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multiaxis motion - 16.23

16.6SUMMARY

Axis limits can be used to calculate motion profiles.

Trapezoidal and smooth motion profiles were presented.

Motion profiles can be used to generate setpoint tables.

Values from the setpoints can then be output by a scheduler to drive an axis.

16.7PRACTICE PROBLEMS

1.a) Develop a motion profile for a joint that moves from -100 degrees to 100 degrees with a maximum velocity of 20 deg/s and a maximum acceleration of 100deg/s/s. b) Develop a setpoint table that has values for positions every 0.5 seconds for the entire motion.

2.Consider a basic servo controller with encoder feedback. The motor will start at a position count of 100, and end the motion at a count of 3000. The motion is to have a maximum acceleration of 300 counts/s/s, and a maximum velocity of 100 counts/s. Find a motion profile that satisfies these constraints. Generate a table of setpoints for the desired position every 2 seconds.

multiaxis motion - 16.24

16.8 PRACTICE PROBLEM SOLUTIONS

1.

Given,

 

deg

 

 

deg

 

ω max

= 20

α max =

100

∆θ = 100 – ( –100) = 200°

--------

--------

 

 

s

 

 

s

2

 

 

 

 

 

 

 

 

The motion times can be calculated.

 

 

 

ω

 

 

20

deg

 

 

 

 

 

 

tacc

= tdec

=

max

=

--------s

= 0.2s

 

 

 

-----------α

max

100------------------deg

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

s2

 

 

 

 

 

 

 

∆θ

ω

max tacc

200deg – 20

deg

0.2s

 

tmax

--------

s

= 9.8s

= ---------------------------------

ω

max

 

= --------------------------------------------------

 

20

deg

 

 

 

 

 

 

 

 

 

 

--------s

 

 

 

 

ttotal

= tacc + tmax + tdec = 0.2s + 9.8s + 0.2s

= 10.2s

t (s)

angle

 

(deg)

0.0-100

0.5-92

1.0-82

1.5-72

2.0-62

2.5-52

3.0-42

3.5-32

4.0-22

4.5-12

5.0-2

5.58

6.018

6.528

7.038

7.548

8.058

8.568

9.078

9.588

10.098

10.5100

11.0100

θ

 

=

1

deg

( 0.2s)

2

+ 20

deg

( 0.5s – 0.2s) – 100deg

0.5s

--100

--------

 

--------

 

 

2

s

2

 

 

 

 

 

 

s

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

θ 0.5s

= –92deg

 

 

 

 

 

 

θ 1.0s

= θ

 

 

 

deg

( 0.5s)

 

 

 

0.5s + 20

--------

= – 92deg + 10deg

 

s

multiaxis motion - 16.25

2.

t

counts

(s)

 

 

 

0

100

2

283

4

483

6

683

8

883

10

1083

12

1283

14

1483

16

1683

18

1883

20

2083

22

2283

24

2483

26

2683

28

2883

303000

16.9ASSIGNMENT PROBLEMS

1.Find a smooth path for a robot joint that will turn from θ = 75° to θ = -35° in 10 seconds. Do this by developing an equation then calculating points every 1.0 seconds along the path for a total motion time of 10 seconds. Do not assume a maximum velocity.

2.Paths are to be planned for a three axis motion controller. Each of the joints has a maximum velocity of 20 deg/s, and a maximum acceleration of 30 deg/s/s. Assuming all of the joints start at an angle of 0 degrees. Joints 1, 2 and 3 move to 40 deg, 100deg and -50deg respectively. Develop the motion profiles assuming,

a)slew motion

b)interpolated motion

3.Develop a smooth velocity profile for moving a cutting tool that starts at 1000 inches and moves to -1000 inches. The maximum velocity is 100 in/s and the maximum acceleration is 50in/s/s.

4.An axis has a maximum velocity of 2.0 rad/s and a maximum acceleration/deceleration of 0.5 rad/s^2. Sketch a trapezoidal motion profile and find the motion time for a -4.0 rad motion.

5.An axis has a maximum velocity of 5m/s and an acceleration/deceleration time of 1s. Sketch a trapezoidal motion profile and find the motion time for a 25m motion.

6.Develop a smooth velocity profile for moving a cutting tool that starts at 1000 inches and

multiaxis motion - 16.26

moves to -1000 inches. The maximum velocity is 100 in/s and the maximum acceleration is 50in/s/s.

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