AnthonyFee
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Is this spec of motor good enough to run a small robot with wheels of diameter 8cm at a speed of roughly 4m\s
Is this spec of motor good enough to run a small robot with wheels of diameter 8cm at a speed of roughly 4m\s
MOTOR, STEPPER 18 DEGREE; Angle, indexing: 18°; Centres, fixing: 25mm; Diameter, external: 20mm; Length / Height, external: 17.2mm; Length, shaft: 6.2mm; Phases, number of: 4; Power consumption: 0.74W; Resistance, phase:
If not could someone please give me the correct spec. it's pretty urgent so I would really appreciate it. thanks!
MOTOR, STEPPER 18 DEGREE; Angle, indexing: 18°; Centres, fixing: 25mm; Diameter, external: 20mm; Length / Height, external: 17.2mm; Length, shaft: 6.2mm; Phases, number of: 4; Power consumption: 0.74W; Resistance, phase:
If not could someone please give me the correct spec. it's pretty urgent so I would really appreciate it. thanks!
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Well, it's kind of a hard to predict what you actually need as I don't know what size your robot will be and weather the main load (mass of the robot)on the robot is actually the motor and the batteries itself.
You can't tell without some calculations, but they need not be too difficult.
The biggest weight is apt to be the batteries, so you also have to decide what you want for range and operating time
To give yourself some margin, require that your robot be able to climb some small incline angle ( A of 10 deg for example) at some velocity (v) .
Now you can calculate the climbing power the motor must deliver:
P = sin(A)* M* g* v with P in Watts M in kg v in m/s g=9.8 m/s^2
You have to go the motor data sheets to find Torque and angular velocity:
The formula shaft power is
P = omega * T with T in N*m omega in radians/s ==> omega = 120 * Pi * (v in RPM)
http://www.318ti.org/notebook/torque/
The biggest weight is apt to be the batteries, so you also have to decide what you want for range and operating time
To give yourself some margin, require that your robot be able to climb some small incline angle ( A of 10 deg for example) at some velocity (v) .
Now you can calculate the climbing power the motor must deliver:
P = sin(A)* M* g* v with P in Watts M in kg v in m/s g=9.8 m/s^2
You have to go the motor data sheets to find Torque and angular velocity:
The formula shaft power is
P = omega * T with T in N*m omega in radians/s ==> omega = 120 * Pi * (v in RPM)
http://www.318ti.org/notebook/torque/
Here is a sample calculation for a small robot:
Let the total mass of the robot be 2 kg including 0.3 kg for a 6 volt, 1.3 AH lead acid battery which lists for $8.00
http://rocky.digikey.com/WebLib/Panasonic/Web%20data/LC-R061R3P.pdf
We require that the robot climb a 10 deg incline at 1 m/s. We can find the climbing power:
P = sin(10)* 2 kg*( 9.8 m/s^2) * ( 1 m/s)
= (0.173) * 2 * 9.8 * 1
= 3.4 watts ==> So the 0.74 W motor you mentioned in the question could not drive this robot.
The current drain from the battery at 3.4 watts is
I = P/V = 3.4/6 = 560 mA
From the battery data sheet (Duration of Discharge vs Discharge Currrent) you can see that the battery would be dead in 1 minute.
On the flat, it might last five times longer. You might decide on a bigger battery. Maybe you can cut down on the mass. Maybe 1 minute is enough.
You may have to go through several rounds of calculations like this to optimize robot performance for your specific requirements.
Let the total mass of the robot be 2 kg including 0.3 kg for a 6 volt, 1.3 AH lead acid battery which lists for $8.00
http://rocky.digikey.com/WebLib/Panasonic/Web%20data/LC-R061R3P.pdf
We require that the robot climb a 10 deg incline at 1 m/s. We can find the climbing power:
P = sin(10)* 2 kg*( 9.8 m/s^2) * ( 1 m/s)
= (0.173) * 2 * 9.8 * 1
= 3.4 watts ==> So the 0.74 W motor you mentioned in the question could not drive this robot.
The current drain from the battery at 3.4 watts is
I = P/V = 3.4/6 = 560 mA
From the battery data sheet (Duration of Discharge vs Discharge Currrent) you can see that the battery would be dead in 1 minute.
On the flat, it might last five times longer. You might decide on a bigger battery. Maybe you can cut down on the mass. Maybe 1 minute is enough.
You may have to go through several rounds of calculations like this to optimize robot performance for your specific requirements.
Horrible job reading the data sheet:
The battery will last for 1 HOUR not 1 minute.
The Y163 motor at 50 Euros would probably work. A slightly smaller (0.5A rather than 1.0A) would be fine too. But I didn't see one on that list.
The battery will last for 1 HOUR not 1 minute.
The Y163 motor at 50 Euros would probably work. A slightly smaller (0.5A rather than 1.0A) would be fine too. But I didn't see one on that list.
ASKER
http://ie.farnell.com/jsp/endecaSearch/searchPage2.jsp?Ntt=stepper+motor&Nty=1&N=401&Ntk=gensearch