RC4-MSS
Motion Safety System
and RC4 Motor Control Receivers
The RC4 Chair Riot provided endless fun and amusement for
USITT 2006 Stage Expo visitors. The RC4-FD wireless motor driver provides
(as one of four available modes) electronic differential steering to
easily
control a set piece using two drive motors. The Chair Riot
is also
equipped
with
1000W
of MR16
lighting, and a Tiny Fogger from Look Solutions.
The RC4-MSS Motion Safety System provides an encode/decode heartbeat sub-system. Loss of control for any reason will safely disconnect motor power in remote set pieces.
Based on the same fail-safe technology used in remote controlled cranes and locomotives, the MSS Motion Safety System will detect any fault that disrupts RC4 wireless control for more than 300ms, and stop the piece.
The MSS Sender injects a precise heartbeat signal through one of the RC4 CV channels. At the remote end, a dimmer is patched to the heartbeat channel and wired to the MSS Detector. As long as the heartbeat signal continues to arrive within specifications, the detector knows that the entire RC4 system is working properly from input through to output.
The MSS Detector provides a high-current relay driver that is protected against over-current and over-temperature. The driver is turned on when the wireless system is operating safely, but goes off when a fault is detected. A large contactor relay should be wired to disconnect main battery power to any motor or other system that must stop in the event of a control system failure.
MSS Detectors are available as standalone modules, and are built-in
to RC4 motion receivers, including the FD Functional Diversity receiver.
"We control wireless motorized pieces with the RC4-MSS, operated from our automation system. It provides excellent reliability and security. Meanwhile, we also use RC4 wireless lighting extensively, controlled from our DMX console. The RC4 covers all the bases."
Ian Phillips, Assistant Head Electrician
The Shaw Festival
Niagara-on-the-Lake, ON
[ RC4 Users]
RX4-FD Functional Diversity Receivers
provide two dimmers, two H-bridge
drivers, and four special control modes: Dimmer, Motor, Differential,
and Servo.
In the same size package as our RX4-STD dimmer!
In all four modes, output channels 1 and 2 are identical to the dimmers on RX4-STANDARD receivers. They can drive resistive or inductive loads and support all regular dimmer parameters (channel, curve, low level, voltage reference, smoothing, etc.)
The FD receiver includes a built-in MSS Detector. When deployed, the detector utilizes output channel 1 to drive an external main-contactor relay.
Dimmer mode emulates the RX4-STANDARD dimmer. Output channels 3 and 4 are also identical to the dimmers in RX4-STANDARD receivers. All four channels behave identically. Parameters for Dimmer mode are edited in the same manner, with the same user interface, as regular RX4 receiver/dimmers.
Motor mode is the simplest enhanced FD mode. Output channels 3 and 4 are bidirectional centre-off motor drives. When the assigned control channel is centered at level 128, the motor driver output is off. Levels above 128 run the motor in the forward direction. Levels below 128 run the motor in the reverse direction. Level 255 is full speed forward; level 0 if full speed reverse. Parameters are available to damp the response of fast control changes, and limit the maximum output power to any desired value from 0 – 100%.
Differential mode provides an effective way to control an electric vehicle. The vehicle frame should be built with a drive motor/wheel on each side, such that powering both motors together will drive straight ahead, and varying the power level to each motor will steer the vehicle to one side or the other. This is sometimes referred to as a “tank drive”. One RC4 control channel is used for speed/direction, the other for steering (left/right). The ideal control is a joystick that rests at centre. Pushing the joystick forward moves the vehicle forward; pulling the joystick back moves the vehicle backward. Moving the joystick left and right steers the vehicle. As an additional driving feature, moving the joystick left/right while in the centre stopped position will spin the vehicle on centre, increasing speed as the joystick is pushed further to either extreme.
Servo mode provides a closed-loop motor positioning system. In this mode, Output channel 3 functions identically to Motor mode. Servo functions are provided by output channel 4. This mode provides the largest number of parameters, allowing system performance to be tuned and tailored to a wide variety of applications and target machines.
RC4 control channels set the top speed of the servo system, and the target position the servo system should move to, with either single-channel (8-bit) or double-channel (16-bit) resolution.
The servo process requires position information from an external quadrature rotary encoder mounted somewhere in the target machine. A servo system looks at the difference between current position and target position (often referred to as positional “error”) and moves the motor to reduce the error to zero. When the target position changes, the servo system follows by moving the motor to the new target position.
Various parameters configure the servo system to avoid overshoot (where the motor passes the target), and hunting (where the motor oscillates back and forth around the target, unable to accurately stop precisely at position). In the language of servo drives, our FD provides a PV feedback loop, meaning power to the motor is Proportional to positional error, and to motor Velocity.
Two limit switch inputs are also provided. User programmed encoder positions
can be assigned to these switch closures to index the servo system to
a physical path or area.
The RC4-SERVO wireless motor controller is ideal for sending
a remote motor, like this winch, to
specific
positions.
Limit
switches
and a rotary encoder are used for positional feedback.
The RC4 system is not wireless DMX.
RC4 is the power of wireless.
Toll-Free
1-866-258-4577
www.theatrewireless.com
Soundsculpture Incorporated / RC4 Wireless accepts no liability for direct, indirect, or consequential damages resulting from the use of any Soundsculpture product or group of products, including the RC4-MSS Motion Safety System. The RC4-MSS has not been evaluated by any 3rd-party safety authority. Soundsculpture does not guarantee the suitability of any product for any purpose; user assumes all risk. RC4 dimmers and the MSS must be used strictly in accordance with manufacturer's instructions and cannot be used for unsupervised operation. Soundsculpture products must be installed and operated only by qualified technicians, only for their intended purpose as outlined in the manufacturer's documentation, and should be inspected and tested on a regular basis to ensure proper operation. A physical deadman switch or other human intervention method must be used in all cases where human safety may be at risk.