Apto

The remote controlled robot, called Apto, was built to operate in two modes of transportation, walking and driving. It was built for the purpose of exploring and interacting with various environments. Its intelligent part consists of an onboard microcontroller featuring an ARM Cortex-M7 processor. Apto’s wide array of sensors include an Arducam 2MP Camera, Current & Voltage Sensor, Accelerometer + Gyroscope, and microphone. The two modes of operation consist of four legs made up of servos for walking, and 2 DC motors connected to wheels for driving. Apto can be broken down into separate subsystems including Power, Guidance Navigation and Controls (GNC), Electromechanics, Network and User Interface.

Hardware was selected in a manner that allowed Apto to have a wide variety of capabilities while still being able to keep its power consumption low. The Teensy 4.1 development board was chosen as it contains a powerful yet small ARM Cortex M7 processor. A 6000mAh 3.6V Lithium Polymer battery was used as the power source of the robot. 9g servos were chosen for the arms, while DC motors will be used for driving mode. A dual motor H-bridge controller will be used for direction and speed control. An accelerometer based around the MPU-9250 IC with an integrated gyroscope will be used for keeping track of trajectories. An OV2640 Mini 2MP camera module will be used for the capturing images of its environment. Other components of the robot include a PS3 controller to control the movement of the robot via Bluetooth, a 0.5W 8 Ohm speaker, microphone, OLED Display, and Neopixel LEDs for lighting. With respect to power, there is a micro-USB charging circuit, current and voltage sensor, LED status indicator and a power distribution board.

SUBSYSTEM

COMPONENT

QUANTITY

POWER

ELECTROMECHANICAL

GUIDANCE, NAVIGATIONS

AND CONTROL

NETWORK

USER INTERFACE

Lithium-Ion Polymer (LiPo) Battery (3.7V 6000mAh Stacked)

Cherry MX Switch

FQP27P06 - P-Channel MOSFET (-60V -27A)

Micro JST 2.0 Ph 2-Pin Connector Plug Male & Female

Longruner MG90S Metal Geared Micro Servo Motor 9G

⅛” Steel Ball Bearings

200

1V-6V DC Hobby Motor EK1894C

Teensy 4.1 ARM Cortex M7 Microcontroller

Arducam Mini Module Camera Shield with OV2640 2 Megapixels Lens

ESP8266 ESP-01 Serial WiFi Module

Pololu Dual Motor Driver DRV8835 Carrier (2-11V 1.2A)

MPU-6050 Accelerometer/Gyroscope IMU

Bluetooth 4.0 USB Dongle Adapter (CSR 4.0)

0.96” I2C Serial OLED Display Module (128x64)

0.5W 8 Ohm Speaker

Dual Shock Wireless PS3 Controller

5mm LED

Electret Microphone

WS2812 Neopixel Individually Addressable LED

POWER

Devices

Vin (3.7V) BAT

ARM1,2,3,4

MOTOR

NEOPIXEL

3.3v-1

WIFI MODULE

DISPLAY

CAMERA

3.3v-3 (250 mA)

