ComMotion Shield can control 4 motors, read their encoders, and monitor their current draw. Because of using I²C this board requires only 2 pins to do all this.
Each FET H-bridge can handle 2.5A continuous and up to 4A peak current. Current monitoring allows the peak current to be limited. Unlike most I²C motor control shields, ComMotion shield does more than just pass on PWM and direction data. The twin ATmega328P processors monitor encoder inputs using their external interrupt pins and control PWM to the motors. This has two major advantages- Accurate speed control for travelling in straight lines, and Full motor torque at low speeds to prevent stalling.
Using encoder feedback, a straight line is easily acheived because the ComMotion shield will automatically compensate for differences such as friction between motors / gearboxes. Using encoder feedback allows the ComMotion controller to increase power to motors to compensate for load. This means that even at very low speeds the controller can prevent stalling under heavy loads by increasing the power to the motors. If encoders are not needed, in the robot, then the shield will work like a standard 4 channel motor controller.
The ComMotion shield has some common configurations pre-loaded. That means that if a robot uses 3 omni wheels at 120° or 4 omni wheels at 90° or 4 mecanum wheels then the ComMotion shield will also do the trigonometry for you. Just give it the desired speed, angle and rotation. The twin processors on the shield will do the math. If the chassis does not match these configurations or it is required to control some motors individually, this shield can do that too.
Most Arduino boards only have 1 serial port which is normally used for software uploading and debuging. With the twin ATmega328P processors you get 2 additional 5V TTL serial ports with FTDI pinout. The serial port on MCU2 is also connected to an Xbee / WiFly socket with voltage translation circuitry and a dedicated 3.3V regulator rated for 300mA. There are 2 major advantages of this- With a preconfigured Xbee, bluetooth or WiFly module connected, no arduino board is needed, and Serial devices such as GPS modules and LCD's can be connected without affecting the serial monitor used for debugging.
This 4 layer PCB has big tracks that allow it to handle current up to 10A. The ground plane shields the MCU's from the electrical noise of the motors. Heatsinking built into the PCB is needed for robotic robustness.
The ComMotion is essentially 2 arduino boards in one with a shared ISP socket that allows either processor to be programmed via a single ISP header. The shield has been designed so that an arduino board can be used as a programmer. Just install the ArduinoISP example code and plug in the ComMotion shield. Short the RST-JP jumper to connect the ComMotions reset circuit to D10 of the Arduino and use the switch to select which processor you want to program.
- Brand: Dagu Hi-Tech Electronic Robot Shop
- Product Code: DRRS039
- Availability: Delivered in 1-3 Weeks
- 12 or more INR 4,600.00