Robo Master GM6020 Brushless DC Motor User Guide

User Manual:

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RoboMaster

GM6020 Brushless DC Motor

V1.0 2018.12

User Guide

Disclaimer

Thank you for purchasing the ROBOMASTERTM GM6020 Brushless DC Motor (hereinafter referred

to as “product”). Read this disclaimer carefully before using this product. By using this product, you

hereby agree to this disclaimer and signify that you have read it fully. Install and use this product in

strict accordance with the User Guide. SZ DJI TECHNOLOGY CO., LTD. and its afliated companies

assume no liability for damage(s) or injuries incurred directly or indirectly from using, installing, or

modifying this product improperly, including but not limited to using non-designated accessories.

DJITM is a trademark of SZ DJI TECHNOLOGY CO., LTD. (abbreviated as “DJI”) and its afliated

companies. Names of products, brands, etc., appearing in this document are trademarks or

registered trademarks of their respective owner companies. This product and document are

in any form without the prior written consent or authorization of DJI.

The nal interpretation right of this disclaimer is reserved by DJI.

Warning

1. Visit the ofcial RoboMaster website and download the RoboMaster GM6020 Brushless DC Motor

User Guide before use. Be sure to read the whole manual and strictly follow the instructions when

using the motor.

2. DO NOT allow any foreign materials to come into contact with the rotors, as it may negatively

affect the performance.

3. Ensure all the cables are properly connected.

4. Ensure the motor is securely mounted.

5. Avoid damage to the cables or wires, as it may negatively affect the performance.

6. DO NOT touch the rotors, as doing so may cause injury.

7. The motor heats when the output torque is high. Although this is normal, take caution to avoid

scalding.

8. DO NOT disassemble the motor, as this may negatively affect the accuracy of the motor’s control

and may lead to permanent malfunction.

Introduction

The GM6020 Brushless DC Motor is a high-performance motor with a built-in driver designed for use

in elds such as educational research, automation, and robotic competition.

The motor boasts a high pole number design, fractional slot concentrated windings, and rare earth

magnets, making it an optimal solution for situations that require low rotational speed, direct driving,

and large torque.

The Field Oriented Control (FOC) algorithm of the built-in driver and the high-precision angle sensor

allows for precision control of the motor's torque and position. If an error is detected, the motor issues

warnings and automatically responds to protect itself. Multiple communication methods are supported

to facilitate the users in motor control and rmware update.

Features

• A hollow shaft to attach slip rings or other accessories when required.

• Compact design combining the motor and driver in one.

• Multiple communication methods are supported (e.g. CAN, PWM).

• With RoboMaster Assistant, users can set parameters online and update rmware.

• Use a CAN cable to acquire information such as rotor position, rotational speed, and motor temperature.

Motor ×1

PWM Cable ×1

XT30 Power Cable ×1 CAN Cable ×1

Overview

GM6020 Motor

1. CAN Port

Connects to the external device and receives the CAN control signal to give feedback to the

motor’s status. The bitrate of the CAN bus is 1 Mbps.

2. Power Port

Connects to a power outlet with a rated voltage of 24 V using the XT30 power cable to provide

power to the motor.

3. PWM Port

Connects to the PWM port on an external device using the PWM cable to control the motor’s

rotational speed and position (analog servo mode). It can also connect to a USB to serial

converter to your computer with the provided PWM cable to set parameters or update the

motor’s rmware via RoboMaster Assistant.

4. Status LED

Indicates the motor’s operating status. Refer to “Status LED and DIP Switch” for more details.

5. DIP switch

Set the motors’ ID and enable or disable the CAN terminal resistance. Refer to “Status LED and

DIP Switch” for more details.

• Use the DIP switch to set ID and to enable/disable the CAN terminal resistance.

• Includes over-temperature and overvoltage protection.

In the Box

CAN Cable

A: CAN_H (Red) B: CAN_L (Black)

A: PWM/RX (White) B: TX (Grey) C: GND (Black)

PWM Cable

Mounting the Motor

Refer to the dimensions below to mount the motor to an appropriate platform.

3 - M4

6 EQS

38.50

58.00

18.00 +0.05

8.00±0.03

22.00±0.05

4.2

4.00 +0.04

3 - M3 4.2 EQS

22.00±0.05

40.00

18.00 +0.05

30°

XT30 Power Cable

1.50 +0.04

66.70±0.10

1.50±0.04

42.00±0.10

Unit: mm

CCW CW

The motor rotor is outfitted with M3 mounting holes at a depth of 4 mm while the motor

stator is outfitted with M4 holes at a depth of 6 mm. Use appropriately-sized screws to

mount properly and avoid damage.

