1. Preliminary preparation

1.1 Hardware Preparation

Table 1 Test tools

serial number	name	quantity	Remark
1	OneRadar R82	1	R82_NR_CAN3_40M_V3.0.0
2	X6 Flight Controller	1	Open Source Flight Controller
3	Radar connection harness	2	Power and communication harness

1.2 Software Preparation

Computer configuration:
Processor: i5-1135G7@2.40GHz (can meet the normal use of Mission Planner)
Onboard RAM: 8Gb/4Gb
System type: 64-bit operating system

Software Configuration:
Mission Planner V1.3.80
Ardupilot 4.5.0 (firmware)

1.3 Precautions for use

①This open source CAN protocol only supports APM firmware version 4.5.0 and above.
②Please use a flight controller that supports APM firmware.
③Please note that the flight controller's flash memory needs to be 2Mb or above.
④When powering on the radar, be careful not to exceed its voltage range of +5V to 28VDC.

2. Radar Installation Instructions

2.1 Radar Installation Notes

There are three points to note when installing:

1. 1. The radar determines the distance of obstacles by emitting millimeter waves forward. Therefore, in order to ensure accurate detection data, there must be no obstructions in front of the radar during installation, especially metal obstructions.
  2. When installing the radar, you need to ensure that the module is facing vertically forward (depending on the flight attitude of the drone, in order to prevent interference from ground clutter, the radar antenna surface angle may need to be appropriately raised according to different models. Generally, it is recommended to raise it by 5°~25° according to the type of drone used by the customer) to ensure the accuracy of the detection data.
  3. The direction of the line output of the radar installed on the drone should take the antenna design into consideration to avoid interference; the antenna should face the front of the drone and the line should be output on the left side, as shown in the following figure:

Figure 1 Radar output line diagram

2.2 Drone application installation

The installation diagram of the one-way obstacle avoidance radar is as follows:

Figure 2 Schematic diagram of obstacle avoidance radar installation

3. Wiring connection

3.1Radar Harness Definition

Table 2 R82 radar port description

Pinout	color	Interface Description	Remark
1	red	DC12V	Positive power supply
2	-	-	-
3	black	GND	Negative pole of power supply
4	-	-	-
5	White	CAN_L	Low level CAN port
6	yellow	CAN_H	High level CAN port
7	-	-	-
8	-	-	-

Figure 3 Schematic diagram of R82 radar harness

3.2Flight controller harness definition

Table 3 Flight controller harness description

color	Interface Description	Remark
red	DC5V	5V power supply (not used yet)
yellow	CAN_H	High level CAN port
White	CAN_L	Low level CAN port
black	GND	Ground wire (not used yet)

Figure 4 Flight controller wiring harness diagram

3.3Flight controller and radar wiring

The power supply of the flight control CAN port is 5V. The wiring here uses an independent power supply of 5V/12V. When using a 5V power supply, it is recommended to provide a current of 0.5A for the radar, otherwise the radar cannot be used normally. If the radar is powered by USB or directly powered by the flight controller, there is a possibility that the radar cannot be powered.

Figure 5 Flight controller and radar wiring

4. Flight controller and radar applications

4.1Open source flight controller and Mission Planner ground station connection

- Open the MissonPlanner ground station and connect the USB cable connected to the flight controller to the computer USB port.
- Find My Computer on the desktop, click Manage, and check the port you are currently connected to.

Figure 6 Port number query

- Click the upper right corner of the ground station to configure the port number and baud rate. Set the baud rate to 115200.

Figure 7 Connection between ground station and flight controller

- After the entire system is connected, proceed to the next step.

Figure 8 Successful connection

- Click the "Configuration/Debug" interface, find all parameters, and find the search button on the right to search for the parameters you need to modify.

Figure 9 Configuration and debugging

4.2Flight controller parameter configuration

4.2.1Flight controller interface basic parameter configuration

Go to the flight controller parameter interface. In order to meet the conditions for opening the R82CAN protocol, first configure the flight controller interface and basic obstacle avoidance parameters, and then you only need to complete the application configuration.

1.According to Table 4 and Table 5 below, we search for keywords, such as "AVOID" and "CAN", find the parameters that match the table, and modify them one by one.

Table 4 CAN1 interface parameter configuration

Parameter name	value	Parameter Introduction
CAN_D1_PROTOCOL	14	Allows use of the MR72CAN communication protocol on the CAN1 port
CAN_P1_DRIVER	1	Enable CAN1 bus
CAN_P1_BITRATE	500000	CAN1 interface bit rate is 500kb/s

Note: When configuring CAN parameters, you need to modify PROTOCOL and DRIVER first, then write the parameters and refresh to configure BITRATE parameters; if you need to use CAN2, you can change "D1", "P1" in the above parameters to "D2", "P2", for example, change "CAN_D1_PROTOCOL" to "CAN_D2_PROTOCOL".

