Stepless pulse count switching

Control means including a counter having at least one serial input, for a system having a counter determines a given parameter relating to operation of the utilization device, and including first and second alternative sources which supply pulses for changing the digital value in the counter;

• wherein said control means further includes;
• source-select switching means having first and second states and means for changing the state, the first state being for using said first source and the second state being for using the second source;
• selection means having first gating means with inputs from the first source and from the source-select switching means enabled with the source select switching means in the first state to pass pulses from the first source, and second gating means with inputs from the second source and from the source-select switching means enabled with the source select switching means in the second state to pass pulses from the second source, and output gating means coupled between the first and the second gating means and said serial input of the counter to pass any pulses to the counter from whichever of the first and second gating means is enabled, with no extra pulse being passed to the counter in response to the switching means changing state;
• wherein said counter is an up-down counter having an up input and a down input which are serial inputs for counting up and down respectively, and said first and second sources also each supply a direction indication which has two possible values for up and down counting respectively;
• wherein said selection means has two outputs coupled to said up input and said down inputs respectively;
• said first gating means has two outputs for up and down counting respectively and is arranged so that when enabled by the first state of the source-select switching means any pulses from the first source are passed to its up or down output depending on the value of the direction indication from that source;
• said second gating means has two outputs for up and down counting respectively and is arranged so that when enabled by the second state of the source-select switching means any pulses from the second source are passed to its up or down output depending on the value of the direction indication from that source:
• said output gating means has two outputs coupled respectively to said up and down inputs of the counter, and is arranged to pass any pulses from the outputs for up counting from either the first or the second gating means to its output coupled to the up input of the counter, and to pass any pulses from the outputs for down counting from either the first or the second gating means to its output coupled to the down input of the counter;
• wherein said utilization device is a mechanical device having a motor for moving the device, an encoder on the device having two output lines providing digital pulse trains indicating the position, rate, and direction of movement in one coordinate for the device;
• pulse feedback means comprising two sets of J-K flip-flops havinq pulse inputs from a clock and respectively from the two output lines of the encoder, and with gate means coupling outputs of the sets of flip-flops respectively to first and second pulse feedback lines;
• said first source being said second pulse feedback line, which has two leads, the direction indication being given by pulses being on one or the other of the leads;
• said second source being a microprocessor;
• wherein said counter is a rate counter which stores a digital code for a commanded rate of movement in said one coordinate, display means coupled to the output of the rate counter for displaying the value of the digital code, the output of the rate counter being also coupled to the microprocessor for feedback information;
• a rate multiplier having parallel inputs coupled to the rate counter output, a clock input receiving serial pulses at a fixed rate, and an output on which there is supplied a train of pulses at a rate which depends on the value of the digital code represented by the output of the rate counter;
• further including a direction-select circuit having inputs from said source-select switching means which indicates either manual or automatic control, with inputs for direction signals either from said second source or from a manual source, with gate means for selecting the direction signal from the manual or second source as determined by the source-select switching means indicating manual or automatic control respectively, and a direction flip-flop coupled to the gates to be set in accordance with the state of the direction signal selected by the last said gate means;
• rate-direction gate means (16T5) for combining the outputs of the direction flip-flop and the rate multiplier to couple the pulses from the rate multiplier to one of two outputs depending on the state of the direction flip-flop;
• a pulse direction control circuit comprising two feedback flip-flops having inputs from said first pulse feedback line, and two command flip-flops having inputs from said rate-direction gate means, a source of feedback clock pulses and command clock pulses which are at the same rate but occuring alternately, the feedback clock pulses being supplied to clock inputs of the two feedback flip-flops, and the command clock pulses being supplied to the two command flip-flops, the outputs of the flip-flops being coupled to monostable devices to provide fixed equal pulse lengths, the output of one feedback flip-flop and one command flip-flop via said monostable devices being combined in one gate, and the outputs of the other feedback flip-flop and the other command flip-flop via said monostable devices being combined in another gate;
• a second up-down counter having having up and down inputs from said gates of the pulse direction control circuit, a digital-to-analog converter having digital inputs from the second up-down counter and an analog output which is reference signal;
• an integrator having inputs from said first pulse feedback line for integrating the pulses to provide an analog feedback signal, servo means having inputs of said reference signal and said analog feedback signal which compares its input signals, the servo means having an output coupled to drive said motor and adjust its rate and direction to the commanded value.