On the top and bottom of the motor there is a boss, with an inner diameter of 18 mm and an outer

diameter of 22 mm. The bosses can help to attach other devices to the motor.

Additionally, on the top of the motor is a blind hole with a diameter of 4 mm and a depth of 4.2 mm.

On the bottom of the motor there is also a boss, with an inner diameter of 8 mm and a height of

1.5mm. Both the blind hole and the boss can help protect the screws from being damaged and also

help locate when mounting.

Make sure to keep the motor away from strong electromagnetic environments and magnetic

materials, like iron. Otherwise, the motor will vibrate or may even malfunction.

Motor Rotation Direction

When viewed from the top of the output axis: counterclockwise rotation (CCW) is called the positive

direction (+) and clockwise rotation (CW) is called the reverse direction (-).

Status LED and DIP Switch

Status LED

Status LED Description

The status LED is used to indicate the motor’s operational status. In situations that indicate warning

and abnormal working conditions, the LED will only indicate the abnormal working condition. In

situations that indicate multiple warning or abnormal working conditions, the LED will only indicate

the condition that emits the least amount of blinks. Note: the driver automatically cuts off the output

stream when it is in abnormal status.

Normal Description

Blinks green N times every second The number of blinks indicate the current ID of the motor

Blinks green slowly PWM communication is normal

Solid green PWM signal is being calibrated

Warning Description

Blinks orange once every second The temperature of motor is higher than 212° F (100° C)

Blinks orange twice every second More than one motor share the same ID connected to the

CAN bus

Blinks orange three times every second PWM signal cannot be detected

Blinks orange four times every second Temperature sensor is abnormal

Blinks orange quickly PWM signal calibration is failed

Abnormal Description

Blinks red once every second The voltage of the power supply is too high

Blinks red four times every second The temperature of motor is higher than 257° F (125° C)

DIP Switch

ID Setting

The rst three bits refer to Bit0, Bit1, and Bit2 which are used to control the motors’ ID. Toggling the

bit to the ON position is recorded as 1 while the off position is recorded as 0.

Bit[2:0] is the ID value of the motor, which will affect the identier of the CAN communication. Their

corresponding relationships are shown as below:

Bit[2:0] 000 001 010 011 100 101 110 111

Motor ID Invalid 1 2 3 4 5 6 7

Feedback identier 0x205 0x206 0x207 0x208 0x209 0x20A 0x20B

Control identier 0x1FF 0x2FF

CAN Resistance Setting

The fourth bit controls if the CAN terminal resistance should be enabled or not. Toggle it to the ON

position to enable the resistance.

Identier: 0×1FF Frame type: Standard

Frame format: DATA DLC: 8 Bytes

Identier: determined by 0×204+ driver ID Frame type: Standard

Frame format: DATA DLC: 8 Bytes

Identier: 0×2FF Frame type: Standard

Frame format: DATA DLC: 8 Bytes

Motor Sending Message Format

The format in which the motor sends feedback data to the CAN bus.

CAN Communication Protocol

Motor Receiving Message Format

Users send command message to the motor to control the voltage output. The controllable voltage

range is -30000~0~30000.

Data Field Description Motor ID

DATA[0] Controls the voltage value in higher order byte (8 bits) 1

DATA[1] Controls the voltage value in lower order byte (8 bits)

DATA[2] Controls the voltage value in higher order byte (8 bits) 2

DATA[3] Controls the voltage value in lower order byte (8 bits)

DATA[4] Controls the voltage value in higher order byte (8 bits) 3

DATA[5] Controls the voltage value in lower order byte (8 bits)

DATA[6] Controls the voltage value in higher order byte (8 bits) 4

DATA[7] Controls the voltage value in lower order byte (8 bits)

Data Field Description

DATA[0] Controls the rotor mechanical angle in higher order byte (8 bits)

DATA[1] Controls the rotor mechanical angle in lower order byte (8 bits)

DATA[2] Controls the rotational speed in higher order byte (8 bits)

DATA[3] Controls the rotational speed in lower order byte (8 bits)

DATA[4] Actual torque current in higher order byte (8 bits)

DATA[5] Actual torque current in lower order byte (8 bits)

DATA[6] Motor temperature

DATA[7] Null

Data Field Description Motor ID

DATA[0] Controls the voltage value in higher order byte (8 bits) 5

DATA[1] Controls the voltage value in lower order byte (8 bits)

DATA[2] Controls the voltage value in higher order byte (8 bits) 6

DATA[3] Controls the voltage value in lower order byte (8 bits)

DATA[4] Controls the voltage value in higher order byte (8 bits) 7

DATA[5] Controls the voltage value in lower order byte (8 bits)

DATA[6] Null Null

DATA[7] Null

Sending frequency: 1KHz

Rotor mechanical angle value range: 0 ~ 8191

Rotor speed value unit: rpm

PWM Signal Description

PWM signal control

A PWM signal with an input frequency of 50Hz and a pulse width of 1000-2000 μ s. Users can

switch between speech control mode and position control mode inside RoboMaster Assistant.

