2.1 Basic Concepts of Mechanisms(10) ℃rank(曲柄): a link which makes a complete revolution and is pivoted to ground Rocker(摇杆): a link which has oscillatory( back and forth) rotation and is pivoted to ground Coupler( connecting rod,连杆): a link which has complex motion and is not pivoted to ground Ground(机架): any link or links that are fixed (nonmoving) with respect to the reference frame Note that reference frame may in fact itself be in motionCrank(曲柄): a link which makes a complete revolution and is pivoted to ground. Rocker（摇杆）: a link which has oscillatory(back and forth) rotation and is pivoted to ground. Coupler(connecting rod，连杆): a link which has complex motion and is not pivoted to ground. Ground（机架）: any link or links that are fixed (nonmoving) with respect to the reference frame. ( Note that reference frame may in fact itself be in motion.) 2.1Basic Concepts of Mechanisms(10)