Roli Rover by EZ-Robot
A rugged rover you drive, teach and expand
Roli is EZ-Robot's tracked, planetary-rover style robot: an EZ-B v4 controller, motor-driven treads, servo arms with grippers and a camera. Connect it to Synthiam ARCx and drive it with live video, pick things up, follow colors and faces, and program it to patrol, all from a web browser.
How Roli works with Synthiam. Roli's brain is an EZ-B v4, which runs EZB firmware out of the box. ARCx connects to it over Wi-Fi with the Ezb Connection robot skill. Roli's treads are DC motors on an H-bridge motor controller, so the Hbridge Movement Panel is its drive system, and Camera Source (ezb) brings in the video. We recommend ARCx: it runs on Windows, Linux and Raspberry Pi and is used from any web browser. ARC, Synthiam's Windows application, works with Roli too.
What is Roli Rover?
Roli is a Wi-Fi, planetary rover style robot kit from EZ-Robot. Think of it as a small space rover that drives over different surfaces on rugged treads and can be expanded with add-on parts. It pairs an EZ-B v4 controller with a sturdy rover base designed to be a reliable workhorse.
In the box (from EZ-Robot's product page):
- EZ-B v4 Smart Robot Controller and EZ-B v4 Camera block
- Tracked rover body with a 2.5 A motor controller (H-bridge) for the treads
- Five lever servos and three rotation servos for building arms, grippers and the camera neck
- LiPo robot battery and balancer charger
- Extension wires, spiral wire wrap and a USB Wi-Fi dongle
What “13 female EZ-Bit connections” means
Roli's body has 13 female EZ-Bit connections: snap-in mounting points for compatible add-ons (“EZ-Bits”), such as:
- Sensors (distance, light, line sensors and more)
- Outputs (LEDs, buzzers, extra servos or other modules)
- Expansion parts that make the robot do more than drive
Roli at a glance
| Type | Tracked rover robot kit |
|---|---|
| Maker | EZ-Robot |
| Controller | EZ-B v4 (EZB firmware) |
| Drive | Two DC-motor treads on an H-bridge with PWM speed control |
| Arms and head | Lever and rotation servos, grippers, camera |
| Audio | Speaker built into the EZ-B v4 |
| Expansion | 13 female EZ-Bit connections |
| Connection | Wi-Fi (USB/serial possible, see the EZ-B v4 page) |
| Power | LiPo battery, balancer charger included |
| Size | 24.1 × 34.3 × 30.5 cm, 1.75 kg |
| Synthiam uses it for | Driving, live video, grabbing, tracking, patrols, teaching |
| Website | ez-robot.com |
What you can do with Roli in Synthiam
Start with driving, then add the camera, the arms and sensors one at a time. Each feature is a robot skill, and they all work together.
- Drive like a rover on carpet, tile and other common surfaces.
- Pick things up with the servo arms and grippers.
- Add sensors such as distance or line sensors to make it smarter.
- Create autonomous behaviors: avoid obstacles, follow a color, patrol.
- Customize the look with accessories and add-ons.
- Learn robotics basics: motors, power, sensors and programming.
Drive
The Hbridge Movement Panel has its own on-screen joystick with proportional speed and arcs. The Movement Joystick, a gamepad through Joystick or a script drive it too.
Rover cam
Camera Source (ezb) streams the camera for first-person driving. Camera Snapshot saves photos of what Roli finds.
Arms and grippers
Move each joint with the Servo skill, save arm moves like Reach and Grab with Auto Position, and aim the camera neck with Servo Pad.
Follow colors and faces
Color Tracking, Face Tracking and Glyph Recognition find things; Vision Detection Tracking Script turns Roli toward them and drives up to them.
Talk
Set Project audio in Ezb Connection to the EZB speaker and text to speech and the Sound Board play from Roli itself. Speech Phrase Recognition adds voice commands.
AI
Autonomous AI can look through the camera, describe what it sees and decide where to drive. ARCx is also an MCP server for AI agents like Claude.
Program patrols
Blockly, JavaScript or Python in the Script skill. Run a patrol at set times with Script Scheduler.
Custom control screen
Build a touch-friendly Custom UI with a joystick, gripper buttons and the camera view, and use it from a phone or tablet.
Remote access
With Exosphere, drive Roli from anywhere in a web browser and invite others to use it for telepresence.
