An apparatus comprises a continuously flexible device and an actuation mechanism that acts to bend and straighten the continuously flexible device. The apparatus also includes a sensor apparatus that generates bend information about at least a portion of the continuously flexible device. The apparatus also includes an electronic data processor. The electronic data processor generates (i) external force information about at least one of a magnitude or a direction of an external force applied to the continuously flexible device, or (ii) both the external force information and internal force information about a bending force applied to the continuously flexible device by the actuation mechanism from (a) the generated bend information and (b) information representing at least one mechanical property of the continuously flexible device.
