Robot for Working in Small-Diameter Piping

21 February, 1997

TOKYO--Toshiba Corporation today announced that it has developed the world's first miniature inspection robot able to operate inside piping with a diameter as small as one inch (25mm). The robot can undertake visual inspections and identify and collect foreign objects. It is ideal for industrial applications in such locations as electric power generation plants.

Internal inspection of pipes with a diameter of around an inch relies on disassembly, a time-intensive and often difficult task. Toshiba's new robot provides a reliable solution. Despite considerable research into small robots that can negotiate small-diameter pipes, it is the first equipped to carry out visual inspections and collect foreign bodies.

The robot is 110mm long and has an external diameter of 23mm at its widest point. It weighs 16g and can speed along at 6mm a second. The robot's vision is provided by a highly compact 1/4-inch, 410,000 pixel CCD camera mounted above its two-digit hand, a rubber flexible micro actuator (FMA). A synchronous motor provides the drive to a planetary wheel mechanism controlled by planetary reduction gears and worm gears. Maneuvering is enhanced by the robot's flexible link, a rubber tube between the front and back wheels that allows the robot to negotiate curves and bends.

The robot's movement and operation is remotely controlled by an operator. The movement of the CCD and FMA hand are coordinated by a wobble motor. A metal ring on the motor's drive shaft is covered with a wave generator, a rubber doughnut with six air chambers running along its length. Adjusting air pressure in these tubes changes the pressure exerted on the metal ring and the drive shaft, and so moves the CCD and FMA hand in concert. Once the CCD identifies a foreign object and moves to pick it up, the operator can precisely move and control the FMA. Adjusting air pressure in the three compartments of each digit provides left right and up down movement, and gives the FMA its grip.

The multiple wheels in the planetary wheel mechanism are driven by planetary reduction gears and worm gears which keep them pressed against the walls of the pipe. Use of the planetary wheel mechanism assures the drive force required for controlled ascents and descents of vertical pipes.

The new robot will be featured at Tomorrow 21, an exhibition of Toshiba's technologies at Tokyo International Forum, next to Yurakucho Station, from March 4 to 9.


1. CCD camera
A 1/4-inch CCD camera with 410,000 pixels. The ultr-compact camera has an external diameter of 7mm and is 12mm long. It transmits high resolution images to an external monitor via a cable.

2. Flexible Micro Actuator (FMA) hand
A rubber 2-digit hand with three degrees of freedom. The rubber tube is fiber-reinforced along its circumference and divided into three compartments. Movement and capture of foreign objects is controlled by pneumatic pressure supplied by external equipment.

3. Miniature pneumatic wobble motor
The drive arm of the miniature wobble motor is encased in a metal ring covered by a donut-shape rubber tube with six air chambers. Air injected into the chambers changes the pressure exerted on the metal ring, causing it to move, so controlling the oscillation of the drive arm. The drive capability is more than 10 times that of a conventional small-size motor, with a maximum output torque of 7mNm (power to hold an object of 70g in weight at a distance of 1cm).

4. Planetary wheel mechanism using planetary reduction gears and worm gears
The planetary reduction gear mechanism employs one internal gear with different tooth number is added to the planetary gear mechanism consisting of three gears around the central axis (solar axis) and surrounding internal gears in order to increase the reduction rate. Multiple wheels which mesh with the worm gears driven by this reduction gear press against the pipe wall. The strong traction allows the robot to travels inside the pipe in vertical direction.

Information in the press releases, including product prices and specifications, content of services and contact information, is current on the date of the press announcement,but is subject to change without prior notice.