We are developing a simple movement measurement system that uses one camera and a small number of markers and the software to visualize that data and support movement analysis. Figure 1 shows the configuration of the simple movement measurement system. By using markers developed by the National Institute of Advanced Industrial Science and Technology that are much more accurate than conventional ones there is no need for major measurement equipment, such as motion capture equipment, and it is much easier to bring the equipment to take measurements. In this system, both the position and attitude of each measurement point (marker) can be measured, and the reference accuracy has a maximum position margin of error of 5 mm and a maximum attitude margin of error of 2 degrees. In addition, a handheld camera can also be used for the measurements.

Fig. 1. The configuration of the simple movement measurement system

Fig. 2. Example of a simple movement measurement

We have also further developed the above simple movement measurement system to make a prototype system that uses the body segment positions acquired from the markers to estimate and visualize the floor reaction force on the bottom of the feet when walking. Movements can be measured and the floor reaction force estimated with a low-cost configuration made up of one camera, about ten markers, and one personal computer. (Right side of Figure 2)