MIC

ACCELEROMETER

MOTOR CONTROLLER

Logic

Teensy Output

Device

Device Input

PWM

ARM1-1 DATA

DATA

PWM

ARM1-2 DATA

DATA

PWM

ARM1-3 DATA

DATA

GPIO

MOTOR CONTROLLER

MODE

GPIO

MOTOR CONTROLLER

APHASE

PWM

MOTOR CONTROLLER

AENBL

GPIO

MOTOR CONTROLLER

BPHASE

PWM

MOTOR CONTROLLER

BENBL

PWM

ARM2-1 DATA

DATA

PWM

ARM2-2 DATA

DATA

PWM

ARM2-3 DATA

DATA

PWM

ARM4-1 DATA

PWM

ARM4-2 DATA

DATA

PWM

ARM4-3 DATA

DATA

SCL1

DISPLAY

SCL

SDA1

DISPLAY

SDA

SDA0

ACCELEROMETER

SDA

SCL0

ACCELEROMETER

SCL

GPIO

ACCELEROMETER

INT

PWM

DATA

PWM

DATA

SCL2

CURRENT SENSOR

SCL

SDA2

CURRENT SENSOR

SDA

MOSI1

CAMERA

MOSI

SCK1

CAMERA

SCK

PWM

WING DATA

PWM

Extra PWM Pin

GPIO

NEOPIXEL

DATA

GPIO

POWER LED

POS

GPIO

PUSH POWER BTN

KILL

PWM

ARM3-1 DATA

DATA

RX8

WIFI MODULE

TX8

WIFI MODULE

PWM

ARM3-2 DATA

DATA

PWM

ARM3-3 DATA

DATA

CS1

CAMERA

MISO1

CAMERA

MISO

A16

MIC

OUT

A17

SPEAKER

POS

Apto’s structural design does not only influence the way it interacts with its environment but, it also determines how complex the software and hardware have to be. One of Apto’s main features is its ability to act as a two-wheeled tank driven robot or as a 4-legged quadruped robot at any given moment. It accomplishes this using an innovative mechanical design which allows for the legs to be tucked inside the wheels while driving. In the event Apto wishes to move as a quadruped (potentially to move over an obstacle), the legs can extend out of the robot and begin walking.

The arms and wheels have clearance to move due to the use of a custom designed inverted turntable gear system. Essentially the wheel of the robots acts as a bearing with its inner circumference acting as a gear which is driven by a small DC motor located at the base of the robot. This is mirrored across both sides of the robot and allows Apto to drive using a dual motor driver circuit.

Front View

Back View

Top View

Bottom View

Side View

The electrical design of the robot began with building a schematic around the hardware selected. This involved reading through the datasheets for each of the components to determine the pinout for every IC and breakout board used in the project. The next step was to map each of these pins to an input or output pin on our microcontroller. Again, to ensure the correct operation of each component, the Teensy datasheet was followed. Certain pins needed to be prioritized due to the large number of sensors, specifically to reserve PWM pins for sending data to each of the servos. To accommodate all the onboard electronics, we needed to design a custom PCB that could fit our needs. We split electrical components onto two different PCBs labelled as the main and auxiliary boards.

The software & communication hierarchy present for Apto exists as many layers working with each other to exchange data. We specifically chose to build our software hierarchy this way in order to standardize communication across an app, cloud database, and robot itself. The figure below showcases the communication between the robot, controller, app, and cloud. Note that both Bluetooth and WIFI protocols are used in this communication system. This was chosen by design as we saw Apto’s best use of Bluetooth communication was at close range where the user can visually see the response of the robot to the input. Then, the ESP8266 WIFI module is used to communicate and log telemetry data onto a cloud database. The use of Wi-Fi in this scenario is an excellent representation of how IOT is currently utilized throughout society. In our case Apto logs its data remotely to an android app to poll it and display its contents through a GUI.

DEVICE

PACKAGE

QUANTITY

MC14093B-TSSOP14

4UCONN_20329

TSSOP16

PN87520

SOT23-5

SOT23-BEC

LED-0603

CHIP-LED0603

Resistor

Capacitor

LABEL

IC1

IC2

DESCRIPTION

4093DT Quad 2-input NAND schmitt trigger for power button

INA260 Voltage Current Sensor IC

Female Micro USB Connector

Female USB-A Connector

USBBT

MCP73831 Miniature single cell fully integrated Li-Po charging IC

MMBT2222ALT1 NPN Transistor

Red charge status LED

Blue power LED

D11

LED

0603

3 Pin SMD

5 Pin SMD

16 Pin SMD

14 Pin SMD

0603

R5 Main, R2,R7 Aux

1K Ohm

R3 Main

R2 Main, R1 Aux

330 Ohm

100 Ohm

10K Ohm

100K Ohm

2K Ohm

R4 Main

R1,R8,R11,R12 Main

R3,R4,R5,R6 Aux

R6,R7 Main

Capacitor

0.1uF

1uF

4.7uF

Capacitor

C6 Main

C1 Main

C3,C4 Main

0603

The process of making a quadruped robot walk involves the development of a walking gait. A gait by definition is a person’s (or an object’s) manner of walking. Creating an effective walking gait is imperative for Apto’s mobility as it will determine how well it can traverse rough or uneven terrains. In order to develop a robot’s walking gait, we typically require an algorithm that can calculate movements of all joints based only on the desired endpoint. This concept is known as inverse kinematics which in our scenario is more desirable than traditional forward kinematics. This is because from a developer’s point of view, we only want to send commands informing our program to move Apto’s foot from x1, y1 to x2, y2. Programmatically, this can be accomplished by first declaring structures which represent the body and legs of the robot. To learn more about the software behind Apto and how exactly the walking gait is implemented, check out the complete code over on our Github.

Each arm was programmed and tested using the rig pictured above. This held the individual arms in the correct position to mimic the main chassis.

