Grooved cam is fixed.
The red sun gear rotates on a fixed bearing.
The yellow planet arm rotates on a bearing that is coaxial with the red sun gear.
The green gear sector (planet gear) has follower roller which rides in the cam groove.
If the yellow planet arm is input link rotating regularly, the red output gear can get variety in the kind of motion depending on the cam groove contour and ratio of tooth numbers.
The contour is a concentric ellipse in this video. 1 full revolution of the input corresponds 1 full revolution of the output. The output rotates back two times in a cycle.