The HD2 robot is the largest treaded robot we offer as a standard item. It is designed to carry heavy loads (up to 100lbs) while maintaining its maneuverability on all different types of terrain, including the ability to easily ascend and descend stairs. The chassis is made from aircraft grade aluminum and painted with an industrial bed liner. The design uses all laser cut parts with mortise and tenon design for precise alignment and mating of the parts. The frame is ribbed and gusseted making it very rigid. We weld all the aluminum together using TIG for a solid chassis. The robot is sealed and can be made water tight. The wheels are supported with inner and outer race sealed ball bearings (the wheels are not cantilevered or direct driven from the motor shaft). Each of the four wheels is driven by a powerful IG52 gear motor and heavy duty #35 chain. The custom treads are made with an aggressive All Terrain pattern and positive traction. The molded continuous (no splice) rubber tracks are re-enforced with 4 ply of Terylen mesh. Guide teeth are mounted internally to the rubber tracks and cut to mate with the matched wheels for positive timing and superior tracking (virtually impossible to derail under any condition). The tracks are driven by UHMW/Rubber wheels with timed teeth that match the pattern on the tracks.
The robot is completely symmetric and invertible. The robot can be driven by a simple RC system, one of our custom controllers, or a PC. The robot has the ability to climb stairs and go over most terrain. It is about 38 inches long and 20 inches wide by about 9 1/2" high (tread height). There is a very large center cavity for batteries, electronics, cameras, computers, etc. As a standard option we also offer a chassis that is 6 inches wider (~26inches wide). The Standard Chassis is much better suited for fitting trough doors, etc, but if you have a lot of equipment you need to mount on or in the chassis a wider frame can be used. The picture above shows two standard-width chassis and two wide chassis. The motors are half inside the tread and protrude halfway into the center cavity. The bottom cover is flanged and all the holes are laser cut and then hand tapped for a perfect fit and seal. The robot is currently geared with a 1:3 reduction (gear motor to drive wheels). Custom gearing can be requested, usually without a price impact.
We have different battery options that will work with the HD2. Below we have pictures of different robots with different battery configurations shown. We recommend the K2 25.6V LiFePO4 battery packs. At least two are needed to run the robot. The 24V 10000 mAHr NiMH Battery Packs will also work well in the robot. At least two of these are needed to run the robot as well. The reason for this is both of these battery packs have a 25 amp overload protection built in and in a stall situation the HD2 will pull more than 25 amps.
The OD of the wheels with the tread is about 9.75 inches, so with the recommended 285 RPM powerful IG52 gear motors ground speed is about 2.5 mph. Different gear motors can be selected in the options section. The robot weighs around 60 pounds without batteries, etc. It is capable of carrying another 50+ lbs. The robot itself is designed to carry even more weight, but since it has skid steering turning in deep grass, carpet etc. will be difficult with very heavy loads. See more about motor options in the Gear Motor Options section below.
An HD2 tank has the following approximate current draws:
Different gear motors can be selected in the options section. The robot weighs around 60 pounds without batteries, etc. It is capable of carrying another 40-140lbs depending on motors and gear ratios. The robot itself is designed to carry even more weight, but since it has skid steering, turning in deep grass, carpet etc. will be difficult with very heavy loads. If you are going to carry more than 100 lbs. we recommend using four Type 04 IG52 136 RPM motors. If desired, the tank can be run with only two Type 04 IG52 136 RPM motors or two Type 04 IG52 285 RPM motors and let the other two wheels idle. With only two Type 04 IG52 136 RPM motors it runs well as it is able to carry an additional 60 lbs. up stairs with no effort. With two Type 04 IG52 285 RPM motors the robot works well and still runs full speed but has a little bit of difficulty doing pivot turns in deep grass. We also offer IG52 gear motors with encoders. If you plan on using encoders only two motors with encoders are required since the front and back wheels are tied together on each side by the cleated belts and they will be traveling the same speed. Below is a table to help you select motors.
The current draw is approximate average. Higher inrush spikes will be experienced.
The robot weighs about 60lbs 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 depending on the surface on which it is driven since it has skid steering. With heavy loads turning in deep grass, on carpet, and on other high friction surfaces will be difficult. If the robot is driven on on smooth surfaces such as dirt or tile, pivot turning with heavier loads can be achieved.
Only the front or rear motors need encoders since the front and back motors are synchronized by the cleated belt.
Do NOT put different RPM motors on the front versus the back. Bad things will happen