Archives of Design Research

Segway is originally designed for a standing ride. It has a simple structure with a T-shaped handle installed on the foot plate and two wheels (Figure 3).

As soon as the user turns it on and gets on its foot plate, a gyro sensor installed on the foot plate recognizes the center of the user’s weight to keep a balance and induces the user to maintain a stable posture readily. It is operated by the shifts of the center of the user’s weight. If the users move their center of gravity forward, it goes forward whereas if they move back to their original position, it stops. When the center of gravity moves backward, it goes back, too. To change the direction, they can turn the lever near the handle (Figure 4).

Figure 3 The Segway used on the experiment

Figure 4 The lever to change the direction

According to the result of driving in the standing position, its self-balance function makes it operate in a natural balance as if it were a part of the user without causing any

instability resulted from the two wheels (Figure 5).

Figure 6 shows the stool on the foot plate. The gyro sensor recognizes the center of the user’s weight in the sitting position and keeps the balance. Since the sitting lowers the center of gravity, it can not only maintain a more stable condition but also respond to subtle movements more sensitively than the standing ride.

Figure 5 Standing-position drive

Figure 6 Sitting-position drive

Chair unit (1) made of reinforced corrugated cardboard (Figure 7) was set on the foot plate of the Segway (Figure 8).

Figure 7 The chair unit (1)

Although the model with chair unit (1) has the Segway’s handle, this experiment supposed a model without the handle as in Figure 9. So the user did not touch anywhere near the handle to move. However, the lever placed near the handle was used to change the direction.

Figure 8 The model with chair unit (1)

Figure 9 The image from which the handle part is deleted

The size of chair unit (1) is L470 ×W460 × H680 mm, and the height of its seat is 350mm, the length is 390mm, the angle is 3°, and the angle of the backboard is 115° (Figure 10).

Figure 10 The size of chair unit (1)

Movement experiments described below were conducted with the model equipped with chair unit (1) in the Segway

(1) Pick up books and move (Table 1).

Pick up two books on the wagon and move while holding them. After putting the books on the table, try to move away from it.

(2) Move while holding a tray (Table 2).

Pick up the pot from the wagon and pour water from it to three cups on the tray. Move to the table while holding the tray, and then put the tray on the table. Again, hold the tray lying on the table and move to the wagon to place the tray on it again.

(3) Open the door with a door closer and go out (Table 3).

Approach to the door with the door closer. Open the door and push it to go out.

(4) Use the elevator (Table 4).

Push the button at the entrance of the elevator and go into it. Press the button to reach the destination and change the direction up to 180°. Get off the elevator.

Regarding the movement experiments

In (1), it made a slight movement due to the change of the central axis of gravity resulted from the addition of two books. However, if the user is familiar with the sense of balance in the Segway, he may be able to keep the balance changing the center of gravity naturally.

In (2), there was no noticeable problem while the user moved holding the tray after pouring water from the pot to the cups in the static state.

In (3), the user was able to go forward pushing through the door with his hand using the Segway’s force to move forward against that from the door going back to the original position for the door closer.

In (4), the user changed the direction up to 180° in the elevator with rather a small radius of rotation and then got off it to the forward direction. And it was easily done.

	Pick up the books lying on the wagon in the static state.
	There was a slight movement for the weight of the books, but he could recover the balance again naturally.
	(After changing the direction with the lever of the handle), he advanced forward holding the books with his both hands.
	Approach to the table and stop it to put the books on the table. *It slightly moved forward since the center of gravity went forward.
	Move backward.

	Pour water from the pot into the three cups on the tray in the static state.
	Pick up the tray lying on the wagon in the static state. Hold the tray with both hands and move to the table.
	After approaching to the table and stopping it, hold the tray with one hand and put it down on the table. * It slightly moved forward since the center of gravity went forward.
	(After changing the direction with the lever of the handle,) Hold the tray with both hands and move to the wagon.
	Come back to the wagon and stop it to place the tray on the wagon.

	Approach to the door.
	Open the door with the operation of the lever on the door and advance forward.
	Push the door further and move forward.
	Pass through the door while pushing it.
	Go out while pushing the door.

	Push the button at the entrance of the elevator
	Go into the elevator.
	Press the button to reach the destination in the elevator.
	(With the lever of the handle), change the direction up to 180°.
	Get off the elevator.

Discussion with the users was conducted in a way to exchange opinions with two actual wheelchair users (Table 5) while watching the videos recoding movement experiments, (1) through (4) (Figure 11).

It was promising as a device of transport operated in the sitting position to which two-wheel self-balance driving was applied. On the other hand, there also were some problems pointed out.

