# Artificial-Hand Technology--Current State of Knowledge in Designing and Forecasting Changes
## 6 Conclusions  
Artificial hands have come a long way. As a consequence of the broadening knowledge and technical capabilities, they have evolved into more complex and sophisticated purposes. Telemanipulation tasks not only started a dynamic growth of research for industry hands, but also impacted replacement passive prostheses with electric ones. The most important have been the last 40 years, when electronic parts became miniaturized, new, more efficient actuators were designed, high-resolution sensors and materials, and 3D printing technology becoming more common. All of them resulted in humanlike sizes and kinematic devices, of which the prehensile abilities allowed to execute both precise grasps from whole-hand taxonomy and some kind of inhand manipulation, reflecting human dexterity. Hence, current applications assume that humanoid robots able to replace humans at work and take care of them require the provision of versatile end effectors and prostheses replacing the functionality of amputated limbs. Hand-construction analysis, i.e., finger and joint configuration, demonstrates that robotic hands with human shape are the most desired, which the biggest group of five-fingered and 16-19 DOM devices confirms. However, looking at joint types, complete and inseparable solutions like hinge and ball joints are preferred over biomimetic ellipsoidal and saddle ones, which not only have a complicated geometry but also require special connections--ligaments--to keep parts together. Since these joints have only been used in few appliances, they still require better exploration and may be used in future devices. Although the fact that pneumatic actuators are able to drive the hand with acceptable dynamics, motor-based ones are most frequently used due to the availability of miniature units as well as broadly developed control strategies. Provided statistics presented the undeniable domination of this type of drive unit and an increasing interest in unconventional actuators. While soft  
Figure 7: Timeline of interest in artificial tactile sensing. pneumatic actuators own typical problems, i.e., need for additional equipment and power source, artificial muscles are perceived as worthy successors because of human-muscle abilities like linear contraction, volume, and being lightweight. Regrettably, current solutions using SMA, TCP, and EAP actuators exhibited some problems with control, especially with regard to time response. Because of this, new smart materials have been strongly developed so that they will supersede conventional rotating devices in the near future. Currently, the focus should be on the implementation and testing of these new types of artificial muscles, which were partly mentioned in Section 4. Applying them in robotic-hand systems would speed up the verification of their dynamic properties and the suitability for this specific system. With reference to sensory systems, the most challenging task is to replicate human skin with its sophisticated tactile sensing. Commonly used contact sensors or arrays changing resistance due to external forces allow to precisely detect a manipulating object or superficial inland moving. Multidisciplinary research on this topic proved the importance of versatile skin purposes and would lead to robotic hands with natural abilities. According to this, development of ultrastretchable polymer sensors should be continued to supercede recently used macrosensors, which are either bulky or at risk of measurement errors (estimating methods). In fact, it is difficult to distinguish one specific factor that would directly affect the entire structure because all of them are strongly correlated, but, based on the included analyses, the biggest impact on artificial hand development is from the active parts--actuators. Application of biomimetic muscles first of all leads to a reduction of construction volume, which makes the overall design more humanlike. More space in the outline of the hand allows for a larger number of and more advanced sensors.