NXT-WheelChair-Control

A library for controlling wheelchairs with R-Net technology used in the NXT Wheelchair project. Library code is based on the code written by redragonx in https://github.com/redragonx/can2RNET and refactored into an object-oriented format.

Installation notes

Brainflow is very confusing to install. Install it by building from source. Build instructions here and Python installation instructions here. This worked installing on the Pi. It must be built from source because they don't offer binaries for arm64.

Usage Instructions

1. Connect a PiCan v2 Hat to a motorized wheelchair's can interface
2. Follow Raspberry Pi socket setup here
3. Using raspi_config disable login over serial and enable hardward serial support
4. Run the main file on a Jetson Nano in client mode
   • python3 main.py client
5. Run the main file on the Raspberry Pi in server mode
   • python3 main.py server
6. Use the provided example socket command to direct the wheelchair on the Jetson Nano
   • Example function in src/wheelchair_interface/clientserver/socket_client.py

Package breakdown

An explanation of each package within the wheelchair_interface main package.

clientserver

The clientserver package handles the implementation of the protocol on the Raspberry Pi and Jetson Nano side.

• nano_client.py
  • Client which receives commands from a socket and passes them over UART to the Pi
• pi_server.py
  • Server which accepts commands over UART and passes them to the wheelchair
• socket_client.py
  • Contains functions to be called within the user's program to send socket commands on the Jetson Nano

protocol

The protocol class contains implementation functions of the protocol discussed in doc/piNanoProtocol.md.

• processor.py
  • Implementation of encode and decode functions for sending instructions over UART
• resources.py
  • Common constants used in different files

input_receivers

The input_receivers package contains example implementations of RNetController or receivers to be run independent and speak to the client in clientserver.

• headtilt.py
  • Interfaces with a head accelerometer and leverages the functionality of clientserver
• WASD.py
  • Runs independently of clientserver and speaks directly to the RNetController.

rnet_controller

The rnet_controller package handles direct communication with the wheelchair through the can protocol. It includes a class to abstract away specific bitstrings used to control the chair and instead gives it an object-oriented interface.

• RNetController.py
  • Class to abstract low-level communication into object-oriented class

Usage

The RNetController class implements the code in an object-oriented format. Once instantiated with the bus number the following functions are available for use:

• drive_forward_seconds
• drive_back_seconds
• turn_left_seconds
• turn_right_seconds

Each have the calling convention of function(seconds: int), where seconds is the amount of time you want the action to repeat.

Other less explanatory functions are as follows:

• set_speed_range
  • Takes an integer 0 through 100 which sets the wheelchair speed to that number.
• stop_chair
  • Takes no arguments.
  • Sends a stop command to the wheelchair, though it should stop on its own after a move timer expires.
• close
  • Takes no arguments
  • Closes the open socket with the can system. Always good practice to close connections.