DESCRIPTION WHEEL DRIVE CONTROL DEVICE, WHEEL DRIVE CONTROL METHOD, AND PROGRAM THEREOF TECHNICAL FIELD [0001] The present invention relates to a wheel drive control device, a wheel drive control method, and a program thereof. Priority is claimed on Japanese Patent Application No. 2009-262902, filed November 18, 2009, the content of which is incorporated herein by reference. BACKGROUND ART [0002] Large cranes which hoist containers are placed at a pier along a bay, and the like. Specifically, these cranes include an RTG (Rubber Tired Gantry-crane), a container crane, an overhead crane placed on a ceiling in a factory, and the like. Regarding these cranes, a carriage called a trolley, which hoists a cargo and moves, moves on a rail provided over the cranes, and thereby transfers the cargo, such as the hoisted container, from one point to another point. For example, the cargo is transferred from a ship to a container yard on a coastal land. [0003] Thus, a trolley moves on wheel tracks, such as rails, which are provided over cranes. If functional force between the trolley wheel and the wheel contacting surface decreases, the trolley wheel spins out, in other words, the trolley wheel slips. The decrease in the frictional force between the trolley wheel and the wheel contacting surface is caused by, for example, attachment of rainwater onto the wheel contacting surface, attachment of dust and other foreign substances, and the like. If wind blows while a crane is placed outdoor, frictional force is not decreased. However, the torque of the trolley required to resist against wind force acting on cargo or the like exceeds the frictional force between the wheel and the wheel contacting surface, thereby causing the trolley wheel to spin out. [0004] Here, the cargo lifted by the crane has to be precisely unloaded at a predetermined cargo unloading place. In order to enhance the operability of transferring cargo and the like, it has been demanded to reduce spin out of wheels of a trolley. Technique of preventing trolley wheels from spinning out is disclosed in Patent Document 1. CITATION LIST [Patent Document] [0005] [Patent Document 1 ] Japanese Unexamined Patent Application, First Publication No. 2006-76685 DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention [0006] Regarding the aforementioned technique disclosed in Patent Document 1, however, it is necessary to provide many sensors and to perform complicated calculations in order to prevent the trolley wheels from spinning out. [0007] For the above reason, an object of the present invention is to provide a wheel drive control device, a wheel drive control method, and a program thereof, which can reduce spin out of wheels of a crane device, such as a trolley. Means for Solving the Problems [0008] A wheel drive control device of the present invention is a wheel drive control device that performs drive control on a wheel of a crane device that moves while supporting a hoisting unit. The wheel drive control device includes: a load detector configured to detect load of a cargo hoisted by the hoisting unit; and a torque limit value determining unit configured to increase, according to the load of the cargo, a limit value of torque at the time of acceleration of the crane device up to the maximum limit value of the torque, and determine a limit value of the torque associated with the load. [0009] The torque limit value determining unit may be configured to decrease, according to the load of the cargo, a limit value of the torque at the time of deceleration of the crane device down to the minimum limit value of the torque, and determines a limit value of the torque associated with the load. [0010] The limit value of the torque is a value for each load of the cargo which is calculated by a formula of load per wheelxa coefficient of function between the wheel and a wheel contacting surface )μx(wheel radius D/reduction ratio)xa margin a (a