# The Development of Teleoperated Driving to Cooperate with the Autonomous Driving Experience
## 3 Designs and Developments
### Vehicles  
The prototype vehicle developed for this study is based on the EVT Plus D 6s electric multi-purpose golf cart, modified to incorporate electronic steering control via a steer-by-wire system. Since the base model lacks an electric power steering (EPS) system, a DC motor (24 V, 350 W, 450 rpm) was selected to provide sufficient torque--estimated at 17.6 Nm with a safety factor of two--for stationary steering. The torque was amplified using a belt gear system, tripling the motor output. To monitor the steering position, a 10 k\(\Omega\), 10-turn potentiometer was installed via custom gear teeth to avoid over-rotation and damage. The steering system is controlled using an Arduino board, which sends PWM signals to a high-capacity H-bridge DC motor driver capable of supporting up to 200 A and voltages of 12-36 V. A PID controller ensures fast and accurate adjustments through continuous feedback. Because electric golf carts lack direct speed feedback, two measurement systems were developed. The first uses the internal speed sensor of the CURTIS 1268 controller, which outputs a frequency signal proportional to the vehicle's speed. This frequency was calibrated using 2D LiDAR to correlate the measured displacement with speed values. The second method involves a wheel-mounted incremental rotary encoder with a resolution of 60 pulses per revolution, connected via a 6 mm flexible cable. This dual-sensor setup provides reliable and redundant speed tracking under various conditions. For throttle control, voltage readings from the potentiometer ranged from 0 to 4.4 V, correlating directly with speed. A 12-bit MCP4922 DAC was used to regulate this voltage via SPI, with effective values ranging from 0 to 3600 out of a maximum of 4095. For braking, to avoid direct control of hydraulic pressure, a 400 W servo motor provides torque, which is converted into linear force using a five-lead ball screw to actuate a custom hydraulic pump. The motor operates in torque control mode, responding to inputs between \(-\)10 V and +10 V. Since the control board provides only 0-5 V, an op-amp circuit was designed to convert this signal appropriately. The integrated control unit, including comprising steering, speed, and braking systems, is compactly housed beneath the vehicle's second-row seat. To support onboard electronics, a compact lightweight  
Figure 3: Illustrates the overall software and communication architecture, highlighting the modular structure, inter-node communication, and fallback safety logic. LiFePO4 battery with an active balancing battery management system (BMS) was selected. This setup improves efficiency and safety while reducing weight, as detailed in Figure 4.  
The electrical system shown in Figure 4 powers all vehicle control modules and sensors. It distributes regulated voltage from the main battery to subsystems such as the steering motor, brake actuator, and throttle emulator, which are central to both autonomous and teleoperated control. Additionally, power is supplied to the on-board computing units running ROS and Autoware, the 5G modem for real-time communication, and peripherals such as LiDAR and GNSS receivers. This system ensures stable operation of all components involved in low- and high-level control logic. For safety, the vehicle includes two emergency stop modes. The first, accessible from either the vehicle or a control station, halts automation and fully engages the brake until a complete stop is reached. The second mode, operable only via a button on the vehicle, cuts off power to all accessories except the computer and communication modules. To facilitate environmental sensing, a Velodyne VLP-16 3D LiDAR scanner is mounted on the vehicle's roof. Emitting 16 laser beams in a \(\pm 15^{\circ}\) vertical range while rotating 360\({}^{\circ}\) horizontally, the LiDAR calculates object distance using time of flight (TOF). Positioned 2.5 m high, it ensures full forward visibility and avoids roof interference. A three-axis adjustable mount enables tuning for varied tasks.