Introduction to Motion Analysis

The introduction of CAD/CAM software packages has provided engineers with the ability to carry out many different aspects of the design process with a computer. If one were to design a simple item such as a chair or frame, the CAD/CAM software will allow you visualize it in Three-dimension, carry out the structural analysis with Finite Element Analysis and finally prepare a full fabrication drawing with BOM table. However, if one were to design a complex equipment with multiple dynamic parts that move in relation to each other, the motion analysis is required.

Motion analysis is critical in understanding how the equipment and its mechanism functions before it is built. Besides providing a visual simulation of the motion, the motion analysis can also enable engineers to calculate power consumption, sizing of motors, stresses due to motion and interfering parts. With such information, the engineer will have a better understanding of the mechanism and why it behaves in certain ways. The design process can be improved by modifying the current design and achieve superior design iterations using a more cost-efficient and time-saving virtual prototype.

Figure 1 – Scissor Lift


Using the example of the scissor lift, an engineer will have questions with regards to the various aspect of the design.

  • Will the mechanism move as intended? Or will the linkages and rods seize during operation?
  • How to size the hydraulic cylinder in order to achieve the required height and speed?
  • What is the relation in speed between the cylinder and scissors mechanism?
  • What are the reactions forces that are generated in the equipment? Will those forces affect the structural integrity of the equipment?
  • Is there any excessive displacement that might cause the equipment to fail?
  • Operating slope angle the equipment can work on?

Using motion analysis, results in the form of charts, reports, and animations can be used to improve and validate the scissor lift design.

Following are examples of motion animation done on a CAD/CAM package.

Figure 2 – Scissors Mechanism for 180 Degrees Rotation with use of Hydraulic Cylinder


Figure 3 – Excavator


Figure 4 – Carden Joint


Figure 5 – Bridge Layer Tank


Figure 6 – Rotational to Linear Motion Converter


If you are interested in using motion analysis for your design process or just need an animation for presentation or marketing, do contact us at



Matt Goh
NAC Consultancy Pte Ltd

Relevant article(s):
Introduction to Finite Element Analysis (FEA)
How accurate is Finite Element Analysis (FEA) Simulation?
Types of FEA Application – Part 1 Linear Static Analysis