1)Design a fourbar linkage with the lengths of the links to move the object in t

Question

1)Design a fourbar linkage with the lengths of the links to move the object in the following figure from position 1 to 2 using points A and B for attachment. Add a driver to limit its motion to the range of positions designed, making it a sixbar. All pivots should be on the base.

2)Design a fourbar linkage with the lengths of the links to move the object in the following figure from position 2 to 3 using points A and B for attachment. Add a driver to limit its motion to the range of positions designed, making it a sixbar. All pivots should be on the base.

3)Design a fourbar linkage with the lengths of the links to move the object in the following figure through three positions shown using points A and B for attachment. Add a driver to limit its motion to the range of positions designed, making it a sixbar. All pivots should be on the base.

Explanation / Answer

1)   When the ball is moved to a point that this mechanism can't handle, the rocker and connecting rod will be separated from the crank. However, the end of the connecting rod will try to reach to the tip of the crank. This is because the connecting rod and follower use forward kinematics to reach to the tip of the crank.

2)    The positions of the mechanism when the rocker is at a limit position are called the dead-centre positions of the four-bar. Since the rocker is moving in one direction before it reaches the limiting angle and since it moves in opposite direction after it passes this limit position, the velocity of the rocker at the limiting position must be zero. Hence, we can define a dead-center position as the position in which the rocker has instantaneously zero velocity.

3)   Extended dead-center position is when the crank and the coupler links are extended (q12=q13) and folded dead-center position is when the crank and the coupler are folded on top of each other (q13=q12+p). The oscillation angle of the rocker between the dead-center positions and measured from the extended dead-center to the folded dead-center position is called the swing angle, y. There is a corresponding crank rotation,f.

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