portfolio: electronic development

node board

in a distributed mechantronics project the designer is often faced with the challenge of bringing together many sensors in physically remote locations to a common point where sensory information is processed. Routing sensor wire bundles through moving joints presents both packaging and reliability problems. We address this challenge by designing an embedded module called the NodeBoard – a compact sensor interface board that can be daisy chained on a manageable four wire bus. Each board can simultaneously digitize a variety of typical mechatronics sensors such as potentiometers, force sensors, switches, and capacitive sensors. In addition, each board houses an accelerometer. The boards communicate with the master controller via the CAN bus.

Specifically the capabilities of the node board include:

• 1Mb/s CAN bus communication
• pass through 5V supply & communications signals
• 6 ratio-metric 14 bit force sensor channels (with built in wire break detection)
• 2 ratio-metric 12 bit potentiometer channels (with built-in wire break & short circuit detection)
• 4 hall sensor switch channels with integrated filters
• 2 capacitive operator presence sensors channels
• 3 axis, 13 bit accelerometer
• 2 led status indicators
• 8 bit MCU with resources available for additional algorithms
• built-in supply monitoring
• ESD protection on all I/O lines
• compact 32 x 25 x 7.6 mm package

for a complete list of the node board's technical specifications click here.

fish-steak motor controller

kinea's approach in developing the electronic hardware for a robotic fish (see ghostBot) was to design a stackable "fish-steak" (in reference to the culinary term due to their orientation) actuator design. Each segment (fish-steak) contains a motor, drive-train and the custom designed motor controller in a single integrated module. The steak modules mate with one another with a stack-through connector which runs along the spine of the fish and carries power and CAN bus signals. Each fish-steak is individually addressable by an external master controller.
Fish-steak capabilities include:

• Brush motor amplifier capable of ±2.8A peak at 36 V bus with built in over-current, under-voltage and short circuit protection
• Incremental encoder interface
• Stackable design for rapid assembly and repair
• Closed loop motion control with on-line adjustable parameters
• Configurable motion tracking limits
• Active current control based on the thermal model of the actuator
• Light weight, CANOpen like communication protocol