In this paper, we study the stability of smooth solitary waves for the
b-family of Camassa-Holm equations. We verify the stability criterion
analytically for the general case b>1 by the idea of the monotonicity of the
period function for planar Hamiltonian systems and show that the smooth
solitary waves are orbitally stable, which gives a positive answer to the open
problem proposed by Lafortune and Pelinovsky [S. Lafortune, D. E. Pelinovsky,
Stability of smooth solitary waves in the b-Camassa-Holm equation]