The latest wave of home automation technologies succeed at making life easier. Not only are we experiencing (yet another) digital revolution with pictures, music and video, we are also entering the age of robotics. Take Japan, for example. Humanoid robots such as the Honda Asimo are under development. Asimo and robots like him will reduce the labor shortage caused by Japan’s declining population. In other countries, the idea of owning a two-legged robot is quite far-fetched at this time. However, vacuum, floor cleaning and pool cleaning robots are becoming fairly common. Another domestic chore taken-on by the consumer robotics industry is lawn mowing. The KA Lawnbott LB3500 is the newest addition to the Lawnbott line-up.
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Most people have not heard of a robotic lawn mower. The reaction when first seeing one is as expected: “What is that on the lawn? Is it a remote control car?” They back up; they get out of their car for a closer look. After closer inspection, they see it’s a lawn mower. With a look of amazement and a mouth open, the first thing they want to know is “How does it work?” and “How does it know where to go?”
These are good questions. I’m sure by now you have a vision of this lawn mower taking off into the street or mowing your neighbor’s lawn. The good news is, the manufacturer has thought through these issues.
Navigation is actually quite simple. A thin insulated wire is staked all around the property. There is an RF signal in the wire and a sensor in the robot. When the robot encounters the wire, it simply backs-up and goes in another direction. Lawnbott uses the wire to navigate back to the recharging station. Lawnbott is self-recharging.
The Lawnbott uses a random pattern to mow. This may seem unusual, only because we are accustomed to mowing in straight lines for our own benefit. That is – to get out of the sun as fast as we can. Mowing in a random pattern assures the best grass health and the best looking lawn.
Lawnbott does not wait until the grass is long to mow it. Instead, Lawnbott recharges itself in its charging base. It can be set to come out as often as needed to keep the lawn mowed or it can be constrained to work in one or two time windows each day on days it is programmed to mow. Lawnbott keeps up with mowing, so the lawn always looks its best.
Lawnbott costs less than a lawn service while keeping the lawn at a neat and optimal grass height. Lawnbott owners save up to $12,000 over the 8-10 year life of the Lawnbott, vs. paying a service to mow.
Lawnbott LB3500 Installation
Installation of the LB3500 is straightforward. The first step is to survey the property and decide where to lay the wire. The wire needs to be layed in a continuous loop around the property. The minimum distance of any parallel lengths is 70 cm (28 inches). Any closer than that and the RF signal begins to cancel. As long as a continuous loop of wire is layed, the robot finds its way around the property completely autonomously. Generally, it can drive over sidewalks or driveways, if necessary, to reach an area of grass. Every lawn is different, but almost always, a continuous loop can be layed.
The LB3500 has a floating shell that detects collisions in all directions. It is not necessary to place the wire around every tree. Although, if you want to avoid scratches on the Lawnbott shell, it would be wise to do this. Trees or planting areas in the middle of the yard are easily wired out. Whenever the wire is placed very close together (touching in parallel but not crossing) and in a counter-clockwise manner, the RF signal cancels and the signal becomes invisible to the robot. This is illustrated in Figures 1 and 2:
The wire is staked down with plastic pegs. This holds the wire to the surface of the ground. There is no need to bury the wire, because the grass completely absorbs both the wire and the pegs within a few weeks. Pegs can be placed up to 2 Â½ feet apart, if the grass is sparse. If the grass is thick or spongy, pegs should be placed closer together (1-2 feet apart). Some people prefer to bury the wire anyway. The wire can be buried up to 4″ deep. A signal booster is available which improves signal strength when the wire is buried or is longer than 2000 ft.
The wire connects to two quick-connect terminals in the charging base. Proper orientation of the wire is the only tricky thing about installation. The Lawnbott follows the wire back to the base. Figure 3 illustrates proper wire connection and base orientation.
Once the wire is installed, the property should be surveyed for any holes or obstructions that could be a problem for the Lawnbott. Bumpy lawns are generally not a problem, but if there are holes larger than the Lawnbott’s front tires, they will need to be filled and seeded. It’s okay if you don’t find all the holes. Lawnbott will find them for you within the first few weeks of use. If Lawnbott is stuck in a hole, it will stop and beep quietly until you press the start button again. Then you will fill the hole and Lawnbott will not get stuck again in that spot. Also difficult for the Lawnbott are exposed tree roots. These should be wired out. In addition, Lawnbott may become stuck on concrete or landscaping that is a few inches high. That is, if the concrete is shorter than the shell, Lawnbott cannot detect it as an obstruction. Almost always, these obstructions can be wired out or recessed further into the ground.
Setting up the LB3500 with the menus is also very easy. Up to three zones can be programmed. The LB3500 finds a new zone by driving a programmed amount of time to the zone it will mow. The LB3500’s advanced zone control lets the user select the shortest path to the next zone. In addition to zone programming, the menus allow selection of which days of the week to mow, and for up to two work times per day. We like to program our Lawnbott to be out the whole day and let the software decide when to come and go based on battery life or adaptive technology (discussed later). However, some people want their Lawnbott to mow at specific times. The menus are flexible enough to please every user.
