A differential drive robot steers like a tank: two motors, one per side, turn together to drive straight and at different speeds or directions to turn. Set a RoboClaw motor controller to RC mode and a standard hobby radio drives the robot directly. This guide covers the wiring, Motion Studio configuration, and testing.
A differential drive system is one in which only two motors handle both forward and backward motion and steering, the same way a tank steers: both sides drive together for straight travel, and at different speeds or in opposite directions to turn. You have probably seen this system on robots like line followers, sumo bots, and even some larger combat robots. Pairing this drive scheme with an RC radio system is both intuitive and easily accessible: the RoboClaw reads standard servo pulses straight from a hobby receiver, with no other electronics required.
This guide works with any dual channel RoboClaw model. Configuration is done in BasicMicro Motion Studio, which requires a computer running Windows 10 or newer.
Some photos in this guide show an older RoboClaw revision with onboard configuration buttons. Button configuration is deprecated; all current RoboClaw models are configured with Motion Studio.
What You Need
- 1 RoboClaw motor controller (dual channel)
- 2 Brushed DC motors
- 1 RC radio transmitter
- 1 RC radio receiver
- 1 Battery for the RoboClaw
- 2 Female to female servo cables
- 1 USB A to micro-B cable
- 1 Small screwdriver
- 1 Computer with BasicMicro Motion Studio installed
Connect Power and Verify the RoboClaw
- Download Motion Studio from basicmicro.com/downloads and install it. The Installing BasicMicro Motion Studio guide covers the process step by step.
- Identify the positive and negative leads of the battery. Find the two screw terminals on the RoboClaw labeled + and – and loosen their screws. Attach the negative lead first by placing it in the loosened terminal and tightening the screw until the connection is snug, then repeat with the positive lead.
Figure 2: Power wired properly to the RoboClaw. - Connect the USB cable between the RoboClaw and the computer.
- Open BasicMicro Motion Studio. In the upper left corner of the application is a box labeled “Attached Devices”. The RoboClaw should appear here; if not, check the USB connection and confirm power is applied. Select the device and click “Connect Selected Unit”. The Stat1 LED on the RoboClaw will begin flashing. Once the connection is verified, click “Disconnect Selected Unit” to stop communication.
Figure 3: The location in Motion Studio where a RoboClaw is connected. - Disconnect power from the RoboClaw by removing the positive lead first and then the negative lead. If the battery has a disconnect switch, opening the switch works too.
Always remove the positive lead first. Disconnecting the negative lead while the USB cable or other signal grounds are still attached creates a ground loop that can permanently damage the RoboClaw or the connected devices.
Wire and Test the Motors
- Locate the terminals labeled M1A and M1B and loosen their screws. Wire the first motor by placing one bare wire end in each terminal and tightening the screws until the connections are snug. The wiring order does not matter for the first motor.
- Wire the second motor to the terminals labeled M2A and M2B. The order does matter here: note which color wire of the first motor went to M1A and connect the same color wire of the second motor to M2A, then connect the remaining wire to M2B. Make sure all motor connections are secure.
Figure 4: Two motors wired to the RoboClaw properly. - Reconnect power to the RoboClaw as done earlier, negative lead first and then positive.
- Open Motion Studio and reconnect the RoboClaw by clicking “Connect Selected Unit”. Click “PWM Settings” in the left-hand pane to test the motors. Find the box labeled “Control” and move the sliders for Motor 1 and Motor 2. The motors should turn when the sliders move, forward when sliding up and backward when sliding down. If a motor turns the wrong direction, reverse the wiring on that motor.
Figure 5: The motor sliders used to test both motors. - Disconnect the RoboClaw in Motion Studio and remove power from the RoboClaw as done earlier.
Connect the Radio Receiver
- Locate the pin header labeled S1; this is where the output from the radio receiver connects. Using the receiver’s manual, find the throttle channel and connect it to S1 with a servo cable. Both ends of the connection are polarized: on the RoboClaw, the ground pin of S1 is toward the inside of the board, while the polarity on the receiver varies by model and is labeled on some receivers.
Figure 6: One RC channel connected. The RoboClaw powers the receiver from its onboard BEC through the 5V line of the servo cable. If the receiver is powered by an external battery or by the BEC of another speed controller, the 5V lead of the servo cables must be cut or removed entirely to prevent a conflict between voltage sources. The two diagrams below show both configurations.
Figure 7: The 5V line is connected between the RoboClaw and receiver, so the RoboClaw powers the receiver. 
Figure 8: The receiver is powered externally and the 5V line between the RoboClaw and receiver has been removed. - Turn on the radio transmitter.
- Reconnect power to the RoboClaw and open BasicMicro Motion Studio. Reconnect the RoboClaw in Motion Studio as done previously.
- If the receiver needs to be bound to the transmitter, do it now while power is applied.
Configure RC Mode in Motion Studio
- Click “General Settings” in the left-hand pane of Motion Studio. In the pane labeled “Setup”, set the Control Mode to “RC”.
- Look at the RC/Analog Options panel. Check the “Mixing” box: mixing is what allows the RoboClaw to drive the motors differentially, with S1 controlling forward and reverse speed and S2 controlling steering left and right. “Exponential” is optional and adds low-speed control sensitivity near the center of the stick; enable it if preferred. The “Safe Start” options are also worth enabling, since with Safe Start on a motor will not start until its input returns to center.
Figure 9: Location to set the mode and RC options. - Save the settings to the RoboClaw by selecting “Save Settings” from the File menu. The new settings take effect after the RoboClaw resets, which happens when power is removed in a later step.
- Test the throttle channel by moving it up and down. The motors should respond to the throttle input.
- Disconnect the RoboClaw in Motion Studio and remove power from the RoboClaw as done previously.
Connect the Second Channel and Test
- Locate the pin header labeled S2. Connect the aileron channel of the receiver to S2 as done with the throttle channel, observing the same polarity.
Figure 10: Two RC channels connected to the RoboClaw. - Ensure the radio transmitter is still on and center both control sticks.
- Reconnect power to the RoboClaw. At startup the RoboClaw takes about one second to calibrate the neutral stick positions, and the Stat1 LED begins flashing once RC pulses are detected.
- Test that the motors respond properly to each radio channel. Throttle input should cause both motors to turn in the same direction, and aileron input should cause the motors to turn in opposite directions.
Loss of signal between the RC transmitter and receiver, whether from range or from turning the transmitter off, can cause control problems: many receivers continue sending the last known stick positions, which can result in a runaway robot. Two mitigations are available. Many radio systems can be programmed with failsafe positions, so consult the documentation for the system being used. In addition, the RoboClaw’s “RC Timeout” option in the RC/Analog Options panel stops the motors whenever the input signal is lost for more than 100 milliseconds.
Next Steps
The robot can now be driven with the RC transmitter. Some builders keep this as their final control scheme, while others use it as a quick way to test hardware before moving to another control method.
- Combat Robot RC Setup: apply RC mode to a combat robot drivetrain.
- Simple Arduino Control of the RoboClaw: move from radio control to microcontroller control with packet serial and the Basicmicro Arduino library.
Thumbnail photo / CC BY-SA 3.0
