MJ3 Force-Operated Joysticks

Force-operated – also known as stiff stick – joysticks have no moving parts, and are therefore extremely reliable. They are an obvious choice for applications that require careful control of movement within a small control space, such as vehicle-mounted or airborne equipment. We are proud to be one of the few specialist companies to engineer our own miniature force-operated joysticks.

Force-operated joysticks use strain gauges attached to a fixed metal post to convert applied force into a proportional electrical output. Typically a movement of less than 1mm is needed to achieve full-scale output. Daco force-operated joysticks consist of a force-sensitive spring fixed into a base and surrounded by a housing. The force applied to the spring in the plane parallel to the base is resolved into X and Y components. These are sensed separately by strain gauges bonded to the spring and connected to form two half Wheatstone bridges. The resulting analogue output has infinite resolution and is proportional to input voltage and applied force.

Force-operated joysticks are noteworthy for their small footprint. They require less space for mounting and the base assembly is smaller than an equivalent displacement joystick; if a grip is fitted no space is needed to accommodate an arc of travel.

Daco’s force-operated joysticks provide full proportional control yet take no more space than a simple switch. Our devices typically have a body length of approximately 25mm (1 inch). This makes them ideal for fitting in control grips, such as Daco’s MG1, for use as thumbsticks. The low mass of the thumbsticks reduces their sensitivity to vibration and increases the effectiveness of mechanical damping.

Despite their size, our force-operated joysticks are extremely resilient, having an overload capability factor of 10. We have tested all our products to 10,000,000 cycles, with each cycle being full scale in both +ve and -ve directions. All units are fitted with an internal protective bellows that can be supplemented with an external elastomer seal. These features, coupled with the use of fully anodised aluminium exposed components, mean that the devices are suitable for the most demanding applications.

 

Mecahnical

Force, Full Scale 10.5N nominal
Force, maximum ±0.35mm nominal
Deflection, full scale 10.5N Nominal
Weight 25 gms maximum
Life >3x10^6 FS cycles
Temperature Operating: -40°C to +70°C
Storage: -55°C to +90°C
Sealing (Panel sealed) BS 5490 IP67
External materials (front of panel) Anodised aluminium alloy
Epichlorohydrin 60 (elastomer seal)
Joystick Body Black Anodised
Joystick Knob black Anodised

The Daco MP3 force-operated joystick is extremely robust, small and easy to use.

Electrical

Excitation Rated: 10V or ± 5VDC
Maximum: 12V or ± 6VDC
Input Resistance 650 Ohms nominal
Output Resistance (per half bridge): 325 Ohms nominal
No force: ±125mV maximum
Sensitivity: 95mV/N nominal
Full scale (FS): 1.0 ± 0.2VDC
Balance (+FS to -FS): 200mV maximum
Resolution: Stepless
Non-linearity: ±1% FS maximum
Hysteresis at zero:
±0.3% FS maximum
±1.0% FS maximum if elastomer seal used
Interaction: ±5% maximum
Zero offset thermal drift: ±0.04% FS/°C typical
Insulation: >50M Ohms at 50VDC

Daco’s MJ3 modular force-operated joysticks are two-axis devices that use strain gauges to convert applied force into an infinite resolution analogue output, proportional to input voltage and the force applied. They have the following characteristics:

  • Small size
  • Continuous resolution
  • Over 400 possible configurations
  • No moving parts
  • High reliability
  • Sealed to IP67
  • Anodised to give good corrosion resistance
  • Low return-to-zero hysteresis
  • Low weight
  • No backlash
  • Robust, with 10 times overload capability withut damage
  • Two year warranty
  • Engineered using an ISO 9001 / AS9100-approved quality system

The small size of our MJ3 joystick – typically 25mm (1 inch) – lends itself to a variety of mounting arrangements, including fitting in control grips such as Daco's MG1.

The following modular options are available

Number of wires 4 pins
8 pins
Type of knob None
Concave (small)
Concave (large)
Stepped convex
Finger and thumb
Seal type Elastomer
Bellows
Mounting details Bushing*
Threaded
Clamped
Interface** None (bare leads)
None (flying leads)
RS232 (mouse systems)
Sun
RS422 (mouse systems)
RS232 (Microsoft)
PS2
RS232 (Daco absolute)
RS422 (Daco absolute)
USB

* The elastomer seal cannot be fitted to the bushing version.

** All interface circuit boards are connected to the joystick with a 300mm lead.