Arlo Robotic Platform

The Arlo Robotic System is mid-size platform ideal for telepresence and autonomous robots. Simply combine the Motor Mount and Wheel Kit of your choice, aluminum or molded plastic, with the Arlo Base kit and two Caster Wheel Kits to get started. Adding more height is easy with the Arlo Top Deck kit. Adding batteries, sensors and a microcontroller brain will get you rolling fast.

History

In the February 2010 issue of Servo Magazine I wrote an article called, Base on a Budget. The article described ways to create robotic platforms with minimal expense. At the time I created an aluminum chassis (Figure 1 / Figure 2) for the new Parallax Motor Mount & Wheel Kit.

Ken Gracey liked the platform, but thought it could be made simpler and cheaper. He created this wooden platform (Figure 3 / Figure 4), which also moved the battery under the robot and out of the way.

Figure 5 – Round Version of the Wooden Robot

After experimenting with this platform Ken decided to make the platform round (Figure 5) and a new generation of robots was born. This robot would be the father of the Eddie Robot, MadeUSA Robot and Arlo Robotic Platform System. The concept with Arlo is that there is no pre-designed kit. Instead you start with the base and add the parts and accessories needed to create your own platform. I borrowed this concept for the Manta Ray Robot published in the June and July issues of Servo magazine. To make building your Arlo Robot Platform easy Parallax has created a build path chart to get you started.

Figure 6 – Build Path for the Arlo Robotic Platform System

This build path (Figure 6) shows the various options available to you on the path to completion of your very own Arlo Robot. The chart shows the parts required, their part numbers and quantity. It also shows you optional parts. As of the time this article was written the available options were being updated with two changes not reflected in the chart shown. The first change is the Eddie Control Board (#28993) was being discontinued. These boards were designed for the Eddie Robot which, while a similar platform, used a laptop PC to process information and communicate with the Eddie Control Board. Another option was being added but was not yet ready for sale at the time this article was written. I will discuss that later in the article. First let’s have a look at what the Arlo Robotic Platform is made up of.

All Your Base…

Figure 7 – Arlo Robot Base Kit (#28960)

A good base platform is the starting point of any robot and this one has been tested, tried and true. This base (Figure 7) comes with the battery shelf, as well as the hardware needed to connect the base and the battery shelf to the Motor Mount & Wheel Kit. Oh and bonus; the tools required for the hardware are also included! The base is made of high-density polyethylene and provides 220 square inches of usable surface area. The battery shelf can handle one or two 12 VDC @ 8 Ah SLA batteries. You can also mount your own battery using your own hardware.

…Are Belong To Us

A good base requires a good drive / wheel system and the Arlo uses the Parallax Motor Mount & Wheel Kit, which comes in two versions. The first version is the standard machined 6061 aluminum set (Figure 8 / Figure 9) which can support up to 60 lbs.

The second version is a lower-cost molded plastic set (Figure 10 / Figure 11) which can support up to 20 lbs.

Both sets feature rugged 6″ pneumatic tires suitable for a variety of terrain and provide smooth, quiet performance. Both sets also include encoders with 144 positions per revolution which provide 0.14″ of linear travel resolution. The specific tools required are included in the kit although you will also need a #1 Phillips Screwdriver, Flathead Screwdriver, Mallet or Hammer and wooden block. You will also need a pump for the tires.

The Arlo base uses two of the Caster Wheel Kit Rev. B (Figure 12 / Figure 13). These have to be partially assembled and the tools required are included in the kit.

Choose Your Controller

The build path chart for Arlo lists controller boards that Parallax carries, such as the Propeller Activity Board (#32910), BASIC Stamp Board of Education Full Kit (#28803) and even the Propeller Eddie Control Board (now discontinued). At the time this article was written it did not list the Board of Education Shield for Arduino (#35000), however it should. There is no reason you could not use that board to allow an Arduino to be used.

When the Eddie Control Board was used, it provided an on-board dual H-Bridge for driving the motors. While you could use another H-Bridge or motor driver, the option best supported by the Arlo platform is to use two HB-25 Motor Controllers (Figure 14 / Figure 15). You will also need two HB-25 Mounting Brackets (#725-29144) to mount these to the Arlo base. The HB-25 makes it easy for any microcontroller platform to control the motors, making them as easy to control as continuous rotation servos.

Upwardly Mobile

Figure 16 – Arlo Robot Top Deck Kit (#28965)

Need more surface area to mount accessories to? Or maybe you just need more height or to elevate some equipment above the base platform. The optional Arlo Robot Top Deck Kit (Figure 16) is a 17.875″ diameter high-density polyethylene plate with all the mounting hardware required to mount it and add additional decks. It is also easy to drill and customize. It also sports built-in handles to make it easy to lift the robot up.

Sensing Your Environment

There are too many sensors to list here that could be used with the Arlo Robot Platform, however I will cover the options that are already built into the platform. The Arlo Base is already pre-drilled to fit some sensors with stands provided by Parallax. There are positions for up to ten (10) of these sensors and you can mix and match. You also don’t need to fill all the positions, there are there for maximum coverage.

The first option is the PING))) Ultrasonic Sensor + Protector Stand (Figure 17). These are aluminum and include the hardware to mount the PING))) Sensor to the stand. There is also an acrylic stand (Figure 18) available, though you would need to buy the PING))) sensor (#28015) separately. The acrylic stand also comes with the hardware needed to mount the sensor to it.

If you’re looking to mix ultrasonic and infrared sensors for more reliability Parallax offers the Dual PING))) / IR Acrylic Stand with Sensors (Figure 19). This sensor combines the power of the PING))) sensor with the Sharp IR Distance Sensor. There is also an Acrylic IR Stand with Hardware (Figure 20) which will allow you to mount a Sharp IR Sensor (#28995, sold separately).

I Got the Power

You may recall at the beginning of the article I mentioned an option being added that was not ready at the time this article was written. Until recently, tying all the power connections together was quite a task and required a lot of connectors to tie everything in. The new Arlo Power Distribution Board will make things much easier for the customer.

The Arlo Power Distribution Board (Figure 21) provides a 2.1 mm power jack for charging two SLA batteries with the Parallax charger, power and motor switches on an acrylic cover plate, fuses for all circuits and terminal blocks to make connections easier. It also provides 5V@1A, 6.5V@2A and 12V@10A for your robot (Figure 22).

Show & Tell

Parallax built six (6) Arlo Robots with the new Power Distribution Board for the USA Science and Engineering Festival (USASEF) in Washington DC back in April (Figure 23).

These robots were equipped with American flags and wandered around inside the Parallax booth area (20′ x 40′) and were kept corralled by electric dog collar boards modified to notify the robots when they were about to cross the invisible fence (Figured 24).

Final Thoughts

The Arlo Robotic Platform System is a versatile and flexible platform that offers many options and makes building a larger robot platform virtually painless. Depending on the Motor Mount & Wheel Kit used, the robot can carry 20-60 lbs making it useful in industrial and factory environments. It could also be used as a sentry or telepresence robot. Batteries are not included. You will need to provide some wire and common tools when wiring the power systems up. You may also need some cables for the various sensors. Some of these items are available from Parallax. Feel free to contact Parallax Technical Support if you have specific questions about this robot platform that were not covered in this article. You can find videos of the Arlo Robot Platform in action on the Parallax Inc YouTube channel.

Resources

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This project was published in the August 2014 issue of Servo Magazine

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