LT2 and LT2-F Robot Support

Summary

The LT2 is our mid-sized tracked platform. We offer models with and without flipper arms. With the flipper arms, it has the ability to climb stairs and climb over many obstacles that are taller than itself. 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.

We have designed this robot to be as simple as possible without compromising its strength, durability, or functionality. The tracks are chain driven by powerful IG52 gear motors and #25 chain (15:32 reduction). The chassis is made from 3003 aluminum. It is cut in multiple pieces on our CNC plasma machine and then bent on our CNC brake press and welded together. 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. Each battery box is designed to hold one K2 12.8V 11.1Ahr LiFePO4 battery and one 11.1V 5.0Ah Polymer Li-Ion battery pack per side. For a less expensive option 12V 8Ah Lead Acid Batteries can be used instead of the LiFePO4 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 (with the flipper arms) 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 pattern. The center cavity of the chassis is large enough for for the motors, batteries, and motor controller and has some room to spare for other electronics. 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.

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 and any other add-ons 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 without stopping, resetting, or recharging. 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