Oct.30, 2009

Minebea Co., Ltd.

Minebea Successful in Substantially Reducing Cost of "6-Axis Force Sensors": Facilitates Low-Cost Application in "Lifestyle Support Robots"

~Aiming to increase use in nursing care robots, power-assisted systems, etc.~

Minebea Co., Ltd. ("Minebea") has been successful in substantially reducing the cost of "6-axis force sensors", which can simultaneously measure force vertically, laterally and longitudinally as well as the torque of each. Accordingly, the sales price has been lowered to 298,000 yen—less than half the original price of 698,000 yen. This includes all four types, which have force ratings of between 50 N and 1 kN, and takes effect on October 1.

"6-axis force sensors" are essential for their use in detecting the size and direction of force in a wide range of fields, including in articulated robots that perform complicated tasks and in the working parts of assembly machines for automobiles, precision devices and other products.

Minebea's "6-axis force sensors" employ its proprietary optical pickup system*1 and are equipped with an internal DSP*2 which performs high-speed processing. As a result, they are able to provide high-accuracy force detection despite their small size and weight. Based on these features, the sensors have been used in the arms and legs of bipedal humanoid robots that are currently in the R&D stage as well as in drive components such as the joints of power-assisted systems that assist in the performance of various plant operations and other such work. In the future they are likely to be used in "lifestyle support robots*3" that are expected to be in great demand in the years ahead for assisting humans in nursing care tasks and ensuring safety and security, auxiliary transport devices used in plants and other workplaces, remote manipulators and other next-generation robots that will replace humans in performing various tasks. Minebea aims to expand its sales of "6-axis force sensors" by lowering the price, to JPY200million in the year to March 2011.

"Lifestyle support robots" and other next-generation robots that will replace humans in performing various tasks are currently garnering attention for the essential role they might play in covering the labor shortage in Japan caused by the declining birthrate and growing proportion of elderly people. By 2025, the market for these robots is predicted to exceed 3 trillion yen*3. Vigorous research and development is underway, including a national project that was launched in August of this year in aims of achieving practical application. At the same time, in order to bring about practical application and full-scale popularization, it is essential to standardize the main parts and bring down the costs. Minebea's "6-axis sensors" have received high marks performance-wise, having been used by many research bodies and equipped in a number of experimental devices, but the hefty 698,000 yen price tag was an obstacle. Lowering the cost was thus a major issue. For that reason, Minebea went back and thoroughly reviewed the manufacturing process and was successful in reducing the number of processes by around 60% while maintaining the same performance and specifications. That, combined with jig improvements, parts changes and other efforts resulted in a substantial reduction in cost.

image:6-Axis Force Sensors Minebea hopes that this price change will contribute to the growth and development of the market for next-generation robots, including soon-to-be-commercialized "lifestyle support robots". Price-cutting efforts will continue in the aims of eventually bringing the price down to 100,000 yen or less per sensor.

Product Features

  1. Compact size and light weight and low price through adoption of optical sensing system
  2. Interference correction and digital filtering by high-speed internal DSP
  3. Digital signal output is universal, differential signal conforming to RS-422 interface; can be directly connected to sequencers or microcomputers without use of PC (separate power supply is required)
  4. Special PCI board available for connecting to PCs; up to 4 sensors can be connected
  5. Special PCI board enables 100 μs 6-axis data transfer


  • OPFT-50N:
    Fx=50 N, Fy=50 N, Fz=100 N, Mx=My=Mz=2.5 N·m
  • OPFT-100N:
    Fx =100 N, Fy=100 N, Fz=200 N, Mx=My=Mz=5 N·m
  • OPFT-220N:
    Fx=220 N, Fy=220 N, Fz=440 N, Mx=My=Mz=11 N·m
  • OPFT-1kN-CH-B:
    Fx=Fy=Fz=1 kN, Mx=My=Mz=30 N·m
Safe overload 150%R.O.
Ultimate overload 200%R.O.
Accuracy 5% (Incl. non linearity, hysteresis, repeatability and mutual interference)*
Safe temperature range -10°C to 60°C
Temperature effect on zero balance 0.2%R.O./°C
Temperature effect on output 0.2%R.O./°C
Dimensions Φ50×H31.5 mm(OPFT-50N, OPFT-100N, OPFT-220N)
Φ80×H28 mm(OPFT-1kN-CH-B)
Cable Standard 5 m (with RJ-45 connector)
  • *OPFT-1kN-CH-B accuracy is guaranteed to be within range of Fx=Fy=200 N, Fz=400N, Mx=My=Mz=10 N·m.

link to Product Information

*1 Optical pickup system:

A system in which a light source (light-emitting diode) and an optical receiver (divided photodiode) are arranged opposite each other in a single optical unit; light emitted from the light source is received by the optical receiver and converted into data.

*2 DSP:

Short for digital signal processor. It means a "high-speed digital signal processing microprocessor."

*3 "Lifestyle support robot":

A next-generation robot useful in daily life for performing nursing care, chores and safety/security functions. Also called a "service robot." As opposed to industrial robots used at manufacturing plants, these robots are envisioned for use in day-to-day situations in homes and public spaces, so advanced control technology is required. The Japan Robot Association's "Research on the Industrial Ripple Effect of Robot Technology and Market Analysis" published in 2008 estimates that these lifestyle support/service robots will form a 3 trillion yen plus market by 2025.

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