I have Hacked Tower SG90 for continuous rotation. I can control it for forward and backward motion. But I don't know how to stop the servo. I am using arduino nano to control Servo. Here is my code :
#include <Servo.h>
Servo myservo; // create servo object to control a servo
void setup() {
myservo.attach(14);
}
void loop() {
myservo.write(0); // for forward motion
delay(1000);
myservo.write(180); // for backward motion
delay(1000);
}
myservo.write(90)
From Arduino Documentation
Writes a value to the servo, controlling the shaft accordingly. On a
standard servo, this will set the angle of the shaft (in degrees),
moving the shaft to that orientation. On a continuous rotation servo,
this will set the speed of the servo (with 0 being full-speed in one
direction, 180 being full speed in the other, and a value near 90
being no movement).
Related
I have tried varying the duty cycle of the servo motor but it only turns 180 degrees clockwise and anti-clockwise.
You need some measurement device to read the angle, if you want to stick with that servo. With the angle you can implement a closed-loop transfer function to approach the angle you want.
Servos as the FS90R are "continuously rotation servos" and the control signals sets the speed (exactly: the driving current, giving the torque) and direction. For example, see this fine explanation.
If you want to control the angle directly by the control signal, you need "the other" type of servo, described earlier in the linked Wikipedia page.
I'm trying to control my 180 degree servo motors through a Adafruit 1411 Servo shield. However I don't find it simple enough to write the servo's position in angles like the normal servo library without the shield.
Using the Adafruit 1411 Servo shield and Adafruit_PWMServoDriver-library lets you control a servomotor by modifying its pulselength as far as I've realised. To my question..
Is there a way for me to either use the servo shield's output and still write in degrees OR somehow convert these pulselength into angle-degree?
Example of the differences:
Adafruit_PWMServoDriver-library:
pwm.setPWM(Servo, 0, pulseLength);
Servo-library:
Servo.write(45); //Writing in angles like this would be optimal for my project.
Any help in the right direction is much appreciated!
Use the Arduino map function. The following is from the Adafruit instructions:
pulselength = map(degrees, 0, 180, SERVOMIN, SERVOMAX);
Where SERVOMIN and SERVOMAX are values you set according to the range of travel of your servo. This linearly maps a value between 0 and 180 into the range between SERVOMIN and SERVOMAX.
Since you've been doing this with pulse widths so far, you probably already knew the values you need to use.
I have been struggling with arduino and ultrasonic sensor HC-SR04 and PWM.
I am using arduino pro mini. Also using NewPing library.
the newping library example works perfectly if I have just the sonar attached and I get about 170cm when pointing upwards towards the ceiling.
However if I add a pwm call on a different pin(pin 3 in this case) the sonar outputs maximum of 41cm, everything below that works, albeit bit noisily.
I have almost nothing connected to the pwm pin, there is only a capasitor and a resistor. I had a motor as well but removed it for debugging.
Illustration of my wiring:
code:
#include <NewPing.h>
#define TRIGGER_PIN 8 // Arduino pin tied to trigger pin on the ultrasonic sensor.
#define ECHO_PIN 7 // Arduino pin tied to echo pin on the ultrasonic sensor.
#define MAX_DISTANCE 200
NewPing sonar(TRIGGER_PIN, ECHO_PIN, MAX_DISTANCE);
int p = 3;
void setup() {
// put your setup code here, to run once:
pinMode(p,OUTPUT);
Serial.begin(115200);
}
void loop() {
delay(50); // Wait 50ms between pings (about 20 pings/sec). 29ms should be the shortest delay between pings.
Serial.print("Ping: ");
int d = sonar.ping_cm();
Serial.print(d); // Send ping, get distance in cm and print result (0 = outside set distance range)
Serial.println("cm");
analogWrite(p,d);
}
The problem does disappear if I remove everything from the pin 3, but I don't see how this wiring can have any effect, especially with the motor missing.
Any ideas how to get the sonar and pwm working at the same time.
Check the pin color of your HC-SR04. Models with "brass" colored pins have a defect. They might and will return false readings. Models with "silver-y-ish" pins are more precise. The defect isn't there.
Also, try using pins 2 & 3 for the distance sensor and something else for the PWM.
