  The maximum hands-off control is the optimal solution to the L0 optimal
control problem. It has the minimum support length among all feasible control
inputs. To avoid computational difficulties arising from its combinatorial
nature, the convex approximation method that replaces the L0 norm by the L1
norm in the cost function has been employed on standard. However, this
approximation method does not necessarily obtain the maximum hands-off control.
In response to this limitation, this paper newly introduces a non-convex
approximation method and formulates a class of non-convex optimal control
problems that are always equivalent to the maximum hands-off control problem.
Based on the results, this paper describes the computation method that quotes
algorithms designed for the difference of convex functions optimization.
Finally, this paper confirms the effectiveness of the non-convex approximation
method with a numerical example.