SUBSYSTEM

COMPONENT

QUANTITY

POWER

ELECTROMECHANICAL

GUIDANCE, NAVIGATIONS

AND CONTROL

NETWORK

USER INTERFACE

Lithium-Ion Polymer (LiPo) Battery (3.7V 6000mAh Stacked)

Cherry MX Switch

FQP27P06 - P-Channel MOSFET (-60V -27A)

Micro JST 2.0 Ph 2-Pin Connector Plug Male & Female

Longruner MG90S Metal Geared Micro Servo Motor 9G

⅛” Steel Ball Bearings

200

1V-6V DC Hobby Motor EK1894C

Teensy 4.1 ARM Cortex M7 Microcontroller

Arducam Mini Module Camera Shield with OV2640 2 Megapixels Lens

ESP8266 ESP-01 Serial WiFi Module

Pololu Dual Motor Driver DRV8835 Carrier (2-11V 1.2A)

MPU-6050 Accelerometer/Gyroscope IMU

Bluetooth 4.0 USB Dongle Adapter (CSR 4.0)

0.96” I2C Serial OLED Display Module (128x64)

0.5W 8 Ohm Speaker

Dual Shock Wireless PS3 Controller

5mm LED

Electret Microphone

WS2812 Neopixel Individually Addressable LED

POWER

Devices

Vin (3.7V) BAT

ARM1,2,3,4

MOTOR

NEOPIXEL

3.3v-1

WIFI MODULE

DISPLAY

CAMERA

3.3v-3 (250 mA)

MIC

ACCELEROMETER

MOTOR CONTROLLER

Logic

Teensy Output

Device

Device Input

PWM

ARM1-1 DATA

DATA

PWM

ARM1-2 DATA

DATA

PWM

ARM1-3 DATA

DATA

GPIO

MOTOR CONTROLLER

MODE

GPIO

MOTOR CONTROLLER

APHASE

PWM

MOTOR CONTROLLER

AENBL

GPIO

MOTOR CONTROLLER

BPHASE

PWM

MOTOR CONTROLLER

BENBL

PWM

ARM2-1 DATA

DATA

PWM

ARM2-2 DATA

DATA

PWM

ARM2-3 DATA

DATA

PWM

ARM4-1 DATA

PWM

ARM4-2 DATA

DATA

PWM

ARM4-3 DATA

DATA

SCL1

DISPLAY

SCL

SDA1

DISPLAY

SDA

SDA0

ACCELEROMETER

SDA

SCL0

ACCELEROMETER

SCL

GPIO

ACCELEROMETER

INT

PWM

DATA

PWM

DATA

SCL2

CURRENT SENSOR

SCL

SDA2

CURRENT SENSOR

SDA

MOSI1

CAMERA

MOSI

SCK1

CAMERA

SCK

PWM

WING DATA

PWM

Extra PWM Pin

GPIO

NEOPIXEL

DATA

GPIO

POWER LED

POS

GPIO

PUSH POWER BTN

KILL

PWM

ARM3-1 DATA

DATA

RX8

WIFI MODULE

TX8

WIFI MODULE

PWM

ARM3-2 DATA

DATA

PWM

ARM3-3 DATA

DATA

CS1

CAMERA

MISO1

CAMERA

MISO

A16

MIC

OUT

A17

SPEAKER

POS

Apto’s structural design does not only influence the way it interacts with its environment but, it also determines how complex the software and hardware has to be. One of Apto’s main features is its ability to act as a two- wheeled tank driven robot or as a 4-legged quadruped robot at any given moment. It accomplishes this using an innovative mechanical design which allows for the legs to be tucked inside the wheels while driving. In the event Apto wishes to move as a quadruped (potentially to move over an obstacle), the legs can extend out of the robot and begin walking.

The legs and wheels have clearance to move due to the use of a custom designed inverted turntable gear system. Essentially the wheel of the robots acts as a bearing with its inner circumference acting as a gear which is driven by a small DC motor located at the base of the robot. This is mirrored across both sides of the robot and allows Apto to drive using a dual motor driver circuit.

Front View

Side View

The software & communication hierarchy present for Apto exists as many layers working with each other to exchange data. We specifically chose to build our software hierarchy this way in order to standardize communication across an app, cloud database, and robot itself. The figure below showcases the communication between the robot, controller, app, and cloud. Note that both Bluetooth and WIFI protocols are used in this communication system. This was chosen by design as we saw Apto’s best use of Bluetooth communication was at close range where the user can visually see the response of the robot to the input. Then, the ESP8266 WIFI module is used to communicate and log telemetry data onto a cloud database. The use of WiFi in this scenario is an excellent representation of how IOT is currently utilized throughout society. In our case Apto logs its data remotely to an android app to poll it and display its contents through a GUI.