How To Move A rigidbody2D Box Collider up a slope?

I'm making a platformer game and I'm having trouble moving box colliders up slopes, I've been firing 2 raycasts from the bottom of the collider

here's a sample of the current script, which is a modification of one from a tutorial(which uses capsule colliders instead):

 RaycastHit2D front = Physics2D.Raycast(pos + new Vector2((box.size.x / 2) * direction, 0), Vector2.down, groundCheck, ground);
         RaycastHit2D back = Physics2D.Raycast(pos - new Vector2((box.size.x / 2) * direction, 0), Vector2.down, groundCheck, ground);
 if (front)
             {
                 slopeAngle = Vector2.Angle(front.normal, Vector2.up);
                 slopePerp = Vector2.Perpendicular(front.normal).normalized;
                 if (Mathf.Abs(back.normal.y) > 0f)
                 {
                     onSlope = true;
                 }
                 slopeAngleOld = slopeAngle;
             }
             else if (back)
             {
                 slopeAngle = Vector2.Angle(back.normal, Vector2.up);
                 slopePerp = Vector2.Perpendicular(back.normal).normalized;
                 if (Mathf.Abs(front.normal.y) < 1.0f)
                 {
                     onSlope = true;
                 }
                 slopeAngleOld = slopeAngle;
             }

the character slows down a bit before moving at normal speed