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This robot has a closed linkage, and any movements of the bottom cylinder will swing the top arm. The top arm also has a linear slider that moves in and out. This arrangement reduces the load that must be carried by the bottom cylinder.

41.3 ACTUATORS

•There are a large number of power sources that may be used for robots.

•Typical actuators include,

•Pneumatics

-simple, low maintenance

-light, least expensive

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-low payload

-easy to find fault

-hard to do continuous control

•Hydraulic

-large payload

-high power/weight ratio

-leakage

-noisy

•Electrical

-feedback compatible

-computer compatible

-EOAT compatible

-quiet, clean

-low power/weight ratio

•Actuators lead to various payload capabilities as shown in the following list.

Robot	Power	Payload (k.g.)	Max. Vel. (m/s)
Asea IRB/6	Electric	6	0.75
IBM 7535	Electric	6	1.45
Cincinatti T3/726	D.C. Motor	6.4	1.0
Devilbiss	Hydraulic	6.8	1.83
Yaskawa L/10	Electric	10	1.1
Unimation 550/60	Electric	10	1.0
Hitachi	Electric	10	0.99
Unimation 5000	D.C. Motor	14	0.53
VSI Charley #6	Electric	30	1.8
GMF M/1A	Electric	46.7	0.99
Cincinatti T3/776	D.C. Motor	68	0.635
Cincinatti T3/586	Hydraulic	100	0.89

41.3.1 Modeling the Robot

• If modeling only one link in motion, the model of the robot can treat all the links as a single moving rigid body,