A Randomized Controlled Clinical Study about How Seating Combined with Walking Robot Influence Hip Displacement and Ability of Social Life in Children with Cerebral Palsy GMFCS ?-?

INTERVENTION: 1:ordinary chair ;2:Seating ;3:Walking robot ;4:ordinary chair and walking robot ;5:seating and walking robot ; CONDITION: Cerebral palsy PRIMARY OUTCOME: migration index;passive range of motion of hip abduction;GMFCS;Flexion contracture of the hip;spine, pelvic tilt;pain;Limitation of sitting, standing and walking;Length of both legs;Lower limb position;ability of social life; SECONDARY OUTCOME: knee range of motion;ankle range of motion; INCLUSION CRITERIA: 1. Cerebral palsy was diagnosed; 2. Aged above 4 year; 3. GMFCS ?or GMFCS ?; 4. MP 10 % to 30%.