Hemio: the Hemispherical Robot

Hemio the hemispherical bot. This robot unfolds from a bowl/hemisphere shape and can be programmed to move in any direction needed. This instructable contains the instructions to assemble the bot. The bot files can be found on Thingieverse.

Working of this bot can be found here:

Click here to view demo video

above are the important components other than the files.

The m2 screws shown: quantity - 15+

Servo motors: x8

16 Channel Servo driver x1

ESP32 x1

Mount a 4 servo motors on the serv_hold part as shown.

make screw holes onto this bottom_leg part as shown.

Do the same the top_leg part too.

attach the servo horn to bottom_leg. Similarly repeat for the remaining bottom leg parts.

attach both top_leg and bottom_leg parts to second_servo_holdd part

finally attach the combined parts to the ball_shell part. The rods of the top_leg and bottom_leg part should be inserted into any two holes of the ball_shell part(depending on the height you want to set it).

NOTE: There needs to be one empty hole gap between the rods.

attach the second_servo_holdd part to the first_serv_hold part. repeat for the remaining parts.

finally you will have a cool looking robot, Hemio. You can code the servo motors using your preferred microcontroller.

Connect all 8 servo motors to this servo driver.

And refer 16 channel seeervo driver connections to esp32 and connect them.

#include <Wire.h>

#include <Adafruit_PWMServoDriver.h>

// Create the PWM servo driver object

Adafruit_PWMServoDriver pwm = Adafruit_PWMServoDriver();

#define SERVOMIN 150 // Minimum pulse length count

#define SERVOMAX 600 // Maximum pulse length count

#define STEP_DELAY 20 // Delay between steps (in milliseconds)

#define STEP_COUNT 10 // Number of steps for the transition

#define x 200

void setup() {

Serial.begin(9600);

pwm.begin();

pwm.setPWMFreq(50); // Analog servos run at ~50 Hz PWM

delay(10);

}

// Convert angle (0 to 180) to pulse length

uint16_t angleToPulse(int angle) {

return map(angle, 0, 180, SERVOMIN, SERVOMAX);

}

// Set custom positions for all 8 servos smoothly

void setServoPositionsSmooth(int targetPositions[8], int currentPositions[8]) {

for (int step = 0; step <= STEP_COUNT; step++) {

for (int i = 0; i < 8; i++) {

// Calculate intermediate position

int intermediatePosition = currentPositions[i] + (targetPositions[i] - currentPositions[i]) * step / STEP_COUNT;

pwm.setPWM(i, 0, angleToPulse(intermediatePosition));

}

delay(STEP_DELAY); // Delay to create smooth motion

}

// Update current positions to the target positions

for (int i = 0; i < 8; i++) {

currentPositions[i] = targetPositions[i];

}

}

void loop() {

static int currentPositions[8] = {45, 45, 45, 45, 45, 45, 45, 45}; // Initial current positions

int targetPositions1[8] = {120, 120, 120, 120, 50, 50, 50, 50}; // First target positions

// Smoothly transition to the first target positions

setServoPositionsSmooth(targetPositions1, currentPositions);

delay(x); // Wait before moving to the next position

// Define the next target positions

int targetPositions2[8] = {30, 30, 30, 30, 80, 80, 80, 80}; // Next target positions

// Smoothly transition to the next target positions

setServoPositionsSmooth(targetPositions2, targetPositions1);

delay(x); // Wait before the next loop

int targetPositions3[8] = {30, 30, 30, 30, 100,100, 100, 100}; // Next target positions

// Smoothly transition to the next target positions

setServoPositionsSmooth(targetPositions3, targetPositions2);

delay(x); // Wait before the next loop

int targetPositions4[8] = {30, 30, 30, 30, 130, 130, 130, 130}; // Next target positions

// Smoothly transition to the next target positions

setServoPositionsSmooth(targetPositions4, targetPositions3);

delay(x); // Wait before the next loop

int targetPositions5[8] = {20, 20, 20, 20, 100,100, 100, 100}; // Next target positions

// Smoothly transition to the next target positions

setServoPositionsSmooth(targetPositions5, targetPositions4);

delay(x); // Wait before the next loop

int targetPositions6[8] = {20, 20, 20, 20, 80, 80, 80, 80}; // Next target positions

// Smoothly transition to the next target positions

setServoPositionsSmooth(targetPositions6, targetPositions5);

delay(x); // Wait before the next loop

int targetPositions7[8] = {20, 20, 20, 20, 110, 110, 110, 110}; // Next target positions

// Smoothly transition to the next target positions

setServoPositionsSmooth(targetPositions7, targetPositions6);

delay(x); // Wait before the next loop

int targetPositions8[8] = {70, 70, 70, 70, 50, 50, 50, 50}; // Next target positions

// Smoothly transition to the next target positions

setServoPositionsSmooth(targetPositions8, targetPositions7);

delay(x); // Wait before the next loop

// You can define more target positions and repeat as needed

}