As one of the most widely used types of AGV motors, low-voltage servo motors rely not only on the motor body itself but also critically on the selection of connectors for system stability.

The quality of AGV motor connectors directly impacts the performance of AGV equipment. To select a high-quality AGV motor connector, consider the following aspects:
I. Electrical Performance
The electrical performance of a connector primarily includes current rating, contact resistance, insulation resistance, and dielectric strength. For instance, when connecting high-power AGV motors, attention must be paid to the connector's current rating.

II. Mechanical Performance
Mechanical performance includes mating force and mechanical polarization. Mechanical polarization is crucial for DC systems; reverse insertion can cause irreversible damage to the circuit!

III. Termination Method
The termination method refers to how the connector contacts connect to the cable. Selecting the appropriate termination method and using the correct termination technology are critical aspects of connector selection and usage. The most common methods are soldering and crimping. Compared to soldering, high-quality AGV motor connectors should utilize crimping. This provides superior mechanical strength and electrical continuity, allowing the connector to withstand harsher environmental conditions. It is also more suitable for mobile equipment like AGV motors than traditional soldering methods.

IV. Environmental Performance
Environmental performance primarily includes temperature resistance, moisture resistance, salt spray resistance, vibration resistance, and shock resistance. Selection should be based on the specific application environment. For example, in humid environments, higher requirements for moisture and salt spray resistance are necessary to prevent corrosion of the connector's metal contacts. Therefore, selecting an AGV motor connector with suitable environmental performance is particularly important!

V. Installation Method and Form Factor
Connectors come in a wide variety of shapes. Users should primarily select based on straight or right-angle configurations, wire or cable outer diameter, housing fixation requirements, volume, weight, and the need for metal conduit connections. For panel-mounted connectors, selection should also consider aesthetics, styling, and color.

There is a wide variety of AGV motors and application fields, so supporting connectors must be selected based on actual conditions. Leveraging years of experience in servo motor R&D and application, Beijing Hollysys Motor has developed motor leads and adapter cables equipped with various connectors, tailored to AGV industry requirements and the specific usage details of various AGV motors. We will continue to closely follow market trends, providing partners with rapid, comprehensive, and multi-domain motion control products and solutions to create greater value for industry users!

The servo electric wheel, independently developed by Beijing Hollysys Electric Motor, is a product featuring an integrated design of an outer rotor low-voltage servo motor and a tire. Also known as a servo hub motor, it is a variation of the low-voltage servo motor, possessing the high response speed and high positioning accuracy characteristic of servo motors. It can replace the traditional "motor + reducer + tire" structure in AGVs, eliminating the need for additional reducers and external wheels. This results in a simple structure, compact size, and easy installation. Consequently, an increasing number of AGV drive systems are adopting the "servo electric wheel (servo hub motor) + caster wheel" configuration. In addition to the servo characteristics of the low-voltage servo motor ensuring the high-precision, autonomous, and stable operation of the AGV, the selection of tire material is also crucial.
Currently, the tires used in Hollysys Electric Motor's servo electric wheels are primarily made of two materials: rubber and polyurethane. So, what are the respective advantages and disadvantages of rubber and polyurethane tires in AGV motor applications, and which scenarios are they best suited for?

I. Shock Absorption Performance
A tire's shock absorption capability is related to the hardness of its material; the harder the tire, the lower its ability to absorb impact, and the poorer its cushioning performance. Rubber tires have a softer tread and stronger shock absorption, whereas polyurethane tires are harder and offer inferior cushioning. AGVs equipped with rubber-tired servo electric wheels can operate both indoors and on outdoor roads, accommodating diverse operating environments. In contrast, polyurethane tires are generally limited to AGVs operating indoors.

II. Load-Bearing Capacity
The load-bearing capacity of polyurethane tires is approximately twice that of rubber tires. For this reason, hub servo motors for heavy-duty AGVs typically utilize polyurethane tires.

III. Wear Resistance
During operation, when rubber tires experience conventional wear from road contact, they typically shed debris from the tread, leading to abrasive wear and fatigue wear. Polyurethane is a tougher material capable of withstanding wear from rough surfaces; it produces significantly less debris compared to rubber tires. The service life of polyurethane is approximately 4 to 5 times that of rubber, and its wear resistance is twice as high. Consequently, using polyurethane tires reduces the frequency of tire replacements and the associated labor costs.

