HD2 Robot Support
The HD2 is the largest treaded robot we offer as a standard item. It is designed to carry loads up to 200lbs while maintaining its maneuverability on all different types of terrain, including the ability to easily ascend and descend stairs. The chassis is made from 3003 aluminum cut on our CNC plasma machine. A 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 center cavity of the chassis is enclosed providing a good place to mount batteries and electronics. Each of the four wheels is driven by a powerful IG52 gear motor and heavy duty #35 chain. The wheels have a rubber core that is sandwiched between UHMW side pieces. Each wheel assembly contains two double sealed ball bearings, a sprocket, and an idler shaft where it mounts to the chassis. The chassis wraps around each wheel so they can be supported on each side. This allows the wheels to support a heavy loads. The tracks are made from rubber and have an aggressive all terrain pattern. They are molded in one continuous piece (without a splice) and are re-enforced with 4 ply of terylene mesh. Guide teeth are molded on the inside of the tracks and mate with teeth on the wheels for positive timing and superior tracking.
The robot is completely symmetric and invertible. It can be driven by a simple RC system, one of our custom controllers, or a PC. It has the ability to climb stairs and go over most terrain. A large center cavity has plenty of room to house batteries and electronics. As a standard option we also offer a chassis that is 6 inches wider (~26inches wide). The standard size chassis is much better suited for fitting trough doors and narrow spaces but if you have a lot of equipment you need to mount on or in the chassis a wider frame can be a good upgrade. The motors are half inside the tread and protrude halfway into the center cavity. The bottom cover is flanged and all the holes are cnc plasma 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 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 285 RPM IG52 gear motors ground speed is about 2.5 mph. Different gear motors are available that let the robot support higher payloads. The robot weighs around 60 pounds without batteries and with the 285 rpm motors can handle up to 80 lbs, depending on use. The robot itself is designed to carry even more weight, but since it has skid steering turning on high friction surfaces like deep grass or carpet 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:
- 3-5 Amps per side driving straight and flat
- 8-10 Amps per side climbing stairs
- 18-22 Amps per side pivot turning in thick grass
- 8-10 Amps per side pivot turning on concrete
See a PDF Drawing of the standard width HD2.
Gear Motor Options
Different gear motors can be selected in the options section. The robot weighs around 60 pounds without batteries. It is capable of carrying another 40-200lbs depending on which motors are used and how the robot is being used. 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.