Roli's H-bridge connections
EZ-Robot's build guide connects Roli's H-bridge to the EZ-B v4 with a six-wire harness. These are the ports the Hbridge Movement Panel needs to know.
| EZ-B v4 port | Wire color | H-bridge function | Hbridge Movement Panel setting |
|---|---|---|---|
D0 | Green | Left PWM (speed) | Speed Control → Left PWM |
D1 | Blue | Left Trigger A (direction) | Left Motor → Trigger A |
D2 | Purple | Left Trigger B (direction) | Left Motor → Trigger B |
D3 | Grey | Right Trigger A (direction) | Right Motor → Trigger A |
D4 | White | Right Trigger B (direction) | Right Motor → Trigger B |
D5 | Black | Right PWM (speed) | Speed Control → Right PWM |
H-bridge power: the H-bridge's red and black power wires connect to the power pins of port D0, red to red and black to black.
Reversing them can damage the robot.
Connect Roli to ARCx
- Charge and power on. Make sure the battery is charged, power Roli on and wait for the EZ-B v4 to finish starting up.
- Join the robot's Wi-Fi. Out of the box the EZ-B v4 makes its own Wi-Fi network (AP mode). Connect the computer that will run ARCx to it, or put the EZ-B v4 on your home network as the EZ-B v4 page explains.
- Install ARCx and open it in a web browser. Download ARCx.
-
Connect. Add Ezb Connection (Communication category), pick Roli from the address list
or type the address, and press the green connect button. In AP mode the address is normally:
192.168.1.1 - Set up driving. Add the Hbridge Movement Panel (Movement Panels category). Set the ports from the table above, tick the PWM option, and save.
- Drive slowly. In a clear floor space, push the panel's joystick gently forward. If one track runs backwards, swap that motor's Trigger A and Trigger B ports.
- Add the camera, then one extra at a time. Add Camera Source (ezb) and press Start. Only after driving works, add the arms and any extra EZ-Bits, testing each new part. Save the project.
Before you start
- A computer with ARCx (Windows, Ubuntu 24.04 or a Raspberry Pi with Ubuntu 24.04), or a Windows PC with ARC.
- Wi-Fi: the computer connects to the EZ-B v4 directly or through your network.
- A charged battery before you try to connect.
- A safe test area: clear floor space so the rover cannot bump into fragile items.
Need a simple goal?
Start with “connect to Wi-Fi, drive forward and turn, stop.” Once that works, add one EZ-Bit, such as a distance sensor, and try an “avoid obstacles” behavior.
Using ARC instead?
Connect with ARC's EZB Connection and drive with Dual HBridge w/PWM, using the same ports.
Both work, ARCx is recommended
Roli works with both of Synthiam's robot programming platforms, because both speak the EZ-B v4's EZB protocol. If you are starting today, choose ARCx.
| ARCx Recommended | ARC | |
|---|---|---|
| Runs on | Windows 10/11 x64, Ubuntu 24.04 x64 and ARM64, Raspberry Pi (Ubuntu 24.04) | Windows |
| User interface | Any web browser: laptop, tablet or phone, several people at once | Windows desktop application |
| Drive skill | Hbridge Movement Panel | Dual HBridge w/PWM |
| AI agents through MCP | Yes | No |
| Connection skill | Ezb Connection | EZB Connection |
Troubleshooting
- Make sure the computer running ARCx is on Roli's Wi-Fi network (AP mode) or on the same network Roli joined (client mode).
- If Roli does not appear in the address list, type the address by hand. On Windows the scanner only works when that network is set to Private.
- In AP mode the computer has no internet; that is normal. Cloud speech and AI skills need a second connection (Ethernet or the USB Wi-Fi dongle in the box), or put the EZ-B v4 on your home network.
The EZ-B v4 uses two circuit boards that work together during start-up. The top board holds the communication processor and Wi-Fi antenna. The bottom board holds the I/O processor, which handles hardware functions such as port control and the start-up sound. At power on, the communication processor starts first and sends start-up commands to the I/O processor; once the I/O processor answers, the EZ-B finishes starting up and plays the start-up sound.
No start-up sound usually does not mean the speaker is broken. More often it is a sign that the I/O processor is not responding. During connection, the communication processor accepts the connection and performs the first part of the EZB handshake, then hands over to the I/O processor, which must return its firmware ID. If the connection log stops at the firmware ID request and no ID comes back, the I/O processor is not responding, which strongly suggests the bottom board is damaged.
The camera may still work, because the top board's communication processor handles the video stream. A working camera only proves the top board is alive, not that the whole EZ-B is healthy.
The usual cause is electrical damage to the I/O system: ports that were shorted, overloaded, or given too much voltage or current. The EZ-B v4's I/O protection has limits and cannot prevent all damage.
Frequently asked questions
Send Roli on its first mission
Install ARCx, connect with Ezb Connection, set up the Hbridge Movement Panel, and drive with live video from any browser.
