i am a student who is building a pneumatic robot that bowls (like a cricket bowler if you follow the recent sport events). the compressor fills a chamber with air which causes a piston to move foward and ultimately propels an attached arm foward. i am interested in developing the difference equations for the piston arrangment or the fluid mechanics of the bowler. can any one help. this is more fluid mechanics. the energy required to push the mass acting and to propel the arm foward. the arm is pivted at a point and the piston/cylinder is inclined.