Robo Master GM6020 Brushless DC Motor User Guide

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RoboMaster
GM6020 Brushless DC Motor
User Guide
V1.0 2018.12

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 affiliated 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 affiliated
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
copyrighted by DJI with all rights reserved. No part of this product or document shall be reproduced
in any form without the prior written consent or authorization of DJI.
The final interpretation right of this disclaimer is reserved by DJI.

Warning

1. Visit the official 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 fields 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 firmware 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 firmware.
Use a CAN cable to acquire information such as rotor position, rotational speed, and motor temperature.
© 2018 DJI All Rights Reserved.

• Use the DIP switch to set ID and to enable/disable the CAN terminal resistance.
• Includes over-temperature and overvoltage protection.

In the Box
Motor ×1

XT30 Power Cable ×1

CAN Cable ×1

PWM Cable ×1

Overview
GM6020 Motor

1
2
3

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 firmware 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.
2

XT30 Power Cable

CAN Cable
A
B

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

PWM Cable
A

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

Mounting the Motor

Refer to the dimensions below to mount the motor to an appropriate platform.
8.00±0.03
22.00±0.05
18.00

4.00

4.2

+0.04
0

+0.05
0

3 - M4

+0.05
0

6 EQS

22.00±0.05
38.50

30°

40.00

18.00

58.00

3 - M3

4.2 EQS

1.50±0.04

42.00±0.10
1.50
1.50

+0.04
0

Unit: mm

66.70±0.10

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

CCW

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

Blinks green N times every second

Description

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 first 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 identifier of the CAN communication. Their
corresponding relationships are shown as below:
Bit[2:0]

000

001

010

011

100

101

110

Motor ID

Invalid

0x205

0x206

0x207

0x208

0x209

0x20A

0x20B

Feedback identifier
Control identifier

0x1FF

111

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.
© 2018 DJI All Rights Reserved.

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.
Identifier: 0×1FF
Frame format: DATA
Data Field
DATA[0]
DATA[1]
DATA[2]
DATA[3]
DATA[4]
DATA[5]
DATA[6]
DATA[7]

Description
Controls the voltage value in higher order byte (8 bits)
Controls the voltage value in lower order byte (8 bits)
Controls the voltage value in higher order byte (8 bits)
Controls the voltage value in lower order byte (8 bits)
Controls the voltage value in higher order byte (8 bits)
Controls the voltage value in lower order byte (8 bits)
Controls the voltage value in higher order byte (8 bits)
Controls the voltage value in lower order byte (8 bits)
Identifier: 0×2FF
Frame format: DATA

Data Field
DATA[0]
DATA[1]
DATA[2]
DATA[3]
DATA[4]
DATA[5]
DATA[6]
DATA[7]

Frame type: Standard
DLC: 8 Bytes
Motor ID
1
2
3
4

Frame type: Standard
DLC: 8 Bytes

Motor ID
5
6
7
Null

Motor Sending Message Format
The format in which the motor sends feedback data to the CAN bus.
Identifier: determined by 0×204+ driver ID
Frame format: DATA
Data Field
DATA[0]
DATA[1]
DATA[2]
DATA[3]
DATA[4]
DATA[5]
DATA[6]
DATA[7]
6

Frame type: Standard
DLC: 8 Bytes

Description
Controls the rotor mechanical angle in higher order byte (8 bits)
Controls the rotor mechanical angle in lower order byte (8 bits)
Controls the rotational speed in higher order byte (8 bits)
Controls the rotational speed in lower order byte (8 bits)
Actual torque current in higher order byte (8 bits)
Actual torque current in lower order byte (8 bits)
Motor temperature
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.

Speed ( rpm )

max

1080

1000

1480

1920

1500 1520

2000

Pulse Width ( μs )

max

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.

Angle ( ° )

max

1920
1000 1080

1500

2000

Pulse Width ( μs )

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

Configure the motor or update its firmware using a USB to serial converter via RoboMaster Assistant.

Motor

USB to Serial Converter

1. Download RoboMaster Assistant from the RoboMaster official 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 firmware.

Performance

Load characteristics (speed open-loop control)

n(rpm) I(A)
350

300

2.5

250

200
150
100
50
0

P(W)
P

1.5
1
0.5
0

18
15
12

9
6

3
0.5

1.5

η (%)
70
60
50
40
30
20
10
0

T(N·m)
8

Load characteristics (speed closed-loop control)

n(rpm) I(A)
70

2.5

40
30
20
10
0

P(W)
9

7.5

η (%)
45
37.5
30

1.5

4.5

1.5

7.5

0.5

I
0

0.4

0.8

1.2

1.6

22.5

T(N·m)
Operating Range
n(rpm)
400
300
200
100
0

0.6

1.2

1.8

T(N·m)

Continuous Operating Range
η – Electrical Efficiency, T – Torque, I – Current, P – Output Power, n – Rotational Speed
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 figures should be used for reference
only. Make sure to control running time properly in accordance with actual working temperature,
dissipation, etc.

Characteristic Parameters

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

67.85%

Stall Torque (continuous)

0.86N·m

Stall Current (continuous)

0.90 A

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

Phase Number

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

DJI Support

http://www.dji.com/support

WWW.ROBOMASTER.COM
and

are trademarks of DJI.

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