Thesis Questions

Why did you use camera and tracker software instead of IMU if the USC FES system uses IMU?

• Objective of this study is to develop an electrode mapping

• development of another system suitable for the foot

• Main objective getting sidetracked

• First research in FES in USC for finger flexion did not develop and use an IMU system possibly for the same reason.

What did the first research use? (Flex sensor) And why will you not use a flex sensor?

• there would be no location to place the flex sensor compared to the finger na one direction only ang flexion

• the stimulation may produce dorsiflexion, eversion and inversion whose relationship will be looked into whose degrees of freedom is more than 1

Why did you decide to change carrier frequency? And how carrier frequency affects the stimulation

• the amplitude is already used to get the maximum voltage tolerable for the participant leaving the carrier frequency left

•  study by Dumalagan et al., 2023 on the parameterization of FES stimulation parameters, showed that the stimulation is affected by amplitude and carrier frequency.

•  The carrier frequency affects stimulation in a way that the lower the frequency, the stronger the stimulation and more flexion, but at the same time more discomfort, which we will consider a limit as well.

• So we will start from 10 kHz then go lower

How will you map out generated movements and change carrier frequency during testing?

• We will change carrier frequency starting from 10 kHz then gradually decrease it when there is no movement until we either get a movement or reach 1 kHz, then record that movement for that placement.

Do you have an idea for a reference line?

• we have a proposed idea where the reference line will be based on the two points, right tip of kneecap and right tip of ankle bone

• however we are open for suggestions since the criteria this reference line only satisfies is that it is based on anatomical landmarks and part of the stimulation area is covered,

How will you incorporate electrode size into your testing?

• We will apply how the study of Benatiro et al. incorporated the electrode sizing

• where they first started with the mapping and

• after finding the general area of effective stimulation that is WHEN THEY STARTED VARYING THE ELECTRODE SIZES

What electrode size will you begin with?

We will start with 40×40 mm as it is the big electrode that is readily available in the laboratory, and when enough data is gathered to make the grid smaller, only then will we experiment with other electrode sizes.

Why did you choose the right leg?

• Because it does not matter functionality-wise and results-wise,

• but we had to choose one leg on which we will be stimulating,

• its just that set-up wise it is the most easy for our proposed setup

Support your claim that it does not matter functionality wise

So here is the thing functionality-wise, the same as the arm where there is a dominant hand, that is why the study of FES for finger flexion uses the NON DOMINANT ARM. A person also has a dominant leg which they subconsciously use when they walk, climb stairs, or kick. However, in the case of walking it is not as critical whether to pick which leg since both legs are used equally when walking.

Why not both legs?

There are many reasons as to why we should never consider both:
- For safety reasons, if ever there will be a worst case scenario that will happen such as discomfort or fatigue that will occur on one leg and we still proceeded to stimulate on the other one, the participant will be in high risk since both his/her foot may not be usable.

Why did you opt to have 2 cameras?

We plan to use 2 cameras as

• we will not only check the motion of dorsiflexion but

• also other movements like inversion and eversion, which would mean another degree of freedom.

Why will you put the grid on the front-lateral side of the leg?

• Because the common peroneal nerve, which is the nerve that activates the anterior tibialis for dorsiflexion is

• located generally in that area.

• Additionally, existing FES studies for dorsiflexion also use that general area as the stimulation area.

Why do you need to consider feet hanging freely and planted?

•  the long term goal of research FES for dorsiflexion is to help minimize foot drop for stroke patients when walking

•  Walking involves the foot being on air and on the ground, so

• we want to get data that involves both positions so as to gather more information for walking.

• Even though we will not test during actual walking, we believe it is important to consider both setups.

Why do you focus on dorsiflexion?

• because our study wants to address forward movement of walking which mainly involves dorsiflexion.

• Additionally, in the first place, since foot drop is the limited ability to dorsiflex, inducing dorsiflexion would address foot drop.

Why is your setup sitting when walking requires standing?

There two main reasons:
- safety concerns, if the worst scenario happens where there will be fatigue or discomfort felt by the user, this may risk him/her to falling or losing balance.

- second is since it is an introductory research, thus we want to isolate the movement as much as possible and remove any weight bearing effects when standing

Regarding the setup of the foot hanging freely, won’t the participant feel uncomfortable over time?

• we will also make sure the place they will be sitting on will be comfortable enough for them and make sure the upper part of the leg is properly supported

• We will allow the participant to take a break when he wants to. This is to consider the participant’s well being during our testing.

How do you test the accuracy of the motion tracker?

• We will be performing a simple protractor experiment where we will be comparing the data gathered by tracker with the actual value that we could get from a protractor

If you have multiple participants, and the electrode mapping shows dramatically different amounts, how would you generate the final electrode mapping?

• Yea that would be possible since this is a research based study.

• Just like with the output of the study by Benatiro et al., where they found out the nerve position differ from person to person.

• Thus, there was no final electrode mapping common to every person

• HOWEVER, there can be generalizations to be concluded from those data.

• For instance, in the case of Benatiro et al'.’s study they found a generalization that this area is more effective on producing the flexion movement compared to others.

If you have two electrodes and there are n^2 possible locations, how would the mapping look like?

So the mapping is not one mapping but many mappings. (Show transfer method). So, imagine it just like an array where each stable location would have a list of mapping for each offset.

You did not consider whether the right or left leg is more common in foot drop?

• According to statistics, there are more cases of left-sided stroke and left-sided stroke affects the right half of the body, in other words, right-sided hemiplegia. So this would further support the decision to choose the right leg.

Why use Tracker instead of other tracking systems?

Why is your title very generic compared to your objectives? If you could make a new title now what would it be?

The nature of our study is a research based study thus the final result is not yet determined however the title gives you a general idea that our study focuses on addressing foot drop and we will use fes as an intervention.

How do you record if ever there is plantar flexion?

• That would be recorded as negative dorsiflexion and the magnitude of the percentage would still use resting and maximum dorsiflexion as reference values.

Why does your conceptual framework show a closed loop if you utilize post-processing technique?

The conceptual framework shows a closed loop because the post-processing happens also in the FES control system which is basically the computer that we will be using to control the system

Why do you include identifying effective electrode placement and size in your scope when that is your objective?

what we want to state there is that the effective electrode placement and size that will be identified is for triggering ankle dorsiflexion and not for the other movements such as inversion and eversion. Since our definition for effective is that it can generate a dorsiflexion movement with minimal eversion and inversion.

Why is there a need to record and analyze the amount of movement in percentage?

as different people can have different range of motion, the magnitude of maximum voluntary movement of one patient may not be the same magnitude of maximum with another patient.

Since we want to compare fes-induced movement with voluntary, using the maximum voluntary movement as a reference line would give more insight

How do you ensure the integrity of the testimony of the participant regarding history of injury?

We believe that the participant will gain nothing if he/she would lie to us about his/her injury. Instead it would be risky for them. Thus, as much as possible we will try to explain to them about the risks that may happen if he/she lied to us about his/her history of injury.

But if he/she still ever chooses to lie after getting performed, it is beyond us researchers already.

If after testing the tracker software, the accuracy is not enough for your study, what will you do?

 if Tracker is shown to be less accurate than needed, then we may opt to use other such as Kinovea, a free motion tracking software that can measure angular displacement