Wheelchair users with cervical cord damage need not just a seat but also a backboard to withstand the weight (support their upper body) in order to maintain a stable sitting position. However, the load was mostly applied to the seat in the case of chair unit (1).

Figure 11 Discussion with the wheelchair users

Chair unit (2) was designed by improving chair unit (1) (Figure 12).

Although the model with chair unit (2) has the Segway’s handle, this experiment supposed a model without the handle as in Figure 13. And the user did not touch anywhere near the handle to move. However, the lever placed near the handle was used to change the direction.

Figure 12 The improved model with chair unit (2)

Figure 13 The image from which the handle part is deleted

The location of chair unit (2) installed in the Segway is 30mm ahead of chair unit (1).

The user’s sitting position also changed from (1) to (2) as shown in Figure 14

In the case of chair unit (2), the backboard withstands the weight of user’s upper body in both the static and driving state.

Figure 14 Comparison on the changes of the sitting position

(the image from which the handle part is deleted)

The angle of the seat of chair unit (2) changed from 3° to 6°. And the foot plate and armrests were attached on it. The basic dimension of it is as shown in Figure 15.

Figure 15 The size of chair unit (2)

The three wheelchair users (Table 6) were present at the place of the experiments. While everyday movements from (1) to (3) were being conducted, we exchanged our opinions for comparative analysis.

In terms of study methods, the wheelchair user conducted everyday movements in the place supposed as indoors with the experimental model for reproduction. The procedures of the movement experiments are as written below.

Wheelchair	The experimental model
Approach to the bed.	Approach to the bed.
Approach to the bed across the room. Put on the brake and be ready to move to the bed.	Approach to the bed in a parallel way. Move to the bed in the static state.
Move backward from the bed. There was not enough space to move back and change the direction.	Move backward from the bed. No need for backing.

Wheelchair	The experimental model
Approach to the desk. Approach to it while facing it.	Approach to the desk. Approach to it while facing it.
Put on the brake to stop it at the spot that seems easy to work in.	Stop it at the spot seemingly easy to work in. Make it pause or stop.
Drive back from the desk. Move backward and change the direction.	Drive back from the desk. It was possible to rotate it at the spot and keep moving.

Wheelchair	The experimental model
Approach to the kitchen counter while facing it.	Approach to the kitchen counter while facing it.
Put on the brake at the spot seemingly easy to work in and begin to cook.	Stop it at the spot seemingly easy to work in. Make it pause or stop.
Move to the sink. Release the brake and move while relying on the table with hands.	Move to the sink. After setting it on, change the direction and move.
Approach to the sink while facing it.	Approach to the sink while facing it.
Put on the brake and work.	Press pause while it is still on and keep working.
Drive back from the kitchen counter. Release the brake and move backward. Change the direction and keep moving.	Drive back from the kitchen counter. Set it on operation from pause. Change the direction and move backward.

(1)Moving to the bed (Table 7)

Approach to the bed. Approach to the side of it to choose a spot to move to a bed. Try to move back from the bed.

(2) Deskwork (Table 8)

Approach to the desk while facing it. Choose a spot seemingly easy to work in. Try to move backward from the desk.

(3) At the kitchen (Table 9)

Approach to the kitchen counter while facing it. Move to the sink from the cooking counter. Try to move backward from the kitchen.

This study has found the following results based on the movement experiments on chair unit (1) and (2) and discussion with the users.

(1) It responded to subtle changes of the center of gravity in the stable sitting position. The users could drive it only with forward or backward movements of their one hand.

(2) For changing the direction, the manual wheelchair needed more space around to operate the drive wheels. However, it was not necessary for the experimental model.

(3) It was possible to approach to the bed in a parallel way. Once the armrests were folded, the users could move their body to the side to transfer to the bed.

(4) In terms of its operational functions, it needs three switches for ‘operation’, ‘pause’, and ‘stop’. The ‘pause’ switch is for users to stop temporarily on the way to their destination and do a certain intended act before they keep moving to it. This function can be directly connected to ‘operation’ while the user is sitting on it.

(5) ‘Operation’ and ‘pause’ need a converting switch. And they should be operable even when the user’s both hands are occupied.

(6) It should be able to cope with everyday movements that are either fast or slow. For instance, when it approaches to the bed in a parallel way, the speed should be adjustable. Either fast or slow connectivity such as ‘delicacy’ should be available.

(7) User safety for the sitting drive should be ensured. An unexpected physical stop during a sitting drive may frighten the wheelchair user or even cause a dangerous situation. For such circumstances, it should be equipped with appropriate safety policies as well.

And it needs to be able to move for a while even when the power is off for the failure with systems like emergency power supply.

Figure 16 Discussion with the wheelchair users