A 3d printed Mars Rover with DUAL Arduino Electronics
A 3D Printed Perseverance Mars Rover of NASA with dual Arduino Electronics. The first Arduino a NANO, manages all 6 motors (speed and direction) of the 6-Wheel Rover where each wheel is independently controllable using the Arduino Servo libary. The motor speed controller uses the SG90 Servo board including the feedback potentiometer as an Electronic Speed Controller for each of the 6 wheels. Four more servo boards are added to manage the steering process performed on all four corner wheels. So thats 6+4 SG90 Servo boards, 6 acting as Motor ESC and 4 as wheel steering. A 2nd BLE-33 Sense NANO Arduino with a TENSORFLOW AI/ML embedded engine is used to process sensor data (built-in sensors within the Arduino, LIDARS, PIXYCAM, and MPU Gyro Sensor) The BLE-33 Sens NANO communicates with the 1st NANO Arduino via I2c. The entire platform is 3D-Printed with STL files downloaded from the NASA Website/GITHUB and were modified to accomodate the electronics and motors/servos.
https://github.com/nasa/NASA-3D-Resources/tree/master/3D%20Models/M2020-Model-Rover-STLs512020
Rover Electronics mounted on the chassis box;
Sensor/Device List as implemented on the Arduino Codes;
"A TENSORFLOW AI/ML embedded module, 6 individually addressable bidirectional motors for all 6 Wheels, 4 LIDAR Sensors: two for the front two wheels, 1 at the rear wheel, 1 on the head mast, A CMU Pixy Camera mounted in front of the Rover, A streaming camera on the Main Mast accessible using wifi via a Mobile app, Dual Micro controllers in a master slave configuration, two 6 DOF gyro/accelerometers - one on top of the differential bar, another on one on the Nano BLE Sense microcontroller, a light/color/proximity sensor on the ble sense, a barometric/temp/pressure also on the ble sense, an audio mic also on the ble sense, a couple of servos - one for the Mast, and one for the Ingenuity copter deployment, and FOUR more servos for each corner wheel, an RC module to remotely control the bot or feed it with PWM data for subroutine triggers from the 2.4ghz transmitter , A Bluetooth module for mobile app communication..."
The platform also include a mini version of the Mars Ingenuity Helicopter to demonstrate the deployment process using a SG90 Servo to drop the model under the belly of the perseverance rover;
Ingenuity Deployment assembly (Version 1)
Ingenuity Deployment assembly (Version 2)
The Platform uses multiple sensors ((built-in sensors within the Arduino BLE Sense, LIDARS, PIXYCAM, and MPU Gyro Sensor) which can be used for multi-processing/interactive experiments
Below is the connection diagram of all the motors, servos, and sensors. Motor/Servo Control is distributed on the Arduino NANO (Acting as Slave) and the rest of the sensors including those connected to the I2C Bus are being controlled by the Arduino BLE-33 NANO Sense which is acting as the Master. The Coring Motor (Rover Drill Motor) is connected to the BLE33 Sense as well the Servo Library Pins on the Arduino NANO side are fully utilized.
ARDUINO MASTER-SLAVE CONFIGURATION
The Arduninos operates in a master-slave configuration with the Master (NANO BLE Sense) defining 3 modes of operation;
Mode 1: RC Mode
In this mode, control of the Rover is via a FLYSKY GT5 TX and FS-82 Receiver attached to the NANO Slave. The arduino NANO simply receives the channel info data from the transmitter via I-BUS connected to the Arduino RX pin and passes control to the Arduino Servo Library which performs the Motor/Servo control of the Rover.
Mode 2: RC with Sensor Mode
In This mode, The Arduino NANO Slave cascades the FLYSKY Transmitter data to the NANO BLE Sense Master via I2C. The NANO BLE Sense Master then processes the transmitter data together with the sensor data attached to it and sends back to the NANO Slave the Motor/Servo control commands.
Mode 3: Autonomous Mode
In this mode, there is no human intervention from the FLSKY Transmitter. Instead the Arduino BLE NANO Master reads the sensor data , decides on the what motor/servo commands to pass to the Arduino NANO Slave based on the information gathered from the sensors (LIDAR, PIXY, Audio, MPU6050 Gyro/Accelerometer, etc.
LIDARS and the CMU PIXY Camera
The platform has four LIDAR sensors and one CMU PIXY Camera for Visual Recognition
Two of the LIDAR Sensors are attached on each front wheel and one on the back wheel;
And another LIDAR sensor is located on the RSM Mast head side by side with a stand-alone wifi camera ;
A CMU PIXY Camera is attached on the front of the rover for realtime "front-of-rover" image analysis;
Arduino - PIXY CAMERA Processing
LIDAR and CMU Pixy Camera I2C BUS Addressing;
Anything attached on the I2C bus are addressable. The included code manages the pre-programming stuff of setting up the I2C address on the multiple LIDAR sensors so there will be no bus conflicts. Custom I2C Addresses are invidually re-assigned on three of the four LIDAR sensors connected on the same I2C bus. The way to do this is to put 3 of the LIDARS in reset mode while the fourth one is assigned with a new address. Then one by one, the reset line of each is deactivated and assigned with a new address until all four will have unique i2c addresses.
RC Electronics
The platform utlizes the FLYSKY TX-RX modules for receiving user command data from a FLYSKY FS-GT5 Transmitter and is received by the Ardruino Nano Slave via Flysky's I-BUS protocol which is directly fed to the Arduino NANO RX Pin.
Rover Wheels Geared Motors
Each wheel is driven independently by geared motors attaced on the bogie arm assembly.
The motor drivers are from the SG90 Servo boards acting as Electronic Speed Controllers with the feedback potentiometers adjusted for home position (where the motors stop rotating at TX / Steering wheel mid stick position)
Steering Servos.
To reduce the space occupied by the servos, the SG90 servos where disassembled and the electronics attached to the 3d-printed bogie arm. The same Geared Motors on the wheels were used as motors for the servo arms.
3D Model of the Steering Servo mount to accomodate the SG90 Electronics plus a Potentiometer 3d printed "Feed Back Pin" needed for the servo operation.
Potentiometer Feed Back Pin
The Arduino Slave Codes contain routines for an ACKERMAN STEERING and Turn-ON-Spot mode. This is user selectable on the FLYSKY TX switch knobs or via a command from the Master Arduino BLE Sense side.
RSM Mast Servo
The platform also includes a RSM Mast Servo for LIDAR and Wifi Camera Panning. The servo is located at the based of the RSM Mast Assembly
CORING DRILL MOTOR
The Rover Platform also has a Coring Drill Motor which is controllable from the Arduino Master side.
Perseverance Rover Platform Mount
For safekeeping a 3D Model of the platform mount is included;
