Introduction: Seated Segway, or "eB2" (electric Biped Version 2)

Picture of Seated Segway, or "eB2"  (electric Biped Version 2)

These instructions show how to build a seat to fit onto a commercially available electric self-balancing scooter. I designed this device for myself and others who have problems with walking and standing. It takes the place of a wheelchair in a much smaller and lighter package, however, it does not provide enough control or support for someone who cannot stand or walk. While riding the eB2 I have been approached by those who could be helped by a lightweight device. I hope these instructions can help you or someone you know move about in places that require standing and walking. It is excellent for museums, parks, and stores. I have not found it useful in smaller buildings such as my house.

This device is based on a Segway Ninebot MiniPro. This is a small Segway that works exactly like the larger units that have been on the market for several years. It sells for about $600 from Amazon or Walmart. They do not call it a hoverboard, although it shares most of the features of the hoverboards on the market. It has a high quality battery system, not prone to overheating and fires (they claim UL listing).

When you are finished with the build of this device, there will be two subassemblies, and the MiniPro itself. The major subassembly is the seat structure that sits on the foot pads of the MiniPro.

There is no connection to the MiniPro, no screws or brackets to hold it in place other than your weight (explained later). There is also a fabricated steering lever that takes the place of the knee steering bar that comes with the MiniPro.

These instructions presume some woodworking skills, but no great expertise. If you have neither the tools nor the skills, find a friend who can help you cut and assemble. In that case, your tasks are likely to be the simpler ones of filing, sanding, and painting.

SAFETY CONCERNS

Before we begin with actual build instructions, I must mention the problems and dangers of this form of transport. I consider the device EXPERIMENTAL, as no systematic testing has been done to determine who could best use it, and which groups should not try to ride it. I will attempt to make clear the dangers, but you as the end user, or advisor to an end user, MUST EVALUATE THIS FOR YOUR SITUATION. I do not advise the use of this device unless the rider has the AGILITY to step on and off the unit without help. It is also important that the rider have the strength to pick up the device, as there will be times when one is confronted by stairs or even a curb without ADA ramps. A reasonable agility test might be: can one ride a bicycle, and get on and off, by oneself, with confidence? I do not want to encourage use of this by people who could lose control and be injured.

In the MiniPro instructions, the first page shows a cartoon figure with bandages, arm splint, and leg cast with crutch, to emphasize the dangers. The Segway literature suggests age limits of 16 to 60, and weight limits of 60 to 200 pounds. The mandatory training period limits top speed. Maximum speed can be set on the smart phone linked setting. Wear safety gear, particularly a helmet.

My experience is that speed is less likely to be a danger than HITTING OBSTRUCTIONS AT ANY SPEED. The design of the control electronics applies power to each wheel separately (each wheel has a half horsepower motor). While small obstructions of an inch or so can be overcome if approached slowly, larger obstructions will stop the wheels. IF ONE WHEEL IS OBSTRUCTED, THE OPPOSITE WHEEL WILL GET HIGH POWER AS THE ELECTRONICS ATTEMPT TO KEEP THE DEVICE UPRIGHT. THUS THE RIDER GETS PITCHED OFF AS THE DEVICE SPINS SIDEWAYS. I always watch the path and the wheels carefully in any environment that could stop one or both wheels.

There is another limitation of the electronics. While the MiniPro can climb or descend 15 degree slopes, the steering circuit may not turn as intended on anything more than a slight slope.

That said, it has been a great device to get me out of the house and on outings of several hours. In large public buildings it works well even in crowded hallways or elevators. As I mentioned, many have seen how easy it is to use and asked about it for themselves or impaired relatives. Knowing the risks, I believe there are people who will benefit from this. Just be careful, and understand the dangers of the various environments where you ride.

If you have no foot or leg impairments, but you would like to get around easily without being on your feet all day, this may work for you. Museum guards often ask about the device. As for (younger?) people who want excitement and a thrilling ride, I would advise looking elsewhere.

Tools
for constructing the eB2

You will need a few standard woodworking tools:

Screwdrivers, hammer, coping saw

Drill with drill bits and a countersink bit

Skilsaw or table saw

Jig saw, makes cutting the large clearance hole easier than using coping saw

Files, sandpaper, sanding block or palm sander

Optional; router with 3/8 or ½ inch round over bits, dado blade for table saw.

