Du van Re  Eng.

                                    Mechanical Engineering Faculty – HCMC University of Technology. 

                                                                                                                                          ( Vietnamese)


            Today hydraulic transmission is widely applied into human life. For Medicine there are artificial hearts, valves, veins; but the tradition hydraulic actuators can’t be used to insert into human body because of their disadvantages. This lecture introduces a new hydraulic actuator which could be named: “ Bionics hydraulic actuator”. It has structure and operating method different from the tradition ones. With many advantage facts so that it can be insert into human body for the purpose of action recovering. Combing with the effects of modern biotechnology we could make a Biohydraulic actuator which operates with Biofluid. 


            Today, many sceince achievment had be used to replace human body parts. In hydraulic field, many artificial parts such as heart, valve,vein, . . . had be made, only traditional actuators not be used replace for human muscles ( Fig. 1). Because of their characters as below, they could not be insert in to human body:

            - In construction: there are many relation movement parts.

            - Their own action and activation methodes not convenion.

            - Their materials strange with human body.

            - Fluid may damage to human health.

Figure. 1. Traditional hydraulic actuator. 

            Addition to overcome disavantages of the traditional hydraulic actuator, we can use a new construction one based on muscle action and its name could be called: “ Bionics Hydraulic actuator” ( Fig. 2) 

Figure. 2. Bionics hydraulic actuator. 

2. PRINCIPLE  ACTION: ( Fig. 3) 

Figure. 3. Principle action of Bionics hydraulic actuator. 

            Principle action of the Bionics hydraulic actuator is based on the deformation of a tube becomes a sphere when charge it by compressed fluid. When it changes from a tube to a shere, the deformations in different directions are not the same ( anisotropic deforomation), the generatrix of the tube ( non-elongation) become the meridian of the shere; the directrix of the tube ( soft, large elongation) become the latitude of the shere. This deformation makes the actuator expand in two directions and shortening in other direction similar a muscle in the action.         


          Today there is not still  any material may satify for the action of the actuator ( anisotropic deformation with large ratio), the construction of atuator  could be composite material with two mainly compositions:        


3.1. Strengthen composition:

            They are high strength strings knitted to a net. There are many kind of net, the bellow one ( Fig. 4) is a kind of net could sastify for the action of the actuator.


3.2. Seal composition:

            This material must have properties: large enlongation, large elasticity, covenience toughen, seal ability. This composition may be monolayer or multilayer, may be fixed or not  with the strength composition 

Figure. 4. One kind of net ( strengthen composition) 


            In the construction of the actuator there is only one chamber and only one element. The Atuator could act with directional methodes: 

4.1. Charge and discharge at one port: ( Fig. 3)

            - This methode is easy to performance with simply construction.

            - Could not apply in case of bio-fluid using, Because it can cause fluid spoiling. 

4.2. Charge at inlet port and Discharge at outlet port: (Fig. 5)

            Fluid is continously charged through inlet port, the action of the actuator is corresponding to the state of one restrict part at outlet port ( by using another kind of Bionics-hydraulic actuator which do not cause damage to fluid. (Fig. 6))  

                 Figure. 5. Directional methode: Charge inlet port and discharge outlet port.


Figure. 6. Torus bionics hydraulic actuator.



            With a lot of advancements in bio-engineering now, I think that we can manufacture the Bionics hydraulic actuator from bio-materials. In addition to the action way and directional methode, the Bionics hydraulic actuator could be used to insert onto human body ( May use bio fluid to performance).        


            The problem is new and strange, but its action theory had been performanced and immproved, just exist the application. Through this report, I wish the proplem will iterrest to many person and it could be applied on the highest effects in the nearness.  


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