*2.4. Synthesis Module*

The synthesis module focuses on an approach to teaching based on four-bar linkage. It covers the main types of synthesis, i.e., path generation, rigid body motion, and function generation. Path generation synthesis establishes some precision points that must belong to the trajectory of the four-bar linkage coupler, as shown in Figure 17. Rigid body motion synthesis establishes poses in which the coupler element must be placed during its motion, as shown in Figure 18a. Function generation synthesis establishes relations between the angles of input and output that need to be satisfied as shown in Figure 18b.

For each type of synthesis problem, the interface of the program shows to the student all the graphical constructions required to solve the problem and displays all possible solutions to it, as in the case of a non-linear problem. Students can easily identify such graphical constructions as represented in their handbooks.

In the software, the student can easily change the position of any precision point or any desired posture of the output element, and the impact of this modification in the lengths of the resulting bars is shown in real time.

In any synthesis problem, some additional results are provided, such as the line envelope, cubic of stationary curvature, pivot point curve, the Ball point, or cognate mechanisms and their derivations. These are shown in Figure 19.

**Figure 17.** Path planning synthesis; multiple solutions.

**Figure 18.** Rigid body motion (**a**) and function generation (**b**) synthesis.

**Figure 19.** Line envelope, cubic of stationary curvature, pivot point curve, and Ball point. Cognates and derived translational mechanism.
