LT2 and LT2-F Robot Support

Summary

This robot is a smaller treaded robot that was built to be compact in size but still able to climb stairs. It can climb over many obstacles that are taller than itself by using the flipper arms. The robot's flipper arm can lift its nose up, stabilize it from flipping over, and/or lift itself up. The arms can also be used to right itself after flipping over.

This robot is not meant for carrying heavy loads or pulling heavy objects like our HD2 Treaded Robot. The robot is a lightweight, tough robot that can go over and under many obstacles. With the flipper arm it is highly maneuverable. The front wheels are driven with powerful IG52 gear motors with #25 chain. The chassis is made from aircraft grade aluminum. The design uses all CNC cut parts with mortise and tenon design for precise alignment and mating of the parts. We weld all the aluminum together for a solid chassis. The treads are driven by powerful motors and the flipper arm allow this robot to ascend and descend stairs. We have designed this robot to be as simple as possible without compromising its strength, durability, or functionality. The new chassis are made from 1/8" thick aluminum that is cut then bent on a CNC break press. The seams are joined via TIG welding. A one-piece lid mounts on top of the bent chassis. Battery boxes are welded on the side of the chassis to leave room inside the cavity for electronics. The boxes are designed to hold one K2 12.8V 9.6Ahr LiFePO4 battery Pack and one 11.1V 5.0Ah Polymer Li-Ion battery pack per side. For a less expensive option you can use two Interstate 12V 7.2Ah Sealed Lead Acid Batteries instead of the K2 Packs.

The robot axles are solid high strength steel so they will not bend when the robot is dropped. The rear shaft is mounted through1/2" bearings and keyed to accept the machined flipper arms and the custom flipper arm motor and drivetrain. The flipper arm is driven by two custom machined sprockets and high strength #35 chain.

The robot has the ability to climb stairs and go over most terrain. We have spent a lot of time developing this robot so you can use it from the beginning with no issues. The treads are ~2.75" wide with an aggressive All-Terrain rubber pattern. There are different tread options we have developed for you to choose from depending on how you will be using the robot. (Standard pattern, Aggressive Chevron, and one piece Molded Gen 4 tracks). The chassis is approximately 5 inches high x 9.75 inches wide (16 counting battery boxes) x ~19.75 inch wheel center distance length. The total width of the robot is about 18.5 inches wide with the flipper arms. The center cavity is large enough for for the motors, batteries, electronics, cameras, etc. The top is flanged with laser cut holes that are tapped for mounting the lid. The robot is currently geared with a 1:2 reduction (gear motor to drive wheels). Custom gearing can be requested. The OD of the wheels with the tread is about 7 inches, so with the Type 02 IG52 285 RPM motors ground speed is about 4.75 ft/sec.The LT2 robot weighs about 35 lbs and the LT2-F weighs about 42 lbs depending on options, etc.

See a PDF Drawing of the LT2-F.

Gear Motor Options

MOTOR	MOVEMENT	TILES	CONCRETE	GRASS	UPHILL	ROCKS	STAIRS	CARPET
IG52-04 24VDC 285 RPM	Straight	7.6A	8A	10A	8A	6A	13A	8A
IG52-04 24VDC 285 RPM	Pivot Turn	12A	15A	18A	16A	12A	N/A	27A

• The current draw is an approximate average. Higher inrush spikes will be experienced.
• The robot weighs about 35lbs with motors. The weight of the batteries, sensors, controllers, aux equipment, cargo, etc. should be added to this to get the gross weight. The robot itself is designed to carry even more weight, however, since it has skid steering the amount of extra weight depends on the surface on which the robot will be driven. With heavy loads turning in deep grass, on carpet, and on other high friction surfaces will be difficult. If the robot is driven on smooth surfaces such as dirt or or tile, pivot turning with heavier loads can be achieved.

LT2-F NIST Testing

The LT2-F robot has been qualified by NIST (National Institute of Standards and Technology). We first went to the Maryland facility and completed the evaluation. We saw some things that we wanted to improve so developed our own test course back at our facility for further testing. Next, we went to Disaster City, TX, a training facility run by Texas A&M where we spent 4 days testing the LT2-F to the limits. No failures. Same Robot. The testing was grueling. Every obstacle had to be overcome 10 times back to back, no stopping, no resetting, no recharging, no anything. This was taxing on the robot as well as the operator. Evaluators were impressed with our rugged robot design. Here is a list of some of the tasks we performed for testing:

• Endurance 4 hours continuous driving over ramps
• Crossing Ramps Completed 10 laps
• Continuous Ramps Completed 10 laps
• Stepfields Completed 10 laps
• Sand Completed 10 laps
• Gravel Completed 10 laps
• Gaps Completed - 30CM gaps
• Inclines Completed 30 degree
• Hurdles - Completed 30cm high
• Stairs Completed - 45degree
• Towing Completed 40 lbs
• Water Fording Completed -1 foot of water