(1980-1986). Because only the tips of the endoscopes currently being used can bend in two directions with conduit wires, the operation of inserting them into the stomach and colon is difficult, and requires a high degree of technique. For this reason, as one of the fields of utilization for serpentine robots, we have developed an active endoscope which can actively bend in order to conduct examinations for medical therapy and for inspecting the interior of complex machinery.

In 1980-81, we made the prototype of the ELASTOR shown in Photo. 1. This is a device in which each segment is composed of coil springs, and three conduit wires can remotely bend these. The eight sections are driven by a total of 24 wires. The segments are flexible, and when they contact obstacles, because the segments deform without damaging what they touch, there is a high degree of safety. A force compensation spring mechanism is installed in the drive system of the wire to reduce the tensile force of the wires.

In order to be able to make it more compacts, since 1983 we have developed a micro actuator, which utilizes a shape memory, alloy (SMA). We introduced a method of configuration called a x-array in which TiNi

wires, which do not have that low of an electrical resistance value, were connected mechanically in parallel and electrically in series as shown in Fig. 1 in order to conduct Joule heating by a high voltage low current power source. We introduced a servo-control system based on the measurement of electric resistance, and we studied the optimum heat processing method, and then built the model in shown Fig.2 and Photo.2 in 1986. The diameter is 13 mm; the entire length is 250 mm; and it has 5 units. By giving the bending angle command to the lead segment, as shown in Fig.3, and transmitting that to the later segments synchronously with the insertion speed, the device can be inserted smoothly into a winding pathway. The system configuration is indicated in Fig. 3.

References:

1. Shigeo Hirose; Biologically Inspired Robots (Snake-like Locomotor and Manipulator), Oxford University Press ,, , pp. (1993)
2. Shigeo Hirose, Takashi Kado, Yoji Umetani; Tensor Actuated Elastic Manipulator, Proc. 6th IFToMM World Congress, New Delhi ,2, , pp.978-981 (1983)
3. Shigeo Hirose, Koji Ikuta, Yoji Umetani; A New Design Method of Servo-Actuators Based on the Shape Memory Effect, Proc. ROMANSY Symp '84., Udine, Italy, Kogan Page, London ,, , pp.339-349 (1984)
4. Shigeo Hirose, Koji Ikuta, Masahiro Tsukamoto, Koichi Sato, Yoji Umetani; Several Considerations on Design of SMA Actuator, Proc. Int. Conf. on Martensitic Transformation ,, , pp.1047-1052 (1986)
5. Shigeo Hirose, Koji Ikuta, Masahiro Tsukamoto, Koichi Sato; Considerations on Design of the Actuator Based on the Shape Memory Effect, Proc. 7th IFToMM World Cong., Sevilla, Spain ,, , pp.1549-1556 (1987)
6. Koji Ikuta, Masahiro Tsukamoto, Shigeo Hirose; Shape Memory Alloy Servo Actuator System with Electric Resistance Feedback, Proc. IEEE Int. Conf. on Robotics and Automation ,, , pp.427-430 (1988)
7. Shigeo Hirose, Koji Ikuta, Yoji Umetani; Development of Shape-Memory Alloy Actuators. Performance Assessment and Introduction of a New Composing Approach, Advanced Robotics ,3, 1, pp.3-16 (1989)
8. Shigeo Hirose, Koji Ikuta, Koichi Sato; Development of Shape Memory Alloy Actuator. Improvement of Output Performance by the Introduction of a σ-Mechanism, Advanced Robotics ,3, 2, pp.89-108 (1989)
9. Shigeo Hirose, Koji Ikuta, Masahiro Tsukamoto; Development of Shape Memory Alloy Actuator. Measurement of Material Characteristics and Development of Active Endoscopes, Advanced Robotics ,4, 1, pp.3-27 (1990)
10. Koji Ikuta, Masahiko Tsukamoto, Shigeo Hirose; Mathematical Model and Experimental Verification of Shape Memory Alloy for Designing Micro Actuator, Proc. IEEE Micro Electro Mechanical Systems ,, , pp.103-107 (1991)