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Unread 04-02-2017, 23:47
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Richard Wallace Richard Wallace is offline
I live for the details.
FRC #3620 (Average Joes)
Team Role: Engineer
 
Join Date: Jan 2003
Rookie Year: 1996
Location: Southwestern Michigan
Posts: 3,679
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Re: 2.5" CIM Motor stops when climbing

Quote:
Originally Posted by serdaruluer View Post
Winch diameter is 3cm and rope diameter is 1,5cm.
Maximum robot mass = 70 kg. Maximum robot weight = 70 x 9.8 = 690 N.

Effective winch radius = (winch diameter + rope diameter) / 2 = 2.25 cm.

Winch torque needed to lift robot = 2.25 x 690 = 1550 N-cm = 15.5 N-m.

At maximum power, CIM motor torque = 1.2 N-m.

[Note: climbing is fastest at maximum power.]

Climbing time = lift height x robot weight / winch power = 1 meter x 690 N / 330 W = 2.1 sec.

Gear ratio required = 15.5 / 1.2 = 13:1.

Andymark Toughbox with 12.75:1 ratio is in stock as I type this.

All of the above calculations are simplified by neglecting fricition losses. A real robot will require more climbing time.
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Richard Wallace

Mentor since 2011 for FRC 3620 Average Joes (St. Joseph, Michigan)
Mentor 2002-10 for FRC 931 Perpetual Chaos (St. Louis, Missouri)
since 2003

I believe in intuition and inspiration. Imagination is more important than knowledge. For knowledge is limited, whereas imagination embraces the entire world, stimulating progress, giving birth to evolution. It is, strictly speaking, a real factor in scientific research.
(Cosmic Religion : With Other Opinions and Aphorisms (1931) by Albert Einstein, p. 97)

Last edited by Richard Wallace : 05-02-2017 at 07:28. Reason: Climbing time calculation
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