Robot controllers offer a few types of interpolated motion: joint, linear, circular (and I newer models also a spline). Differences between them are quite easy to understand, but the human eye is often too slow to notice the difference during performing path on a real robot.
Robotic Painting with Light
Students at Taubmann College did a great job to visualise how different parameters change the trajectory of a robot’s motion: point-to-point (PTP), linear (LIN), circular (CIR), and spline (SPL).
They also documented differences in motion related with KUKA is a manufacturer of industrial robots and solutions for factory automation. The KUKA Robotics Corporation has 25 subsidiaries worldwide, mostly sales and service subsidiaries, including in the United States,... More C_PTP, C_DIS, C_VEL, and C_ORI approximation settings. You can see the differences in the picture below.
Light painting is a great and simple idea to help understand how the robot works. You can learn more about this experiment here.