Lawnbott LB3500 Robot Lawn Mower â€“ Key Features
The LB3500 is very sophisticated machine. Under the hood, it has two drive motors for the two rear wheels and a single, adjustable-height blade motor for the blade. The two front wheels pivot 360 degrees for zero-turn operation. The rotary blade is light-weight metal in a four-point shape with four razor sharp edges. The first edge cuts the grass blade and the three additional edges chop the grass into fine bits at over 3000 RPM.
LB3500 Under the Hood
The LB3500 mows a very wide area. It comes with two batteries installed and mows over one acre out of the box. Two additional batteries can be added for more coverage reaching a maximum of approximately two acres lawn area (not including the house, driveway, deck, pool, etc.).
The LB3500 is specified to mow 30 degree slopes by the manufacturer. Our experience with the LB3200 Evolution, the previous Lawnbott model, is that it met its 27 degree slope specification without a wheel upgrade. Then when we replaced the wheels with hooked wheels (metal wheels with spikes on both sides) we found it would mow up to 30 degree slopes with no problem.
Lawnbott LB3500 mows 3100 square feet per hour for up to four hours with two batteries and up to six hours with four batteries. Recharge time is approximately two-three hours. The larger the lawn, the more mowing time is required. For example, a typical lawn of 1/4 -1/3 acre requires about 12 hours of total mowing time in a week. This may seem like a lot, but remember that Lawnbott is not allowing the grass to grow long before cutting. Lawnbott keeps up with mowing. In this scenario, Lawnbott mows three times per week and four hours each time.
On the other hand, let’s say the lawn is over one acre in size. Lawnbott needs to mow much more often to ensure the lawn looks its best. In this scenario, Lawnbott would be programmed to mow every day, all day long. Since Lawnbott will need to charge for three hours every four hours, the actual mowing time is somewhat more than Â½ day, or 15 hours per day. The remaining 9 hours, Lawnbott is recharging.
These mowing time scenarios do not consider Lawnbott’s sophisticated software, which is discussed next. It is reasonable to expect Lawnbott to mow 15 hours per day every day on a one acre lot during high lawn growth periods. However, Lawnbott’s advanced software will keep Lawnbott in its charging base when the grass does not need to be mowed.
Also, you may be wondering how Lawnbott can mow such large areas without missing any spots. Statistically, Lawnbott finds every spot in the lawn, given enough time. This is another reason Lawnbott takes longer to mow than the traditional straight-line method one uses with a manual mower. The trade-off is Lawnbott keeps the lawn mowed, while the traditional method usually allows grass to over grow, resulting in long grass clippings, or even worse, large clumps of cut grass laying on the lawn.
There are four software features that optimize mowing performance. The first is variable blade speed, the second is smart spiral focused cutting, the third is adaptive technology and the fourth is advanced zone control.
Variable blade speed adjusts the speed of the blade to match the resistance of the grass. Grass that is long and thick uses more RPMs than grass that is short and sparse. Lawnbott uses variable blade speed to optimize battery energy so it will be out mowing as long as possible before recharging.
When Lawnbott encounters thick or tall grass for a longer distance, it begins a smart spiral. Lawnbott turns the blade speed to its maximum RPMs and drives in spiral pattern. This ensures Lawnbott mows large areas of thick grass without missing any spots.
The third software feature is the most sophisticated. The adaptive technology measures the amount of grass the Lawnbott is cutting. Once Lawnbott determines the entire lawn is mowed, Lawnbott will decide not to come out of the charger for one or more cycles. The adaptive technology ensures Lawnbott only mows when it needs to mow. This extends battery and mower life by reducing wear and tear.
The advanced zone control allows the LB3500 to be programmed for up to three zones. Each zone can be programmed some number of mowing cycles. A mowing cycle is one work time (there can be up to two work times per day) Lawnbott mows the first zone (the main and largest area) for the number of cycles set by the user. Then it recharges. When it comes out to mow the second zone, it drives to the rear of the charger base to find the wire. Then it drives a programmed amount of time along the wire to find the next zone. It recharges and mows the second zone as many times as programmed by the user. Then it will mow the third zone in the same way. Advanced zone control allows the user to choose the shortest path to the next zone. That is, Lawnbott can be told to turn either left or right when it comes out of the charger base.
LB3500 at the Charger
Lawnbott is designed to be kept outside. Its charging base does not require any shelter. Although Lawnbott will function in rain, it is equipped with a rain sensor, since mowing wet grass is not optimal for grass cutting. The rain sensor consists of two metal posts that stick out the back of the Lawnbott’s control panel. Rain creates a conductive path across the posts. The Lawnbott detects the conductive path and begins seeking the boundary wire to travel back to the base. The Lawnbott waits out the storm. That is, when Lawnbott is schedule to mow again, it first checks to see if it is still raining. If the storm is over, Lawnbott mows again at its scheduled time. If not, Lawnbott waits another cycle before trying again.