Materials

The most costly item is the Ninebot MiniPro Segway. This will run approximately $600 and can be sourced from Amazon or Walmart. It comes in black or white. Get this on order while you begin work on the seat and steering bar. There are less expensive hoverboards that might function adequately, however, I have no experience with them. Generally they have smaller wheels, which is not a good thing. Battery capacity may be less. You would have to design a way to steer by differential pressure on the foot pads. The MiniPro is well built, and mine has worked fine for a year and over 100 miles. There is no need to open up the MiniPro chassis which would void the warranty.

Wood parts:

Plywood; ¾ inch plywood, 24 inches by 48 inch piece will yield the various parts required (and a bit more for mistakes). Use a type like AC or Birch faced so the surface is smooth if you intend to paint it (painting seals the edges and prevents/reduces splintering). Also need 4 inches of 1 inch diameter dowel for the steering handle.

Individual parts; see drawings

1. Verticals (2), left and right vary with the clearance hole for steering lever

2. Foot block (2)

3. Seat (1)

4. Seat spacer (1)

5. Front vertical spacer (1)

6. Rear spacer (1)

7. Steering lever (1)

8. Steering handle (2)

9. Foot block shim (2)

Hardware:

5d finish nails (dozen)

Wood screws, countersink, 10 x ¾, (approximately 40), size depends on holes in angle brackets.

L brackets, 5 inches each leg (6 or 8 required), usually about $3 each

Bugle head screws, fine thread, 2 inch and 1-1/4 inch long, (couple dozen)

3/16 X 2 inch dowel screw coupler (1), (or cut the head off a 2 inch screw)

Also, a pad for the seat; minimum 14 X 7 X 1 inch, about $10

Step 1: Cutting, Sanding, Painting the EB2 Parts

Picture of  Cutting, Sanding, Painting the EB2 Parts

Take a look at the drawings for each part. These have the specs for dimensions and some notes for trimming or finishing edges. I have included some options that make aesthetic improvements, but they will increase the time it takes to build, and require more skill and tools. These options include:

1. Curved edges to the main verticals. (nice aesthetic touch)

2. More contour to the seat. (can be added later, involves carving and sanding with power tools)

3. Hiding the angle brackets behind the verticals and foot blocks. (big hassle, just paint them black)

4. Using pocket screws for the spacers between the Verticals. (some pain for small gain)

It is useful to sand, prime and paint the individual parts prior to assembly, since some areas are not easily painted later. I used a gray primer, with a satin finish black topcoat. As you select the areas of the plywood for the various parts, note the areas with the smoothest outer ply for the more exposed areas (although when in use, most parts are hidden or obscured). Some sort of sandable filler for dent or edge voids is a good idea.

If you have access to a router you may want to round the edges of the exposed corners of the verticals and the foot blocks. This can also be done with a coarse file and a sanding block.

The length of the Verticals may need to be adjusted for height of the rider. I am 5 ft. 10 in. and the length of 20 inches (front edge) works for me (inseam is 32 in.). I would adjust the length by about 1.3 in. for every 2 inches of difference in the inseam length. For example; use 18.7 inches if your inseam is 30 inches. You should be able to put your foot flat on the floor when sitting on the seat, but just barely. Remember, this dimension is just the edge of the vertical plywood. When you add the MiniPro (6.25”) and the foot block (.75) and the seat (.75) and the cushion (1 to 1.5?) the total is approximately 29.25. Test this by mocking up the height by placing books on a chair to find what height suits you.

The steering lever will need to be modified if the seat height is changed. See the drawing; the vertical dimension of the handle dimension (11 5/8 and angle 45 degree) should be reduced or increased by the change in seat height.

First cut the various parts out of the plywood. Sanding and edge treatment is best done prior to assembly. The trickiest parts are cutting the large slots to clear the steering lever, and shaping the steering bar at the corners (a jig saw will help here). The large slots do not need accuracy, but note the slots are perpendicular to the bottom cut at the foot blocks, and not parallel to the front and back edges of the verticals. The verticals are canted back by 3.5 degrees, and the top edge, where the seat mounts, is angled forward and not parallel with the bottom edge. As you will see in the photos, there is a clearance groove on the inside, at the bottom of the large slots, to allow full movement of the steering bar. The easiest way to do this is by plunge cutting a circular saw set to a depth of ½ to 5/8 inches. (I cut the groove with a router pegged by a pivot with a radius of 6 ¼ inches, using a 1 inch diameter ball end bit. Big hassle, no advantage)

Now sand and paint all parts to taste. I suggest Satin or Semi Gloss Black. Rustoleum makes a Satin Canyon Black that seems a good match for the black MiniPro plastic.

