」
3.5 Calculations for Motor Selection
3.5.1 Select Motor Capacity
3.5.1.1
Confirm Driving System Structure
On most occasions, when you want to choose a motor, you need to take the structure of driving system
into consideration first. Following are some typical examples of driving system.
Ball screw
Belt drive
Gear wheel&rack,etc
Fig. 3-4 Typical examples of driving system
In addition, you need to confirm some detailed specifications of parts, such as ball screw length, guide
travel as well as belt diameter, etc.
3.5.1.2
Decide the Running mode
You need to consider following aspects to decide the motor running mode: acceleration & deceleration
time, constant speed time, time for stopping, cycle time and movement distance.
Time
Stopping
Deceleration
Constant speed
Acceleration
Cycle time
Velocity
Movement Distance
（
Shadow represents the distance that has been finished
）
Fig. 3-5 Motor Running mode
CAUTION
Running mode affects the selection of motor capacity to a great extent. If there
is no demanding requirement on the acceleration/deceleration time and stopping
time, you can make them longer as desired, therefore, a motor with relatively
small capacity can be chosen.
3.5.1.3
Calculate Load Inertia and Inertia Ratio
Inertia is the power or force used to maintain a certain motion state.
Inertia ratio (J
L
/J
M
) is the result of equivalent value of load inertia to servomotor shaft (with symbol
“J
L
”)