**4.3.2 High-level analysis of the stretch reflex by inverse simulation**

Determination of the input values for the simulator, so that the waveforms obtained with the pendulum test simulator agree as closely as possible with the waveforms for actual knee joint motion measurements, is called inverse simulation. If inverse simulation is conducted for knee joint motion measured with the pendulum test, the waveforms generated in the simulator, as already mentioned, are nearly the same as the measured waveforms for that subject. The constant and command frequency values at this time are values that characterize the individual subject. Therefore, if simulation is conducted based on these constant and command frequency values and waveforms and information for each part of the reflex arc are analyzed, a detailed understanding of the enhancement of the reflex for that subject can be gained.

The results of inverse simulation for one patient with spasticity are shown in Fig. 22. The solid line shows the result of actual measurement, and the broken line shows the result of simulation. There is extremely close agreement between the two results. Considering the sufficient accuracy of the knee joint motion measurement system and this kind of good agreement between the two with this method, the simulator is also assumed to have sufficient accuracy. At the current stage, however, some problems remain in aspects such as the accuracy of constant and command frequency values obtained from the inverse simulation and the time required to implement inverse simulation.

If these problems are solved, it is expected that the following issues can be resolved with application of inverse simulation.

Precise Measurement System

**6. Acknowledgment** 

Vol.42, pp.182-189

pp.370-392

660

No.9, pp.1564-1569

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**7. References** 

for Knee Joint Motion During the Pendulum Test Using Two Linear Accelerometers 41

As a general conclusion, we demonstrated that the developed knee joint motion measurement system does not restrict subjects' movement as other systems do, and that it has many features that other systems do not, such as simple system configuration and the

Future issues are the accumulation of clinical data using the features of this knee joint motion measurement system and quantification estimates of abnormal stretch reflexes such

We sincerely thank the late honorary professor Ken Akashi (Kawasaki Medical School and

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Kawasaki University of Medical Welfare) for his invariable support to this project.

ability to acquire large amounts of information with simple data processing.

as spasticity, rigidity, and rigidospasticity based on those data.

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Fig. 22. Result of inverse simulation of a spastic patient.