IV. Tire Color
Tires made of polyurethane can be produced in various colors, such as yellow or red, allowing for color customization to match the overall design of the equipment. Most rubber tires we see are black because the rubber used to make tires must be durable and wear-resistant, properties that pure rubber lacks. To prevent issues such as blowouts or slippage during operation, a substance called "carbon black" must be added during the manufacturing process. It is the addition of this carbon black that gives rubber tires their black color.

V. Floor Markings
The basic chemical composition of polyurethane ensures that polyurethane tires do not leave marks on the ground; even brightly colored tires will not leave any traces of colorant. However, as rubber tires wear down, the carbon black used as a compounding agent can "shed" onto the ground. Additionally, friction between the ground and the tire softens the rubber, causing it to adhere to the surface and leave marks.

VI. Cost-Effectiveness
Due to differences in raw materials, rubber tires are 25% to 50% cheaper than polyurethane tires. Although polyurethane tires are more expensive, their longer service life offers a distinct advantage in terms of cost-effectiveness.

VII. Heat Build-Up
If polyurethane has a critical weakness, it is heat generation. Polyurethane tires cannot rapidly dissipate internally generated heat. Their normal upper operating temperature limit is generally between 80°C and 90°C. As the temperature rises, dynamic physical properties such as fatigue resistance and flex resistance of the polyurethane material decline significantly, leading to premature tire failure.

In summary, polyurethane tires possess distinct advantages in load-bearing capacity and wear resistance. They are suitable for AGVs operating indoors under conditions requiring high loads, energy efficiency, clean and trace-free environments, or on slippery surfaces. Rubber tires, leveraging advantages such as strong shock absorption and high adhesion, are applied to low-load AGV transport carts that operate both indoors and outdoors and require highly stable operational performance.

 
Servo electric wheels (servo hub motors) are critical for the high-precision and stable operation of AGV transport robots and various service robots. As a supplier of servo electric wheels, Beijing Hollysys Electric Motor will continue to focus on product design and manufacturing processes, constantly improving and refining our offerings to provide the logistics and service robot industries with more optimized and diverse choices.

With the widespread application of AGVs, their supporting products have become increasingly standardized. As the core component responsible for converting electrical energy into mechanical energy, the low-voltage motor plays a crucial role in AGVs; its performance parameters directly determine the vehicle's power and safety. There are four primary types of AGV motors: brushed DC motors, brushless DC motors, DC servo motors, and stepper motors. The power supply typically used is DC24V, DC36V, or DC48V. It is essential to select the appropriate type of AGV motor based on specific application requirements.

When selecting an AGV motor, users should consider their specific starting points and priorities to choose the appropriate motor. If the AGV prioritizes precise control of speed or position, a low-voltage servo motor is recommended; if the AGV does not require high speed regulation accuracy, a brushless motor may be used.

Since their launch, Hollysys Motor's independently developed low-voltage servo motors and integrated low-voltage servo drives have been favored by mobile robot manufacturers. They are currently widely used in various autonomous mobile equipment, including warehousing AGVs, logistics AGVs, various AMRs, stackers, and construction robots.

Leveraging years of technical expertise in the R&D of servo motors and servo drives, Hollysys Electric's low-voltage servo motors and drives are highly acclaimed by AGV/AMR users. In recent years, responding to the demands of the service robot industry, the company has launched a "compact and economical" low-voltage servo electric wheel (also known as a low-voltage servo hub) system. This system includes the two-in-one low-voltage servo drive DS20230E and the 8030 series servo electric wheel.

The low-voltage servo drive DS20230E utilizes a third-generation DSP platform, leveraging the powerful performance of the TMU, FPU, and FDIV to achieve precise control over the position, speed, and torque of the servo electric wheel. In terms of hardware, this low-voltage servo drive employs compact power devices and streamlined I/O ports. By integrating the control board and power board into a single PCB layer, the drive's volume has been significantly reduced, leading to lower costs.

