A joint torque sensing technique for robots with harmonic drives

Hashimoto, Minoru; Kiyosawa, Yoshihide; Hirabayashi, Hiroyuki; Paul, Rohan

doi:10.1109/robot.1991.131728

Cited by 16 publications

(13 citation statements)

References 7 publications

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“…As illustrated in why Rosette strain gauges are necessary for the harmonic drive built in torque sensor, as explained in [9], is to compensate for the elliptical shape of the flexspline. If the strain caused by applied torque is named , while the strain caused by the elliptical shape of flexspline is called , Hashimoto et al [11] illustrated that the strain applied to strain gauges and are (1) where is assumed in [9] to be a sinusoidal modulation of . Thus, (2) In order to cancel the modulation and to detect the actual torsional strain , the information from strain gauges and is necessary.…”

Section: Built-in Torque Sensormentioning

confidence: 99%

“…In this paper we are using the idea of a built-in torque sensor for harmonic drives as first proposed by Hashimoto in 1989 [8]. This method proved to be an economical and effective way of torque sensing for harmonic drives in our setup, as claimed by Hashimoto et al [9]. In our testing station a Wheatstone bridge of four Rosette strain gauges is utilized to sense the torsional torque transmitted through the flexspline.…”

Section: Introductionmentioning

confidence: 99%

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Torque ripple and misalignment torque compensation for the built-in torque sensor of harmonic drive systems

Taghirad

Bélanger

1998

IEEE Trans. Instrum. Meas.

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A harmonic drive is a compact, lightweight, and high-ratio torque transmission device which is used in many electrically actuated robot manipulators. In this paper a builtin torque sensor for harmonic-drive systems is examined in detail. The method proposed by Hashimoto, in which strain gauges are directly mounted on the flexspline, is employed and improved in this paper. To minimize sensing inaccuracy, four Rosette strain gauges are used employing an accurate positioning method. To cancel the torque ripples, the oscillation observed on the measured torque and caused mainly by gear teeth meshing, Kalman filter estimation is used. A simple fourthorder harmonic oscillator proved to accurately model the torque ripples. Moreover, the error model is extended to incorporate any misalignment torque. By on-line implementation of the Kalman filter, it has been shown that this method is a fast and accurate way to filter torque ripples and misalignment torque. Hence, the intelligent built-in torque sensor is a viable and economical way to measure the harmonic-drive transmitted torque and to employ that for torque feedback strategies.

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Section: Built-in Torque Sensormentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Torque ripple and misalignment torque compensation for the built-in torque sensor of harmonic drive systems

Taghirad

Bélanger

1998

IEEE Trans. Instrum. Meas.

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“…Nishi, Uno and Kubo [7] introduced joint strain information in their control system to compensate the oscillation induced by the dynamic control with a feedforward compensation.…”

Section: Kf=lmentioning

confidence: 99%

The effects of joint flexibility on robot motion control based on joint torque positive feedback

Hashimoto

Horiuchi

Kiyosawa³

et al.

Proceedings. 1991 IEEE International Conference on Robotics and Automation

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When positive feedback of joint torques is applied to motion control of robot arms, the nonlinear dynamic couplings between links are canceled and a servo system with high stiffness is obtained.The problems which arise due to joint flexibility in the robot motion control based on joint torque positive feedback are discussed in this paper.We investigate the effects of joint flexibility by numerical and experimental studies on a one-link arm with a harmonic drive.It is shown that the joint flexibility destabilizes the control system with joint torque positive feedback.A low-pass filter is used in the torque feedback loop to improve the oscillation characteristics of the control scheme.

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“…We have developed a new torque sensing technique [6] [7] which employs elasticity in a harmonic drive itself t o measure joint torque. Harmonic drives are widely used as reducers of robots.…”

Section: Yoshihide Kiyosawa Hideki Hirabayashimentioning

confidence: 99%

“…Elasticity of the flexspline is utilized to get the joint torque information, since the torque at a joint axis, not an actuator axis, is transmitted through the flexspline. According to finite element analysis of the flexspline, the diaphragm part in flexspline is suitable as a place where strain gauges are bound [7] . Figure 1 …”

Section: Overview Of the Harmonic Drive With Built-in Torque Sensormentioning

confidence: 99%

Experimental study on torque control using harmonic drive built-in torque sensors

Hashimoto

Shimono

Koreyeda

et al.

Proceedings 1992 IEEE International Conference on Robotics and Automation

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We have proposed the practical torque sensor which utilizes elasticity of harmonic drives. The sensing technique provides joint torque sensing without reducing stiffness of the robot and changing the mechanical structure of the joints. I n this paper, we examine experimentally the characteristics of joint torque control using this torque sensor. Three types of torque control laws are implemented with a one-link arm to find a control method which provides excellent friction reduction and dynamic response in joint torque. The experimental results of joint torque control show that the torque sensor is very useful to compensate the nonlinear friction. Furthermore the torque control is effective to improve the accuracy of the motion control at low velocity and to suppress the vibration caused b y the joint fEexib ility .

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A joint torque sensing technique for robots with harmonic drives

Cited by 16 publications

References 7 publications

Torque ripple and misalignment torque compensation for the built-in torque sensor of harmonic drive systems

Torque ripple and misalignment torque compensation for the built-in torque sensor of harmonic drive systems

The effects of joint flexibility on robot motion control based on joint torque positive feedback

Experimental study on torque control using harmonic drive built-in torque sensors

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