So, I need to build a simple gimbal with three servos to control pitch, roll and yaw. I have a 9dof imu which can give me the euler angles in degrees. Can I just connect these angle errors to servo outputs? As in with 1 degree error, the servo should rotate 1 degree, or do I have to use some form of pid control? I have worked with controlling regular dc motors with pid so that the bigger the error, the faster the motor should rotate to compensate. But it's not like I can adjust the speed the servo rotates at.
I recon there would be a problem when the angle error becomes very high in a small amount of time since the servo would take more time to reach the desired position instead of when the error is very small.
I did a similar project. It isn't perfect, but good enough. Cheap servos can't really be precise because of the cheap potentiometer inside and the horrible plastic gears.
There wont be much error overtime because common servos use a potentiometer and not a rotary encoder. Thus a PID is almost impossible.
I'm trying to create a robot using three HC-SR04 ultrasonic sensors and my Arduino Pro Mini but I've run into a few problems. In short the robot's function is as follows:
The robot is dual wheeled, with an H-bridge (SN754410) driving each wheel.
There's one HC-SR04 sensor on each side of the robot, the left one activates the left wheel motor when it detects a hand in front of it, vice versa for the right side.
i.e. To make the robot go forward, we place our hands near the left and right side of the robot, to make it turn right, we remove the right hand and keep the left one in place, vice versa for turning left, etc.
A third HC-SR04 is located the top of the robot, such that it activates a third motor when the user's hand is hovering above the robot.
My test code is as follows:
#include <NewPing.h>
#define SONAR_NUM 3 // Number of sensors.
#define MAX_DISTANCE 20 // Maximum distance (in cm) to ping.
NewPing sonar[SONAR_NUM] = { // Sensor object array.
NewPing(4, 5, MAX_DISTANCE), // Each sensor's trigger pin, echo pin, and max distance to ping.
NewPing(6, 7, MAX_DISTANCE),
NewPing(8, 9, MAX_DISTANCE)
};
#define ena1 10 //trigger for left motor H-bridge
//#define ena2 11 //trigger for right motor
//#define ena3 12 //for top motor
long sensors[3]; //array to store sensor distances
void setup() {
Serial.begin (115200);
pinMode(ena1, OUTPUT);
//pinMode(ena2, OUTPUT);
//pinMode(ena3, OUTPUT);
}
void loop() {
for (uint8_t i = 0; i < SONAR_NUM; i++) { // Loop through each sensor and display results.
delay(50); // Wait 50ms between pings (about 20 pings/sec). 29ms should be the shortest delay between pings.
sensors[i] = sonar[i].ping_cm();
}
Serial.println(sensors[0]);
if (sensors[0] > 0 && sensors[0] <= 20){
Serial.println("detected");
digitalWrite(ena1, HIGH);
}else{
Serial.println("NA");
digitalWrite(ena1,LOW);
}
}
As you can see, I'm using the NewPing.h library to collect the sensor data. After each iteration of the for loop, the distances detected by the sensors are stored in a sensor array. When a hand is placed about 15-20 cm away from a sensor, the arduino sends a digital "HIGH" trigger signal to the respective H-bridge, activating the respective motor (I only have one of these pins, "ena1", enabled in my code, the other two are commented for the test).
To test my code, I simply connected the H-bridge trigger pin "ena1" to an LED, this pin is activated by the sensor whose distance data is stored in variable "sensors[0]". However, after I compile and upload my code, I notice that the LED simply flickers faintly as I put my hand in front of the sensor. As if the LED is being turned on and off very fast.
The output from the serial monitor is as follows:
15
detected
0
NA
16
detected
0
NA
14
detected
As you can see, by putting my hand about ~15cm in front of the sensor, the sensor returns the correct distance and the "ena1" pin is set to high (as evidenced by "detected" being printed to the screen).
However, the sensor always returns a "0" value at the next iteration of the main loop (while my hand is still in front of the sensor), subsequently setting the "ena1" pin to LOW again, which might explain why the LED is being turned on and off so fast.
I'm not sure why this is happening... Interestingly, by removing the digitalWrite lines from the code, the sensor returns the correct values (i.e. no "0" value when my hand is in front of the sensor).
Any ideas on how I can fix this?
Thanks in advance!
This might be a hardware error. I've seen cases where, if the pins of the HC-SR04 were a brass (gold-ish) color, the sensor had a tendency to throw out a 0 for distance.
My suggestion is to get an other ultrasonic sensor, preferably with more silver-ish colored pins.
Your code looks good though!
Good luck!