The 8030 series servo electric wheel, featuring an integrated motor and outer wheel design, is an ideal adaptation of the low-voltage servo motor. It inherits excellent characteristics such as high precision and high response speed. Eliminating the need for reduction gears, its easy installation and simple structure significantly improve the space utilization of the vehicle chassis. Furthermore, this low-voltage servo electric wheel offers excellent low-speed performance and rapid braking to ensure system safety. Its quiet operation meets environmental noise requirements, while its energy-saving design allows for ultra-long standby times and continuous operation. It also features multiple protection mechanisms, including a built-in temperature sensor, and boasts strong load-bearing capacity, with the two-wheel differential structure supporting loads up to 60kg.

The system composed of Hollysys Electric's low-voltage servo electric wheels and two-in-one low-voltage servo drives has been widely applied in various service robot scenarios with strict size requirements, such as disinfection robots, delivery robots, inspection robots, inventory robots, guide robots, and small cleaning robots. As always, we will strive for continuous innovation to provide more low-voltage servo products for the autonomous mobile industry, including AGVs/AMRs and service robots.

Stepper motors are discrete motion devices that are intrinsically linked to modern digital control technology. Currently, stepper motors are widely used in domestic digital control systems. With the emergence of fully digital AC servo systems, AC servo motors are increasingly being applied in digital control systems. To adapt to the development trend of digital control, motion control systems mostly employ stepper motors or fully digital AC servo motors as actuating motors. Although they are similar in control mode (pulse train and direction signals), there are significant differences in their performance and application scenarios. A comparison of their performance is presented below.

    1. Different Control Precision
    The step angle of two-phase hybrid stepper motors is generally 3.6° or 1.8°, while that of five-phase hybrid stepper motors is generally 0.72° or 0.36°. Some high-performance stepper motors have even smaller step angles. For example, a stepper motor produced by Beijing Hollysys Motor Technology Co., Ltd. (formerly Sifang Motor) for slow-moving wire cutting machines has a step angle of 0.09°. Three-phase hybrid stepper motors can have their step angles set to 0.9°, 0.72°, 0.36°, 0.18°, 0.09°, 0.072°, 0.036°, etc., via DIP switches, making them compatible with the step angles of two-phase and five-phase hybrid stepper motors.
    The control precision of AC servo motors is guaranteed by the rotary encoder at the rear end of the motor shaft. Taking a certain imported brand motor as an example, for a motor with a standard 2500-line encoder, since the driver uses quadruple frequency technology internally, its pulse equivalent is 360°/10000 = 0.036°. For motors with a 17-bit encoder, the motor rotates one revolution for every 2^17 = 131,072 pulses received by the driver, meaning its pulse equivalent is 360°/131072 = 9.89 arcseconds. This is 1/655 of the pulse equivalent of a stepper motor with a step angle of 1.8°.

    2. Different Low-Frequency Characteristics
    Stepper motors are prone to low-frequency vibration at low speeds. The vibration frequency is related to the load situation and driver performance, and is generally considered to be half of the motor's no-load starting frequency. This low-frequency vibration phenomenon, determined by the working principle of stepper motors, is very detrimental to the normal operation of the machine. When stepper motors work at low speeds, damping technology is generally used to overcome low-frequency vibration, such as adding a damper to the motor or using subdivision technology in the driver.
    AC servo motors run very smoothly and do not exhibit vibration even at low speeds. AC servo systems have resonance suppression functions that can cover for insufficient mechanical rigidity. Additionally, the system has an internal frequency analysis function (FFT) that can detect mechanical resonance points, facilitating system adjustment.

    3. Different Torque-Frequency Characteristics
    The output torque of a stepper motor decreases as the speed increases, and drops sharply at higher speeds, so its maximum operating speed is generally 300–600 RPM. AC servo motors provide constant torque output; that is, they can output rated torque within their rated speed (generally 2000 RPM or 3000 RPM), and constant power output above the rated speed.

