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Research Papers

State Estimation Algorithm Based on a Disturbance Observer for a Free-Piston Engine Linear Generator

[+] Author and Article Information
Shigeaki Goto

System and Electronics Engineering
Department II,
Toyota Central R&D Labs., Inc.,
Yokomich 41-1,
Nagakute, Aichi 480-1192, Japan
e-mail: sg-goto@mosk.tytlabs.co.jp

Kazunari Moriya

System and Electronics Engineering
Department II,
Toyota Central R&D Labs., Inc.,
Yokomich 41-1,
Nagakute, Aichi 480-1192, Japan
e-mail: moriya@elmlab.tytlabs.co.jp

Hidemasa Kosaka

Mechanical Engineering Department I,
Toyota Central R&D Labs., Inc.,
Yokomich 41-1,
Nagakute, Aichi 480-1192, Japan
e-mail: h-kosaka@mosk.tytlabs.co.jp

Tomoyuki Akita

Mechanical Engineering Department I,
Toyota Central R&D Labs., Inc.,
Yokomich 41-1,
Nagakute, Aichi 480-1192, Japan
e-mail: e1572@mosk.tytlabs.co.jp

Yoshihiro Hotta

Mechanical Engineering Department I,
Toyota Central R&D Labs., Inc.,
Yokomich 41-1,
Nagakute, Aichi 480-1192, Japan
e-mail: politn@mosk.tytlabs.co.jp

Kiyomi Nakakita

Toyota Central R&D Labs., Inc.,
Yokomich 41-1,
Nagakute, Aichi 480-1192, Japan
e-mail: k-nakakita@mosk.tytlabs.co.jp

1Corresponding author.

Contributed by the Dynamic Systems Division of ASME for publication in the JOURNAL OF DYNAMIC SYSTEMS, MEASUREMENT, AND CONTROL. Manuscript received February 5, 2015; final manuscript received January 25, 2016; published online February 17, 2016. Assoc. Editor: Ryozo Nagamune.

J. Dyn. Sys., Meas., Control 138(4), 041007 (Feb 17, 2016) (10 pages) Paper No: DS-15-1059; doi: 10.1115/1.4032656 History: Received February 05, 2015; Revised January 25, 2016

In order to realize a thin, compact, efficient, and fuel-flexible power-generation system, we have been developing and investigating a free-piston engine linear generator (FPEG), which consists of a two-stroke combustion chamber and an adjustable gas spring chamber. This paper proposes a novel observer algorithm that has two advantages. First, the piston position can be interpolated at high accuracy beyond the resolution of the piston position sensor, which improves the accuracy and stability in controlling the combustion parameters, such as ignition timing and compression ratio. Second, the pressure in the gas spring chamber and the coefficient of damping (lubrication condition) are estimated simultaneously and independently. In this paper, the principle of the developed observer algorithm is described and tested through simulation and experimentation using the developed FPEG system. Based on the simulation, the output of the position sensor (resolution: 0.55 mm) was interpolated with an accuracy of ±0.1 mm. Based on the experimental results for the estimation of pressure in the gas spring chamber and the coefficient of damping, the feasibility of sensorless monitoring of the pressure in the gas spring chamber and the coefficient of damping has been verified.

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References

Figures

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Fig. 1

Schematic diagram of the developed prototype FPEG

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Fig. 2

Conceptual diagram of the linear encoder in the FPEG

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Fig. 3

Schematic diagram of a general disturbance observer

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Fig. 4

Schematic diagram of the developed observer

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Fig. 5

Sliding forces produced in the FPEG

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Fig. 6

Conceptual diagram of velocity characteristics of the sliding forces

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Fig. 7

Principle of convergence: (a) case of negative velocity and (b) case of positive velocity

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Fig. 8

Effect of the resolution margin block: (a) without the resolution margin and (b) with the resolution margin

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Fig. 12

Estimated damping loss and measured power consumption with/without oil flushing

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Fig. 11

Experimental results: (a) coefficient of damping, (b) pressure in the gas spring chamber, (c) enlarged waveform of Fig. 11(b), (d) piston position, and (e) enlarged waveform of Fig. 11(d)

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Fig. 10

Measured Pnorm waveform

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Fig. 9

Simulation results: (a) coefficient of damping, (b) pressure in the gas spring chamber, (c) piston position, and (d) enlarged waveform of Fig. 9(c)

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Fig. 13

History of the real parts of the observer poles during the experiment of generating operation

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Fig. 14

Bode plots of the transfer functions from the encoder noise to the state vector

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