Page 130 - Cam Design Handbook

THB5 8/15/03 1:52 PM Page 118

118 CAM DESIGN HANDBOOK

1

0

Displacement (cm)
Velocity (cm/rad)
Acceleration (cm/rad/rad)
Constraint
–1
0 45 90 135 180
Cam rotation angle (deg)
FIGURE 5.7. Cam follower displacement, velocity, and accleration obtained by spline
synthesis with adjusted knot spacing in Example 3.

TABLE 5.4 Constraints for Example 4

Cam angle Displacement Velocity Acceleration
(degrees) (cm) (cm/rad) (cm/rad/rad)
0.00 0.00 0.00 0.00
45.0 1.02 — 0.00
90.0 2.00 0.00 0.00
135.01.81 — -1.17
150.0 1.61 — —
180.0 1.00 -1.20 0.00
210.0 0.39 — —
225.00.20 — 1.20
270.0 0.00 0.00 0.00

adjust motion characteristics without violating or adding to the constraints. The greater
generality of this method can be easily grasped since nonrational B-splines are a special
case of rational B-splines. The advantage of using rational B-splines will be illustrated in
examples to follow.