Discussion
Robot Platforms

Single Bearing ATR Support

Revision as of 14:05, 3 March 2021 by Skyben (talk | contribs)

https://www.superdroidrobots.com/shop/custom.aspx/atr-mechanical-overview/51/

Summary

These robots are our medium duty platforms that are supported at each axle by one sealed ball bearing. This takes most of the load off of the motor shafts and puts it on the chassis allowing the robot to carry more weight than if the axle was directly mounted to the motor. See the chart below for approximate maximum loading. These robots work on any indoor surface and most outdoor surfaces. Below are the links to different parts you can add onto the robot platform to customize it to your needs.

Keep in mind when building this kit, that the wheels protrude past the front part of the chassis and with enough power, the robot will climb a wall. This gives it he ability to climb curbs and rough terrain, however if the obstacle is high enough the robot will likely flip over. So you want to make sure you have all your components on the top protected and secured for such an event.


Pictures

View a SolidWorks EDrawing to see a 3D image of the robot. You can manipulate the model and see all the pieces from every orientation. A simple way to see all the views is to hit play and it will automatically rotate the robot around for you so you can see all the views. Please note our models are done to a level of completion to get the parts made and metal cut.

Platforms

We offer several different platforms of ATR SBs. One for the IG32 motors, another for the IG42 motors. The same chassis is used for 4WD or 6WD, on the 4WD version, the middle wheels are just omitted and can be added later. The platform made of .125" aluminum, which we cut with our high definition plasma cutter, which is welded together for a solid chassis. We also offer chassis composed of machined tubing that can be custom sized for your application.

Dimensions and weight are listed on the item pages. Note that these dimensions do not include weld filler, which adds a little to the overall dimensions.

Motors and Motor Mounts

Many different motor sizes are available for this kit. The IG32P sized motor is recommended for most applications and will drive the robot over any indoor surface and most outdoor surfaces. The IG32 motors will work fine too depending on how much weight you plan on stacking on the robot (if >10 lbs the medium or larger motors should be used). The larger IG42 and IG52 motors are typically overkill for indoor stuff, but can be used if you want ultimate power. If you want to climb hills, curbs, and other obstacles you should use the large IG42 and IG52 motors.

We carry many different gear motors, these are our standard items.

For mounting the motors we also carry motor mounting plates and tube mounts. To mount the motor, you'll need a plate and a tube. For more information on how to use these see the Motor and Wheel Mounting Methods support page

Wheels and Drive Shafts

The ATR wheels and shafts are sold are sold in sets of two or individually. The SB wheel and shaft sets come with two bearings (one per shaft) and four lock collars (two per shaft), one to secure the axles to the motors and the other to secure the bearing to the chassis. We offer many different types of wheels that allow the robot drive on just about any terrain:

SB Shafts:

To turn, the robot uses "skid steering" which means that the motors are turned at different speeds or in different directions. For example, to turn left, the left two wheels will be turned slower than the right two wheels which will let the robot skid to the left. To make a "pivot turn" or a turn in place the wheels are driven in opposite directions which makes the robot spin. Since the wheels have to overcome friction to skid, the robot will perform differently depending on the surface on which it is driven and the components selected. If the robot is heavy and/or driven on a high-friction surface such as carpet, lower RPM motors should be used since they offer more torque. If you are ordering ATR wheel and shaft sets, you only need 2 sets (for a total of 4 wheels and shafts) for a typical 4WD assembly.

SB Wheel and Shaft Sets:

Another option is to use omni wheels, which are comprised of rollers that eliminate any skidding during turning. These wheels are the best option for high friction, flat surfaces. The Omni wheels and shafts are also sold together as one unit. The shaft comes with a bearing and lock collar that fit right into/onto the motors and motor mounts. The wheels are 4" in diameter. The traction wheels are made of durable urethane to help grip the floor. These wheels also work outdoors. The wheels are either single row wheels or double row wheels. The double row wheels provide a little smoother operation, but both work great. One thing to note with the omni wheels is if you run sideways to a hill, the wheels will side slip down the hill, but if the robot angles up the hill slightly it can overcome this. If you are ordering omni wheels, you will need 4 individual shaft and wheel sets for a 4WD robot.

Hardware

The final item you need to make your kit complete is a hardware package. It includes nuts, bolts washers, nylon spacers (for isolating your electronics and control boards), cable ties, and cable hold downs. We also sell hardware kits for mounting motors and servos.

Chain Coupling

One option that is available with the SB ATR is the coupling of the front and rear axles on each side of the robot. In the standard configuration, the left two motors are wired together as are the right two. While driving on rough terrain, turning, etc., if one wheel stalls or starts to spin, the adjacent motor has to do all the work. When the axles are coupled together it provides power from both motors. We use #25 chain and the same size sprockets to couple the axles along with a UHMW block for chain tensioning (see image below).

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