An endoscope comprising a plurality of concatenated joints, each actuated by a negative coefficient of expansion material such as Ti Ni, is capable of performing highly dexterous maneuvers in three dimensions without built in torsional stiffness, and thereby minimizes invasive trauma. The Ti Ni actuators are coiled around the body of opposing joint halves and are capable of maximizing large angular motion while making the joint dimensions as compact as possible. The actuators also operate with low current and thereby minimize heat dissipation.

An endoscope system includes an endoscope section having a flexible pipe insertable into a body cavity. The flexible pipe is divided into a plurality of segments. Each segment has a mechanism, e.g. shape memory alloy, for varying the flexibility of that segment. A main frame unit has a flexibility control section for controlling the flexibility variation mechanisms to correspond to one of a plurality of flexibility control patterns stored in a database.

A bending mechanism for use with a stereoscope, comprises a tubular body or linear body having a bending part, a movable part which can move in the lengthwise direction of the tubular body or linear body, two actuators formed to act in opposition to each other via the movable part, and a pull wire which extends in the lengthwise direction along the bending part. One end of the wire is fixed to one end side of the bending part and the other end of the wire is fixed to the movable part set at the other end side of the bending part. At least one of the two actuators is a shape memory element. The bending mechanism of the present invention is free from displacement of the movable part when bending action is not needed, since the two actuators are used which act in opposition to each other via the movable part, and thus, buckling of the bending part can be prevented. The simple structure of the activator unit of the present invention facilitates a reduction of the size of the structure. The stereoscope of the present invention is free from buckling of the image guide and the like, and the angle of convergence can be adjusted easily and a desired three-dimensional view can be obtained easily.

Steerable flexible elongate device comprising a flexible elongate member having proximal distal extremities and having a centrally disposed lumen extending into the distal extremity. The flexible elongate member has at least three additional lumens spaced apart circumferentially about the centrally disposed lumen and extending into the distal extremity. A stiffener element is disposed in the centrally disposed lumen and has proximal and distal extremities. Additional flexible elongate elements having a negative coefficient of expansion are disposed in each of the three additional lumens and have proximal and distal extremities. The distal extremities of the stiffener element and the additional flexible elongate elements are secured to the distal extremity of the flexible elongate member. The proximal extremities of the stiffener element and the additional flexible elongate elements are also secured relative to the distal extremity of the flexible elongate member.

A cavity insert device comprising an insert section capable of being inserted into tracts and cavities, a detection circuit for detecting conditions of components making up the device, such as an observation device formed at the distal end side of the insert section, and a fuzzy inference section for synthetically determining a plurality of information signals outputted from the detection circuit and producing control signals to control the components. The fuzzy inference section employs inference rules which are empirically considered to be desirable, and control is made by the control signals obtained with the fuzzy inference. The device is thus operated in a nearly optimum state.