(Position control mode is selected by default).

Speed Control Mode

In this mode, the motor can be controlled to rotate continuously in two directions. The diagram

below describes the mapping between PWM pulse width and speed.

Position Control Mode

In this mode, the motor can be simulated as servo. The diagram below shows the mapping between

PWM pulse width and position. The center point and the rotational angle range can be set inside

RoboMaster Assistant.

max

1000

1080 1480

1520

1920

2000

Speed ( rpm )

Pulse Width ( μs )

1500

Pulse Width ( μs )

Angle ( ° )

max

1000 1080

1500

1920

2000

Motor USB to Serial Converter PC

0.5

1.5

2.5

0 0.5 1 1.5 2

I(A)

P(W)

100

150

200

250

300

350

n(rpm)

η(%)

T(N·m)

PWM Signal Calibration

1. Connect the motor and a PWM-supported device via the provided PWM cable.

2. Adjust the pulse width to the maximum (1900~2100μs) and power on the motor. The PWM signal

calibration starts with the status LED being solid green.

3. Adjust the pulse width to the minimum (900~1100μs) within 3 seconds. The motor driver

will record the pulse width figure, and then enters normal working mode if the calibration is

successful, with the status LED blinking green slowly. If calibration fails, the status LED will blink

orange quickly and the motor’s parameters will not be changed.

Using RoboMaster Assistant

Congure the motor or update its rmware using a USB to serial converter via RoboMaster Assistant.

1. Download RoboMaster Assistant from the RoboMaster ofcial website.

https://www.robomaster.com/en-US/products/components/general/GM6020#downloads

2. Connect the motor to the converter using the PWM cable, and then connect the converter to a

computer. Make sure the PWM cable is correctly connected; black for GND, grey for TX, and white

for PWM/RX.

3. Connect the motor to a power supply.

4. Launch the RoboMaster Assistant and check if the motor is successfully connected to your

computer.

5. Click Settings to adjust parameters.

6. Click Firmware Update and select the version you would like for the controller. RoboMaster

Assistant will automatically download and update the rmware.

Performance

Load characteristics (speed open-loop control)

Load characteristics (speed closed-loop control)

0.5

1.5

2.5

0 0.4 0.8 1.2 1.6

I(A)

1.5

4.5

7.5

P(W)

n(rpm)

7.5

22.5

37.5

η(%)

T(N·m)

Operating Range

η – Electrical Efciency, T – Torque, I – Current, P – Output Power, n – Rotational Speed

n(rpm)

T(N·m)

100

200

300

400

1.20.6 1.8

Continuous Operating Range

The data above was generated in a laboratory setting with an output of 24 V, at the temperature of

77º F (25º C), and under normal dissipation conditions. These gures should be used for reference

only. Make sure to control running time properly in accordance with actual working temperature,

dissipation, etc.

Motor Characteristic Parameters

Rated voltage DC 24 V

Torque constant 741 mN·m/A

Speed constant 13.33 rpm/V

Speed/Torque Gradient 156 rpm/(N·m)

Mechanical Time Constant 3 ms

Phase Resistance 1.8 Ω

Phase Inductance 5.78 mH

Operating Temperature Range 32°~ 131 ° F (0°~55° C)

Max Permissible Winding Temperature 257° F (125° C)

Number of Pole Pairs 10

Phase Number 3

Maximum radial load of bearing(dynamic load) 3.5 KN

Basic static radial load of bearing 2.2 KN

Motor weight Approx. 468 g

Dimensions

Hallow shaft inner diameter: 18 mm

Motor diameter: 66.7 mm

Total height: 45 mm

Cables’ length

XT30 power cable: 500 mm

CAN cable: 500 mm

PWM cable: 500 mm

Characteristic Parameters

Refer to the parameters below to make proper use of your motor.

Motor specications at rated voltage

Maximum no-load speed 320 rpm

No-load current 78 mA

Rated torque (max continuous torque) 1.2N·m

Adjustable speed range (No-load: 0-320 rpm)

(At rated torque: 0-132 rpm)

Torque pulsation factor 3.32%

Locating precision 13 bit

Rated current 1.62 A

Max efciency 67.85%

Stall Torque (continuous) 0.86N·m

Stall Current (continuous) 0.90 A

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DJI Support

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are trademarks of DJI.and

Robo Master GM6020 Brushless DC Motor User Guide

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