    4. Different Overload Capacity
    Stepper motors generally do not have overload capacity. AC servo motors possess strong overload capacity. Taking the Sencron AC servo system as an example, it has speed overload and torque overload capabilities. Its maximum torque is three times the rated torque, which can be used to overcome the inertial torque of inertial loads at the moment of starting. Since stepper motors lack this overload capacity, a motor with larger torque is often required during selection to overcome this inertial torque. However, the machine does not require such a large torque during normal operation, resulting in a waste of torque.

    5. Different Operating Performance
    Stepper motor control is open-loop control. If the starting frequency is too high or the load is too large, phenomena such as lost steps or stalling are likely to occur. When stopping, if the speed is too high, overshoot is likely to occur. Therefore, to ensure control precision, the issues of acceleration and deceleration must be handled properly. The AC servo drive system is closed-loop control. The driver can directly sample the feedback signal from the motor encoder, forming a position loop and a speed loop internally. Generally, phenomena like lost steps or overshoot associated with stepper motors do not occur, making the control performance more reliable.

    6. Different Speed Response Performance
    It takes a stepper motor 200–400 milliseconds to accelerate from a standstill to working speed (generally several hundred revolutions per minute). AC servo systems have better acceleration performance. Taking a certain brand's 400W AC servo motor as an example, it only takes a few milliseconds to accelerate from a standstill to its rated speed of 3000 RPM, making it suitable for control occasions requiring rapid start and stop.

    In summary, AC servo systems are superior to stepper motors in many performance aspects. However, stepper motors are also frequently used as actuating motors in applications with less stringent requirements. Therefore, in the process of designing a control system, factors such as control requirements and cost must be comprehensively considered to select the appropriate control motor.

   In the family of speed reducers, planetary reducers are widely used in transmission systems for control motors such as servo, stepper, and brushless DC motors (hereinafter referred to as drive motors) due to numerous advantages such as compact size (basically the same diameter as the motor), high transmission efficiency (85-90%), wide reduction range (1:3-100), and high precision (small backlash). While ensuring precise transmission, they can reduce speed, increase torque, and reduce the ratio of load inertia to drive motor inertia. However, in actual use, faults caused by improper installation often occur; shaft breakage of the reducer and drive motor is one of the main fault types. Analyzing the mechanism of shaft breakage helps customers understand how to correctly install planetary reducers and better utilize their functions.
I. Shaft Breakage Issues Caused by Non-Concentricity
      Some users experience breakage of the drive motor's output shaft after the equipment has been running for a while. Why does the drive motor's output shaft twist off? When we carefully examine the cross-section of the broken drive motor output shaft, we find that the outer ring of the cross-section is relatively bright, while the color of the cross-section becomes darker towards the center of the shaft, finally showing fracture marks (point-like marks) at the shaft center. This phenomenon is mostly caused by the non-concentricity of the drive motor and the reducer during assembly.

