**4. Conclusion**

In this study, we have introduced a simulator of our biomimetic, myoelectric prosthetic hand (*Osaka Hand*), which is operated by the subject's EMG signals, and displays in 3D a virtual arm and a prosthetic hand.

We have demonstrated that the simulator output agrees sufficiently for practical use with the finger angle of the prosthetic hand when both are given the same input.

Usefulness of the simulator has been shown in the experiments of controlling angle and stiffness of the hand. After a short period of training, subjects were able to control quite accurately the simulated hand. The precision achieved by an amputee subject was nearly as good as the precision obtained by the three non-amputee subjects, even though the amputee had not actively used his forearm muscles for four years.

This kind of powered myoelectric prostheses is not yet widely known. For example, in Japan only 350 units have been sold in the last 30 years (report of the Ministry of Health, Labour and Welfare of Japan). Our simulator could be accessible to physicians and related staff and be used to offer the opportunity to a wider group of amputees to try a myoelectrically controlled prosthesis.

The simulator can also be used for EMG signal processing and modeling. For example, when new features are added to the *Osaka Hand*, such as a new control program, the simulator can help in the design and testing phases, since it is easier and less expensive to make modifications in the model than in the actual prosthesis.

This simulator could be easily adapted to any myoelectric prosthesis, by performing just a few simple modifications on its software.