Step 2: Assembling the EB2

Picture of  Assembling the EB2

Attaching the spacers to the verticals; front and back spacers get mounted to the verticals first, the seat spacer gets screwed to the seat first, and mounted last. (on version 2, I mounted the spacers with Kreg pockets screws so no fasteners were visible, this is a hassle)

Use fine thread bugle-head screws (sheet rock screws) to attach the verticals to the spacers and the seat to the seat spacer (attach the seat to the spacer prior to attaching the spacer between verticals). Two inch screws work well, although shorter screws will be necessary to attach the seat to its spacer.

Order of assembly; if you decide to mount the angle brackets hidden behind the Verticals, then the Foot Blocks should be mounted to the Verticals prior to attaching the spacers.

Attaching the foot blocks to the verticals; Begin by using a couple of finish nails in the bottom of the foot blocks (pre-drill for nails) into the verticals (to prevent movement while attaching the L brackets). Do not put the nails in an area that will get a screw for the L brackets. Note the foot blocks are offset by 1/4 inch toward the center of the verticals. Use 3 brackets on each side if the rider is less than 160 pounds, 4 brackets if over 160. If the rider is over 200 pounds 5 L brackets may be required. There is a lot of stress on this joint. Be sure to check the screw sizes that match the holes in the angles. (I mounted the angles in slots on the back of the verticals and the bottom of the foot blocks so the hardware would not show, this is a big hassle and time-suck). Shorter screws or trimmed screws are required if you set the angles into slots. Pre-drill holes for all screws.

Use fine thread bugle-head screws (sheet rock screws) to attach the verticals to the spacers and the seat to the seat spacer (attach the seat to the spacer prior to attaching the spacer between verticals). Two inch screws work well, although shorter screws will be necessary to attach the seat to its spacer.

Step 3: Seat for the EB2

Picture of  Seat for the EB2

The simple seat version 1, has a bevel cut at the front edge. The cushion I used (for over 100 miles) is a gardeners knee pad, which is 14 X 7 X 1 inches after cutting off the handle. This works fine, however, I wanted a bit more comfort on version 2, so I added a thicker edge to the new seat and shaped it to allow a greater angle and concavity as shown in the photos (the edge thickness was increased by gluing a strip of oak to the plywood seat). This may not be necessary if one gets a thicker cushion. It may be useful to also cover the seat with fabric (future upgrade).

The Seat Spacer is mounted to the center of the bottom of the seat, centered in both directions. Use screws 1 1/4 inch long to mount the spacer to the seat.

Once you have the device fully assembled and spend some time on it, it may become clear that the location of the seat needs moving forward or backward. The screws can be removed from the Verticals, and the seat can be moved by sliding between the Verticals.

Step 4: Steering Lever for the EB2

Picture of  Steering Lever for the EB2

The steering lever is an extension of the lower half of the steering bar that comes with the MiniPro. Notice the stock steering bar has a sliding section to adjust the height of the knee pads. Just below the sliding section is a large label with a warning. Carefully remove the label to reveal the four screws holding the upper sliding part to the lower part. Replace the label a bit lower down the same surface. Remove the screws. Then remove the plastic bushing (probably orange or red), it will just pull out. Now you have the lower section that will mate to the fabricated plywood lever with 4 screws (10X3/4 inch wood countersink screws work well).

When cutting the Steering Lever shape, recall that it may need modifying if the Verticals were modified from the suggested 20 inch front edge length. The 11 5/8 length on the Lever drawing must be changed if the Vertical height has been changed.

You will need to shape the lower end of the plywood lever to fit into the triangular lower section, as shown in the photos. This can be tedious. Files, small saws, sanding will help here.

Note: It may be easier to start with 1/2 inch plywood and forget the shoulders shown in the lower left portion of the drawing. Make the vertical section on the drawing 1 3/4 wide, like the portion just above it. Much less shaping is required. Shape the part so it fits snugly into the lower section. Then install the screws (pre-drill the wood).

The handle on the end of the lever is made from a 1 inch Hardwood dowel. It can be shaped by putting a screw into the chuck of a drill and running it against sandpaper or a belt sander as shown.

Step 5: Learning to Ride the EB2

Picture of  Learning to Ride the EB2

The MiniPro is like the larger Segways, you lean forward to go forward, and lean back to slow, stop, or move backward. Steering is with the knees, which push the steering bar left or right. Your version will steer with the Steering Lever with its handle on the right side of the seat.

