Hall Effect Sensors and CAN Bus Joystick Controllers

By Bob Wojcik

Hall Effect Sensors

Hall effect sensors use magnetic principles to measure the angular movement of the joystick handle. The Hall effect sensors are non-contact devices so there is no need to consider wear conditions over the service life of the sensor. These units are highly reliable, have excellent signal to noise ratio and therefore they are also very stable. These sensors may also be direct replacements for potentiometer-type controllers.

There are various output protocols available, including Single Edge Nibble Transmission (SENT) and Pulse Width Modulation (PWM). Advanced protocols may provide error detection as well as wire breakage or short circuit detection. If the system monitors safety concerns, multiple sensors can provide redundancy for parallel joystick signal synchronization as well as error detection to shut down the system, insuring a safe condition.

CAN Bus Communication

The CAN bus system enables flexible control processing and sensor information. From this information, the system will generate the electrical signals required to control machine functions, valves, or communicate to vehicle motions. The entire wiring requirement may be reduced to a bus cable and a power Supply Line.

Joysticks are also available with CAN bus communications capability. CAN bus is a communication highway using coded signals over a two wire network and directing the coded signals to a programmed function on a vehicle or within machine control. Associated with these Joystick controllers are the following:

• CAN bus (OCI-3) – CanOpen, J1939
• Thumper solenoid driver electronics on board
• UFO (PWM output PCB with trim pot adjustments– PWM electronics are remote mounted).

The CAN bus system solution is most commonly found controlling electrically actuated valves on mobile hydraulic systems, but the systems are gradually gaining ground for machine and line control in industrial plants.

Target applications areas include local authority, harvesting, forestry, and construction machinery as well as systems for lifting/lowering and boom/mast positioning. In these applications, the positions and linear or rotary speeds of hydraulic actuators are controlled in open and/or closed loop modes. The CAN bus system represents an optimum solution for application-specific controls.