       When the concentricity between the drive motor and the reducer is well guaranteed during assembly, the drive motor output shaft only bears rotational force (torque), and the operation will be very smooth without a pulsating sensation. When they are not concentric, the drive motor output shaft also bears radial force (bending moment) from the reducer's input end. The effect of this radial force will force the drive motor output shaft to bend, and the direction of bending will constantly change as the output shaft rotates. If the concentricity error is large, this radial force causes the local temperature of the motor output shaft to rise, and its metal structure is continuously damaged, eventually leading to the fracture of the drive motor output shaft due to local fatigue. The greater the concentricity error between the two, the shorter the time until the drive motor output shaft breaks. At the same time as the drive motor output shaft breaks, the reducer input end also bears radial force from the drive motor output shaft. If this radial force exceeds the maximum radial load that the reducer input end can bear, the result will also cause deformation or even fracture of the reducer input end or damage to the input support bearing. Therefore, ensuring concentricity during assembly is crucial!
       Analyzing from the assembly process, if the drive motor shaft and the reducer input end are concentric, then the drive motor shaft surface and the reducer input end hole surface will fit very well, their contact surfaces will be tightly attached, and there will be no radial force or space for deformation. If they are not concentric during assembly, there will be misalignment or gaps between the contact surfaces, creating radial force and providing space for deformation.
      Similarly, the output shaft of the reducer may also break or bend, and the reasons are the same as those for the drive motor shaft breakage. However, the output of the reducer is the product of the drive motor output and the reduction ratio, so the output is greater relative to the motor, making the reducer output shaft more prone to breakage. Therefore, when users use the reducer, they should pay even more attention to ensuring concentricity during the assembly of its output end!
II. Shaft Breakage Issues Due to Insufficient Reducer Output
       If it is not the drive motor shaft that breaks, but the reducer output shaft that breaks, in addition to poor concentricity in the assembly of the reducer output end, there are the following possible reasons.
       First, incorrect selection results in insufficient output of the matched reducer. Some users mistakenly believe that as long as the rated output torque of the selected reducer meets the working requirements, it is sufficient, but this is not the case. First, the value obtained by multiplying the rated output torque of the matched drive motor by the speed ratio must in principle be less than the corresponding rated output torque provided in the reducer product catalog; second, the overload capacity of the drive motor and the maximum working torque required in actual application must also be considered. Theoretically, the maximum working torque required by the user must be less than 2 times the rated output torque of the reducer. Especially in some application occasions, this criterion must be strictly observed; this is not only for the protection of the internal gears and shafting of the reducer, but more importantly to avoid the output shaft of the reducer being twisted off. If these factors are not considered, once there is a problem with the equipment installation and the reducer output shaft is stuck by the load, the overload capacity of the drive motor will still cause it to continuously increase output until the force borne by the reducer output shaft exceeds its maximum output torque, and the shaft will twist off. If the rated output torque of the reducer has a certain margin, the terrible situation of twisting off the output shaft can be avoided.
       Secondly, during the acceleration and deceleration processes, if the instantaneous impact torque borne by the reducer output shaft exceeds 2 times its rated output torque, and this acceleration and deceleration are too frequent, it will eventually cause the reducer shaft to break. If this situation occurs, careful calculation should be made to consider increasing the torque margin.
III. Correct Installation of the Reducer
       Correct installation, use, and maintenance of the reducer are important links to ensure the normal operation of mechanical equipment. Therefore, when you install a planetary reducer, please be sure to assemble it strictly in accordance with the installation sequence below.
       Step 1: Before installation, confirm that the motor and reducer are intact, and strictly check whether the dimensions of the parts connecting the drive motor and the reducer match. This refers to the dimensions and fit tolerances between the positioning boss and shaft diameter of the drive motor flange and the positioning groove and hole diameter of the reducer flange; wipe off dirt and burrs on the mating surfaces.

      Step 2: Unscrew the plug on the process hole on the side of the reducer flange, rotate the input end of the reducer to align the clamping hexagon socket screw cap with the process hole, insert a hexagon tool, and loosen the clamping hexagon socket screw.

       Step 3: Hold the drive motor so that the keyway on its shaft is perpendicular to the clamping screw of the reducer input end hole, and insert the drive motor shaft into the reducer input end hole. During insertion, it must be ensured that the concentricity of the two is consistent and the flanges on both sides are parallel. If the concentricity is inconsistent or the flanges on both sides are not parallel, the cause must be investigated. In addition, hammering is strictly prohibited during installation; this prevents excessive axial or radial forces from hammering from damaging the bearings of both, and also allows judging whether the fit of the two is appropriate through the feel of assembly. The method to judge the concentricity and flange parallelism of the fit is: after the two are inserted into each other, the flanges of the two are basically close together, and the gaps are consistent.

       Step 4: To ensure that the force on the flange connection between the two is uniform, first screw on any of the drive motor fastening screws, but do not tighten them; then gradually tighten the four fastening screws in diagonal positions; finally, tighten the clamping screw of the reducer input end hole. Be sure to tighten the drive motor fastening screws first before tightening the clamping screw of the reducer input end hole.

Note: The correct installation between the reducer and the mechanical equipment is similar to the correct installation between the reducer and the drive motor. The key is to ensure the consistency of the concentricity between the reducer output shaft and the input shaft of the driven part.
IV. Conclusion
      With the continuous in-depth development of control motor applications, the application of planetary reducers in the field of motion control transmission will also increase. We hope that you ensure the correct installation of the planetary reducer before use, bringing reliability and safety guarantees to the operation of your equipment!