Once you receive the MiniPro, it would be a good idea to follow the instructions that come with it. There is a tutorial with instructions and warnings about safety, which indicates the use of safety gear including a cycling helmet. As mentioned earlier, to use the seat addition on the MiniPro one should be able to walk and stand without aid, and be able to get on and off the device without aid. Getting familiar with the MiniPro is important to safety. Again, the eB2 is an EXPERIMENTAL device. The more you know about its limitations and potential dangers, the safer you will be.

The MiniPro tutorial shows how to get on the device. Getting on is likely to feel precarious during your first attempts. Once you have learned to get on the device in its stock configuration, then practicing with the seat in place is likely to be easier.

Note that there is no connection of the eB2 structure to the MiniPro (except for the steering lever). The reason for this is that there is a deadman switch in each of the foot pads on the MiniPro. The small shim that is mounted to the foot blocks is intended to activate the deadman switch, thus allowing the MiniPro to wake up. The MiniPro is designed to switch off immediately if the rider steps off or falls off. You do not want the device running full speed and injuring others (or breaking things) once you are not controlling it.

First attempt to ride the eB2: with the seat in place (the seat foot blocks should be centered fore and aft on the foot pads) and the steering lever locked on, turn on the device. Wear your helmet. Stand in front of the device with your hands reaching behind you, with your palms on the left and right edges of the seat. Push down on the seat to engage the switches in the foot pads (you will hear the beep as the device wakes up). Now you can maneuver to sit down. As you slide your bottom onto the seat your feet will stabilize you since they are still on the ground. Then lift your feet and start your ride. The MiniPro has a speed limit for the first kilometers of use. All early rides should be on level ground or inside on a level floor. DO NOT try to sit on the eB2 without the power on, it will fall over with you on top of it.

As you learn to balance and steer, there are actions that you should be careful to avoid. I mentioned the issues in the introduction. The biggest potential danger I have encountered is when one wheel gets obstructed as against a curb, wall, or post like a chair leg. When this happens the unobstructed wheel gets full power, which is likely to spin the device as it pivots around the stopped wheel. At this point the self balancing electronics that keep the unit upright are unable to function, and you are likely to fall off. If this happens slowly you may be able to step off: if it happens quickly, or if you are backing up you are likely to lose your balance and fall. My friend broke his collarbone when one wheel of a large Segway hit an obstruction. Search Youtube for “usain segway accident” to see what happens when a rider is not watching for obstructions.

Another caution is to be aware of stairs, ledges, edges, drop-offs. Obviously very dangerous.

Another caution I suggest is never put your hands in your pockets when riding. If you were to fall, you would need your hands and arms ready to protect yourself. Also, be sure the Minipro is turned off when lifting the device, otherwise small deviations from vertical will cause the wheels to spin madly.

Once you are comfortable getting on and off the seat of the eB2 with it powered up, do some short rides without steering input. This is to familiarize yourself with the amount of lean required to get the eB2 going. It will only take small tilts of your arms or head to get it moving, it can be quite subtle. It does not take long to get the feel for forward and backward acceleration. You will find that slowing and stopping so you do not hit others or obstructions is not immediate, like a bicycle. Leaning back slows and stops you, but you will need some five or ten feet in front to of you to stop. So do not go fast when there are people about that can step into your path.

In Summary, wear a helmet, go slow, and ALWAYS watch for obstructions (anything higher than 1 inch) that could stop one or both wheels. And when around other people, go slower...........

Step 6: ADDENDUM

1. There are now multiple versions of the MiniPro Segway for sale, and it is not always clear which is the version that will work with the seat addition. Segway has released a version called MiniPro 2018, or it might be called version MiniPro 260 (as opposed to the original that might now be called MiniPro 320). The newer one has a slightly smaller battery, 260 watthour rather than 310. If the device is claiming 12.6 mile range rather than the original 14 or 15 mile range it is the newer unit. It may sell for less than the original, I have seen it for $50 less than the original. Prices as of December 2017 bounce around $500 to $600.

The lower range is really not an issue. I have ridden mine (15 mile range) for 5 hours in a museum without running down the battery below 60%. I have never run out of juice. I think 12.6 mile range would not be a problem if that is what is available, either variant would be fine.

There is a less costly variant that I have not tested. This is called MiniLite. It sells for around $350. I cannot recommend this unit for the addition for a seat. I don't know if the dimensions will accommodate the seat as it is designed, and I do not know if the steering handle will work with the MiniLite. If you have one and try the seat addition, please make a comment as to its utility.

Comments

kksjunior (author)2017-10-04

Great idea! i will definitely vote for this.

Swansong (author)2017-10-04

That would be really fun to ride around! Neat idea :)

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