Downhole tool with navigation system

A downhole tool for use in a well bore comprising:

• an onboard navigation system for determining the location of the tool within the well bore;
• and
• at least one activator for activating a functional component of the tool at one or more locations within the well bore;
• wherein:
• the tool is moved along at least a partial length of the well bore via an external force;
• the functional component comprises a brake operable to slow the tool, stop the tool, release the tool, or a combination thereof;
• the brake is operable to set the tool against a casing or against an open hole wall in the well bore;
• and
• the brake comprises a dissolvable component that is dissolved to unset the tool.