Table 5 Obstacle avoidance parameter configuration

Parameter name	value	Parameter Introduction
AVOID_ENABLE	2	Enable proximity sensor obstacle avoidance
AVOID_ANGLE_MAX	1000	The maximum obstacle avoidance angle in non-GPS mode is 10°
AVOID_BEHAVE	1	When avoiding obstacles, the drone stops.
AVOID_MARGIN	5	In GPS mode, the obstacle avoidance distance is 3 meters
AVOID_DIST_MAX	10	Obstacle avoidance distance in non-GPS mode is 10 meters

Note: The above parameter values are only suitable recommended parameters. The actual values can be modified according to customer requirements.

2.As shown in the figure, we configure the basic parameters in Table 4 and Table 5 to meet the conditions for enabling obstacle avoidance.

Figure 10 CAN1 interface configuration

Figure 11 Obstacle avoidance parameter configuration

4.2.2Obstacle Avoidance Radar Application Configuration

In the previous chapters, we have modified the basic parameters of the flight controller. Now let's configure the one-way obstacle avoidance radar.

Table 6 Configuration of one-way obstacle avoidance sensor 1

Parameter name	value	Parameter Introduction
PRX1_TYPE	17	Connecting the R82 proximity sensor
PRX1_RECV_ID	0	The ID of the radar allowed to be received is 0
PRX1_YAW_CORR	0	The sector shown on the radar is directly ahead

Note: When configuring PRX parameters in the default parameters, you need to set PRX1_TYPE first, write the parameters and refresh the parameters before you can configure the subsequent parameters. When modifying PRX_RECV_ID, you need to restart the flight controller once to display the modification of this parameter.

1.According to the above table, configure sensor 1 as shown in the figure:

Figure 12 Sensor 1 configuration

2.After configuring the sensor parameters, we click "Flight Data", return to the main interface, and use "Ctrl+F" to open a hidden interface "Temp".

Figure 13 “Temp” interface

3.Click "Proximity" in the lower right corner and a "Radius" interface will appear, in which you can observe the target data output by the radar in real time.

Figure 14 “Radius” interface

4.In the range of 315° to 45° in the figure, red lines will be displayed. Each red line represents a target obstacle, and a maximum of three targets can be displayed in one range.

Figure 15 Radar data display

5. FAQ

Q：In which modes can the obstacle avoidance of the R82CAN protocol be used?

A：Radar obstacle avoidance is divided into simple obstacle avoidance and algorithm obstacle avoidance. R82 uses simple obstacle avoidance, so it currently only supports LOITER mode and ALT_HOLD mode. If you need to use obstacle avoidance in AUTO or RTL mode, please modify the parameters OA_TYPE = 1 (BendyRuler obstacle avoidance algorithm), OA_MARGIN_MAX = 5 (obstacle avoidance distance is 5 meters)

Q：Can the radar ID number be modified arbitrarily to match the flight controller's CAN protocol?

A：The flight controller parameter PRX_RECV_ID changes with the ID of the radar itself. For example, the ID of the radar I got is 5, so I change the flight controller parameter to PRX_RECV_ID = 5; if the flight control parameter PRX_RECV_ID is set to 9, the radar itself needs to change its ID to 9 to correspond to the CAN protocol.

Q：How does Mission Planner divide the radar display interface?

A：As shown in the figure above, the radar display interface is composed of a 360° circular interface, and the circular interface is divided into a sector at 45°, and two sectors are divided into an interval, that is, 315° to 45° is the first interval, 45° to 135° is the second interval, 135° to 225° is the third interval, and 225° to 315° is the fourth interval, that is, the first interval is the front, the second interval is the right, the third interval is the rear, and the fourth interval is the left.

Q：Can the open source R82CAN protocol connect multiple radars to achieve multi-directional obstacle avoidance?

A：Yes, we support up to three R82 radar cascades for obstacle avoidance in three directions. You can refer to the open source CAN protocol multi-radar cascade user manual for more information.

Q：R82 obstacle avoidance distance and installation issues?

A：The installation of the radar needs to take into account the angle changes caused by the obstacle avoidance of the navigation and hovering drones, as well as the radar's field of view. At the same time, due to the delay in the braking of the drone caused by the radar data transmission, in order to ensure the flight of the drone, the installation needs to control the flight speed and the extension of the braking distance caused by the delay.

Q：Standard test data process?

A：After completing the configuration of parameters, the radar and flight controller need to be powered on again to ensure that the data takes effect. At the same time, the radar test is affected by the millimeter wave indoor multipath, and the indoor data is inaccurate. After verifying that the hardware connection and parameter configuration are normal, the radar test needs to be carried out in an open outdoor area.

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