The rain sensor also doubles as a wet grass detector. When the grass is very wet (spongy), water will be sprayed onto the rain sensor. The water is detected as rain and Lawnbott heads back to the charging station. Thus, Lawnbott only mows in ideal grass conditions.
Even though Lawnbott can be out in the rain, it is not water proof or water tight. Lawnbott should not encounter standing water.
Generally speaking, robotic lawn mowers are safer than standard lawn mowers because there is no need to be near the robotic mower while it is working. Many standard lawn mower injuries are caused by flying debris. These injuries are eliminated with robotic mowers when used properly (that is, you watch from a distance, it mows).
In addition, the Lawnbott LB3500 has safety-touch sensors around the edges of the shell. The sensors shut the blade off when touched. Likewise, the handle bar immediately shuts the blade off when the robot mower is picked up.
The Lawnbott LB3500 has a built-in alarm. The alarm sounds whenever the mower is lifted by its handle. In addition, the user may set a four digit code. The code must be entered to activate the mower. Therefore, a thief would not be able to use the mower on a different lawn.
The Lawnbott LB3500 is equipped with Bluetooth for control from a compatible cellular telephone. There is a special program that is loaded on the cell phone. The cell phone can be used to control the lawn mower that is, turn left or right, on or off, spiral, etc. The Lawnbott does not need to be controlled since it works fully autonomously, once it is set up. The Bluetooth feature allows a user to drive the Lawnbott to a specific place in the lawn.
LB3500 Controlled by Bluetooth Phone
Lawnbott LB3500 requires very little maintenance. A thorough annual cleaning is a good idea. During use, grass may build up in the wheel wells, especially in rainy seasons or if mowing overnight. This grass should be cleaned out on a weekly basis. A winter charger kit is available for charging the Lawnbott batteries in the off season. This keeps the batteries in top condition. A convenient carrying handle is on the rear of the robot for easy maintenance.
LB3500 Carried by Handle
Lawnbott LB3500 has several upgrades available. The first is the possibility of adding two additional batteries. The second is a spiked wheel upgrade. The spiked wheels prevent wheel slippage on wet grass and also give it additional traction on hills. As mentioned above, a winter charger kit can be purchased for keeping the Lawnbott’s Lithium Ion batteries in top condition over the winter months. The transformer cover enables the power supply and signal transmitter to be mounted outside near the charging station. A signal booster is available for large or complex yards.
The LB3500 is relatively simple under the hood, considering its sophistication. The two rear wheel drive motors are completely encased, for safety and reliability. The drive motors are much more powerful than past Lawnbott models. Likewise, the blade motor power has increased since the blade size has increased from 12 inches to 14 inches in diameter from previous models. The shell and handle bar safety sensors are wired to the main controller mother board, which is mounted near the rear of the unit, close to the control panel. The mother board has a main controller, RF signal receiver board and cable interfaces to the piezo electric alarm, safety sensors, motors, etc. There is an RF coil at the front of the robot that senses the RF signal in the perimeter wire. The coil is located well within the robot to ensure the LB3500 mows up to the edge of the lawn.
Lawnbott has several benefits over mowing with a riding tractor or push mower. First, Lawnbott keeps up with mowing. The 1/3 rule of grass cutting (cut no more than 1/3 the length of the total grass height at any one time for optimum grass health) is easily obeyed by the Lawnbott. Lawnbott’s random mowing pattern is the best pattern to keep grass healthy.
The second benefit of the Lawnbott LB3500 over traditional mowing methods is time or money savings. That is, rather than spending hours in the heat and humidity mowing yourself, you save time and stay comfortable. If you pay a service to mow, you can save up to $12,000 over the life of your Lawnbott.
There isn’t much of a downside of owning a robotic lawn mower, except for a learning curve for installation, use and lawn preparation. Lawnbott is fun to watch and gives you a great looking lawn!
About the Author
Gail Jones is an expert in consumer robots at Paradise Robotics, a KA Authorized Lawnbott Dealer. Paradise Robotics specializes in consumer robotics, including consumer and commercial lawn mower robots, vacuum and floor cleaner robots, pool cleaner robots and automated pet products.
KA (a US distributor) and Zucchetti (an Italian manufacturer) have partnered to bring robotic lawn mowers to the United States and Canada. Zucchetti sells through their distribution channels in Europe. KA is developing new distribution channels through independent, locally-owned and operated sales and service centers in North America. Zucchetti has been in the robot lawn mower business for about five years. Zucchetti’s and KA’s partnership began over two years ago. Paradise Robotics became a KA Authorized Dealer in 2006.