RageBridge 2 is a no-frills, robust dual-channel DC motor controller for robotic and vehicular drivetrain applications.
Equals Zero Designs was 2012 by MIT mechanical engineering graduate Charles Guan and electric vehicle and robot builder Adam Bercu. The collaboration was initially launched with the hobbyist and Maker community in mind, with hopes of designing products that would fill the voids in the market for which no confident solutions exist. This ultimately led to the introduction of a DC controller they called RageBridge, which flew off the shelves in a matter of months.
“Motor controllers have been historically one weak leak in an otherwise robust design. They can be expensive, compication and often overrated,” Guan explains. And now a few years later, the duo has returned with the latest generation of their board.
RageBridge 2 is a no-frills and robust dual-channel DC motor controller for robotic and vehicular drivetrain applications, all integrated onto a single ATmega328P powered board. Each channel can drive motors between 8V and 40V at 50A continuously per channel. This ultra-wide input range maximizes versatility and enables it to be used in a variety of different systems. Meanwhile, a large and fully-isolated heat sink base allows you to attach it to a metal chassis for even better thermal performance.
Since the launch of their first version, they have taken the best traits of the earlier device’s design and enhanced its packaging, reliability, as well as the accuracy and speed of the current limiting algorithm. Among the noticeable upgrades include newer MOSFETs, optimized switching speeds, a “single channel” option, and automatically-selecting inputs that let you simply plug in an analog joystick and have an instant electric vehicle controller.
RageBridge 2 differs from most DC motor controllers available today because of its user-selected active current limiting feature. As its creators note, the ability to maintain a set current ceiling greatly can drastically improve the reliability of DC motor systems. With just a turn of a screwdriver, users can easily adjust the RageBridge 2’s current ceiling. The motor output current is sample 15,000 times every second, and if it is over the threshold, the output voltage is reduced each cycle until the current falls under the limit.
“The vast majority of controllers simply do not have any protection. That means a sudden short, drivetrain lockup, or motor failure will destroy the controller as it tries to flow the motor stall current. Sizing a controller to handle motor stall current is very impractical and expensive, often resulting in controllers being many times bigger than they need to be,” Bercu writes.
“Many popular DC motor controllers today advertise ‘overcurrent protection.’ But often, they mean is the controller will shut down upon a certain current threshold, and often requires a power cycle or the load to drop to zero before enabling again. This means that under heavy acceleration, your robot or vehicle might just turn off all of a sudden, leaving it (or you) stranded. Once again, the controller has to be many times overrated in order to handle the load.”
Interested? Guan and Bercu are currently seeking $5,000 on Indiegogo and plan to begin shipping the first batch of RageBridge 2s in late October 2015.