DC motors are a popular choice for remote-controlled vehicle projects due to their simplicity, high efficiency, and ease of control. According to Hughes and Drury (2013), brushed DC motors are cost-effective and suitable for small-scale applications [27]. In the ”Multi-mode RC Car” project, the DC motor serves as the primary driving force, enabling the car to move flexibly and respond quickly to control signals.
Classification of DC Motors
DC motors are typically divided into two main types:
• Brushed DC Motor:This is the most common type of DC motor, characterized by its simple design and low cost. However, due to the direct contact of brushes with the rotating part, they are prone to wear and require maintenance after prolonged use.
• Brushless DC Motor (BLDC):These motors offer higher efficiency and durability as they do not have brushes. However, they are more expensive and require complex control circuitry.
In this project, the selected motor is abrushed DC motordue to its low cost, ease of control, and suitability for small applications like remote-controlled cars.
Specifications of 6V 200RPM DC Motor
Figure 2.12 shows a DC motor with two main connections, demonstrating simplicity in design, yet providing flexible control of speed and direction of rotation. This diagram emphasizes how the current is used directly to convert the control signal into driving force, ensuring high performance in practical applications.
• Operating Voltage:3V - 12V (optimal at 6V)
• No-load Current: 70 - 150mA
• Stall Current:Up to 1A
Figure 2.12: DC Motor
• Rotation Speed:200 RPM at 6V
• Torque:0.8 kgãcm
• Motor Shaft Diameter:5mm (compatible with common wheels)
• Motor Weight:Approximately 50 - 80g (depending on type)
• Average Lifespan: 1000 - 2000 continuous operating hours Controlling the DC Motor
The DC motor has two primary connection terminals:
• Terminal 1 (Motor +): This is the positive terminal, receiving positive voltage from the controller or H-Bridge circuit.
• Terminal 2 (Motor -):This terminal is grounded or reverses the voltage to rotate the motor in the opposite direction.
To adjust motor speed, Pulse Width Modulation (PWM) is applied. PWM allows modification of the average voltage supplied to the motor, thereby controlling the rotational speed.
H-Bridge Circuit - DC Motor Direction Control
The H-Bridge circuit is a widely used circuit designed to control the direction of a DC motor by reversing the current flowing through the motor. It is named ”H-Bridge” because its structure resembles the letter ”H”, with the DC motor placed in the middle of the ”bridge”. In this project,L298N ICis used to control two independent DC motors.
Operating Principle
The H-Bridge circuit consists of four switches (typically MOSFETs or transistors) arranged to form two parallel branches. By selectively opening and closing these switches, the circuit controls the flow of current through the motor, thereby determining its rotation direction. The key operating states of the H-Bridge circuit are:
• Forward Rotation: Switches S1 and S4 are closed, while S2 and S3 remain open. Current flows from the positive terminal, through S1, the motor, and S4, and then returns to the negative terminal.
• Reverse Rotation: Switches S2 and S3 are closed, while S1 and S4 remain open. Current flows from the positive terminal, through S3, the motor, and S2, and then returns to the negative terminal.
• Motor Stop: All switches are open, preventing current from flowing through the motor.
• Motor Braking: Two switches on the same branch (e.g., S1 and S2, or S3 and S4) are closed simulta- neously. This creates a short circuit across the motor, generating resistance and stopping the motor more quickly.
L298N Specifications:
• Input Voltage:5V - 35V
• Maximum Current:2A per channel
• Number of Channels:2 (capable of controlling two motors)
• Control Mode:PWM control to adjust motor speed Application of DC Motors in Multi-mode RC Car
• Wheel Drive System:Two DC motors are mounted on the rear wheels to provide the main driving force.
• Steering and Direction Mechanism: A small motor or servo is responsible for controlling the front wheels’ direction.
• Autonomous Mode:The DC motors work in combination with the HC-SR04 ultrasonic sensor to avoid obstacles in autonomous mode.
Comparison of DC Motors with Other Motor Types
Motor Type Advantages Disadvantages
Brushed DC Motor Easy to control, low cost Wears quickly, lower efficiency Brushless DC Motor High efficiency, durable Expensive, complex control
Stepper Motor Precise positioning, small steps Low speed, complex design Servo Motor Precise angle control Low torque, limited to 180°
Table 2.4: Comparison of DC Motors and Other Motor Types
Table 2.4 provides an overview of common motor types, including: Brushed DC Motor, Brushless DC Motor, Stepper Motor, and Servo Motor. Each motor type is evaluated through two main criteria: advantages and disadvantages, helping readers better understand the features and limitations of each type.
In addition, table 2.4 provides an overview so that users can easily compare and choose the motor type that best suits the requirements of the project. In applications that require precision and reasonable cost, stepper motors or servo motors may be the ideal choice. Meanwhile, for simpler requirements, brushed DC motors are the economical choice. If durability and performance are a priority, brushless DC motors will be the top choice, despite the higher cost.
Conclusion
DC motors are an ideal choice for the Multi-mode RC Car project due to their simplicity, ease of integration, and low cost. This motors can be applied in RC cars, fans, drones, electric vehicles, 3D printers, CNC machines, etc. Combined with the L298N H-Bridge circuit, the system can accurately control the speed and direction of movement, fulfilling operational requirements in both remote control and autonomous modes.